Is my mold's Class 101 or 102 rating a PM interval?

No. Classes 101 to 105 rate a mold's expected lifetime, from over one million cycles for Class 101 to no more than 100,000 for Class 104. Set the PM interval from the moldmaker's maintenance points and your repair history.

Should PM be triggered by shots or by calendar days?

By shots, because wear follows cycles rather than days. A three-shift mold reaches its interval far sooner than a single-shift one, so this page converts shots left into production days.

What should I do when the order needs more shots than remain?

Pull the mold at the PM count and finish the order afterward, or split the order so PM falls between runs. Either way, book toolroom time for the day shown here.

Where do I get shots since the last PM?

Subtract the mold counter reading logged at the last PM from the reading now. Mold monitors such as Progressive's CVe display the tool's cycle count and can alert you when PM is due.

Injection Molding calculator

Mold Preventive Maintenance Shot Threshold Calculator

Find the shots and production days left before a mold's preventive maintenance, and whether PM lands mid-order. You need the PM interval, shots since last PM, cycle time and order size.

What this calculator does

Shots and production days left before a mold's PM, and whether it falls due before the current order finishes.

Formula used

Shots left before PM = PM interval − shots since last PM
Run hours to PM = MAX(shots left, 0) × cycle time (sec) ÷ 3,600
Production days to PM = run hours to PM ÷ press run hours per day
Shots to finish the order = parts left ÷ cavities, rounded up; shots to spare = shots left − shots to finish
PM interval used (%) = shots since last PM ÷ PM interval × 100

Inputs explained

PM Interval: From your PM plan or the moldmaker's stated maintenance point.
Shots Since Last PM: Mold counter now minus the reading logged at the last PM.
Cavities: Working cavities; blocked-off cavities do not count.
Parts Left on This Order: Good parts still to mold, plus your scrap allowance.
Cycle Time: Actual cycle from the press display, not the quoted cycle.
Press Run Hours per Day: Hours per day the press is scheduled to run this mold.

How to use the result

Best suited to booking toolroom time for a PM, deciding whether a mold can finish an order.
Counts shots only; a mold that starts flashing or sticking needs attention before the counter says so. Does not set the PM interval; that comes from your plan, the moldmaker or your repair history.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 280.569 (BLS, Aug 2026), up 6.6% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

Is my mold's Class 101 or 102 rating a PM interval? No. Classes 101 to 105 rate a mold's expected lifetime, from over one million cycles for Class 101 to no more than 100,000 for Class 104. Set the PM interval from the moldmaker's maintenance points and your repair history.
Should PM be triggered by shots or by calendar days? By shots, because wear follows cycles rather than days. A three-shift mold reaches its interval far sooner than a single-shift one, so this page converts shots left into production days.
What should I do when the order needs more shots than remain? Pull the mold at the PM count and finish the order afterward, or split the order so PM falls between runs. Either way, book toolroom time for the day shown here.
Where do I get shots since the last PM? Subtract the mold counter reading logged at the last PM from the reading now. Mold monitors such as Progressive's CVe display the tool's cycle count and can alert you when PM is due.

Last reviewed 2026-10-01.