technical audit report of chittaranjan locomotive works ... · technical audit report of clw 1....

of 15 Issued on : 29.03.2016 Report No. RDSO/2016/EL/TAR/0004 Rev ‘0’

Prepared by Checked by Issued by

GOVERNMENT OF INDIA

MINISTRY OF RAILWAYS

Technical Audit Report of Chittaranjan Locomotive

Works Chittaranjan, for assembly of bearings of three

phase locomotive Traction Motors (TM) and Motor

Suspension Units (MSU)

Report No.: RDSO/2016/EL/TAR/0004 Rev ‘0’

Issue Date: 29.03.2016

Approved by

EDSE(Co-Ord) Signature

Issued by

Electrical Directorate Research, Designs and Standards Organisation

Manak Nagar, Lucknow-226011

lR;eso t;rs



Status of Revision

SN. Date of Revision Page No. Revision Reason for Revision

1. Originally issued in letter form vide letter no.

EL/2.2.13 dated 18.1.2016

2. All 0 Issued in Technical Audit Report Format



Technical Audit Report of CLW

1. Technical audit for 3-phase traction motor bearings:

Technical audit of CLW for 3-phase traction motor bearings has been carried out jointly in

association with M/s FAG & M/s SKF on 6.1.2016 & 7.1.2016. Observations are given

below:

(i) Bearing main storage: Bearings were stored in a dry room, separated from other

components. But bearings were directly kept on floor with stack of more than 5

bearings and adjacent to wall. Two NDE side bearings (Ceramic coated) cartons were

fallen down in tilted condition. It seems that FIFO system is not being followed as

bearings of year 2013 and 2014 were also seen together. Lot of dust and dirt observed

on stacked bearing cartons.

Photo 1 to 3: Bearings stored in main store depot

Recommendation: CLW is advised to keep the bearings little away from walls to

avoid ingress of water/moisture in a stack of not more than 5 bearings. Bearings should

also not be stored directly on floor. FIFO system should be used to avoid prolonged

storage. If bearings are to be stored for more than one year, it is advised to dip the same

in preservation oil and repack the same for further use / storage. Storage area should

always be kept clean. Detailed procedure on re-oiling with preservation oil will be

given by M/s FAG and M/s SKF to RDSO for further circulation.

(ii) Bearing sub-storage in the section: Bearings were stored in a dry room, separated

from other components. Maximum bearings were stacked in rack, a few quantity were

kept on floor with stack of 6-7 bearings and adjacent to wall. Few inner racers were

kept open in one carton box for mounting purpose but racer running surface was

touching with other rings.



Photo 4 & 5: Bearings Stored in Section

Recommendation: Advised to keep the bearings little away from walls to avoid

ingress of water/moisture in a stack of not more than 5 bearings. Bearings should not be

kept open for long and should only be opened from box at the time of mounting only.

Open bearing kept for long time can lead to rust formation.

(iii) Handling: Handling of bearing is done with bare hands.

Photo 6 & 7: Handling of Bearings with bare hand

Recommendation: Bearings should be handled with protective industrial gloves. Lint

free cloth should be used for cleaning purpose.

(iv) Measurements taken before mounting: No measurements were taken before

mounting for any component. The end frame housing bore diameter (for DE & NDE)

were not measured with bore dial gauge with least count of 1 Micron. No check sheet

was available for critical parameters.

Recommendation: It is recommended to check fit & dimensions of each component

before mounting. All parameters should be checked as per drawing and should be

within limits. Out of tolerance parts should not be used for bearing mounting.



(v) Use of assembly components in kit form: On visual inspection, few casted mating

parts were found defective with metal filling at critical portion of labyrinth ring side.

CLW is not following the assembly of components in kit form as per RDSO

requirement. Good parts and rejected parts are kept aside with no proper tags. Handling

/ storage of components is not up to the mark.

