common trouble shooting in stitching

Common Trouble Shooting

APRL 302

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In all cases, it is necessary to check the machine for

the correct settings. In most cases this will eliminate the fault

Faults may be due to numerous causes

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problem

machine

adjustment

mechanical

handling technical

Wrong specs.

Wrong thread

instructions

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Remember the key..

Machine

fabric

handling

thread

Pre process

attachment speed

needle

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1.Thread Breakage

One of the most common problems on a production floor

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Causes

Machine Handling Thread Needle Fabric Speed

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Mechanical

1. Thread channels jagged: check and polish all thread guiding parts. Check for correct thread, run according to operating instructions

2. Blunt, crooked or wrong needle type: insert new needle

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Thread break- Causes

3. Needle hole too small or excessively thick needle thread: fit throat plate with larger diameter hole or re-machine the needle hole. Use needle thread according to specifications. Observe relationship between needle and the yarn

4. Badly worn hook, sharp edges: fit new hook and adjust

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Thread break- Causes

5. Bobbin case tension too high, thread catches. Tighten screws sufficiently- if this creates an excessive tension, slightly bend the check spring

6. Thread clearance between bobbin case support and hook inadequate. The clearance should be enough to allow the thickest thread gauge to pass through smoothly

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Thread break- Causes

7. Hook, bobbin case top and bottom sections nicked by needle: polish or use new parts.

8. Thread clearance insufficient between hook bottom and bobbin case bottom.

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9. Needle hole nicked(damaged) by needle: lightly trim the edges, polish the needle hole. If necessary fit new needle plate

10.Hook catches the needle loop too late or too early: adjust hook or loop lift

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Handling by operator

1. Faulty threading: check thread run according to operating instructions

2. Needle threaded from the wrong side: always thread the needle from the long groove side.

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Thread break- Causes

3. Needle too high: adjust the needle height

4. Needle too low-insert needle as far as it will go: observe operating instructions

5. Sewing without bobbin’ even break the needle

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Thread break- Causes

5. Excessive tension: adjust tension according to the material being sewn. Observe operation instructions

6. Excessive bobbin thread tension: adjust tension according to operating instructions

7. Pulling fabric for fast feeding Train operator

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Needle

1. Bent or damaged needle

2. Hot needle –use high grade needle/air coolers

3. Liquefied lubricant jammed or clogged needle hole

4. Wrong needle

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Thread

1. Wrong relationship between needle and thread. Observe specifications and only use good quality thread

2. Knotty or brittle thread: only use good quality thread of specified thickness and twist

3. Heat up and break due to Insufficient lubricant

4. Low elastic thread

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Fabric

1. Tightly woven fabric, jamming not allowing stitch to form

2. Synthetic fabric sticky due to hot needle does not allow thread to pass

3. Thick layer of fabric –too high friction

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Speed

Should not be a reason as speed increases productivity

High speed increases friction hence heat, weaken thread.

High SPCM

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2.Needle Breakage

1. Wrong hook setting: adjust hook according to specifications.

2. The needle is bent and clears the hook point: fit new needle.

3. Needle too small for the needle hole or material.

4. Needle protection during its cycle.

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Needle break- Contd

5. Wrong needle to thread ratio: observe specifications

6. Knotty or uneven thread: only use good quality thread

7. Needle breaks on entering into the material: feed wrong in relation to needle position

8. Bobbin case incorrectly fitted: press in bobbin case until it clicks into place

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Needle break- Contd

9. Throat plate incorrectly fitted: lightly tighten throat plate set screws in a diagonal sequence and then tighten firmly

10.The material is pushed or pulled during sewing: check needle seats, guide more lightly

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Needle Break- Contd

11.Feeder too high: move material along during its forward movement or back feeding: adjust feed dog height

12.Feed dog timing incorrect: adjust feed dog

13.Hook worn: fit new hook

14.Needle drops out during sewing: fit new needle screw in needle bar

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Needle Break- Contd

15.Needle bar excessively worn: fit new needle bar or bush

16.Excessive thread tension, needle bends and is caught by the hook point: set correct tension to suit sewing material: see operating instructions

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3.Slip Stitching

1. Needle wrong, bent or incorrectly fitted: fit new needle. For correct fitting refer to operating instructions

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Slip stitch- Contd

2. Faulty threading.

3. Observe thread run according to operation instructions.

4. Faulty take up: adjust take up spring.

5. Wrong hook setting: set up properly.

6. Needle thread ratio incorrect: use needle system.

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Slip stitch- Contd

7. Hook point damaged: polish or insert new hook.

8. Needle hole is too large and material is drawn in: use throat plate having a smaller needle hole- observe purpose of the machine.

