Change cart and checklist
A cart brings the next mold, its hoses and its tools to the press before it stops, loaded from that mold's checklist.
| Cost | About $10,200 |
| Payback | About 6 months |
| Limitation | It saves nothing on a change where the next job is not known before the press stops. |
What changes
While the old job still runs, a cart brings the next mold to the press.
The same cart carries that mold's cooling water hoses, fittings and tools, picked from its checklist.
A mold too heavy for a cart waits on its pallet beside the press.
When the press stops, the swap starts at once and nothing is left to fetch.
What it costs and could save
- Six carts with hoses and tools, and a checklist for every mold, cost about $10,200.
- That could save about $20,300 per year, a payback of about 6 months.
Why it works
| Mechanism | - A press earns only while it makes parts.
- Fetching a mold, hoses and tools does not need the press stopped.
- It can be done while the old job still runs.
- Each minute of fetching moved ahead of the stop is a minute the press runs.
- The swap itself is not rushed, and the first parts are checked as they are today.
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| Math | - We count 15 minutes off each of 2,200 mold changes per year, which is 550 press hours.
- A freed press hour is counted at $55 when an order fills it, and we count 70 percent of them as filled.
- That is about $21,200 per year.
- Hoses, fittings and tools replaced on the carts take off about $900, which leaves about $20,300.
- Six carts and the checklists cost about $10,200 once, a payback of about 6 months.
- Each minute off a change is worth about $1,400 per year.
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| Industry evidence | - The standard method for shortening a change moves every task that does not need a stopped machine to before the stop.
- Published cases of injection molders that shortened their mold changes report cuts of 30 to 60 percent.
- Our 15 minutes is about a quarter of the median change here.
- Makers of clamps that need no bolts report a change of about a quarter of an hour on one press.
- The minutes for a ready cart alone are our estimate until one change is timed.
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| Limitations | - A freed press hour is money only when an order fills it.
- We count 70 percent as filled, because about one order in seven shipped late last year, so orders do wait for presses.
- If no order waits, the press only stands idle at another time and nothing is saved.
- We saw one change, on one press, and did not time it.
- The cart saves nothing on a change where the next job is not known before the press stops.
- The minutes come back if a shift stops loading the cart ahead.
- The job log's change times show it each week.
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Illustrative sample. The plant, the walk and the footage are synthetic.