Every loom has a speed (RPM — picks per minute) and every quality has a pick density (PPI — weft insertions per inch). Together they tell you how much cloth the loom could weave in a shift if it never stopped. But looms do stop — a warp end breaks, the weft breaks, the beam is changed, the power goes. Efficiency = what was woven ÷ what could have been woven.
The formula
One metre of cloth takes PPI × 39.37 picks (1 metre = 39.37 inches). The loom inserts RPM × 60 picks an hour.
Efficiency % = actual metres ÷ possible metres × 100
Planned metres = RPM × 60 × hours × efficiency ÷ (PPI × 39.37)
If the loom's counter shows picks, it is simpler still: efficiency % = picks on the counter ÷ (RPM × 60 × hours) × 100.
Example
A loom runs at 600 RPM on a 50-pick quality, 12-hour shift. The shift gave 180 m of cloth.
- Possible picks: 600 × 60 × 12 = 4,32,000
- Picks per metre: 50 × 39.37 = 1,968.5
- Possible metres: 4,32,000 ÷ 1,968.5 = 219.46 m
- Efficiency: 180 ÷ 219.46 × 100 = 82.0%
Run the same loom at 85% and the shift gives 219.46 × 0.85 = 186.54 m. Put your own numbers into the Loom Efficiency calculator; for planning, the Loom Production calculator also gives metres per day and per month.
What a few points are worth
One loom runs at 75% (165 m a shift), another at 85% (186.5 m). The gap looks like only 21.5 m a shift. Over two shifts × 30 days it is about 1,290 metres per loom per month. In a 24-loom unit that is roughly 31,000 metres — without adding a single loom. That is why efficiency has to be watched shift by shift and loom by loom; the unit average hides it.
Common measuring mistakes
- Using the brochure RPM. Use the RPM set on the panel, and update it when a quality change brings a different speed.
- Counting hours differently. 12 hours one day, 11 after tea breaks the next — pick one rule and stick to it.
- Quality PPI vs actual PPI. If the pick setting differs from the quality, the weight changes and the efficiency figure is wrong.
- Leaving out fent. Fents and B-grade pieces were still woven — count them for efficiency, and look at them separately for quality.
Ways to raise efficiency
- Record why the loom stopped. Warp break, weft break, beam change, mechanic, power — a week's record shows where most of the time goes.
- Cut beam-change time. Have the next beam, drawing-in and droppers ready before the current beam ends. An idle loom is the biggest loss.
- Better warp. Even sizing and beam tension, few broken ends in the beam. Every warp break is a stop.
- Waterjet: clean water, filters and nozzle cleaning on time. Airjet: steady air pressure, hunt down leaks, compressor maintenance on schedule.
- Humidity and heat. Air that is too dry or too damp both raise breaks on a sized warp.
- Choose the right RPM. Higher RPM does not always mean more metres — if breaks rise, output falls. Find the speed that gives the most metres for each quality.
- Preventive maintenance. Oiling, belts, healds and reeds checked on a fixed day — don't wait for a breakdown.
- Shift handover. Looms shouldn't stand while shifts change; the incoming weaver should know what is running where.
Higher efficiency does not only add metres — it lowers the cost of each metre, because wages, rent and the fixed part of power are spread over more cloth. Work out power with Power cost per metre.
In Loomiro
In Loomiro the shift hours are entered once in Settings. Every Taka Entry records the metres against its loom, and the Loom page shows each loom's efficiency with a 30-day chart — RPM × shift hours against picks actually woven. The machine efficiency report puts every loom side by side, so you can see which one is falling behind. The dashboard also lists looms whose beam is about to finish, so the next beam is ready in time.
Loomiro works out efficiency from the metres in taka entries; it does not read the loom's counter directly yet. So taka entries need to be made daily, against the right loom.
Try yesterday's shift on one of your looms in the Loom Efficiency calculator.