retrofit anti-vibration devices: a study of their ... · isolating hand grips. retrofit devices...

Prepared by the Health and Safety Laboratory for the Health and Safety Executive 2013

Health and Safety Executive

Retrofit anti-vibration devices: a study of their effectiveness and influence on hand-arm vibration exposure

RR990Research Report

Emma Shanks, Graeme Hunwin and Mick Mole Health and Safety LaboratoryHarpur HillBuxtonDerbyshire SK17 9JN

This project set out to try to determine what benefits, if any, could be gained in terms of reducing vibration exposure by retrofitting different types of anti-vibration device to different hand-held machines. Four types of device were selected for laboratory investigation: anti-vibration handles, spring balances/tensioners, a vibration reducing flange and chisel sleeves.

The results from all the different devices used in this project, with the exception of the chisel sleeves, demonstrated that an end user cannot be confident that their chosen retrofit device will in fact reduce vibration to the user and in turn reduce exposure. Indeed, the exact opposite may be true. Advice to end users should emphasise the need to speak to their suppliers to determine what, if any, retrofit devices are suitable for their particular equipment.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.


HSE Books


© Crown copyright 2013

First published 2013

You may reuse this information (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit www.nationalarchives.gov.uk/doc/open-government-licence/, write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email [email protected].

Some images and illustrations may not be owned by the Crown so cannot be reproduced without permission of the copyright owner. Enquiries should be sent to [email protected].

Acknowledgements

The lead author would like to thank the tool operators for their unending patience and tool manufacturers for the loan and use of their machinery.

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EXECUTIVE SUMMARY

The Supply of Machinery (Safety) Regulations 2008 (SMSR) [i] require manufacturers of equipment to ensure that their products, as supplied by them, conform to the Essential Health and Safety Requirements (EHSR) of the SMSR. For vibration this specifically means that:

“machinery must be designed and constructed in such a way that risks resulting from vibrations produced by the machinery are reduced to the lowest level, taking account of technical progress and the availability of means of reducing vibration, in particular at source. The level of vibration emission may be assessed with reference to comparative emission data for similar machinery.” (SMRS Schedule 2, Part 1, Annex I, Paragraph 1.5.9).

If an end user modifies the machine, it is they, and not the manufacturer, who then bears overall responsibility for the EHSR for that piece of machinery. The use of retrofitted vibration reducing devices could be seen as a modification in this respect. It is therefore essential that the end user can be sure that use of a retrofit device for the purpose of reducing vibration will be beneficial. Modern power tools are frequently advertised as “anti-vibration” or “vibration reduced”. The mechanisms and devices used to minimise the vibration transmitted to the operator vary from more sophisticated internal mechanisms to vibration isolation mountings on engines or isolating hand grips. Retrofit devices intended to reduce the vibration transmitted to the operator are also available, however, there is some doubt as to the suitability and performance of such devices. The Health & Safety Executive (HSE) therefore asked the Health & Safety Laboratory (HSL) to investigate these devices so that HSE would be better able to advise duty holders of the benefits, or otherwise, of their use.

A range of different devices intended to reduce vibration and/or improve the ergonomics of power tool use were tested under laboratory conditions. The overriding conclusion drawn from the results of this testing is that, with the exception of the use of chisel sleeves, it is not possible to buy a retrofitting device which can be fitted to a power tool and that will then in all cases reduce the vibration transmitted to the operator.

The data gathered during this project indicated that it is not possible to predict if fitting an angle grinder with a retrofit anti-vibration support handle will result in the anticipated lower vibration levels at both hand positions. Lower vibration levels may be experienced at the hand position where the handle has been replaced, but this may unpredictably alter the dynamics of the machine, potentially increasing the vibration levels at the second hand position. Vibration levels depend on the individual handle and machine design combination. It also does not follow that the more expensive retrofit device will always give the best result, for example, a 50p handle was found to reduce the vibration levels far more than the £11.50 handle on one of the machines. Careful consideration should be given to retrofitting anti-vibration handles and advice sought from the original machine manufacturers.

Examples of successful use of spring balances, or tensioners, are known, for example suspended nut runners on engine assembly lines and suspended sand rammers at stone making premises. These examples are for impactive machines. This project looked at the use of the spring balance with heavy duty angle grinders. The use of a spring balance could not be shown to be of any great vibration reducing benefit, although small, measurable reductions in vibration levels were observed when such devices were put into use. Anecdotal evidence from the machine operators indicated that the machines were much more comfortable to use when

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attached to a spring balance because the operator no longer needed to support the full mass of the machine while controlling the head of the grinder.

A vibration reducing flange (VRF) used to clamp grinding or polishing disks produced mixed results. In some cases it was found to reduce vibration levels by between 1% and 12% on either the support or the throttle handles; but it also caused increases of between 3% and 94% in others. The manufacturer of the VRF claimed to reduce the vibration load on the handle by up to 30%.

A vibration reducing chisel sleeve successfully reduced vibration when compared with the plain chisel on both limestone and granite for one stone hammer by up to 64%. For another stone hammer the reduction was 49% on the limestone. The use of a chisel sleeve also reduced vibration on the throttle handle of a stone hammer by 3% to 5% for a larger machine and by between 45% and 70% for a smaller machine. A second vibration reducing sleeve design successfully reduced vibration when compared with a plain chisel on limestone for a stone hammer by up to 23% when measuring the total value, or by 40% in the dominant axis. End users of the second design also benefited from improved thermal and ergonomic comfort. The use of vibration reducing chisel sleeves may require operators to modify their working techniques in some circumstances.

The results from all the different retrofit anti-vibration devices used in this project demonstrate that, with the exception of chisel sleeves, an end user cannot be confident that their chosen retrofit device will in fact reduce vibration to the user and in turn reduce exposure. Indeed, the exact opposite may be true. Advice to end users should emphasise the need to speak to their suppliers to determine what, if any, retrofit devices are suitable for their equipment.

[i] The Supply of Machinery (Safety) Regulations 2008. SI 2008/1597. London: TSO; 2008.

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CONTENTS PAGE

1. INTRODUCTION ...................................................................... 1

2. METHODOLOGY ..................................................................... 2 2.1 Vibration reducing devices 2 2.2 Measurement, equipment and machine operators 3 2.3 Anti-vibration handles 4 2.4 Spring balances / tensioners 6 2.5 Vibration reducing flange (VRF) 8 2.6 Chisel sleeves 9

3. RESULTS ............................................................................... 11 3.1 Anti-vibration handles 11 3.2 Spring balances / tensionsers 11 3.3 Vibration reducing flange (VRF) 11 3.4 Chisel sleeves 11

4. DISCUSSION AND ANALYSIS ............................................. 18 4.1 Anti-vibration handles 18 4.2 Spring balances / tensioners 22 4.3 Vibration reducing flange (VRF) 23 4.4 Chisel sleeves 25

5. CONCLUSIONS ..................................................................... 27 5.1 Anti-vibration handles 27 5.2 Spring balances / tensioners 27 5.3 Vibration reducing flange (VRF) 27 5.4 Chisel sleeves 27 5.5 General comments 28

6. REFERENCES ....................................................................... 29

7. LIST OF APPENDICES ......................................................... 30

Appendix A Measurement equipment …………………………………………… 31 Appendix B Anti-vibration support handles – full measurement results……… 36 Appendix C Spring balances / tensioners – full measurement results…….….. 47 Appendix D Vibration reducing flange – full measurement results………...….. 49 Appendix E Chisel sleeve – full measurement results……………………..…… 50

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1. INTRODUCTION

Modern power tools are frequently advertised as “anti-vibration” or “vibration reduced”. The mechanisms and devices used to minimise the vibration transmitted to the operator vary from more sophisticated internal mechanisms to anti-vibration mountings on engines or anti-vibration handles. Many tool manufacturers and suppliers advertise anti-vibration handles available as retrofit devices. The small amount of information collected previously by the Health & Safety Laboratory (HSL) has been for individual combinations of power tool and vibration isolating device. Previous measurements by HSL on a new angle grinder [1] showed that a retrofit device from the same manufacturer caused an increase in the frequency weighted vibration of ~35%. The same research also showed that even when an anti-vibration handle is intended for use with a particular machine, it could cause an increase in the vibration exposure of the operator by adversely affecting vibration at the second hand position. Further investigation of the properties and performance of retrofit anti-vibration handles was needed to clarify how effective or otherwise they might be and to investigate what influences effectiveness. The purpose of the work reported here was to look for more general trends in performance for particular types of device with particular types of power tool, so that the Health & Safety Executive (HSE) would be better placed to give advice and guidance to duty holders.

The aims of the research were:

1. To investigate the effect on vibration magnitudes likely to arise with a variety of retrofit anti-vibration devices;

2. To identify any common trends in performance (by class of power tool type, etc.) for different devices (handles, resilient sleeves, etc.) and;

3. To publicise the results of the research for all stakeholders and, if appropriate, include a summary in a format which might be adaptable as, for example, a case study that can be made be accessible to supervisors and users.

The objectives to achieve these aims were:

1. To identify what retrofit devices are available for different types of commonly used power tool;

2. To assess the performance of the different types of device on a range of tools to get some indication of the success rate of such devices;

3. To identify what properties influence the effectiveness of particular devices; 4. To publish the results of the research to raise awareness of the issues and provide HSE

with information so that they can better advise stakeholders on the question of using retrofit devices

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2. METHODOLOGY

2.1 VIBRATION REDUCING DEVICES

During background for this project, a number of vibration reducing, or vibration eliminating, products were considered. These are listed in Table 1.

Table 1. A selection of vibration reducing or eliminating products

Vibration reducing device Application Anti-vibration side handle Use on an angle grinder instead of the ‘standard’ side handle. Grinding wheel balancers Pedestal grinders.

Rear handle bushing Separates rear (trigger) handle of an angle grinder from the rest of the machine body.

Comfort grip A rubber and wood device designed to fit on a pistol grip air powered stone chisel. Can be single handed or double handed.

Elephant trunk suspension system

Horticultural equipment. The device takes the mass of the machine allowing for easier use and lighter grip.

