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Textile Costing · Lecture 23
Plant Machinery Analysis
Capacity of each machine in a finishing plant: speed, set-up time, efficiency, double passes and the share of fabric that visits it.
CapacitySet-up & efficiencyBottleneck
Capacity is speed × time × efficiency — and efficiency hides the set-ups
For a continuous machine the run of 10,000 m at 50 m/min takes 200 min, but each run also needs cleaning (30 min) and preparation and matching (60 min). The calculated efficiency is run time ÷ (run + set-up); subtract another 10% for miscellaneous losses. A machine that passes the fabric twice (double thermosol, dye + wash) has its capacity halved for that fabric. The plant’s overall capacity is the bottleneck.
| A | B | |
|---|---|---|
| 1 | Proposed run size (m) | |
| 2 | Speed (m/min) | |
| 3 | Production time for one run (min) | 200.0 |
| 4 | Average cleaning (min) | |
| 5 | Average preparation and matching (min) | |
| 6 | Set-up time per run | 90 |
| 7 | Calculated efficiency | 69.0% |
| 8 | Miscellaneous efficiency losses | |
| 9 | Net efficiency | 59.0% |
| 10 | Machines | |
| 11 | Capacity of machine (m/day) | 42,455 |
| 12 | Share of fabric needing a double pass | |
| 13 | Capacity adjusted for double pass (m/day) | 33,964 |
blue = input (edit me)grey = formula (click to see it)
The whole plant
| Machine | Speed m/min | Efficiency | Capacity m/day | Notes |
|---|---|---|---|---|
| Singeing, desizing, scouring & bleaching | 120 | 80% | 138,240 | one machine or split in two; long bleaching runs |
| Mercerizing | 50 | 80% | 57,600 (155,520 overall) | only 50/135 of the fabric is mercerized |
| Thermosol dyeing | 50 | 59% | 42,455 → 34,000 | 3,000 yd minimum run; double passes |
| Pad steam (dyeing + washing) | 70 | 57% | 57,571 → 46,000 | set-up 70 min |
| Stenter for dyeing | 50 | 59% | 42,455 → 34,000 | |
| Stenters for setting & finishing (2) | 90 | 80% | 207,360 ÷ 2.25 = 92,160 | double pass for all non-stenter-dyed fabric, sometimes after mercerizing |
| Printing | 50 | 67% | 48,185 | set-up 60 min; less for colour change, more for design change |
| Calendering | 70 | 80% | 80,640 (201,600 overall) | 40% of fabric |
| Sanforizing | 70 | 80% | 80,640 (161,280 overall) | 50% of fabric |
Overall: dyeing and printing capacity = continuous 34,000 + batch 10,000 + stenter-dyed 34,000 + printing 48,185 ≈ 126,000 m/day; finishing = 34,000 + 92,160 ≈ 126,000 m/day. The plant is balanced at about 126,000 m a day; the thermosol and stenter-dyeing ranges, at 34,000 each, are the lines to watch.