Industrial engineering calculator
Calculate the number of machines needed for each operation and by machine type from an operation breakdown, daily target, working hours and planned efficiency.
Machines required
18machines
| Operation | Machine | Exact | Allocated |
|---|---|---|---|
| Shoulder join | Overlock 4T | 1.25 | 2 |
| Neck rib join | Overlock 4T | 1.79 | 2 |
| Neck top stitch | Flatlock | 1.5 | 2 |
| Sleeve attach | Overlock 4T | 2.86 | 3 |
| Side seam | Overlock 4T | 3.21 | 4 |
| Sleeve hem | Flatlock | 1.96 | 2 |
| Bottom hem | Flatlock | 1.79 | 2 |
| Label attach | Single needle lock | 0.89 | 1 |
Machines for an operation = daily target × operation SMV / (working minutes × efficiency)
| Symbol | Meaning | Unit |
|---|---|---|
| Q | Daily target | pcs |
| SMV_op | Operation SMV | min |
| T | Working minutes per day | min |
| η | Planned efficiency as a fraction | - |
Minutes available per machine = working minutes × planned efficiency. For each operation, machines = daily target × operation SMV / minutes available per machine. Each operation is rounded up, then totals are grouped by machine type.
Defaults: a T-shirt with eight operations (total SMV 4.27), target 1,200 per day, 8 hours, 70% efficiency.
The gap between 15.25 and 18 shows the cost of rounding each operation separately. Look for operations on the same machine type that one operator can combine, such as shoulder join and neck rib join. Then confirm the layout with line balancing.
An operation that needs 1.25 machines in theory needs two machines unless it can share a machine with another operation. Review the rounded result and combine operations where the machine type and layout allow.
Many factories keep a small number of spares for breakdowns and style changes. Add them after the calculation.
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Line balancing spreads the operations of a garment across operators and machines so work flows at the target rate without piles of WIP or idle people. A practical step-by-step method with a worked example, balancing efficiency and common mistakes.
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How to set an hourly and daily production target from SMV, manpower, working minutes and planned efficiency. Worked examples for new and running styles, learning curve targets and why a target at 100% efficiency is not a real target.