Saw clamping system Eliminates the need for the operator to hold a metal cutting reciprocating saw by clamping the saw to the work piece and using gravity to allow the saw to make progress.

Drilling rigs

Reduces or eliminates the direct contact between the user and an electric impact drill by jig mounting the drill at the appropriate working height. This also has an ergonomic advantage of allowing the operator an improved working posture.

Tensioners / spring balances

Used with heavy tools such as nail guns, sand rammers and angle grinders. Bears the load of the tool allowing the user a lighter grip. Also allows mass to be added to a system to damp vibration.

Consumables Saw blades, grinding discs, ceramic abrasives, steels for road breakers or chisels – some specifically claim to reduce vibration.

Sleeves / resilient coatings Can be applied to part of a machine that is gripped by the user.

After discussion with HSE, four types of retrofit anti-vibration device were identified for assessment within the scope of this project:

1. Anti-vibration support handles;

2. Spring balances or tensioners;

3. A vibration reducing flange (VRF); and

4. Two chisel sleeves.

The first three of the four devices were compatible with angle grinders. The chisel sleeves were designed for use with tools such as stone hammers or chipping hammers. For measurements using the first three devices, eight electrically powered angle grinders were used. All angle grinders were well maintained with the exception of machine E. The machines are detailed in

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Table 2. For measurements using the chisel sleeves, two new pneumatic stone hammers were used (Table 3).

Table 2. Angle grinder machine details

Machine ID Disc diameter (mm) Mass (kg) Notes A 125 2.4 Built in auto-balance mechanism. B 230 7.0 New condition. C 230 6.5 Decoupled throttle handle. D 180 6.2 New condition. E 125 2.0 Used condition. F 230 6.9 Decoupled throttle handle. G 125 2.4 New condition.

H 125 2.5 Same machine as G but with additional auto-balance mechanism.

Table 3. Stone hammer machine details

Machine ID A B Grip style closed bow pistol

No. of impacts (min-1) 3000 3900 Air pressure (bar) 3-6 6

Mass (kg) 2 0.65

Illustration (not to scale)

2.2 MEASUREMENT, EQUIPMENT AND MACHINE OPERATORS

Triaxial hand-arm vibration measurements were made at the hand locations on each machine using three single axis piezoelectric accelerometers bolted to a mounting block. Mechanical filters were used where necessary. The blocks were fixed to the machine handles using either a plastic cable tie and tensioning gun system, cyano-acrylate glue, or in the case of the resilient chisel sleeve, using a hand-held adaptor. Data from the accelerometers were collected and processed using a real-time frequency analysis system giving frequency-weighted vibration total values for each measurement location over the ISO 5349-1: 2001 [2] hand-arm vibration frequency range, unless stated otherwise. Five consecutive measurements were made for each of three operators on each machine. The overall arithmetic mean, a, was obtained from the mean vibration total values for the three tool operators. A value for the individual tool deviation, K, was also calculated according to the provisions of BS EN 12096:1997 Annex B.2 [3], where a single machine is used to declare the vibration emission. Detailed equipment information can be found in Appendix A.

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2.3 ANTI-VIBRATION HANDLES

Anti-vibration handles are readily available from machine and tool catalogues, both trade specific and in the DIY market. Anecdotal evidence suggests that anti-vibration handles are seen by some duty holders as an ‘easy fix’ for high vibration machines as well as an inexpensive and easy way to reduce machine users’ vibration exposure.

Eight anti-vibration handles were selected for use in the project. The handles were sourced from freely available machine and tool catalogues as well as directly requested from specific manufacturers. The handles ranged in price from £0.50 per unit to £23.50 per unit. The majority of handles were priced around £10.00. Table 4 illustrates the different handle designs.

Eight machines were selected for use with the eight handles. Due to the different types of fitting and handle thread sizes not all handles fitted all machines. Table 5 shows which handle/machine combinations were used. The selected handles were in addition to those originally supplied with each machine.

Vibration measurements were made for each handle/machine combination shown in Table 5. The counter balance pulley system measurement set up used to carry out vibration emission measurements according to BS EN 60745-2-3 [4] (Figure 1) was used as a controlled measurement environment to compare the performance of the various handles, using three machine operators and five measurements per operator. The emission measurement set up does not require the machine to be grinding but instead makes use of an artificial wheel, made of aluminium, with a specific unbalance. The artificial wheel is fitted to the grinder in the normal manner, and the grinder made to free-run at maximum speed while being held by an operator who applies a known feed force (the counterbalance mass of the machine being used). For each operator, after each measurement, the artificial wheel is loosened and repositioned at 72 degrees from its previous position on the machine shaft. For ease of reference and repeatability each artificial wheel used during this project was marked up at sequentially numbered 72 degree intervals. The emission measurement set up and procedure is designed to give repeatable and reproducible data.

Table 4. Illustration of different retrofit anti-vibration handle designs (not to scale)

Handle ID Unit price Handle illustration

A £0.50 (£10.00 for 20 units)

B £15.00

C £11.45

D £10.50

G £13.65

I £8.35

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F £23.50

H £11.50

Handles F and H had what appeared to be a removable mass at the outer end of the handle. The mass was a piece of metal that screwed into the end of the handle, with a mass of 46 grams. It was not clear why the mass was removable. Because it was removable, it was decided to use the handle both with and without the mass in position.

Table 5. Handle/machine combinations used

Machine A B C D E F G H Handle Thread M8 M14 M14 M14 M10 M14 M8 M8

own -

A M8

B M10 C M14 D M10 F M14 *

F (nm)† M14 *

G M14 H M8

H (nm) † M8

I M8 * * * The anti-vibration handle was the same as that originally supplied with the machine. † Handles F and H were fitted with a removable mass. ‘nm’ indicates the handle was used with ‘no mass’.

Figure 1. Working position of machine operator and application of force (taken from BS EN 60745-2-3)

Vibration measurements were made at both hand positions (support and throttle handles). On the support handle, successive measurements were made at three separate locations: closest to the machine, known as the ‘inner’ location; at the centre of the handle underneath the gripping zone, known as the ‘middle’ location; and at the handle’s furthest point from the machine,

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known as the ‘outer’ location. The measurement locations are illustrated in Figure 2. Data from the three separate support handle locations indicate if the vibration characteristics change along the length of the anti-vibration handle.

Figure 2. Measurement locations for anti-vibration handles on angle grinders

(taken from BS EN 60745-2-3; modified by HSL)

2.4 SPRING BALANCES / TENSIONERS

Spring balances, or tensioners, are designed to take the load of heavier machines, making them easier to handle by the machine operators. Suspending the machine load also allows for mass to be added to a high vibration machine, thereby lowering its vibration emission without ergonomically overloading the machine operator (Vibration Solutions, case study 38).

Two spring balances were selected for use in this project, to be used in conjunction with the three heaviest angle grinders. Both spring balances were freely available on the open market. Both spring balances cost in the region of £200 per unit. Table 6 gives an outline technical specification for each spring balance. The term ‘stroke’ relates to the length of cable contained within the spring balance.

Table 6. Technical specifications for spring balances used

Spring Balance Net weight Capacity Stroke Illustration

A 2.2 kg 6-8 kg 2000 mm

B 4.9 kg 4-7 kg 2000 mm

Vibration measurements were made for each spring balance/machine combination for both spring balances and the three machines. The measurement set up from Figure 1, including out of balance aluminium wheels and five wheel positions (as defined in the vibration emission test for electrical grinders BS EN 60745-2-3), was used as a controlled measurement environment to compare the influence of the spring balances on the vibration data. Vibration measurements were made at both hand positions (support and throttle handles). On the support handle, successive measurements were made at the ‘inner’, ‘middle’ and ‘outer’ locations (Figure 2).

Two separate spring tensions for each spring balance/machine combination were used. The first tension setting, adjusted separately for each machine mass and known as ‘full spring’ or ‘f’,

‘inner’

‘outer’

‘middle’

throttle ‘inner’ ‘outer’

‘middle’

throttle

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allowed the machine to fully retract up and away from the operator. This meant that the spring balance fully supported the mass of the machine but required some effort by the operator on both grip and push forces to keep the machine in an operating position. The second tension setting, known as ‘half spring’ or ‘z’, allowed the machine to be supported at the operating position in a horizontal plane by the operator very lightly supporting the throttle handle. This meant that the operator applied only a minimal grip and push force in order to operate the machine correctly, but the tension was not enough to fully support the mass of the machine when the operator was absent.

For all the machines, the support handle could be mounted on either side. To suspend the machines from the spring balances, an extra bolt was inserted into the empty support handle hole. A short sling of cord was fixed from the extra bolt to the inner part of the support handle. The spring balance cord was fixed to the sling (Figure 3a). One machine, machine F, could also be suspended from a central point above the machine head (Figure 3b). Vibration data were gathered for a ‘full spring’ set up with machine F suspended in this manner from spring balance B. A full measurement matrix is shown in Table 7.

Figure 3a. Machine suspended from two points

Figure 3b. Machine suspended from single point

Table 7. Spring balance/machine combinations used

Spring balance

Spring balance tension setting

No. of support points

Machine

B C F

A Full 2 Half 2

B Full 2 Half 2 Full 1

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2.5 VIBRATION REDUCING FLANGE (VRF)

The vibration reducing flange (VRF) is a combination of the wheel washer and the wheel nut that hold the grinding wheel or cutting disc in position on the spindle of the grinder (Figure 4). The wheel washer and wheel nut supplied with a grinder is made from solid metal. The vibration reducing wheel washer and wheel nut have a resilient material of approximately 1mm thickness covering the surface that comes into contact with the grinding wheel or cutting disc (resilient coating is orange, shown in upper images in Figure 4).

