What hydraulic pressure do I set after moving the mold to another press?

Divide the plastic pressure by the new press's intensification ratio. The default 17,667 psi plastic needs 1,500 psi hydraulic at 11.78:1 but only about 1,202 psi at 14.7:1.

Where do I find the intensification ratio?

Check the machine manual first. Otherwise divide the maximum injection pressure for your screw diameter by the maximum hydraulic pressure, or read both off the machine's pressure graph. An all-electric press reads plastic pressure directly, so use 1:1.

Why is the default use limit 80% of maximum?

Autodesk Moldflow Adviser turns fill confidence yellow when pressure drop passes 80% of the maximum machine injection pressure, and red at 100%. Change the limit if your plant works to its own rule.

Why is cavity pressure so much lower than this?

The melt loses pressure through the nozzle tip, sprue, runner and gate, and the further it flows from the barrel the lower it gets. Only sensors in the mold measure cavity pressure.

Injection Molding calculator

Injection Pressure Calculator

Convert the peak hydraulic pressure on a press monitor into plastic pressure, and see how close fill runs to the press maximum. You need the reading and the press spec sheet's maximum hydraulic and injection pressures.

What this calculator does

Plastic pressure at the nozzle from a hydraulic press reading, and how much of the available injection pressure the fill uses.

Formula used

Intensification ratio = maximum injection (plastic) pressure ÷ maximum hydraulic injection pressure
Peak plastic pressure = peak hydraulic pressure × intensification ratio
Share of maximum used = peak hydraulic ÷ maximum hydraulic × 100; reserve = maximum plastic − peak plastic
Peak plastic pressure in bar = psi × 6,894.757 Pa per psi ÷ 100,000 Pa per bar
Hydraulic peak at your limit = maximum hydraulic pressure × use limit % ÷ 100

Inputs explained

Peak Hydraulic Injection Pressure: Highest first-stage pressure on the press monitor, in hydraulic psi.
Maximum Hydraulic Injection Pressure: Maximum machine hydraulic pressure for injection, from the spec sheet or manual.
Maximum Injection Pressure for This Screw: Plastic (specific) pressure for your screw diameter, from the press spec sheet.
Pressure Use Limit: Highest share of maximum pressure you accept; Moldflow flags above 80%.

How to use the result

Best suited to moving a mold to a different-ratio press, checking whether short shots are pressure limited.
Gives pressure at the nozzle; the nozzle tip, sprue, runner and gate use part of it before the cavity. A pressure limit set below the press maximum in your process caps fill sooner.

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

What hydraulic pressure do I set after moving the mold to another press? Divide the plastic pressure by the new press's intensification ratio. The default 17,667 psi plastic needs 1,500 psi hydraulic at 11.78:1 but only about 1,202 psi at 14.7:1.
Where do I find the intensification ratio? Check the machine manual first. Otherwise divide the maximum injection pressure for your screw diameter by the maximum hydraulic pressure, or read both off the machine's pressure graph. An all-electric press reads plastic pressure directly, so use 1:1.
Why is the default use limit 80% of maximum? Autodesk Moldflow Adviser turns fill confidence yellow when pressure drop passes 80% of the maximum machine injection pressure, and red at 100%. Change the limit if your plant works to its own rule.
Why is cavity pressure so much lower than this? The melt loses pressure through the nozzle tip, sprue, runner and gate, and the further it flows from the barrel the lower it gets. Only sensors in the mold measure cavity pressure.

Last reviewed 2026-10-01.