Buyer's guide
What to send with an injection mold RFQ
Most quotations get delayed by the same handful of missing details. This is what a mold maker actually needs to price your tool accurately — and what happens when each item is left out.
Why the quote depends on the data
An injection mold is quoted from geometry, not from a description. Two parts that look similar in a rendering can differ by a factor of three in tooling cost because one has an undercut that needs a slide and the other doesn't. When information is missing, a mold maker has two options: make an assumption, or ask. Assumptions produce quotes that change later. Questions produce delay.
The list below is ordered by how much each item moves the price. If you can only send three things, send the first three.
The ten inputs that set a mold price
| Input | Why it changes the price |
|---|---|
| 3D part data | Everything starts here. Wall thickness, draft, undercuts and parting line all come out of the model. STEP or IGES is ideal; STL works for a first look but can't be measured reliably. |
| Cavity count | The single biggest lever. A 4-cavity mold is not four times a single — it's typically 2–2.5×, and it changes the required press size. |
| Annual volume | Drives cavity count and steel choice. 20,000 parts a year and 2 million a year are different tools entirely. |
| Resin or alloy | Shrinkage differs by material, so the steel is cut to a different size. Glass-filled resins are abrasive and push you toward harder steel. |
| Expected mold life | P20 for a bridge tool, hardened H13 or S136 for millions of shots. This is a steel and price decision, not a detail. |
| Tolerances | General tolerances are cheap. A few tight features are fine. Tight tolerances everywhere multiply the finishing and inspection work. |
| Surface finish | SPI A1 mirror polish, a texture spec (MT/VDI number), or as-machined. Polishing hours are real hours. |
| Gate and ejector constraints | If certain faces must be free of gate vestige or ejector marks, say so up front — it can force a hot runner or a different parting line. |
| Runner type | Cold runner is cheaper to build; hot runner costs more up front and less per part. Volume decides which is right. |
| Press specification | If the mold will run on a machine you already own, its tonnage, tie-bar spacing and ejector pattern constrain the mold base. |
If you don't know some of these yet — that's normal, and it isn't a reason to wait. Send what you have and mark the rest as open. A mold maker can quote against sensible assumptions and state them, so you can see exactly what would change if an assumption is wrong.
The checklist
Filled boxes are what we genuinely can't quote without.
- 3D model — STEP, IGES, Parasolid or STLNative CAD is welcome too. One file per part.
- Target annual volume, or total quantityEven a rough range is enough to size the tool.
- Resin or alloyGrade if you have it — "ABS" and "PC/ABS 30% GF" lead to different tools.
- 2D drawing with critical dimensionsYou only need to dimension what actually matters. Mark the datum.
- Expected mold life in shotsOr just tell us the programme length and we'll work it back.
- Surface finish and textureSPI grade, MT or VDI number, or a photo of an acceptable reference part.
- Gate and ejector restrictionsWhich faces are cosmetic, which must stay clean.
- Colour and any secondary operationsPad printing, assembly, inserts, ultrasonic welding.
- Press details, if the tool runs on your machineTonnage, tie-bar spacing, ejector pattern, shot size.
- Where you want it builtChina, Vietnam, or either — this affects lead time and duty.
- Target price and target dateNot to negotiate against, but so we can tell you honestly whether it's achievable.
What you should get back
A quotation worth comparing states more than a number. Ours covers:
- Tooling price, with cavity count and steel specified
- Part price at the stated volume, so you can see the total cost of ownership
- Lead time to T1 samples, separately from lead time to shipment
- Any DFM issues we found — thin walls, missing draft, undercuts that need a slide
- The assumptions we made where your data left something open
That last point matters most when you're comparing quotes. A cheaper number that assumed a cold runner and 2 cavities is not competing with a higher number that assumed a hot runner and 4.
The five things that delay a quote
- A PDF instead of a 3D model. A drawing can't be sectioned, and wall thickness can't be checked from it.
- No volume figure. Without it, cavity count is a guess, and cavity count is most of the price.
- "Standard tolerances" on a part that has none. If a feature must fit something else, dimension it.
- Undercuts nobody mentioned. They're usually solvable, but they change the tool, so they're better raised on day one than after the quote.
- An assembly file with no indication of which parts you want tooled.
About sending files
An NDA is available on request before any file exchange — ask for it in your first email and we'll send one back the same day. Part data is only seen by the project engineer assigned to your enquiry.
If your CAD files are large, email them directly to [email protected] rather than using the web form, and mention the project name so they're matched to your request.
Ready to send yours?
A project engineer reviews every request directly — not a sales desk. The more of the checklist you can fill in, the sharper the quote comes back.
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