The vibration reducing wheel nut and wheel washer combination was suitable for use on one of the available grinding machines (Machine C). Vibration measurements were made for the machine using its supplied wheel washer and wheel nut and for the machine using the vibration reducing wheel washer and wheel nut. The measurement set up from Figure 1, including the BS EN 60745-2-3 standard tests using an out of balance aluminium wheel and five wheel positions, was used as a controlled measurement environment for comparison of vibration data. Vibration measurements were made at both hand positions (support and throttle handles). On the support handle, successive measurements were made at the ‘inner’, ‘middle’ and ‘outer’ locations (Figure 2).

Figure 4. Vibration reducing wheel washer (left) and wheel nut (right) and its location

within the machine (centre)

A further series of ‘simulated real’ vibration measurements were also made, grinding a piece of 8mm thick mild steel clamped securely to a work bench, using an appropriate grinding disc. Vibration measurements were made for both the supplied and vibration reduced wheel nut and wheel washer, at the ‘inner’, ‘middle’ and ‘outer’ support handle locations (Figure 2). The first set of ‘simulated real’ measurements was made with the grinding disc in a random position (compared to positions 1 to 5 for a standard emission measurement). Care was taken to ensure that the disc position was not changed when the wheel nut and wheel washer were swapped over to avoid changing the relative out-of-balance of the grinder and the grinding disk. The grinding disc was then marked up with positions 1 to 5 and further ‘simulated real’ measurements were made at positions 2 and 5, for the ‘inner’ and ‘outer’ support handle locations only. This was to try to establish how much variability in results was due to disc position. A full measurement matrix is shown in Table 8.

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Table 8. VRF measurements

Machine C Wheel position

Own wheel nut / washer Vibration reducing wheel nut / washer ‘inner’ ‘middle’ ‘outer’ ‘inner’ ‘middle’ ‘outer’

Set up from BS EN

60745-2-3

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Results taken from data obtained at Table 2.

2 3 4 5

Simulated real

Random 2 5

2.6 CHISEL SLEEVES

A chisel sleeve is a device designed to improve the ergonomic comfort of the chisel whilst also reducing the operator’s vibration exposure. Chisel sleeves were found in two forms:

1. A bespoke chisel that fits in to a vibration-isolating holder, which in turn fits in to any standard powered stone hammer, identified as Sleeve 1 (Figure 5a); and

2. A thick resilient-material sleeve for retrofitting to a plain chisel, identified as Sleeve 2 (Figure 5b).

Both types of device were used in this project. The performance of each device was compared with that of a plain chisel (Figure 5c). The manufacturer of Sleeve 1 claimed a vibration reduction of approximately 65%, as well as improved working comfort and “reduced heat and coldness transfer”. The manufacturer of Sleeve 2 claimed a 50% vibration reduction.

All chisel sleeve measurements were intended to investigate if the chisel sleeves reduced vibration at the chisel hand location when compared with a plain chisel. During the course of an earlier investigation, looking at the performance of hand-held mounting devices, it was noticed that Sleeve1 had the effect of reducing the vibration magnitude measured on the stone hammer itself as well as the chisel. So, during the Sleeve 1 measurements, data were also collected for the vibration magnitudes on the body of the stone hammer when using a plain chisel and when using Sleeve 1. This was not possible to replicate during the Sleeve 2 measurements as all available data channels were simultaneously in use on the chisel (plain chisel, cable tie mounting on Sleeve 2 and hand adaptor mounting on Sleeve 2 all measured simultaneously).

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Figure 5a. Sleeve 1 Figure 5b. Sleeve 2 Figure 5c. Plain chisel

For Sleeve 1, a series of vibration measurements were made on the plain chisel without a sleeve and then on Sleeve 1. For Sleeve 2, simultaneous measurements were made on the plain chisel and on the chisel sleeve, using two different mounting techniques: a formed metal hand adaptor that the operator gripped onto the sleeve (two different types) and the standard HSL tensioning cable tie and mounting block. The use of the different mounting techniques was to allow comparison with previous measurements on Sleeve 2, cited in HSE publication HS(G)170 Vibration Solutions, and to investigate the influence of the mounting technique on the resultant vibration magnitudes. Two pneumatic stone hammers (A and B, Table 3), were used with Sleeve 1 and one stone hammer (B) was used with Sleeve 2. Two different types of stone were used: granite and limestone (Figures 6a and 6b). The measurement procedure was carried out in accordance with BS EN ISO 28927-11:2011 [6], the emission standard for stone hammers which calls for actual chiselling of stone. A measurement matrix for the chisel sleeves is shown in Table 9.

Figure 6a. Granite block

Figure 6b. Limestone block

Table 9. Chisel sleeve measurements

Stone Hammer Stone Plain chisel Sleeve 1 Sleeve 2

A Granite Time

restriction prevented data

gathering.

Limestone

B Granite

Limestone * *Use of different mounting techniques

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3. RESULTS

For all results, the frequency weighted vibration total values for both the hand positions are shown. For anti-vibration handles, spring balances and the VRF, the support handle data shows the results for the ‘inner’, ‘middle’ and ‘outer’ locations. The throttle handle data is also presented for the three separate support handle measurement locations. The throttle handle transducers were not moved between measurements. The repeated throttle handle data gives an indication of repeatability of the measurements when the support handle transducers were moved between the ‘inner’, ‘middle’ and ‘outer’ locations. For the chisel sleeve the data is presented in terms of the tool handle and the chisel grip. The ‘inner’, ‘middle’ and ‘outer’ support and throttle handle locations do not apply to the chisel sleeve results.


Figures 7a to 7h illustrate the results for each handle/machine combination used. Full results can be found in Appendix B.

3.2 SPRING BALANCES / TENSIONSERS

Figure 8 shows the results for each spring balance/machine combination for both the full spring (f) and half spring (z) conditions. All data shown in Figure 8 is for the machines supported either side of the machine head. Figure 9 shows the comparison for spring balance B with machine F where the machine was supported from a single point above the machine head. Full results can be found in Appendix C.


Figure 10 shows the results for the vibration reducing flange (VRF) when used in the Figure 1 set up. Figure 11 shows the results for the simulated real vibration measurements when grinding 8mm thick mild steel. Full results can be found in Appendix D.

3.4 CHISEL SLEEVES

Figure 12a shows the results for Sleeve 1 with two different stone hammers on two different types of stone. The result for stone hammer A on granite using a plain chisel is absent due to DC shift. Figures 12b and 12c show the results for Sleeve 2 on a plain chisel used with stone hammer B in limestone, single axis and triaxial results and comparisons respectively. Full results can be found in Appendix E.

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Figure 7a. Machine A with different support handles Figure 7b. Machine B with different support handles

Figure 7c. Machine C with different support handles Figure 7d. Machine D with different support handles

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Figure 7e. Machine E with different support handles Figure 7f. Machine F with different support handles

Figure 7g. Machine G with different support handles Figure 7h. Machine H with different support handles

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Figure 8. Results for spring balance/machine combinations (supported at two points)

Figure 9. Results for spring balance/machine combination (supported at one point)

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Figure 10. VRF (used in EN 60745 set up)

Figure 11. VRF; simulated real data (grinding 8mm thick mild steel)

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own flange vibration reduced flange

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

support EN 60745-2-3 (average of five wheel positions) support sim. real (random wheel position)

throttle EN 60745-2-3 (average of five wheel positions) throttle sim. real (random wheel position)

0

1

2

3

4

5

6

7

8

9

10

inner out inner out

ow n vrf

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

support sim. real (random w heel position) throttle sim. real (random w heel position)

support sim. real (w heel position 2) throttle sim. real (w heel position 2)

support sim. real (w heel position 5) throttle sim. real (w heel position 5)

16

Figure 12a. Two stone hammers with and without Sleeve 1; limestone & granite

(Note: no data for Stone hammer A, granite, plain chisel due to signal distortion)

0

5

10

15

20

25

30

35

Plain chisel Sleeve 1 Plain chisel Sleeve 1 Plain chisel Sleeve 1 Plain chisel Sleeve 1

Limestone Granite Limestone Granite

Stone hammer A Stone hammer B

Freq

uency weighted acceleratio

n (m

/s2 )

Tool handle Chisel

17

Figure 12b. Sleeve 2, stone hammer A, limestone, single axis (y-axis) (Note: VS =

“Vibration Solutions” – data taken from the case study in this HSE publication for comparison)

Figure 12c. Sleeve 2, stone hammer A, limestone, triaxial

26.0 13.0 7.5 6.5 4.5 8.2 5.20

5

10

15

20

25

30

Freq


n, 32H

z to 1kH

z (m/s

2 )

VS case study 15 'before'

VS case study 15 'after'

HSL plain chisel (1)

HSL cable tie (1)

HSL adaptor (1)


HSL adaptor (2)

8.6 8.0 6.9 8.7 6.70

2

4

6

8

10

12

Freq


n, 32H

z to 1kH

z (m/s

2 )


HSL cable tie (1)

HSL adaptor (1)


HSL adaptor (2)

18

4. DISCUSSION AND ANALYSIS

For anti-vibration handles, spring balances and the VRF, the support handle data were measured for the ‘inner’, ‘middle’ and ‘outer’ locations. The throttle handle data were also measured for the three separate support handle measurement locations. The throttle handle transducers were not moved. The repeated throttle handle data give an indication of repeatability of the measurements when the support handle transducers were moved between the ‘inner’, ‘middle’ and ‘outer’ locations. For the chisel sleeve the data were measured for the tool handle and the chisel grip. The ‘inner’, ‘middle’ and ‘outer’ support and throttle handle locations do not apply to the chisel sleeve results.


All eight anti-vibration handles were sourced from freely available machine and tool catalogues as well as directly requested from specific manufacturers. Table 2 illustrates the different handle designs. All eight handles were marketed as having anti-vibration properties. The design illustrations show that all the handles, bar one, have some sort of vibration isolation system at the inner end of the handle. The one without this design is handle D. When handle D was first received it was noted that this did not look like an anti-vibration handle. Measurement results showed that it did not behave as an anti-vibration handle. It is of concern that an accessory may be marketed as anti-vibration when it does not possess any properties that distinguish it from a standard handle.