9. Needle too low: fit needle as specified in operation instructions.

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Slip Stitch- Contd

10.Needle too high: alter needle bar height

11.Poor needle quality: use good grade needles

12.Insufficient presser bar pressure - with thick materials the needle raises the material: adjust presser bar

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Slip Stitch- Contd

14.Right-hand twisted thread: left-hand twisted thread should be used in most machines.

15.Hook catches thread loop too early or too late: adjust loop lift according to instructions.

16.Insufficient or excessive tension: adjust the tension to suit the material to be sewn, in accordance with operating instructions.

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Slip Stitch- Contd

17.The thread ‘twirls’, irregular loop formation. Thread too sharply twisted: only use good quality thread with the indicated gauge and twist.

18.Thread unevenly thick and brittle: do not use thread, which has been stored too long under dry conditions. Only use good quality thread in the indicated gauge and thickness.

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Slip Stitch- Contd

19.Needle too far from hook point: adjust clearance between needle and hook point.

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4.Uneven Seams- Stitch Patterns

Here, faults may be caused in the same manner as indicated under ‘thread breakage’ and ‘slip stitches’.

Looping of threads above or below the material: adjust needle and bobbin thread tension according to operating instructions.

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Uneven Seams- Contd

Poor and knotty thread: only use good quality thread. For gauge and twist see instructions.

Forward and reverse stitch of different length: observe adjustment instructions.

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Uneven Seams- Contd

Hook has run out of oil. Guide groove rough, bobbin case on edge: observe oiling details in operating instructions. Fit new hook and adjust.

Faulty threading: observe thread run according to operating instructions.

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Uneven Seams- Contd

Tensioning discs dirty, fouled or sticky: clean components and, if necessary, re-polish. All parts should be able to move freely.

Thread-guiding components rusty or rough: remove rust and re-polish.

Thread take-up incorrect: adjust take-up spring. (Adjust resilience according to material thickness).

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Uneven Seams- Contd

Needle too high or too low: fit needle according to operating instructions or adjust needle bar height.

Thread fails to pass smoothly over hook: re-polish all thread contact points. Observe settings.

Feed dog setting wrong: set to feed dog figures given in instructions.

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Uneven Seams- Contd

Fouled hook. Hook prevented from rotating evenly: clean hook. Observe setting.

Machine sews in curve: check feed dog position. Check contact of presser foot on feed dog.

Bobbin irregularly wound, wrongly inserted or threaded: re-wind, insert and thread according to operating instructions.

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Uneven Seams- Contd

Machine fails to sew over seams and folds: incorrectly set presser foot pressure. Adjust feed dog height. Set presser foot pressure to suit material thickness according to operating instructions.

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Uneven Seams- Contd

Coarse feed dog teeth ruffle the material: use correct feed dog teeth as specified by the manufacturer. For thin, lightweight materials use fine-toothed feed dog. Coarse and saw-tooth type feed dogs should be used only for such material for which they have been intended. (Observe the setting.) (Feed dog follow-up movement).

Irregularly wound bobbin thread: when winding up, make sure that the threads lie adjacent to one another.

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5.Oil leaks or Insufficient oil

Machine loses oil on hook regulation screw: Simme ring not tight. Replace Simme ring.

Oil feeds despite throttled regulation screw: check conical part of regulation screw for unevenness.

Oil leaks on hook shaft, hook drive shaft and feed shaft: check and replace Simme rings.

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Oil leak- Contd

Too much oil in the sump of the head. Oil pipe damaged: check and replace oil pipe.

Oil leak on hand wheel. Too much oil supply to rear arm shaft bushing: seal wick in supply pipe with additional piece of felt.

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Oil leak- Contd

Grooves of hook drive shaft insufficiently or not oiled. Oil shield faulty: adjust, mouth of oil shield must be exactly above oil hole of bushing.

No oil supply to control window (oil rise pipe): adjust clamp and hose.

Hook not lubricated: regulate oil supply according to instructions.

Front bushing without oil. Spray lubrication missing: adjust lubrication according to instructions.