Needle fragment injury on an overlock with the guard removed
In a job-work unit of 40 overlock machines, an operator on a 4-thread overlock running at 6,000 stitches/min was finishing a knit order. The needle guard had been removed six months earlier because it slowed down threading. No eye protection was worn. The needle broke and a fragment struck the operator 5 mm below the eye; she was treated at a clinic and returned the next day. Investigation found: no needle issue or return register, no record of when or why the guard was removed, no eyewear in the unit, cut thread and fabric waste on the floor near the machine, an exhaust that has not been cleaned for months, and a shift of 10.5 hours with one 30-minute break. Three operators on the same row complained of wrist and neck pain. The owner says the answer is simple: buy goggles for everybody and finish the order.
1. Sort the findings into immediate causes, contributing causes and root causes, and rank the hazards by risk. Explain the ranking.
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Immediate cause of the injury: a needle broke at 6,000 spm with no guard fitted, and the fragment travelled to face height.
Contributing causes: no eye protection; needle breakage going unrecorded, so nobody knew the machine had a breakage pattern; high speed combined with possibly wrong needle size or point for the knit, which increases breakage; poor housekeeping allowing fragments to travel on the floor and fabric.
Root causes (the ones that will produce the next injury):
- A guard could be removed and stay removed - no permit, no inspection, no accountability for machine safety devices.
- No needle control system (issue, return, breakage record, fragment reconciliation).
- No PPE standard and no enforcement.
- Production pressure accepted as a reason to remove a safety device - a management norm, not an individual fault.
- Fatigue and ergonomic load: 10.5 hours with one break, plus wrist and neck pain reported by three operators.
- Neglected exhaust and housekeeping - respiratory and slip/trip risk.
Risk ranking: needle fragment to the eye is highest (severe harm, high probability at 6,000 spm with no guard); then unguarded moving parts and belt/pulley contact; then musculoskeletal disorders (high probability, cumulative); then respiratory exposure from the uncleaned exhaust; then housekeeping as an aggravating factor for all of them.
2. Set out the controls in the order of the hierarchy of control, with the specific action, the responsible person and how each control is verified.
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Elimination/substitution
- Review needle size and point for the knit and reduce machine speed to the process capability (for example 5,000 spm); lower speed reduces needle breakage, which removes the source of the fragment. Verified by breakage count per 1,000 pieces before and after.
Engineering controls
- Refit the needle guard on all 40 machines - this is the single highest-value action, because it stops fragments at the source. Verified by a machine-by-machine checklist signed by the mechanic, plus a monthly spot audit of 10 machines.
- Fit or repair the exhaust and set a cleaning schedule. Verified by a dated cleaning log and a visual check.
Administrative controls
- Needle control register per machine per shift: count out, count in, record every break, reconcile fragments before a new needle is issued.
- A written rule that safety devices are removed only under a documented permit signed by the owner, with the machine locked out until the device is back.
- Shift and break review: cap at 8-9 hours with the statutory breaks, and rotate tasks.
- Training and a short assessment on the broken-needle procedure and machine guarding.
PPE
- Impact-rated eye protection for all operators and for anyone in the machine rows, with replacement lenses available; goggles alone are the last line, not the answer.
Medical/ergonomic follow-up: posture and table height check, and referral of the three operators with wrist and neck pain.
3. The owner insists that goggles for everyone are enough. Write the response you would give, including how you would communicate the change to a workforce that fears lost earnings, and what records you would keep.
Read the worked answer
To the owner, plainly: goggles protect the eyes but they do not stop needles breaking, and they do nothing for a fragment that lands in a finished garment, in a bundle or on the floor. A guard costs a fraction of one claim and does not slow production once operators are trained to thread with it in place. If a fragment ships in a school uniform, the cost is a recall, not a clinic visit. The guard, the needle register and the eye protection are one package; any one alone leaves the risk open.
Communicating to the workforce - the fear is lost earnings, so address it with numbers and with their involvement:
- Explain in the local language, on the floor, with the broken needle and the guard in hand: what happened, what changes, what does not change (the piece rate and the shift pattern).
- Involve the operators in the guard refit: let the fastest operator on each row test the guarded machine and report the time difference, so the claim that it slows threading is tested, not assumed.
- Make reporting a near miss or a needle break a normal, blameless act with a named person to report to; a register that gets someone punished will be empty within a week.
- Ask the three operators with wrist and neck pain what would help and act on one item immediately, so the consultation is visibly real.
Records Machine safety checklist per machine with dates; needle issue and breakage register; permit for any safety device removal; PPE issue sheet; training attendance and assessment; housekeeping and exhaust cleaning log; near-miss reports; the incident report and clinic record for this injury; monthly audit results. Keep them for at least the period the buyer's code of conduct and the factory's own policy require, and make them available for buyer or inspector review.