Taking machine E as an example; machine E (2.0kg and 125mm disc diameter) was supplied with a small, hollow, plastic support handle. This is typical of the support handles supplied with this size of machine. The vibration data for machine E with its own support handle were, as expected; lower at the ‘inner’ position and higher at the ‘outer’ position with a near linear relationship with position suggested by the value given at the middle position (see Figure 7e). This pattern changed for the different support handles that were used. Handle B reduced the vibration total values at the ‘middle’, 39%, and ‘outer’, 42%, locations, with an increase of 24% at the ‘inner’ location, when compared to the data to machine E with its originally supplied support handle. However, the use of handle B as a support handle had the effect of raising the vibration magnitude on the throttle handle compared to its own handle or Handle D, as can be seen in Figure 7e. The combination of machine E with handle B was the only machine/handle combination where the vibration magnitude on the throttle handle was increased by the introduction of an anti-vibration support handle.

Not all substituted anti-vibration support handles were successful in reducing the vibration measured on the support handle. Handle D, observed as not having any anti-vibration design features, behaved precisely like a small, hollow, plastic handle, similar to that supplied with machine E originally.

By looking at the individual transducer information it was possible to identify which axes had the most influence on the changes in the vibration total values for each handle. Figures 13a to 13c show machine E with the transducer mounting locations for the support and throttle handles. Figures 14a to 14c illustrate the changes in vibration magnitude on the different axes for the different handles for machine E. Full results, including highest axis and highest magnitude hand position, for each handle/machine combination are given in Appendix B.

19

Figure 13a. Machine E, ‘inner’ support (Ch1-3)

& throttle (Ch4-6)

Figure 13b. Machine E, ‘middle’ support (Ch1-3);

throttle unchanged

Figure 13c. Machine E, ‘outer’ support (Ch1-3);

throttle unchanged

From Figure 14a it can be seen that different handles have different influences on the separate axes and in this case at both hand positions. When using its own support handle, channel 3 (up/down motion) is the highest axis at the support handle and channel 5 (fore/aft motion) is the highest axis at the throttle handle; when using handle B, channel 2 (left/right motion) is the highest axis at the support handle and channel 4 (left/right motion) is the highest axis at the throttle handle; when using handle D, channel 1 (fore/aft motion) is the highest axis at the support handle and channel 5 (fore/aft motion) is the highest axis at the throttle handle.

At the support ‘inner’ location, for all handles used with machine E, there was no particular pattern relating to which was the highest axis of vibration. Neither, was there any particular pattern for the ‘middle’ and ‘outer’ support handle measurement locations for machine E (Figures 14b and 14c). Similarly, there was no discernible pattern for any of the 34 machine/handle combinations for which data were gathered. Some retrofit anti-vibration handles offered a reduction in the measured vibration, where others saw an increase in the measured vibration. It was also not always the same handle that offered the same vibration reduction or increase. The measured vibration levels were very much dependent on the handle/machine combination. The vibration reduction or increase did not appear to be price dependent either.

Ch1

Ch2 Ch3

Ch4

Ch5 Ch6

Ch1 Ch2

Ch3 Ch1

Ch2 Ch3

20

Figure 14a. Machine E, ‘inner’ support

handle location, all axes, all handles

Figure 14b. Machine E, ‘middle’ support handle location, all axes, all handles

Figure 14c. Machine E, ‘outer’ support

handle location, all axes, all handles

0

5

10

15

20

25

30

ch1 ch2 ch3 total ch4 ch5 ch6 total

support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n inner B inner D inner

0

5

10

15

20

25

30


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n middle B middle D middle

0

5

10

15

20

25

30


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n outer B outer D outer

21

Some manufacturers make handles for both small and large machines (handles B & C and handles G & I). It was noted during the project that the design was not consistent for individual manufacturers. Figure 15a shows handles B and C, from a single manufacturer. Handle B is designed for a smaller machine whilst handle C is for a larger machine. Similarly, Figure 15b shows handles I and G, again made by the same manufacturer, but not the same one as for handles B and C. Handle I is designed for a smaller machine; handle G is for a larger machine.

For handles I and G, the anti-vibration system design appears to be the same, but the rest of the handle design is not. Handle I is much smaller. It is also less robust, closely resembling a small, hollow plastic handle. The larger handle G has a form of comfort grip included, as well as being generally larger and better able to accommodate an adult hand. Ergonomic design recommendations (NIOSH 2004 [7], Chengalur SN et al 2004 [8], Dreyfuss 2002 [9]) are that cylindrical handles used in a power grip, where all the fingers wrap around the handle and the hand is used to apply a high force, should have a minimum length of 10cm, a recommended length of 13cm and a diameter of 4cm. Table 10 details the dimensions of handles I and G compared with the recommended dimensions.

Table 10. Handles dimensions compared to ergonomic recommendations

Handle Length (cm) Diameter (cm) I 9.5 3.5 (narrowing to 3.0) G 10.8 3.8 (narrowing to 3.4)

Ergonomic design 10 (minimum)

13 (recommended) 4.0

Figure 15a. Handles B & C Figure 15b. Handles I & G

The smaller handle I clearly falls short of the ergonomic design recommendations. Whilst G is larger, its grip diameter remains a little on the small side. This could mean that the machine operator is unable to maintain a suitable power grip on the machine.

B C I G

22

It was generally noted that the larger disc diameter machines were supplied with anti-vibration support handles. The need for retrofitting a support handle on these larger machines seems less likely. In two cases, machines C and F, the design of the whole machine meant that the throttle handle was also mechanically decoupled from the body of the machine. The smaller disc diameter machines were supplied with hollow plastic handles. These have a tendency to resonate and amplify machine vibration. It is with these smaller machines that retrofit anti-vibration support handles are more likely to be used.

It was also noted that it was not necessarily the most expensive retrofit anti-vibration support handle that gave the best result. For example, handle A (£0.50) on machine A reduced the vibration levels far more than handle H (£11.50) on machine A.


Spring balances, or tensioners, are designed to take the load of heavier machines, making them easier to handle by the machine operators and reducing the forces needed to operate them. Depending on how the spring tension is set, a spring balance could require the operator to use a larger push and grip force on the machine, effectively damping the machine and reducing the amount of vibration measured at the transducers, or using a much lighter grip and push force, which is beneficial from an ergonomic point of view, but which may actually result in higher vibration magnitudes on the handles of the machine. Forces were not measured as part of this project; the amount of push and grip force required was determined by the spring balance/machine combination (‘full spring’ or ‘half spring’).

Figure 16 shows the comparison of vibration magnitudes for the three machines, two spring balances and two load settings against the measured data for the set up in Figure 1. For machine B, a measurable reduction in vibration magnitude was observed on the throttle handle, with a smaller, but nonetheless measureable, increase at the support handle. This might indicate that the use of a spring balance allowed more energy to be transferred to the consumable, potentially increasing work rates and productivity. For machine C support handle levels increased at the ‘inner’ and ‘outer’ locations whilst decreasing at the ‘middle’ location; throttle handle levels remained static at the ‘inner’ and ‘middle’ locations whilst decreasing at the ‘outer’ location. For machine F, support handle levels increased at the ‘middle’ and ‘outer’ locations whilst decreasing at the ‘inner’ location; throttle handle levels decreased at all handle locations. For all machines, consideration of the K values puts any measured change well within the measurement uncertainty.

Although the set up shown in Figure 1 has been shown to produce vibration magnitudes that are representative of in-use vibration magnitudes, simulated real work here may have had added value and perhaps this is the next step in identifying how effective these types of devices could be (see also Vibration Solutions case study 38).

23

Figure 16. Comparison of measured vibration with and without spring balances


The vibration reducing flange (VRF) claims to reduce vibration on the rear handle of an angle grinder “by up to 30% and an average of about 12.4%” [10]. For the Figure 1 measurement set up, the HSL measured vibration using the VRF showed an 11% decrease at the ‘inner’ location, 6% decrease at the ‘middle’ location and a 3% increase at the ‘outer’ location on the support handle when compared to the vibration magnitudes measured using the machine’s own flange. At the throttle handle decreases of 5%, 1% and 5% were observed for the support ‘inner’, ‘middle’ and ‘outer’ locations respectively (Figure 17).

For the ‘simulated real’ measurements, the VRF showed a 4% and 12% decrease at the ‘inner’ and ‘middle’ locations respectively and a 94% increase at the ‘outer’ location on the support handle when compared to the vibration magnitudes measured using the machine’s own flange. At the throttle handle decreases of 6% and 8% were observed at the ‘inner’ and ‘middle’ support handle locations and an increase of 49% for the ‘outer’ location (Figure 18).

For both set ups, but more particularly for the ‘simulated real’ set up, a change on the throttle handle vibration magnitude was observed. This would not normally be expected but was thought to be attributable to an out of balance associated with the grinding disc. Further repeats of the simulated real support handle ‘inner’ and ‘outer’ locations were carried out using the grinding disc fixed on to the machine shaft in different positions. Comparisons of these repeat measurements with the original data (Figures 19 and 20) showed that the anomalies were caused by the grinding disc. The VRF appears to amplify an inherent out of balance in the grinding disc. This is possibly due to the VRF’s resilient layer, which, when working in shear, amplifies the out of balance.

