Analyze · draft and mould halves
Draft analysis for STEP files
See which faces of a moulded part will slide out of the tool, which need more draft, and which are trapped — with the parting line drawn for you. Pick the direction the mould opens, or let PartCheck find it. Free, in your browser, nothing uploaded.
What it helps you catch
- Walls with too little draft, which drag on the steel, scuff and stick as the part is ejected.
- Undercuts — faces that cannot leave the mould at all without a side action or a lifter, each one adding tooling cost.
- The best way for the mould to open, before a toolmaker has to ask.
- Where the parting line will fall, so it does not end up across a cosmetic face.
What you see
- Positive draft
Drafted past your target angle: releases cleanly.
- Requires draft
Will come out, but with less draft than your target: the faces to add draft to.
- Negative draft
Trapped: cannot leave the mould in either direction. These need a side action, or a redesign.
- Parting line
Drawn where the two halves of the mould meet, with the direction the mould opens shown as an arrow.
The Tool halves map shows the same part another way: which half of the mould forms each face, which faces either half could form, and which neither can.
How to use it
- 1
Open your part and pick Draft
Drop a STEP file on the page, choose Analyze, then the Draft map.
- 2
Set the direction the mould opens
Auto finds the direction that traps the least. Or choose an axis, pick one of the alternatives PartCheck suggests (each shows how much it would trap), type a direction, or drag it round on the part.
- 3
Set your target angle
1° by default, adjustable up to 10° — for a textured surface, or a moulder who asks for more.
- 4
Read the figures
How much of the part is trapped or under-drafted, the average draft, and how many side actions the part would need.
- 5
Download the report
The Draft Analysis Report: the part from the front and from below, the opening direction, the parting line, the figures, and what the alternative directions would cost.
Good to know
Draft analysis reads the shape alone: it does not estimate ejection force or friction, and it does not know your surface finish. For a full check of the part against moulding rules — draft included — run the injection moulding DFM check.
Questions
What draft angle should I use?
PartCheck starts at 1°, a common minimum for smooth faces. Textured faces and deep walls usually need more — your moulder will say how much. Set the target to match.
Can it find the best direction for the mould to open?
Yes. Auto picks the direction that leaves the least trapped, and the alternatives are listed with what each would trap.
Does it work for die casting too?
Yes: any part pulled from a tool in one direction needs draft, and the map reads the same.
Is my file uploaded?
No. The analysis runs in your browser, and it is free with no account.
Try it on a real part
The demo is a moulded enclosure lid in two revisions, drawn in CAD. It opens in the tool with no files needed — or open your own STEP files. Nothing is uploaded: the analysis runs in your browser.