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Seam

control


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This operator’s booklet for the seaming operation control on tin plate cans is the result of our knowledge and experience after years of work in this field. The aim of this work is to examine the most common problems that one can encounter in the process of can closing. IMETA produces complete equipment and spare parts for every kind of seamer. IMETA is specialised in the construction of specific seaming tools such as rolls and chucks. Nevertheless, IMETA is essentially a “Service Company” which takes care of materials, design and advice regarding seaming and seamers. Our production is completed by a specialised lab for the research of the most appropriate forms for closing various containers and for the control and rating of seam, together with a qualified Customer Service.


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INTRODUCTION

Many parts of the tin plate can are important in the canning process, but since we are essentially interested in the adequate closing we will discuss about seam and its most common defects. The formation of double seam is the result of two separate operations precisely related in timing. In the first part of the seaming process, the end curl is clinched to the body flange. The end is made of three thickness, while the can is made of two thickness. The purpose of the second operation during the process is to complete the closing by pressing these thickness tightly. The sealing compound, previously applied to the end, will form an elastic gasket to compensate the imperfections and ensure an hermetic closure can. Measurements, visual inspections and tests can be used in order to note variations in the finished seam. The pictures of this booklet describe some of the most common defects and their degree of importance, the most probable cause of the defect, the possible imperfect parts in the seamer, as well as some corrective measures to be taken in order to eliminate the most important faults. Part B of this booklet serves to underline some of the visual defects that can be evident in the general aspect of the can. The visual aspect of the closing is very important for the quality and in many cases the inspection will warn the operator about a serious defect to be corrected in order to have a good closing. Part C describes some of the imperfections which can be noted only by disassembling the can structure and examining its interior. We normally suggest to measure the seam in three points: 1. Around 10 mm on both sides of longitudinal solder of the can. 2. Directly on the longitudinal solder.


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INDEX

PART A - General information and data………………….…....…....6

- Approximate table for the conversion of the “base box” weight into tin plate thickness ………………………..…. 7

- Seam dimensional terminology ……….……………...… 8

- Seam terminology ………………………………………... 9 PART B - Seam visual test ……………………….……………..… 10

- Normal 1st operation Seams……………………….…… 11

- Tight 1st operation seams……....…………………….….12

- Loose 1st operation seams………….……………..……13

- Sharp seam……….……………….……………….….….14

- Cut-over on longitudinal solder…..…………………...…15

- Droop………….……………………………………...……16

- Spur.………….………………………………………...….17

- False seam………………………….……………….........18

- Incomplete seam………...….…………………………....19

- Damaged end curl………………………………………...21

- Knocked down can flange………………………….…….22

- Transverse mismatching between can and cover …....23

- Deformed can body………………………………….……24

- Mushroomed can flange……………………………….…25

- Normal 2nd operation seams…………………………....26 PART C - Seam Internal inspection ………….…………………..…27

- Countersink depth control with special gauge …….…..28

- Countersink too deep ………..………..………………….29

- Seam height beyond maximum….…………………....... 30


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- Seam height under minimum ….…………………... 31

- Seam disassembly and control………….….…...….. 32

- Wrinkles in the cover hook ……….……….………… 33

- Reverse wrinkles………………..…..………………… 34

- Jumped seam ………...……..…..…………….……… 35

- Cross-over droops………….……………………….…. 36

- Short cover hook………………….………………….… 37

- Long cover hook……………………………………….. 38

- Short can body hook………………………………..…. 39

- Long body hook…………………………………….…. 40

- Pressure mark……………………………………….…. 41

- Data………………………………………………….….. 42


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GENERAL INFORMATION AND DATA

PART A


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APPROXIMATE TABLE FOR THE CONVERSION OF THE “BASE BOX” WEIGHT INTO TIN PLATE THICKNESS POUND WEIGHT PER BASE BOX

APPROXIMATE THICKNESS IN INCHES

APPROXIMATE THICKNESS in mm

45 0.0050 0.13 50 0.0055 0.14 55 0.0061 0.15 60 0.0066 0.17 65 0.0072 0.18 70 0.0077 0.19 75 0.0083 0.21 80 0.0088 0.22 85 0.0094 0.24 90 0.0099 0.25 95 0.0105 0.26