0

1

2

3

4

5

6

7

8

9

10

inner middle outer inner middle outer inner middle outer

B C F

Freq


n (m

/s2 )

Support handle, Full spring,Balance A

Support handle, Full spring,Balance B

Support handle, Half spring,Balance A

Support handle, Half spring,Balance B

Support handle, No balance

Throttle handle, Full spring,Balance A

Throttle handle, Full spring,Balance B

Throttle handle, Half spring,Balance A

Throttle handle, Half spring,Balance B

Throttle handle, No balance

24

Figure 17. Machine C, comparison of

vibration total values with machine’s own

and vibration reduced flange: EN 60745-2-3 set up

Figure 18. Machine C, comparison of

vibration total values with machine’s own

and vibration reduced flange:

simulated real set up

Figure 19. Machine C, comparison of different grinding

disc positions; ‘inner’ support Figure 20. Machine C, comparison of different grinding

disc positions; ‘outer’ support location

0

2

4

6

8

10

12

total total

support throttle

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

C own flange inner

C own flange middle

C own flange outer

C vib. red. flange inner

C vib. red. flange middle

C vib. red. flange outer

0

2

4

6

8

10

12

total total

support throttle

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

C own flange inner

C own flange middle

C own flange outer

C vib. red. flange inner

C vib. red. flange middle

C vib. red. flange outer

0

1

2

3

4

5

6

7

8

9

10


support throttle

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

C inner sim real own C inner sim real vrf C inner sim real own2

C inner sim real vrf2 C inner sim real own5 C inner sim real vrf5

0

1

2

3

4

5

6

7

8

9

10


support throttle

Freq

uenc

y w

eigh

ted

acce

lera

tion

(m/s

2 )

C outer sim real own C outer sim real vrf C outer sim real own2

C outer sim real vrf2 C outer sim real own5 C outer sim real vrf5

25

4.4 CHISEL SLEEVES

All chisel sleeve measurements were intended to investigate if the chisel sleeves reduced vibration at the chisel hand location when compared with a plain chisel. During the course of an earlier investigation, looking at the performance of hand-held mounting devices, it was noticed that Sleeve1 had the effect of reducing the vibration magnitude measured on the stone hammer itself as well as the chisel. So, during the Sleeve 1 measurements, data were also collected for the vibration magnitudes on the body of the stone hammer when using a plain chisel and when using Sleeve 1. This was not possible to replicate during the Sleeve 2 measurements as all available data channels were simultaneously in use on the chisel (plain chisel, cable tie mounting on Sleeve 2 and hand adaptor mounting on Sleeve 2 all measured simultaneously).

Results showed that Sleeve 1 was very effective at reducing the measured vibration when compared with a plain chisel on the two different types of stone. The results also showed that the vibration was reduced on the stone hammer itself by up to 70% for stone hammer B as a consequence of using it in combination with the vibration reducing sleeve. This reduction is an unexpected but advantageous benefit in terms of protecting the operator against vibration exposure. However, only a slight reduction in vibration magnitude was observed on the handle of stone hammer A, a bigger and more powerful machine than stone hammer B. Table 11 shows the percentage reductions for each stone hammer on each type of stone.

Table 11. Percentage reduction in vibration for Sleeve 1

Stone hammer Medium Vibration reduction

Tool with plain chisel to tool with sleeve 1 Plain chisel to Sleeve 1

A Limestone 5% 49%

Granite 3% DC shift*

B Limestone 70% 64%

Granite 45% 59% *All attempts at reducing signal distortion through mechanical filtering systems were not successful in overcoming the high-level impactive vibration magnitudes produced when using a plain chisel with stone hammer A on granite.

The comparison between the two types of stone using Sleeve 1 showed that the vibration magnitudes were higher on the granite than on the limestone. This is believed to be because the granite is a much harder stone than the limestone, and consequently the amount of vibration transmitted back to the chisel due to the shocks when the chisel impacts on the stone are higher for the granite. Both materials are within the apparent density range specified in the current standard test for stone hammers, BS EN ISO 28927:11 2011. The results from the measurements on the chisel sleeve and the two types of stone have important implications for the specification of test material in this test code, since only the apparent density is currently specified in the standard. Also, there is considerable scope for differences in declared emission values, depending on the type of chisel used for the measurement.

A German study (Kaulbars 1996 [11]) has shown that when using a traditional powered stone hammer and plain chisel, skilled stonemasons alter their grip on the chisel to modify the action of the chisel. A loose grip on the chisel allows it to vibrate, reducing the power into the work piece and allowing the stonemason more control over the work. This technique is not possible with vibration reduction sleeves such as Sleeve1. So when using sleeve type devices with pneumatic tools, a more sophisticated tool is required, for example with an in-built or in-line regulator to adjust the air pressure to the tool so that its action can be effectively controlled.

26

This solution is often more expensive than the traditional hammer and plain chisel and may be one reason why plain chisels are preferred.

For the analysis of the Sleeve 2 data, a reduced frequency range of 32Hz to 1kHz was used. This was to allow direct comparison of results between Vibration Solutions case study 15 and the HSL measurements. The case study data, compiled circa 1984, used single axis (y, dominant axis) data with results in the 32Hz to 1kHz frequency range. Results for Sleeve 2 showed a reduction in vibration magnitudes when compared to a plain chisel, but the margin of reduction was dependent on the mounting technique of the transducers onto Sleeve 2. The margin of reduction also depended on whether single axis or triaxial data were used. To facilitate a comparison with the Vibration Solutions case study 15 single axis data were used.

Two different hand adaptors were used with Sleeve 2 to investigate the influence of the type of adaptor on the measured vibration magnitudes. The two types used are shown in Figures 21 and 22. Both figures show the simultaneous measurement locations used for the two adaptors (plain chisel and on Sleeve 2). Hand adaptor 1 was a 0.5mm thick steel sheet formed to wrap around Sleeve 2, allowing a large surface area contact. Hand adaptor 2 was a narrow section of formed aluminium. On both adaptors, the transducer block was fixed using cyano-acrylate glue. Table 12 shows the percentage reduction for each available comparison for Sleeve 2 against the plain chisel measurement.

Figure 21. Sleeve 2 with hand adaptor 1 Figure 22. Sleeve 2 with hand adaptor 2

Table 12. Percentage reduction in vibration for Sleeve 2

Source data Single axis comparison Triaxial comparison Vibration Solutions case study 50% Not available

HSL cable tie system 14% 7% HSL adaptor 1 40% 21% HSL adaptor 2 36% 23%

The results for the two different hand adaptors are very similar for both the single axis and triaxial data comparison. This suggests that the hand adaptor design was not as influential on the measured vibration magnitudes compared to mounting with the cable tie system. The latter gave higher vibration magnitudes than the hand adaptors. This was thought to be due to the cable tie compacting the sleeve, providing a more rigid fixing than with the hand adaptors.

The HSL data indicate that a vibration magnitude reduction of at least 7%, and up to 40%, can be achieved using Sleeve 2 on a plain chisel when used with a small pneumatic stone hammer, chiselling limestone. The Vibration Solutions case study was for the chiselling of defects on steel castings. End users of such a device also benefit from improved thermal and ergonomic comfort.

27

5. CONCLUSIONS


The data gathered during this project indicates that it is not possible to predict if fitting a machine with a retrofit anti-vibration support handle will result in the anticipated lower vibration levels at both hand positions. Vibration levels depend on the individual handle and machine design combination.

For the larger disc diameter angle grinders, the need for retrofit support handles seems less likely as the vibration transmission paths appear to have been designed out at source. The support handle, and in some cases the throttle handle, have integral anti-vibration design; for the throttle handle this meant it was mechanically decoupled from the body of the machine.

It is far more likely that retrofit support handles will be used for smaller disc diameter machines. This type of machine is typically supplied with a small, hollow, plastic handle that tends to resonate and amplify the vibration from the body of the machine. Should a duty holder wish to use a retrofit anti-vibration support handle, they should be careful in their choice, as not every handle will reduce the vibration; some may actually increase the vibration, for example handle C on machine B. It also does not follow that the more expensive retrofit device will always give the best result, for example handle A (£0.50) on machine A reduced the vibration levels far more than handle H (£11.50) on machine A. Careful consideration should be given to retrofitting anti-vibration handles and advice sought from the original machine manufacturers.


The use of a spring balance may have the potential to cause an increase in measured vibration magnitudes, due to the reduced forces needed to operate the machine, which result in less damping of the handles by the operator’s hand and arm, but this effect was not measured. The use of a spring balance could not be shown to greatly affect the measured vibration magnitudes when used with angle grinders in a vibration emission measurement situation, although small, measurable reductions in vibration levels were observed.

Anecdotal evidence from the machine operators indicated that machines were much more comfortable to use when attached to the spring balances because the operator no longer needed to support the full mass of the machine as well as trying to work a piece of material. Examples of successful spring balance use are known, for example suspended nut runners on engine assembly lines and suspended sand rammers at stone making premises. These examples are for more impactive type machines rather than the smoother running angle grinder. Spring balances should not be ruled out as an option for improving the ergonomics of the work situation.


The vibration reducing flange (VRF) claims to reduce the vibration load on the handle by up to 30%. The HSL measured vibration levels recorded reductions of between 1% and 12% on either the support or the throttle handles, but also recorded increases of between 3% and 94%. The results do not inspire confidence in this type of retrofit anti-vibration device and caution should be exercised if considering such device.

5.4 CHISEL SLEEVES

Sleeve 1 successfully reduced vibration when compared with the plain chisel on both limestone and granite for stone hammer B by up to 64%. For stone hammer A the reduction was 49% on

28

the limestone. Measurements on the granite were affected by measurement distortion. The use of the chisel sleeve also brought about a reduction on the stone hammer of 3% to 5% for the more powerful machine and between 45% and 70% for the smaller machine. The use of this design of vibration reducing chisel sleeve may require the operator to modify their technique in some circumstances.

Sleeve 2 successfully reduced vibration when compared with the plain chisel on limestone for stone hammer B by up to 23%, total value, or by 40% in the dominant axis. End users also benefit from improved thermal and ergonomic comfort.

5.5 GENERAL COMMENTS

The results from all the different retrofit anti-vibration devices used in this project, with the exception of the chisel sleeves, demonstrate that an end user cannot be confident that their chosen retrofit device will in fact reduce vibration to the user and in turn reduce exposure. Indeed, the exact opposite may be true. A retrofit device may affect the dynamics of a machine which can change the vibration levels in unpredictable ways. If retrofit devices are not used with the machines for which they were intended, they should be applied with caution. Advice to end users should emphasise the need to speak to their suppliers to determine what, if any, retrofit devices are suitable for their equipment.

29

6. REFERENCES

1. Heaton R, Hewitt S. Research Report RR717: Evaluation of EN 60745 test codes BS EN 60745-2-3:2007 angle grinders. Sudbury: HSE Books; 2009.

