Maintenance, Safety and Workshop Practice
This domain tests preventive maintenance, breakdown measures, safe loom work and workshop discipline.
Core rules
- Preventive maintenance follows a schedule for lubrication, cleaning, belt and brake checks, reed and heald inspection, and stop-motion testing. Condition monitoring uses vibration, temperature and oil analysis.
- MTBF = operating time / number of breakdowns. MTTR = total repair time / number of breakdowns. Availability = MTBF / (MTBF + MTTR).
- Spare-parts control balances critical spares against capital tied up. Critical spares are those that stop the loom or create safety risk.
- Lockout/tagout isolates energy before cleaning, clearing jams or changing parts. Guards must not be bypassed for speed.
- PPE in the weaving shed includes hearing protection, safety footwear and eye protection where required. Noise, dust, lint and ergonomic strain are key hazards.
- 5S and housekeeping reduce fire risk, oil stains and breakdowns. Lint accumulation near motors and brakes is a fire hazard.
Worked example
A loom runs 450 h with 5 breakdowns and 25 h total repair time. MTBF = 450 / 5 = 90 h. MTTR = 25 / 5 = 5 h. Availability = 90 / (90 + 5) = 94.7%.
Traps
- Reversing MTBF and MTTR.
- Calculating availability as MTBF / total calendar time.
- Treating a guard bypass as a maintenance saving.
- Keeping no critical-spares list.
- Recording breakdowns without cause codes, so repeat faults are invisible.