100 0.0110 0.28 107 0.0118 0.30 112 0.0123 0.31 118 0.0130 0.33 128 0.0141 0.36 135 0.0149 0.38


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SEAM DIMENSIONAL TERMINOLOGY


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SEAM TERMINOLOGY

1ST OPERATION 2ND OPERATION

MEASURES TO BE KEPT OVERLAP LENGTH

CONTROLLED CALCULATION

- Height (End hook + body hook + end thick.) - seam height

- Thickness

OVERLAP % PERCENTAGE

End hook +body hook + end thick.– seam height

X100

Seam height – (2 end thick. + body thick.)


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SEAM VISUAL TEST PART B


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NORMAL 1ST OPERATION SEAMS

It is essential to have a good 1

st operation seam in order to have a good finished seam.

The 1st

operation is essential to control the cover hook, the body hook, the countersink depth, the wrinkling in the cover and in the end hook. The 1

st operation also determines the height of the finished 2

nd operation seam, i.e. the

narrower the profile of the 1st

operation roll is, the narrower the finished seam will be, when all the regulations are correct. The width and the thickness of the 1

st operation seam will vary depending on the tin plate

thickness, on the can diameter and groove profile. Every can manufacturer will have standards to be followed as strictly as possible. It is very useful to observe carefully the bottom part of the 1

st operation seam in the

overlap of the longitudinal solder. At this point, where there is a double body thickness, the end curl should get as close as possible to the can body, maintaining a smooth radius, without creating a flat at the bottom of the seam with a cut of the can body. Once the best condition has been reached, it is possible to take the measurements and this dimension can be used as a parameter of intermediate control. When starting up a seamer, or when new seam rolls are installed or readjusted in order to correct a defect of a seam, it will always be necessary to eliminate the 2

nd operation rolls

and to control the series of cans canned with 1st

operation only. Remember, if you haven’t got an adequate 1

st operation seam, it is very difficult, if not

impossible, to have a good or acceptable finished seam.


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TIGHT 1ST OPERATION SEAMS If the 1

st operation seaming is too tight, its bottom will be almost plane, as illustrated, or

the cover hook will be turned back into the body hook. CAUSE

a) 1

st operation roll too tight.

b) 1st

operation groove profile too narrow

REMEDY a) Loosen 1st operation roll b) Replace the roll with one

with a wider profile.


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LOOSE 1If the 1

st operation is too loose, the cover hook won’t be in touch with the can body

causing an insufficient folding of the end curl necessary to form a good hook and a

good overlap.

CAUSE REMEDY

a) Roll too loose. a) Tighten roll.

b) Groove profile worn out. b) Replace 1st

operation roll

with a new one.

c) Roll groove profile too wide c) Replace the roll with one with a

narrower profile


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SHARP SEAM The seam has a sharp edge all around the can on the upper internal cover edge. CAUSE REMEDY a) The 1

st operation roll a) Readjust the roll height with

too high or too low relating to a maximum 0.08 mm clearance chuck flange. between the roll profile and b) 1

st operation roll too tight. the top of the chuck flange.

b) Loosen roll. c) The chuck flange may be c) Check if the rolls are damaged worn because the and replace them if necessary. 1

st operation roll profile Replace chucks and readjust

touches on it. rolls. d) Use of the roll profile too narrow. d) Replace 1

st operation rolls.

e) Seaming chuck bells too tight e) If the sharp seam appears or damaged. on one seaming station only, probably the chuck bell is bent: put it in the correct position. If the problem exists in all stations, adjust the chuck bell turret.


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CUT-OVER ON JUNCTURE

The metal is fractured on the top of the seam; generally it happens at the juncture. Also

see the conditions which cause a sharp seam.

CAUSE REMEDY

a) Excessive solder at the cross over a) Contact the can manufacturer.

b) Solid and semisolid product entrapped b) Check the filling procedure to

in the seam. detect excesses. It could be

necessary to set a topper

to ensure an adequate

head space.

c) Defective notching of can body blank. c) Contact the can manufacturer.