Photo 8: New components and rejected components stored together

Recommendation: For good performance of bearings, all mating parts should also be

of high quality and dimensions as per drawing requirement. Any defect in dimension or

metal filling can lead to bearing failure. It is recommended to use assembly components

in kit form. Components supplier supplies the material in kit form, but TM shop

receives the same in open condition from stores and kit is disturbed. It is recommended

to use one kit for one motor assembly. New material and rejected components should

be stored separately with proper indication.

(vi) Bearing mounting area: Bearing mounting area needs improvement in terms of

cleanliness. Other activities like component cleaning, air blowing etc. are also done

near the bearing assembly area.

Recommendation: Bearing assembly area should be clean and dust free. No other

activity should be performed near the bearing assembly area. It is recommended to

separate the bearing assembly area from cleaning area. Further scope of improvement

to clean the area is still there.

(vii) Grease: The grease used for the bearings is Servoplex SHC 120. Grease is kept in a big

covered drum nearer to the mounting area with lot of dirt and dust aside. Greasing is

done by hands with gloves. Total quantity of grease to be used in a motor is measured

but no measurement is done for grease quantity for DE as well as NDE side. CLW

informed that people are well experienced and hence grease measurement is not done.



Photo 9 & 10: Grease Drum Location & Grease

Recommendation: Even though people are well experienced, still it is recommended

to check the grease quantity before filling. Small covered containers can be used to

perform such activity. Grease drum should be kept separate in clean area.

(viii) Induction Heating of the End frames:

Induction heaters are used for heating of End frame for mounting of the bearings. Two

induction heaters were available; however, one induction heater was not equipped with

temperature setting. Heating was done for predefined time and temperature is measured

by Temperature Gun. In other Induction heater, desired temperature can be set.

Temperature difference of about 25oC was observed between display of induction

heater and temperature gun. Thus, when heating is done for predefined time and

temperature is measured using temperature gun, it may lead to overheating.

Photo 11 & 12: Induction Heaters of TM Shop No. 21

Recommendation:

(a) CLW should procure sufficient number of induction heaters equipped with essential

features like temperature display, temperature hold, auto cut off & de-

magnetization.



(b) Induction heating should always be done in temperature mode as same/similar

components of different manufactures may have different properties.

(c) Only Calibrated Temperature Guns should be used, if required.

(ix) Induction Heating of the Inner Racers & Dynamic Balancing of Rotors:

As per present practice being followed, inner racer is mounted before dynamic

balancing of the rotor and dynamic balancing is carried out with racers mounted on the

shaft. Due to this, Bearings needs to be opened and handled separately at two locations

which is not desirable. The induction heater of the 3 Phase rotor shop is defective and

induction heater of Hitachi TM assembly area (Shop no. 23) is used which is of old

design without essential features of temperature setting and demagnetization. Heavy

magnetism was also observed on the racers.

Photo 13: Magnetized Racer Photo 14: Induction Heater of Shop no. 23

Photo 15: Balancing done with racer



Recommendation:

(a) CLW should procure sufficient number of induction heaters equipped with

essential features like temperature display, temperature hold, auto cut off & de-

magnetization.

(b) Dynamic balancing should be carried out without racer mounted on the shaft.

(c) Bearing should be opened and provided simultaneously in the end frames and

rotor.

(x) Measurement of RC after assembly: CLW is measuring DE end RC as per SMI-278

by using jack and dial gauge. But they are not multiplying measured reading by 0.86 as

per SMI-278.

Photo 16: Measurement of RC

Recommendation: CLW is advised to follow the SMI-278 completely.

(xi) Marking done by CLW on bearing components: CLW is following the practice of

unique marking by way of etching on the bearings. Etching is done on brass cage of

6FRA6068TM DE & NDE bearings and on rollers of 6FXA7059 NDE side bearings.



Photo 17: Marking on cage of NJ320 Photo 18: Marking on cage of NU2236 (DE side) bearing of

(NDE side) bearing of 6FRA 6068 6FRA 6068

Photo 19: Marking on rollers of NJ219 (NDE side) bearing of 6FXA 7059

Recommendation:

(a) The electrical etching process is used which produces sparks and it should not be

used for bearing.

