Calculate injection-moulding cycle time from wall thickness.
A moulded part's unit cost is dominated by its cycle time, and cycle time is dominated by cooling. ARCNM computes the cycle time from the part's wall thickness and its polymer. That covers cooling, injection and ejection. ARCNM recognises ribs and screw bosses as features formed in the cycle, not machined. It prices the part on your injection-moulding press across the lot-size grid.
At a glance
- Inputs
- STEP model of the moulded part; polymer from the drawing or material selection
- Machine classes
- injection-moulding machine of your fleet
- Standards applied
- ISO 1043 polymer designations · DIN 8580
- DfM checks
- rib thickness ratio, rib draft, boss parent-wall thickness, sharp internal corner, wall variation, undercut requires slide
- You get
- cycle time, cost per part on the machine, lot-size curve per environment for the moulded-vs-machined comparison
What do you get for a moulded part?
You get the cycle time for the part. Thicker walls make a longer cycle, and the polymer sets the pace. You also get the cost per shot on your press and the material line. You see the unit cost at every lot size. Thin, uniform walls are the single biggest lever. The result shows it: change the wall and the cycle time moves with it.
What about the mould tool?
ARCNM prices the moulding operation from the geometry: cycle time, press rate and material. Run the same part in a machining environment as well. Then lay your tool quote over the two lot-size curves to find the break-even quantity.
Which moulding features are recognised?
- Ribs and screw bosses, routed to the moulding cycle on a press and to milling on any other machine.
- Wall thickness from the 3D model, driving cooling time and DfM checks for thick sections.
- Polymer from the drawing's ISO 1043 code or your material selection, with the cooling behaviour of its family.
- Follow-on steps from the drawing as subcontract lines: painting and laser marking.
Moulding or machining — how the economics differ
| Injection moulding | CNC machining | |
|---|---|---|
| One-time cost | the mould tool | fixture and program (small) |
| Cost per part | seconds of press time + resin | minutes of spindle time + stock |
| Curve shape | steep — tooling dominates until thousands | flat — setup is spread over the first few dozen parts |
| Design levers | wall thickness (thick walls cool slowly), draft, uniform walls | setups, tolerances, removed volume |
| Break-even | in the thousands — once the tool is paid off per part | below that — there is no tool to pay off |
Read on
Frequently asked questions
Can ARCNM calculate injection-moulding cost from a STEP file?
Yes, when your machines include an injection-moulding press. ARCNM derives the cycle time from the geometry and prices the shot on that press.
Moulding or machining — where is the break-even?
Run the same part in an environment with a press and in one with machining centres. Each environment stores its own lot-size curve. The curves cross where tooling amortisation beats machining time. ARCNM shows both curves side by side.