The quantity of material in the welding is

more than the roll profile can take.


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DROOP

A smooth portion of the seam extends below the normal line.

This can happen in any part of the seam, but it generally happens at the lap. A small

amount of droop can be tolerated because of the additional thickness of metal and solder in

that point.

CAUSE REMEDY

See “Sharp seam” from “a” to “e”

and “Cut-over” from “a” to “c”.

OTHER CAUSES:

a) 1st

operation roll worn. a) Replace roll.

b) Roll bearing worn b) Replace bearing.

c) Improper cover curl. c) Contact the cover

manufacturer.

d) Excessive amount or irregular distribution d) Contact the cover

of sealing compound. manufacturer.

e) Body hook too long. e) Check pin height and lower

chuck spring adjustment.

f) Excessive solder at cross over. f) Contact the can

manufacturer.


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SPUR

Similar to droop, but sharper and smaller. It does not extend below the seam like droop and it

can happen in any part around the seam. It is possible to see or feel a big spur by rubbing a

finger around the seam. In serious cases the cover hook bends back on itself.

CAUSE REMEDY

a) Wrong adjustment of the 1st

operation a) Adjust the roll in diameter and

roll. height in relation to the top

b) 1st

operation profile too wide. of the chuck lip.

b) Replace roll with one with

a narrower profile.

c) 1st

operation profile worn. c) Replace 1st

operation roll.

d) Excessive sealing compound d) Contact cover manufacturer.

in end curl.

e) Product entrapped in seam. e) Check the filling procedure to

detect excesses of product. It can

be necessary to install a topper

to ensure an adequate head

space.

f) Wrinkling in seaming panel before f) Contact cover manufacturer.

the seam.


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FALSE SEAM A portion of the seam is completely unhooked. The cover hook is folded outside the body hook instead of being folded under it.

CAUSE a) Can flange bent or knocked down. b) Cover’s curl damaged or flattened. c) 1

st or 2

nd operation roll is not fast enough to off position, so that the roll’s lip can

damage the cover’s curl. d) Bad assembly of can and cover.

REMEDY a) Verify if the can is damaged before or after entering the seamer. If it is damaged before,

check can handling system and verify if the can enters properly in the filling machine (See “mushroomed can flange”). If the flange is damaged inside the seamer, check the timing of the cap (star or sections) feed system and of the passage system between can feed and seaming turret (chain pushers or sections). (See spare parts index and Instruction Manual of Your seamer). Check the cap guide rails to verify if they are properly aligned to let the can lift up without interfering with the flange.

b) Check the cover feeding system to verify if the damage is occurring at that point. Adjust the blades on the feeding screws (or other particular components of Your feeding system) in order to separate the covers smoothly. Normally if there is an interference damaging the cover curl, it is necessary to check the covers’ braking and all the feed and handling of the covers.

c) Check if the off seaming turning is sufficiently fast and easy. Check for broken seaming lever shaft spring and replace it if necessary.

d) See “Damaged flange”.


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INCOMPLETE SEAM

Second seaming operation is not completed. The thickness of the seam on either side of the

lap is more than the rest of the seam.

CAUSE REMEDY

a) Seam chuck is worn or a) Replace the seam chuck.

undersized for cover being used. To remove it, first unloose the

chuck using a drift and a

hammer in the holes ( check the

direction of the screw thread).

b) Height between cap and chuck b) Reset the height following the

too high for the can height. formula on next page:

If the incomplete seam

happens only on one seaming

station, check the height of the

cap as to the chuck. The height

tolerance between all caps must

be within 0.05 mm.

c) Lower chuck bearings are not perfectly c) Remove the lower plates and clean

spinning (in rotating can machines). the lower bearings. Lubricate with

fluid lubricant. If the bearings

are not spinning after having

cleaned them, replace them.

d) Insufficient pressure on the lower d) See parts index and instruction

lifter spring. manual of Your seamer.

e) Chuck radius does not match e) Replace chuck.

cover radius or chuck not

fitting perfectly the cover.

f) Roll bearing is jammed f) Replace the bearing.

preventing roll from rotating.

g) 1st

and 2nd

operation rolls too tight. g) Properly adjust the rolls.

h) Lower lip of 1st

or 2nd

operation h) Reduce lip diameter or use a

roll touching the can body. roll with a shallower groove.

i) Excessive vertical clearance of i) Replace seaming chuck spindle

seaming chuck spindle. bearing.

j) Oil or grease on the chuck or j) Clean.

cap.