2. British Standards Institution. BS EN ISO 5349-1: 2001 (Incorporating Corrigenda Nos 1 and 2). Mechanical vibration — Measurement and evaluation of human exposure to hand-transmitted vibration — Part 1: General requirements. London: BSI; 2001.

3. British Standards Institution. BS EN 12096:1997. Mechanical vibration. Declaration and verification of vibration emission values. London: BSI; 1997.

4. British Standards Institution. BS EN 60745-2-3:2007. Hand-held motor-operated electric tools — Safety — Part 2-3: Particular requirements for grinders, polishers and disk-type sanders. London: BSI; 2007.

5. Vibration Solutions. HS(G)170. Sudbury: HSE Books; 1997.

6. British Standards Institution. BS EN ISO 28927-11:2011. Hand-held portable power tools – Test methods for evaluation of vibration emission. Part 11: Stone hammers (ISO 28927-11:2011). London: BSI; 2011.

7. Easy Ergonomics: a guide to selecting non-powered hand tools. California Department of Industrial Relations and National Institute for Occupational Safety and Health. Report number: 2004-164; 2004.

8. Chengalur SN, Rodgers SH, Bernard TE. Kodak’s Ergonomic Design for People at Work. Second Edition. Hoboken, New Jersey: John Wiley & Sons, Inc.; 2004.

9. Tilley AR of Henry Dreyfuss Associates. The Measure of Man and Woman: Human Factors in Design. Revised Edition. New York: John Wiley & Sons, Inc.; 2002.

10. Riedel S, Gillmeister F, Stang C. Reduction of the vibration exposure at angle grinders using a special wheel flange (Reduzierung der Schwingungsbelastung bei Winkelschleifern mit Hilfe eines speziellen Flansches). Zentralblatt fur Arbeitsmedizin, Arbeitsschutz und Ergonomie 2008; 58: 164-171.

11. Kaulbars U. Vibration exposure at workplaces of stone masons (Schwingunseinwirkungen an Arbeitsplätzen von Steinmetzen). BIA. Report number: 06/96; 1996.

30

7. LIST OF APPENDICES

Appendix A Measurement equipment

Appendix B Anti-vibration support handles – full measurement results

Appendix C Spring balances / tensioners – full measurement results

Appendix D Vibration reducing flange – full measurement results

Appendix E Chisel sleeve – full measurement results

31

APPENDIX A: MEASUREMENT EQUIPMENT

Table A1. Equipment for measurements carried out 02/02/2011 to 11/03/2011

Item Channel ID Manufacturer Model Serial No. Sensitivity (pC/ms-2) HSL ID Last

calibration Calibration

interval

Tran

sduc

ers

Ch1 B&K* 4393V 10692 0.326 715 Aug 2010 1 year Ch2 B&K 4393V 30026 0.318 728 Aug 2010 1 year Ch3 B&K 4393V 32162 0.293 764 Aug 2010 1 year Ch4 B&K 4393V 30063 0.294 734 Aug 2010 1 year Ch5 B&K 4393V 31718 0.302 760 Aug 2010 1 year Ch6 B&K 4393V 31675 0.309 758 Aug 2010 1 year

Cha

rge

ampl

ifier

s

Ch1 B&K 2635 1473734 - 509 Dec 2009 2 years Ch2 B&K 2635 1709839 - 601 Apr 2010 2 years Ch3 B&K 2635 1709921 - 602 Jun 2009 2 years Ch4 B&K 2635 1473733 - 508 Jun 2009 2 years Ch5 B&K 2635 1493485 - 570 Feb 2010 2 years Ch6 B&K 2635 1625036 - 727 Feb 2010 2 years

Calibrator - B&K 4294 1639418 - 775 Nov 2010 1 year Pulse front end - B&K 3032A 2325758 - 704 Nov 2010 2 years

Laptop - Toshiba Tecra 47097412H - - - -

* B&K: Brüel & Kjær

System calibration check carried out at 1mV/ms-2.

grahamschofield

Cross-Out

32

Table A2. Measurements carried out 06/10/2011 to 19/10/2011



interval

Tran

sduc

ers

Ch1 B&K* 4393V 10692 0.326 715 Jul 2011 1 year Ch2 B&K 4393V 30026 0.318 728 Jul 2011 1 year Ch3 B&K 4393V 32162 0.293 764 Jul 2011 1 year Ch4 B&K 4393V 30063 0.294 734 Jul 2011 1 year Ch5 B&K 4393V 31718 0.302 760 Jul 2011 1 year Ch6 B&K 4393V 31675 0.309 758 Jul 2011 1 year

Cha

rge

ampl

ifier

s

Ch1 B&K 2635 1473734 - 509 Dec 2009 2 years Ch2 B&K 2635 1709839 - 601 Apr 2010 2 years Ch3 B&K 2635 1709921 - 602 Jun 2011 2 years Ch4 B&K 2635 1473733 - 508 Jun 2011 2 years Ch5 B&K 2635 1493485 - 570 Feb 2010 2 years Ch6 B&K 2635 1625036 - 727 Feb 2010 2 years





33

Table A3. Measurements carried out 10/01/01/2012 to 04/07/2012



interval

Tran

sduc

ers

Ch1 B&K* 4393V 10692 0.326 715 July 2011 1 year Ch2 B&K 4393V 30026 0.318 728 July 2011 1 year Ch3 B&K 4393V 32162 0.293 764 July 2011 1 year Ch4 B&K 4393V 30063 0.294 734 July 2011 1 year Ch5 B&K 4393V 31718 0.302 760 July 2011 1 year Ch6 B&K 4393V 31675 0.309 758 July 2011 1 year

Cha

rge

ampl

ifier

s

Ch1 B&K Nexus 2056119 - 673 Sep 2011 2 years Ch2

Ch3 Ch4

B&K Nexus 2056117 - 672 Jun 2011 2 years Ch5 Ch6





34




interval Tr

ansd

ucer

s

Ch1 B&K* 4393 2279751 0.317 707 Sep 2012 1 year Ch2 B&K 4393V 10693 0.320 716 Sep 2012 1 year Ch3 B&K 4393 10701 0.323 717 Sep 2012 1 year Ch4 B&K 4393V 32163 0.307 765 Sep 2012 1 year Ch5 B&K 4393V 32760 0.297 768 Sep 2012 1 year Ch6 B&K 4393 1665258 0.313 594 Sep 2012 1 year

Cha

rge

ampl

ifier

s

Ch1 B&K 2635 1473734 - 509 Dec 2011 2 years Ch2 B&K 2635 1473733 - 508 Jun 2011 2 years Ch3 B&K 2635 1709921 - 602 Jun 2011 2 years Ch4 B&K 2635 2448012 - 720 Aug 2011 2 years Ch5 B&K 2635 2448013 - 721 Aug 2011 2 years Ch6 B&K 2635 2448014 - 722 Aug 2011 2 years

Calibrator - B&K 4294 2361765 - 710 Aug 2012 1 year Pulse front end - B&K 3560 2423351 - 718 Dec 2011 2 years

Laptop - Toshiba Tecra M5 37124006H - - - - Laptop - DELL Latitude 15506 - - - -



35


Item Channel ID Manufacturer Model Serial No. Sensitivity

(pC/ms-2) HSL ID Last calibration Calibration interval

Transducers

Ch1 B&K* 4393 2279751 0.317 707 Sep 2012 1 year Ch2 B&K 4393V 10693 0.320 716 Sep 2012 1 year Ch3 B&K 4393 1873329 0.323 717 Sep 2012 1 year Ch4 B&K 4393V 32163 0.307 765 Sep 2012 1 year Ch5 B&K 4393V 32760 0.297 768 Sep 2012 1 year Ch6 B&K 4393 1665258 0.313 594 Sep 2012 1 year Ch7 B&K 4393V 32162 0.293 764 Aug 2012 1 year Ch8 B&K 4393V 31675 0.309 758 Aug 2012 1 year Ch9 B&K 4393 1873331 0.320 654 Sep 2012 1 year

Charge amplifiers

Ch1 B&K 2635 1473734 - 509 Dec 2011 2 years Ch2 B&K 2635 1473733 - 508 Jun 2011 2 years Ch3 B&K 2635 1709921 - 602 Jun 2011 2 years Ch4 B&K 2635 2448012 - 720 Aug 2011 2 years Ch5 B&K 2635 2448013 - 721 Aug 2011 2 years Ch6 B&K 2635 2448014 - 722 Aug 2011 2 years Ch7 B&K 2635 1658804 - 597 Aug 2012 2 years Ch8 B&K 2635 1493483 - 568 Apr 2010+ 2 years+ Ch9 B&K 2635 1709839 - 601 Apr 2010+ 2 years+

Calibrator - B&K 4294 2361765 - 710 Aug 2012 1 year Pulse front end (2003) Ch1 to Ch6 - B&K 3560 2423351 - 718 Dec 2011 2 years Pulse front end (2001) Ch7 to Ch9 - B&K 3560 2325758 - 704 Nov 2012 2 years

Laptop - DELL Latitude 15506 - - - -

* B&K: Brüel & Kjær + Instruments known to be out of calibration during measurement. Equipment checked in-house 21 February 2013 prior to external UKAS accredited calibration.

System calibration check carried out at 0.316mV/ms-2.

36

APPENDIX B: RESULTS FOR ANTI-VIBRATION HANDLES

Bold text indicates highest vibration magnitude axis. Shaded box indicates highest vibration magnitude hand location. Ch1 & Ch4 = x axis; Ch2 & Ch5 = y axis; Ch3 & Ch6 = z axis.

