Why doesn't screw recovery add to the cycle?

Because it runs during the cooling timer, starting when hold ends. Only recovery that outlasts the timer adds time, and then every cycle grows by the overrun.

How far inside the cooling timer should recovery finish?

A common rule of thumb is 1 to 2 sec before the cooling timer ends. Routsis sets screw speed so recovery takes about 80% of the cooling time, after finding the feed zone temperature that recovers fastest.

Why is cooling time in this cycle longer than my cooling timer?

It counts pack and hold too, since the part cools from end of fill, plus any wait for screw recovery. Compare it with the mold cooling time estimate, which uses the same clock.

Where do I measure mold open, eject and close time?

At the press, from the start of clamp opening to clamp close complete, with ejection and part takeoff included. For a new mold, time a similar tool on the same press.

Injection Molding calculator

Injection Molding Cycle Time Calculator

Build a mold's cycle from its phase times and see whether it meets the cycle you quoted. You need the setup sheet timers, screw recovery time and mold open, eject and close time.

What this calculator does

Cycle time from fill, pack and hold, cooling and mold movement times, checked against your quoted cycle.

Formula used

Cooling phase = the longer of cooling timer and screw recovery
Cycle time = fill + pack and hold + cooling phase + mold open, eject and close
Shots per hour = 3,600 ÷ cycle time; versus quote = 3,600 ÷ cycle time − 3,600 ÷ quoted cycle
Headroom = quoted cycle − cycle time; recovery wait = screw recovery − cooling timer, if positive
Cooling time in this cycle = pack and hold + cooling phase

Inputs explained

Fill Time: Injection time to transfer, from the press monitor or setup sheet.
Pack and Hold Time: Hold timer, ideally set from a gate seal study.
Cooling Timer: Cooling timer setting, which starts when hold ends.
Screw Recovery Time: Recovery delay, plasticizing and decompression time, from the press monitor.
Mold Open, Eject and Close Time: Clamp open through clamp closed, including ejection and part takeoff.
Quoted Cycle Time: Cycle the quote or standard cost was built on.

How to use the result

Best suited to checking a new mold against its quoted cycle, spotting screw recovery that holds the mold shut.
Uses phase times you enter; get cooling from the mold cooling time calculator and hold from a gate seal study. Shots per hour is the machine rate; it excludes downtime, startup scrap and changeovers.

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

Why doesn't screw recovery add to the cycle? Because it runs during the cooling timer, starting when hold ends. Only recovery that outlasts the timer adds time, and then every cycle grows by the overrun.
How far inside the cooling timer should recovery finish? A common rule of thumb is 1 to 2 sec before the cooling timer ends. Routsis sets screw speed so recovery takes about 80% of the cooling time, after finding the feed zone temperature that recovers fastest.
Why is cooling time in this cycle longer than my cooling timer? It counts pack and hold too, since the part cools from end of fill, plus any wait for screw recovery. Compare it with the mold cooling time estimate, which uses the same clock.
Where do I measure mold open, eject and close time? At the press, from the start of clamp opening to clamp close complete, with ejection and part takeoff included. For a new mold, time a similar tool on the same press.

Related guides

Last reviewed 2026-10-01.