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ALIMENTARY PRESERVES INDUSTRY SEAMERS

Example:

Factory finished can height

including cover mm 116.0 –

Chuck lip thickness* mm 3.2 +

Spring deflection mm 0.6 +

Can height decrease due

to the seaming operation mm 0.6 =

Total mm 4.4 4.4 =

Correct height between bottom of chuck’s 111.6

lip and lower chuck plate mm

CANNING INDUSTRY SEAMERS

Example:

Flanged can height

(only body) mm 116.4 –

Chuck lip thickness* mm 3.20 +

Spring deflection mm 0.60 +

Depth of the figure

obtained in lower chuck plate

(variable) mm 1.58 +

Can height decrease

due to the seaming

operation mm 0.60 =

Total mm 5.98 5.98 =

Correct height between bottom of chuck’s

lip and lower chuck plate mm 110.4

* The chuck lip thickness will vary

depending on the cover countersink depth.


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DAMAGED END CURL The end curl flattens in one or more spots folding back instead of clinching the body hook.

CAUSE

a) Covers damaged during handling or shipping. b) Maladjustment or imperfect timing of blades on feeding screws to the cover feed

turret. c) Improper alignment of cap guide rails. d) The 1st or 2nd operation roll fails to return to off position damaging the end curl while the end is lifted into the seaming position.

REMEDY

a) If the covers are shipped in tubes or bags, they can present damaged items on top and on bottom of the pile. The operator should check very carefully when feeding the cap storage and reject all the damaged ends. The operator must also take care when filling a new tube or bag in the store. If the new parcel of covers falls on the covers that are already stored, there can be damages in the curling of the bottom cover which stands on the feeding screws.

b) Check the alignment between seaming and cap feed turrets and that between can feed and discharge rails. The covers must be transferred to the cap pushers smoothly and without hesitation.

c) Align cap guide rails in order to centre the cover exactly above the can at the make-up point and also provide clearance over the curled cover for free movement during the separation and the delivery to cap guide rails.

d) Check if there is a good return to the roll’s off position. Also verify if the seaming lever springs are broken and replace them if necessary.


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KNOCKED DOWN CAN FLANGE

Condition similar to false seam.

CAUSE REMEDY

a) Can flange damaged in can a) Check the entire handling system.

handling system. Check if a “mushroomed flange”

occurs caused by filler or

in the can manufacture.

b) Cap guide rails out of alignment. b) Realign the guides to prevent

cover and can flange from

colliding.

c) Cap feed turret and can c) Time again the cap feed turret

feed chain pusher are and the can feed chain pusher

out of time with seaming to the seaming turret.

turret.

d) The 1st

and 2nd

operation rolls d) Check if there is a good return to

are slow returning to the off position, the roll off position.

letting the lower lip of the roll damage Verify if the seaming lever springs

the end curl and the can flange are broken and replace them if

while lifted into the seaming position. necessary.

e) Improper regulation of cap entering cam e) Reset the cam so that the

in the position of accompanying of the knockout shaft touch gently the

covers. cover while transferred

to the seaming chuck with the can.


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TRANSVERSE MISMATCHING BETWEEN CAN AND

COVER

A defective regulation or assembling of the equipment causes an improper alignment of

the can with the cover during the seam operation; as a consequence, the seam will be

completely disjointed on one side of the can.

CAUSE REMEDY

a) Wrong timing of the a) Time again can feed chain.

transfer of the can feed chain

to the seaming turret.

b) Wrong timing of the b) Time again cap feed star to

cap feed star to the seaming the seaming turret.

turret.

c) The cap feed guides and the can c) Realign the cap guide rails to

feed rail can be improperly aligned prevent cover and flange from

at the make up point. binding and regulate the can

guide of entry in order to leave

approximately 0.5 mm of clearance.

d) Improper setting of the extractor’s d) Adjust the cams or knockout rod

cams in the position of accompanying height.

of the covers or knockout rod height

e) Improper adjustment of cap e) The cover matching star must

guide rails with the cover matching star. release the cover curl when

cover is seated on seaming

chuck.

f) Improper adjustment of cap pushers f) Readjust placing cover

on the body flange and place

can body with cover in cap feed turret.