Table B1. Results for anti-vibration handles

Machine Handle Support

block position

Support Throttle

Ch1 Ch2 Ch3 Total Ch4 Ch5 Ch6 Total

A own inner 2.5 1.8 3.4 4.6 4.1 2.7 2.3 5.4 A own middle 2.6 3.5 5.5 7.1 4.0 2.7 2.2 5.3 A own outer 4.7 2.1 8.9 10.4 3.8 2.7 2.2 5.2 A A inner 2.0 3.4 3.4 5.2 4.0 2.8 2.3 5.4 A A middle 0.6 2.2 1.3 2.6 3.9 2.6 2.2 5.2 A A outer 1.3 3.2 2.2 4.1 3.9 2.7 2.2 5.3 A H inner 2.4 2.1 2.4 4.0 3.9 2.1 2.0 4.9 A H middle 3.1 7.3 6.3 10.2 4.9 2.3 2.1 5.8 A H outer 4.4 2.1 11.5 12.5 4.9 2.2 2.1 5.8 A H no mass inner 2.7 2.2 2.1 4.1 3.9 2.3 2.3 5.1 A H no mass middle 3.6 5.0 6.9 9.4 3.7 2.2 2.0 4.8 A H no mass outer 7.3 2.3 10.2 12.8 3.7 2.1 2.4 5.0 A I inner 1.7 3.0 2.2 4.1 4.3 2.4 2.2 5.4 A I middle 1.6 3.8 3.0 5.2 4.3 2.3 2.1 5.3 A I outer 2.0 2.8 4.5 5.7 4.3 2.3 2.1 5.3

B own inner 1.9 4.3 1.9 5.1 5.2 1.6 5.9 8.0 B own middle 0.9 2.8 1.2 3.2 4.9 1.6 5.8 7.8 B own outer 2.4 3.8 1.4 4.7 4.8 1.5 5.6 7.5 B C inner 1.7 3.4 2.4 4.5 4.8 1.7 5.2 7.3 B C middle 3.5 3.8 4.4 6.9 4.6 1.8 5.3 7.2 B C outer 5.4 3.5 4.7 8.1 4.7 1.8 5.1 7.1 B F inner 2.2 3.5 2.0 4.5 4.8 1.7 5.4 7.4 B F middle 1.0 3.5 1.4 3.9 4.7 1.7 5.2 7.2 B F outer 2.3 3.4 1.8 4.5 4.5 1.7 5.1 7.0 B F no mass inner 2.2 3.2 2.1 4.4 4.8 1.6 5.2 7.3 B F no mass middle 1.4 3.5 2.0 4.2 4.7 1.6 5.5 7.4 B F no mass outer 3.4 3.5 3.6 6.1 4.4 1.6 5.2 7.0 B G inner 2.0 3.3 2.0 4.4 4.6 1.8 5.2 7.2 B G middle 2.4 4.1 3.7 6.1 4.6 1.7 5.0 7.0 B G outer 4.8 3.4 5.3 8.0 4.4 1.6 5.3 7.0

C own inner 1.7 3.8 1.9 4.6 3.5 3.9 2.9 6.0 C own middle 2.6 3.6 3.3 5.6 3.6 3.9 3.0 6.1 C own outer 5.5 4.2 3.2 7.7 3.7 4.3 3.0 6.4

37


block position

Support Throttle


C C inner 1.4 4.2 2.0 4.9 3.6 4.1 3.1 6.3 C C middle 2.4 3.3 2.7 5.0 3.6 4.1 3.0 6.2 C C outer 5.3 4.3 2.9 7.5 3.8 4.4 3.1 6.6 C F inner 1.8 4.0 1.9 4.8 3.6 4.3 3.0 6.4 C F middle 0.8 3.0 1.2 3.3 3.5 4.3 3.0 6.3 C F outer 2.3 3.7 1.4 4.6 3.4 4.4 3.0 6.3 C F no mass inner 1.9 3.9 2.0 4.8 3.6 4.3 3.0 6.4 C F no mass middle 1.3 3.2 1.9 4.0 3.5 4.2 3.0 6.3 C F no mass outer 4.0 4.0 2.7 6.4 3.5 4.4 3.0 6.4 C G inner 1.8 3.9 1.7 4.7 3.5 4.3 3.0 6.3 C G middle 3.4 3.4 2.7 5.6 3.5 4.3 3.0 6.3 C G outer 2.6 3.8 2.3 5.3 3.5 4.4 3.0 6.4 D own inner 2.1 4.2 2.6 5.4 5.6 1.6 4.0 7.1 D own middle 2.4 1.5 4.3 5.2 5.7 1.7 4.0 7.2 D own outer 6.0 5.3 8.2 11.5 5.6 1.7 4.0 7.1 D C inner 2.4 4.3 2.5 5.5 5.8 1.8 4.1 7.3 D C middle 1.9 1.6 3.8 4.6 5.8 1.8 4.1 7.3 D C outer 4.9 4.3 4.9 8.3 5.7 1.8 4.0 7.2 D F inner 2.4 3.6 2.4 4.9 5.4 1.8 4.0 7.0 D F middle 0.9 1.3 1.2 2.0 5.4 1.7 3.9 6.9 D F outer 1.5 3.2 2.1 4.2 5.4 1.8 4.0 6.9 D F no mass inner 2.5 3.4 2.6 4.9 5.5 1.9 3.9 7.0 D F no mass middle 1.4 1.5 1.8 2.8 5.6 1.9 4.0 7.1 D F no mass outer 2.3 3.8 3.7 5.8 5.5 1.9 4.0 7.1 D G inner 2.5 4.3 2.4 5.5 5.6 1.8 4.0 7.2 D G middle 1.8 1.6 3.6 4.4 5.7 1.8 4.1 7.3 D G outer 4.5 4.3 4.8 8.0 5.7 1.9 4.0 7.2

E own inner 5.0 3.5 5.8 8.4 7.2 8.2 4.7 11.9 E own middle 8.1 10.0 13.1 18.4 7.1 10.9 5.5 14.2 E own outer 14.1 3.2 21.8 26.2 5.7 10.8 5.4 13.4 E B inner 3.3 7.7 6.2 10.4 12.7 11.7 6.2 18.4 E B middle 2.4 8.6 6.7 11.2 11.6 10.9 5.9 17.0 E B outer 5.3 7.1 12.2 15.1 13.0 13.4 6.9 20.0 E D inner 5.4 3.8 5.1 8.3 4.4 10.9 5.4 13.0 E D middle 8.2 8.5 8.0 14.3 3.8 8.9 4.4 10.7 E D outer 14.7 4.6 16.5 22.6 3.4 10.4 5.2 12.1 F own inner 1.9 4.0 2.3 5.0 3.9 4.5 3.7 7.0 F own middle 1.0 2.3 1.6 3.0 4.1 4.7 3.7 7.2 F own outer 2.9 3.8 2.0 5.2 4.0 4.6 3.7 7.2 F C inner 1.6 3.9 2.5 5.0 4.0 4.7 3.6 7.2 F C middle 3.6 2.8 4.0 6.2 4.2 4.9 3.7 7.4 F C outer 5.1 4.3 5.5 8.7 4.0 4.9 3.6 7.3

38


block position

Support Throttle


F G inner 1.4 4.2 2.2 5.0 3.9 4.8 3.5 7.1 F G middle 3.0 2.8 4.1 5.9 4.1 5.0 3.7 7.5 F G outer 4.6 4.4 5.0 8.1 3.9 4.9 3.6 7.2 G own inner 3.7 6.4 3.9 8.4 6.9 3.6 2.9 8.3 G own middle 3.0 6.1 7.5 10.3 7.3 3.7 2.9 8.7 G own outer 8.0 6.7 7.5 13.0 7.2 3.9 3.2 8.8 G A inner 4.3 7.1 4.5 9.5 6.4 3.6 2.9 7.9 G A middle 1.4 3.0 1.8 3.8 6.2 3.6 2.9 7.8 G A outer 3.0 6.7 3.0 8.0 6.4 3.5 3.1 7.9 G H inner 4.7 6.0 3.4 8.5 6.6 3.7 3.0 8.1 G H middle 2.5 4.4 2.5 5.7 6.6 3.6 3.1 8.1 G H outer 1.4 5.6 3.2 6.6 6.4 3.2 2.9 7.7 G H no mass inner 3.7 5.9 4.6 8.4 6.7 3.5 3.0 8.1 G H no mass middle 2.3 4.4 3.5 6.0 5.9 3.1 2.8 7.2 G H no mass outer 2.3 5.6 4.9 7.9 6.0 3.2 2.9 7.4 H own inner 1.2 2.7 2.4 3.8 3.2 1.5 1.6 3.8 H own middle 1.1 2.8 3.2 4.4 3.2 1.4 1.6 3.9 H own outer 2.1 3.0 7.0 7.9 3.5 1.5 1.7 4.2 H A inner 1.8 3.0 2.9 4.6 3.3 1.5 1.7 4.0 H A middle 0.6 1.9 1.3 2.4 3.2 1.5 1.7 3.9 H A outer 0.9 3.0 2.0 3.7 3.3 1.4 1.7 4.0 H H inner 2.5 2.1 2.4 4.1 3.0 1.3 1.6 3.7 H H middle 1.4 2.4 1.3 3.0 3.2 1.4 1.7 3.9 H H outer 1.2 2.5 1.4 3.1 3.2 1.4 1.7 3.9 H H no mass inner 2.1 2.2 2.5 4.0 2.9 1.3 1.5 3.5 H H no mass middle 1.4 2.8 2.1 3.7 2.8 1.3 1.5 3.4 H H no mass outer 1.4 2.2 2.5 3.6 2.9 1.3 1.6 3.6

39

Figure B1. Graphical results for machine A

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN inner A inner H inner H no mass inner I inner

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN middle A middle H middle H no mass middle I middle

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN outer A outer H outer H no mass outer I outer

40

Figure B2. Graphical results for machine B

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n inner C inner F inner F no mass inner G inner

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n middle C middle F middle F no mass middle G middle

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n outer C outer F outer F no mass outer G outer

41

Figure B3. Graphical results for machine C

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


42

Figure B4. Graphical results for machine D

0

2

4

6

8

10

12


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


0

2

4

6

8

10

12


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


0

2

4

6

8

10

12


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )


43

Figure B5. Graphical results for machine E

0

5

10

15

20

25

30


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n inner B inner D inner

0

5

10

15

20

25

30


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n middle B middle D middle

0

5

10

15

20

25

30


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

ow n outer B outer D outer

44

Figure B6. Graphical results for machine F

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN inner OWN no mass inner C inner G inner