(b) Etching should not be done at rollers and cage.

(c) If required, marking by vibratory pen or Laser engraving should be done.



(xii) Mounting of the bearings: For Cylindrical roller bearing the outer ring with roller

assembly already fitted in end frame should be lowered carefully in magnet frame to

avoid oblique mounting and mounting marks on inner race. Little swiveling movement

should be done on end frame to avoid mounting marks.

(xiii) Technical seminar: At the end of audit, a technical seminar is organized by M/s SKF

& FAG for officers, SSEs/JEs and technicians and the findings of the audit as well as

Dos and Don’ts of bearings were discussed.

Photo 20: Technical Seminar

2. Technical audit for Motor Suspension Unit :

Technical audit of CLW for Motor Suspension Unit (MSU) has been carried out jointly in

association with M/s KMRI, Howrah & M/s Kay Pee Equipments, Howrah on

08.01.2016. Observations are given below:

(i) Bearing storage: Bearing storage at Shop floor (Wheel set shop no. 9) found to be poor.

Large size MSU bearings were kept in vertical position with dust and dirt and in open

condition. No separate room/dust free environment available for bearing storage &

assembly.



Photo 21 & 22: MSU Bearings Stored in Wheel Shop

Recommendation: Bearing assembly and storage should be done in dust free area.

Separate room/dust free environment should be made available for bearing storage and

handling.

(ii) Greasing: Greasing of bearings is done with bare hands.

Photo 23: Greasing of Bearings with bare hands

Recommendation: Bearings should be handled with protective industrial gloves. Lint

free cloth should be used for cleaning purpose.

(iii) Measurements taken before mounting: No measurements are being done before

mounting for any assembly components. It was informed that all components are pre-

inspected by CLW inspection cell.

Recommendation: It is recommended to check the actual fits and dimensions of MSU,

assembly components (mating parts) and axle bearing seating area.



(iv) Use of Assembly components along with MSU tube in Kit form: It is recommended

that the Suspension tube and its assembly components should be used in kit form and

should not be mixed or interchanged. However, the components were not stored in kit

form

Photo 24 & 25: Assembly components lying in scattered condition

Recommendation: It is recommended to store and use assembly components in kit

form. One kit should be used for one MSU.

(v) Induction heating of the bearing racer: Induction heater used is old without

temperature setting properties. It was informed that new induction heater is also

available but under breakdown.

Photo 26 & 27: Induction Heater without temperature setting & display in Wheel Shop



Recommendation:

1. CLW should procure sufficient number of induction heaters equipped with

essential features like temperature display, temperature hold, auto cut off & de-

magnetization.

2. Induction heating should always be done in temperature mode as same/similar

components of different manufactures may have different properties.

(vi) Flame heating of MSU bearing seating area:

MSU bearing seating area is directly heated by flame heating whereas induction heating

is prescribed as per ABB document no. AEB 452511 ‘Drive 15 AN 21 R1 Instructions

for Assembly and Disassembly’. However, it was informed that LPG flame heating is

also permitted in document no. AEB050483, ‘Wheel Set assembly procedure’ at page

number 20.

Photo 28 & 29: Direct flame Heating of MSU

Recommendation:

1. CLW should procure proper induction heater for heating of the MSU and follow

the procedure given in ABB document no. AEB 452 511 ‘Drive 15 AN 21 R1

Instructions for Assembly and Disassembly’. Induction heating is better than

LPG flame heating which may cause change in properties of the material.

Induction heating alone is also prescribed in ‘Maintenance & Repair Manual of

WAG-9 Locomotive’ document number 3EHW411416 chapter 2.06.

2. It was observed that Oxy-actylene flame was used in the shop due to non-

availability of the LPG. Use of Oxy-actylene flame is prohibited as it can cause

distortion in MSU tube.