Adjust cap pushers to contact cover

curl diameter.


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DEFORMED CAN BODY

There are deformations under the finished seam. This normally occurs near the juncture but

can also occur all around the can.

CAUSE REMEDY

a) The 2nd

operation roll profile a) Set the 2nd

operation roll in order

is too low in relation to the chuck lip. to leave approximately 0.15 mm

between the roll groove and the upper

b) 1st

and 2nd

operation roll too tight. surface of the chuck lip.

b) Adjust the rolls.

c) The 1st

operation roll is too high c) Set the 1st

operation roll in order to

in relation to the chuck lip. leave at most 0.08 mm between the

roll groove and the upper surface

d) Lower lip under the groove of the 1st

of the chuck lip.

d) Reduce lower diameter of the roll

and/or 2nd

operation rolls is touching and replace it with one with a more

the can body. shallow groove profile.

e) Lower chuck bearings do not turn smoothly. e) Clean the bearings and lubricate

them with a fluid lubricant.


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MUSHROOMED CAN FLANGE

A mushroomed can flange is an overformed flange causing a long body hook. It is not

possible to detect this condition until the seam has been stripped to check the body and

cover hook.

CAUSE REMEDY

a)Excessive pressure of the lower chuck a) Reduce lower chuck spring pressure.

spring during manufacture of can

b)Lower chuck groove worn b) Replace with new lower chuck plates.

(only in the can manufacture).

c)Excessive lift cylinder pressure on c) Check lift cylinder pressure for correct

filler. pressure.

d)The can flange has been damaged in d) Check the whole can handling system.

can handling system.


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NORMAL 2ND OPERATION SEAM The 2

nd operation roll has the function to flatten the 1

st operation seam pressing the folds

of metal tightly enough to allow the sealing compound to fill the left spaces. The ideal condition for a 2

nd operation should be a well rounded seam with no sharps

on the top of the countersink and minimal Droop at juncture. Seam specification are normally set by every can manufacturer or by the quality control staff of each company. In any case, the thickness of the finished seam is normally 3 times the thickness of the plate in the cover + two times the thickness of the plate in the can body + a space of 0,07 to 0,15 mm ( for soft drink cans the space is 0,25 mm). The pressure ridge (which is a sign in the inner part of the can body around the cover directly opposite to the chuck) is caused by the pressure of the 2

nd operation roll and is

to be analysed carefully during the seam control. The visual inspection is the only way to determine a right pressure ridge. The pressure ridge has to be clearly visible in order to assure a good 2

nd operation seam.

Visual inspection is essential but not sufficient to determine the quality of the finished 2

nd operation.

A cross section of the 1st and 2nd operation made with proper profiles will show a good overlap with very small voids at each end of the hooks, filled with sealing compound.


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SEAM INTERNAL INSPECTION

PART C


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COUNTERSINK DEPTH CONTROL WITH

SPECIAL GAUGE


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COUNTERSINK TOO DEEP The countersink should have the same thickness of the chuck lip until a maximum of about 0.10 mm greater.

CAUSE a) Excessive backlash between the profile of the 1st operation roll and the

chuck lip. b) The chuck diameter is too large for can cover. c) The chuck lip thickness is too great. d) 1

st operation roll is worn.

REMEDY a) Readjust the 1

st operation roll leaving a maximum of 0.08 mm

clearance between the roll groove and the top surface of the chuck lip. b) Replace chucks. c) Replace the chuck with one of right thickness. d) Replace the 1

st operation roll.


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SEAM HEIGHT BEYOND MAXIMUM

If the 2nd

operation is too tight causing an excessive pressure on the seam, the metal is stretched and the seam increases its height determining bad hooks or a reduction of overlap. This seam tends to reduce the can’s sealing power especially at juncture.