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN middle OWN no mass middle C middle G middle

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN outer OWN no mass outer C outer G outer

45

Figure B7. Graphical results for machine G

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN inner A inner H inner H no mass inner

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN middle A middle H middle H no mass middle

0

2

4

6

8

10

12

14


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN outer A outer H outer H no mass outer

46

Figure B8. Graphical results for machine H

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN inner A inner H inner H no mass inner

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN middle A middle H middle H no mass middle

0

1

2

3

4

5

6

7

8

9

10


support throttle

frequ

ency

wei

ghte

d ac

cele

ratio

n (m

/s2 )

OWN outer A outer H outer H no mass outer

47

APPENDIX C: RESULTS FOR SPRING BALANCES

Table C1. Results for spring balance A

Spring tension Machine Support block

location Support Throttle


Full spring (f)

B inner 1.5 4.4 2.0 5.0 4.9 1.4 5.4 7.4 mid 0.7 2.9 1.2 3.2 4.6 1.4 5.1 7.0 out 2.1 4.5 1.1 5.1 4.4 1.5 5.0 6.9

C inner 1.0 4.0 2.3 4.7 3.3 4.0 3.1 6.1 mid 2.9 3.8 2.7 5.6 3.4 4.0 3.0 6.0 out 6.8 4.2 3.5 8.8 3.5 4.2 3.1 6.3

F inner 2.4 3.3 2.5 4.8 3.8 4.5 3.8 7.1 mid 2.2 3.1 2.9 4.8 3.8 4.6 3.8 7.1 out 2.6 4.0 5.4 7.3 3.6 4.5 3.8 6.9

Half spring (z)

B inner 1.4 5.1 1.6 5.5 4.5 1.4 5.1 7.0 mid 0.9 3.4 1.2 3.7 4.5 1.4 5.0 6.9 out 2.0 4.9 1.8 5.6 4.7 1.4 5.0 7.0

C inner 2.2 3.9 1.9 4.9 3.3 4.3 3.1 6.2 mid 1.5 3.5 2.2 4.5 3.4 4.5 3.0 6.4 out 6.5 4.2 3.9 8.7 3.5 4.3 3.0 6.3

F inner 1.8 3.8 2.3 4.8 3.6 4.7 3.2 6.7 mid 1.3 2.3 2.3 3.5 3.8 4.4 3.2 6.6 out 2.5 3.8 2.4 5.1 3.8 4.8 3.4 7.0

48

Table C2. Results for spring balance B

Spring tension Machine Support block

location Support Throttle


Full spring (f)

B inner 1.6 4.6 1.9 5.2 4.5 1.3 5.3 7.1 mid 0.7 3.3 1.1 3.6 4.2 1.4 4.9 6.6 out 2.0 4.9 1.6 5.6 4.6 1.5 5.1 7.0

C inner 1.4 3.9 1.9 4.6 3.2 3.9 3.1 6.0 mid 2.1 4.1 2.3 5.2 3.5 4.0 3.1 6.2 out 5.6 4.2 2.7 7.6 3.5 4.2 3.1 6.3

F inner 2.1 3.5 2.5 4.8 3.7 4.5 3.6 6.9 mid 1.2 2.7 2.4 3.8 3.9 4.5 3.6 7.0 out 2.5 3.6 3.2 5.5 3.8 4.4 3.6 6.9

Half spring (z)

B inner 1.4 4.7 1.6 5.1 4.2 1.3 5.3 6.9 mid 0.8 3.2 1.1 3.5 4.3 1.3 5.0 6.7 out 1.7 5.0 1.8 5.6 4.7 1.4 5.5 7.4

C inner 2.0 4.0 1.8 4.9 3.1 3.9 2.9 5.8 mid 1.4 3.3 2.0 4.2 3.2 4.0 2.9 5.9 out 5.6 4.2 3.0 7.8 3.0 4.2 2.9 6.0

F inner 2.0 3.7 2.2 4.8 3.9 4.7 3.3 6.9 mid 1.3 2.4 2.1 3.5 4.0 4.7 3.4 7.0 out 2.4 3.8 2.8 5.3 3.8 4.5 3.4 6.8

Full spring (f) (centre

support) F

inner 1.9 3.3 2.6 4.6 3.4 4.3 3.6 6.5 mid 1.9 3.0 3.0 4.7 3.6 4.4 3.7 6.8 out 2.5 3.8 4.0 6.2 3.5 4.4 3.6 6.7

49

APPENDIX D: RESULTS FOR VIBRATION REDUCING FLANGE

Bold text indicates highest vibration magnitude axis. Shaded box indicates highest vibration magnitude hand location. Ch1 & Ch4 = x axis; Ch2 & Ch5 = y axis; Ch3 & Ch6 = z axis.

Table D1. Results for vibration reducing flange

Flange used Support

block location

Support Throttle


Using EN 60745 measurement set up – results after five wheel positions

Own inner 1.7 3.8 1.9 4.6 3.5 3.9 2.9 6.0

middle 2.6 3.6 3.3 5.6 3.6 3.9 3.0 6.1 outer 5.5 4.2 3.2 7.7 3.7 4.3 3.0 6.4

Vibration reducing

inner 1.4 3.7 1.1 4.1 2.2 4.0 3.5 5.7 middle 2.4 4.2 1.9 5.3 2.5 4.1 3.7 6.1 outer 6.2 3.8 2.7 7.9 2.4 4.2 3.7 6.1

Simulated real (grinding 8mm thick mild steel) – single random wheel position

Own inner 2.1 1.1 1.3 2.8 2.2 1.5 2.0 3.4

middle 2.0 1.2 1.3 2.7 2.0 1.3 1.8 3.0 outer 2.0 2.6 2.3 4.1 2.0 1.0 1.8 2.9

Vibration reducing

inner 2.0 1.1 1.4 2.7 2.2 1.3 1.8 3.2 middle 1.7 1.1 1.2 2.4 1.9 1.2 1.6 2.8 outer 3.6 6.0 3.7 8.0 2.4 2.0 2.9 4.3

Simulated real (grinding 8mm thick mild steel) – wheel position 2

Own inner 1.4 1.0 1.2 2.1 2.1 1.8 2.3 3.7 outer 1.6 1.2 1.4 2.5 2.3 1.9 2.4 3.9

Vibration reducing

inner 5.0 2.5 1.8 5.9 3.3 3.6 4.5 6.7 outer 1.8 1.0 1.1 2.3 2.2 1.6 1.4 3.0

Simulated real (grinding 8mm thick mild steel) – wheel position 5

Own inner 1.6 1.2 1.4 2.5 2.3 1.9 2.4 3.9 outer 2.0 2.6 2.3 4.1 2.0 1.0 1.8 2.9

Vibration reducing

inner 1.8 1.0 1.1 2.3 2.2 1.6 1.4 3.0 outer 3.6 6.0 3.7 8.0 2.4 2.0 2.9 4.3

50

APPENDIX E: RESULTS FOR CHISEL SLEEVES

Sleeve 1

Table E1. Sleeve 1 results

Stone hammer Medium Chisel

used Tool handle Chisel


A Limestone

Plain 8.6 6.0 4.2 11.4 10.6 21.5 11.5 26.7 Sleeve 1 8.9 5.8 1.8 10.8 6.5 8.0 8.5 13.5

Granite Plain 9.7 8.7 4.5 13.8 DC shift*

Sleeve 1 10.6 7.5 3.2 13.4 11.0 10.2 10.3 18.3

B Limestone

Plain 13.4 10.1 6.5 18.1 4.7 9.6 5.1 12.0 Sleeve 1 4.3 2.8 1.2 5.3 2.3 2.8 2.3 4.4

Granite Plain 14.1 12.0 5.6 19.7 8.3 14.2 7.3 18.1

Sleeve 1 8.7 5.9 2.2 10.8 4.2 4.7 3.9 7.4

* All attempts at reducing signal distortion through mechanical filtering systems were not successful in overcoming the high-level impactive vibration magnitudes produced when using a plain chisel with stone hammer A on granite.

Sleeve 2 Stone hammer B; limestone. To facilitate a comparison with Vibration Solutions case study 15, a reduced frequency range of 32Hz to 1kHz was used for all the Sleeve 2 analysis. For completeness, the full frequency range total values, 4Hz to 1kHz, are included I Table E2.

Table E2. Sleeve 2 results

Adaptor 1 Adaptor 2

32Hz to 1kHz ISO 5349-1:2001 32Hz to 1kHz ISO 5349-

1:2001

HSL

cab

le

tie m

ount

ing Ch1 3.0 3.0 n/a n/a

Ch2 6.5 6.5 n/a n/a

Ch3 3.6 4.0 n/a n/a

Total 8.0 8.3 n/a n/a

Plai

n ch

isel

Ch4 3.0 3.1 2.1 2.2

Ch5 7.5 7.6 8.2 8.3

Ch6 3.0 3.0 2.1 2.2

Total 8.6 8.8 8.7 8.8

Han

d ad

apto

r

Ch7 3.5 3.6 2.3 2.3

Ch8 4.5 4.5 5.2 5.3

Ch9 3.7 3.8 3.4 3.5

Total 6.9 6.9 6.7 6.7

Published by the Health and Safety Executive 10/13



RR990

www.hse.gov.uk

This project set out to try to determine what benefits, if any, could be gained in terms of reducing vibration exposure by retrofitting different types of anti-vibration device to different hand-held machines. Four types of device were selected for laboratory investigation: anti-vibration handles, spring balances/tensioners, a vibration reducing flange and chisel sleeves.

The results from all the different devices used in this project, with the exception of the chisel sleeves, demonstrated that an end user cannot be confident that their chosen retrofit device will in fact reduce vibration to the user and in turn reduce exposure. Indeed, the exact opposite may be true. Advice to end users should emphasise the need to speak to their suppliers to determine what, if any, retrofit devices are suitable for their particular equipment.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

retrofit anti-vibration devices: a study of their ... · isolating hand grips. retrofit devices...

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