(vii) Measurement of Axial End Play & Radial End Play after assembly: Wheel-shop is

not measuring the Axial End Play of NDE bearing and Radial End Play of both Ends.

Recommendation: It is advised to measure axial and radial end play and keep the

records. The prescribed values are specified in paragraph no. 3.16 & 3.17 of ABB

document no. AEB 452511.

(viii) Torque wrench of 9.5 Nm is not available.

Recommendation: Torque wrench of 9.5 Nm to be procured and used.

(ix) Socket head screw bolt (Allen key bolt) of M12X30 (Grade 8.8) of different makes are

used in one assembly of supporting ring. The bolts were of Unbrako and L.B. make.

Unbrako is CLW approved source while LB make bolts are not approved.

Recommendation:

1. CLW should only use approved make of fasteners.

2. In one MSU tube, only one make of fasteners should be used and mixing should

not be done.

3. Some socket head screw bolts were tested by CLW lab. As per lab report no.

M/6/195/03 dated 7.1.2016, “The samples conform to IS:1367(pt-3):2002 Gr 8.8

as referred by DIN 7984. But too much variation in hardness within samples

noted. It indicates that proper heat treatment has not been done to achieve the

homogeneus hardness property. It is suggested that (i) Hardness in the relevant

Drg./Specifications must be restricted within 28-32 Rc or (ii) higher grade i.e.

10.9 is suggested as an alternate and superior material”. CLW is advised to

take appropriate action on this.

(x) Measurement of Gap between Suspension tube and Supporting ring is not in practice as

prescribed (C clearance Standard Value 0.1 to 0.7 mm). ’C’ Clerance of 4 assembled

MSU was measured and found less than 0.1 mm. M/s KP & KMRI advised to submit

detailed technical report within one month giving reasons of not achieving the clearance

and its effect on MSU and bearing life.

Recommendation: ‘C’ Clearance should be measured and recorded.

(xi) Cleaning of MSU bearing seating area & components: Before fitment of Bearings,

Bearing seating area of MSU and assembly components must be cleaned properly to

remove anti-rust paint completely.



Photo 30 & 31: MSU & assembly Components being used without complete removal of anti-rust paint

(xii) Holding of bearing race (DE) and bearing ring (NDE) during fitment

As per chapter 2.06 page 26/36 (rev. 12.2001, Indent No. 3EHW-411416) of

Maintenance & Repair Manual of WAG-9 Locomotives for Wheel-set, while assembling

DE side bearing following procedure is recommended:

”Install the bearing race into the DE of the Suspension Tube seat. The serial

number on the bearing race must be facing towards the drive end of the suspension

tube. Press the bearing race up against the stop until the suspension tube has been

cooled. The bearing race will sit slightly above the lip of the seat and be correctly

positioned later in the procedure”

Similarly for NDE bearing also following procedure is recommended on page no. 29-

30/36 chapter 2.06 page 26/36 (rev.12.2001 , Indent No. 3EHW-411416)

”Heat the inner bearing ring to 100 degree C using suitable induction heating

equipment. Position the inner bearing ring onto the axle shaft until it stops against the

labyrinth ring. Press the ring against the labyrinth ring and hold until cool.”

The steps of holding bearing race in case of DE bearing and inner bearing ring in

case of NDE till the cool down are not being followed.

Recommendation:

The above mentioned procedure should be followed completely as it critical for proper

assembling of MSU. Earlier also, RDSO vide letter number EL/1.3.10 dated 1.9.2011 had

advised CLW to follow the correct procedure.

(xiii) Other observations:

(i) CMM is not working. It should be repaired and used for measurements.

(ii) CLW has to implement rotary curing for stators after VPI, as recommended in

RDSO’s MS 355 Rev ‘2’ dated 18.11.2010 which is essential to ensure uniform

distribution of resin for first 8 hours at 5 rpm at 150oC till gel formation takes place,

followed by stationary curing for adequacy of the bonding.

technical audit report of chittaranjan locomotive works ... · technical audit report of clw 1....

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