CAUSE REMEDY

a) 1st

operation rolls are a) Replace the 1st operation roll. worn over the limit.

b) The groove of the 1st

operation b) Ask to the can manufacturer roll is loose. for right seam dimensions.

c) The regulation of the 2nd

operation c) Ask to the can manufacturer roll is too tight. for right seam dimensions.

d) The groove of the 2nd

operation d) Replace the 2nd operation rolls. rolls is worn.


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SEAM HEIGHT UNDER MINIMUM

If the 2nd

operation is too loose the seam could leak because the metal folds have not been pressed tightly enough and the sealing compound does not fill the vacuums left by the metal.

CAUSE

a) The groove of the 1st

operation roll is too narrow. b) The groove of the 2

nd operation roll is too great.

REMEDY a) Check the dimensions of the folded seam with

the can or cover manufacturer and determine the most appropriate.

b) Check the dimensions of the folded seam with the can or cover manufacturer determine the most appropriate.


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SEAM DISASSEMBLY AND CONTROL

There are many systems of controlling the seam such as those advised by the manufacturer or user of cans and covers; one way is the use of a special projector. This system only serves to check one cut section of the seam. The frequency of control depends on the standards of each company; however, random inspections should be made on each can for all seaming stations at least every four hours and as soon as the seamer warms up or after a short shut down. In addition, a complete inspection should be made after every jam up of the machine. In case a defective seam occurs in one head, it is necessary to control a second one from the same head before proceeding to the adjustment. In case of a big defect the seamer has to be carefully inspected before further controls. On high speed lines hundreds or thousands of scraps can occur if the machine is not immediately inspected and an action is not taken. In order to obtain good results form the control tests it is important to take note of all the measurements taken and to consider the results as a definite rule. In order to obtain a complete check the seam must be stripped and torn down as follows:


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WRINKLES IN THE COVER HOOK

A wrinkle in the cover extending to the body hook can be detected only after disassembling the seam for the control.

CAUSE REMEDY

a) 1st

operation roll is loose. a) Readjust the roll. b) 2

nd operation roll is loose. b) Readjust the roll.

c) 1st

or 2nd

operation profile is worn. c) Replace the 1st

or 2nd

operation roll. d) 1

st operation profile is too wide. d) Replace the 1

st operation roll with

another having a narrower profile. e) Improper curl in the cover. e) Call the cover manufacturer. f) Wrinkles or corrugations in the f) Call the cover manufacturer. panel or in the curl of the cover.

If there already are wrinkles in the cover panel before the seaming operation, they can not be stretched even if the 2

nd operation rolls

are tight.


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REVERSE WRINKLES

It’s a wrinkle that extends towards the lower part of the can body. The sharp edge of the reverse wrinkle can perforate the can causing a loss of product. This kind of wrinkle is formed during the 1

st operation and can not be stretched even setting a

tight 2nd

operation. Commonly the reverse wrinkles occur only in covers produced from double reduction (DR) plate.

CAUSE REMEDY

a) The 1st

operation roll a) Adjust the 1st operation correctly. is too tight.

b) Covers received with b) Discuss the problem with the manufacturer defective curls containing of the covers. wrinkles.


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JUMPED SEAM The seam presents a looseness following for approximately 13 mm after the cross-over. CAUSE a) 2

nd operation seaming cam spring too loose.

b) Seamer running at higher than designed speed. c) Excessive solder at side seam.

REMEDY a) Tighten the seaming cam spring screw until it is barely possible to turn the seaming cam

eccentric pin to the off seam position. This will make the preload so great that for all practical purposes the spring will not be caused to deflect further, even with excessive lap thickness. When seaming beer or soft drinks, a special solid spacer should be used to replace the seaming cam spring.

b) Reduce speed until the defect disappears. Call the can manufacturer.


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CROSS-OVER DROOPS

An extra thickness of the lap of side seam determines a slight deformation of cover hook in this point. This defect has to be corrected immediately.

CAUSE REMEDY

See “Droops” See “Droops”


37

SHORT COVER HOOK CAUSE

a) 1st

operation roll too loose. b) Deep countersink limiting the available metal for cover hook. c) 2

nd operation roll too loose.

d) 1st

operation roll groove profile worn. e) 1st operation roll groove profile too wide. f) Insufficient cover curl caused by too small cut edge diameter in manufacture of can

cover. g) Excessive lower lifter spring pressure. h) 1

st operation roll taper roller bearing or roll pin worn.

i) Seaming lever shaft upper and/or lower bushings in upper turret worn. REMEDY

a) Adjust the roll properly. b) See “Deep countersink”. c) Adjust the roll properly. d) Replace 1st operation roll. e) Replace 1st operation roll with one with a narrower profile.

f) Call the cover manufacturer. g) Reduce spring pressure (See “Long cover hook”). h) Replace pin or taper roller bearing. i) Replace worn lever shaft bushings.


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LONG COVER HOOK

CAUSE

a) 1st

operation roll too tight b) 1st operation roll groove profile too narrow. c) Excessive cover curl caused by too large cut edge diameter in manufacture of

can cover. d) Shallow countersink caused by worn or improper chuck. e) Short can body hook caused by insufficient lower lifter spring pressure.

REMEDY

a) Adjust 1st

operation roll. b) Replace the roll with one having wider groove profile. c) Call the can manufacturer. d) Replace chuck. e) Increase spring pressure to have a correct body hook.


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SHORT CAN BODY HOOK There is not enough material to form the body hook. This condition can be easily detected disassembling the seam. If this defect is not corrected there can be leaks.

CAUSE SPRING CUSHION DESIGN LOWER LIFTER SEAMERS

a) Insufficient base plate spring pressure. b) Excessive distance between chuck and base plate. c) Lower lifter spring broken or damaged. d) A long body hook in can shop ends may determine a short body hook in the cannery

end. e) Underflanged can bodies.

SPRING SOLID DESIGN LOWER LIFTER SEAMERS Incorrect height adjustment between seaming chuck and lower lifter base plate.

REMEDY a) Increase lower lifter spring pressure or replace with stronger spring. b) Readjust pin gauge height. c) Replace the lower lifter spring. d) Call the can manufacturer. A long body hook in cap shop is normally associated

with a damage of can body flange. See “e”. e) Call the can manufacturer. The seamer can not finish the flanging operation. f) Adjust the new height. (See remedy for “Long body hook”).


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LONG BODY HOOK There is too much material to form the body hook. This condition can be easily detected disassembling the seam. If this defect is not corrected, there can be leaks which cause product spoilage. CAUSE SPRING CUSHION LOWER LIFTER SEAMERS

a) Excessive lower lifter spring pressure. b) Inadequate pin gauge height between chuck and lower base plate. c) Mushroomed flange.

SPRING SOLID LOWER LIFTER SEAMERS

d) Inadequate pin gauge height between seaming chuck and lower base plate. REMEDY

a) Reduce lower lifter spring pressure or replace with a weaker one. A too long body hook can reduce the cover hook. b) Adjust pin gauge height properly. c) See “Mushroomed flange”.

d) Reset pin gauge height raising the upper seaming turret slightly higher than the can to be seamed. Put a seamed can into one of the seaming station and centre it. Lower the seaming turret until the lower chuck mandrel has compressed 0,5 mm. Remove can and run another through the seaming cycle. Always maintain 0,5 mm the lower lifter spring deflection during the seaming cycle.


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PRESSURE MARK

It should be a very clear impression around the inside of the can body which is made evident when the cover countersink is disassembled after stripping the seam for inspection. This is an important moment of the control. If there is not a pressure mark or if it is light, it indicates a loose seam even in absence of cover wrinkles. A pressure mark which is heavy at the bottom and light on the top may indicate a 2

nd operation roll groove profile not

adequate to the can or cover being seamed. When using tin plate can bodies and aluminium covers, the pressure mark can be visible only at the side seam.

CAUSE REMEDY

a) Inadequate adjustment of a) If the pressure mark is too light,

the 2nd

operation roll. tighten 2nd

operation roll. If it is too

heavy, loosen it.

b) 2nd

operation roll groove b) Replace the roll with one having

profile not correct. the adequate groove profile.


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