A custom injection molding quote arrives in 24 to 72 hours when the enquiry is complete, and takes two weeks when it is not. The difference is almost never the supplier's speed — it is whether the ten pieces of information below were in the first email.
This guide is the checklist we send to new customers, published so you can use it with any supplier.
Why quotes are slow
| What the buyer sends | What the supplier must do | Resulting delay |
|---|---|---|
| "We need this part, please quote" + photo | Ask for drawings, material, volume | 3 – 10 days of email |
| STEP file only | Model the tool, guess tolerances and material | 2 – 5 days, and the quote is provisional |
| STEP + 2D drawing | Price the tool and part | 24 – 72 hours |
| Full package (this checklist) | Price confidently | 24 – 48 hours, and the number holds |
The supplier is not being difficult. Without a drawing they cannot size the tool, without a volume they cannot amortise it, and without a material they cannot calculate the part cost. Every missing item becomes an email round trip.
The ten items to send
1. 3D model (STEP or IGES preferred)
| Format | Acceptable | Note |
|---|---|---|
| STEP (.stp) | Best | Universal, exact geometry |
| IGES (.igs) | Good | Older but reliable |
| Parasolid (.x_t) | Good | Common from SolidWorks/NX |
| STL | Poor | Faceted, no exact surfaces — used for rough quotes only |
| PDF / photo | Not sufficient for tooling | Fine for an early indication |
Ask the supplier to confirm the model opens and that draft angles are modelled in. A model without draft means the supplier must add it, which changes the part.
2. 2D drawing with tolerances
The 3D model gives geometry; the drawing gives tolerance, surface finish and critical features.
| Item to include | Why |
|---|---|
| General tolerance block | Sets the default |
| Critical dimensions marked | Sets where cost goes |
| GD&T where it matters | Position, flatness, profile |
| Datum features | Makes inspection repeatable |
| Surface finish callout | SPI grade or Ra |
| Cosmetic surface definition | Which faces are visible |
| Material and colour | Named grade, not "ABS" |
Our guide to tolerance specification covers how to write these so they can be inspected.
3. Material grade
"ABS" is not a material specification — it is a family. The grade decides the price:
| What to state | Example |
|---|---|
| Polymer and grade | ABS, medium-impact, injection grade |
| Brand if specified | LG HI-121H, or "equivalent" |
| Filled or unfilled | 30% glass fiber |
| Flammability | UL94 V-0 required? |
| Food contact | FDA / EU 10/2011 required? |
| UV stabilised | For outdoor parts |
| Colour | Standard, custom match, or masterbatch |
If you have no preference, say so — a supplier can recommend a grade and price it. What they cannot do is guess whether you need V-0.
4. Annual and monthly volume
| State | Why it matters |
|---|---|
| Annual quantity | Sets tooling amortisation |
| Monthly call-off | Sets cavitation and machine size |
| Order pattern | Even, seasonal, or one-off |
| Expected life of the programme | Sets tool life requirement |
A quote for 5,000 pieces a year and one for 500,000 are different tools, different cavitation and different prices. Giving only "we need a lot" makes the quote meaningless.
5. Surface finish and appearance
| Requirement | What to state |
|---|---|
| Cosmetic faces | Which surfaces are visible |
| Finish grade | SPI A-1 / A-2 / B-1 / C-1 / D-1, or Ra value |
| Texture | MT grade if textured (MT-11010, MT-11020) |
| Gloss | Target gloss units at 60° |
| Colour match | Standard chip, Pantone, or RAL |
| Acceptable defects | Written limits, not "no defects" |
6. Tool life and ownership
| Item | Options |
|---|---|
| Required shots | 100k / 500k / 1M / 5M |
| Steel class | P20, 718H, S136, H13 |
| Ownership | Buyer-owned (typical) or supplier-owned |
| Transfer terms | Can the tool be moved later? |
| Maintenance | Who pays, and to what schedule |
Tool life is a cost driver that buyers often forget to mention. A 100,000-shot tool and a 5,000,000-shot tool for the same part can differ by 50 percent in price.
7. Colours and decoration
| Item | Detail |
|---|---|
| Colour | Masterbatch, pre-compounded, or painted |
| Printing | Pad print, screen print, laser |
| Assembly | Clips, screws, ultrasonic welding |
| Inserts | Metal inserts molded in or installed after |
| Packaging | Bulk, bagged, boxed, palletised |
Every secondary operation adds cost and lead time, and none of them can be priced if unstated.
8. Quality and certification requirements
| Requirement | Why it changes the price |
|---|---|
| ISO 9001 | Baseline |
| IATF 16949 | Automotive — PPAP, traceability |
| ISO 13485 | Medical — validation, documentation |
| UL yellow card | Electrical — material must be listed |
| First article report | Inspection time |
| PPAP level | Documentation and sampling |
| Material certificates | Traceability |
Our guide to vetting a supplier covers how to verify these claims.
9. Delivery terms and destination
| Item | Example |
|---|---|
| Incoterm | FOB Xiamen / CIF Hamburg / EXW |
| Destination port or address | — |
| Required delivery date | First shipment and steady state |
| Shipping mode | Sea, air, rail |
| Packaging standard | Export carton spec |
FOB and CIF quotes differ by the freight, and a supplier cannot quote CIF without knowing the destination.
10. Anything unusual
| Item | Why to flag it early |
|---|---|
| Very thin walls (under 1 mm) | High injection pressure, special steel |
| Very thick sections (over 6 mm) | Long cycle, sink risk |
| Undercuts | Slides add tool cost |
| Threads | Unscrewing or collapsing cores |
| Optical requirements | Different tooling and process |
| Food or medical contact | Material and documentation |
| Existing tool to be transferred | Inspection and adaptation |
Injection molding quote request template
Part name:
Annual volume: Monthly call-off:
Material (grade): Colour:
Tool life required: Tool ownership:
Cosmetic faces: Finish / texture:
Tolerance class: Critical dimensions:
Secondary operations: Assembly:
Quality standard: Certificates needed:
Incoterm: Destination:
Target delivery:
Attached: STEP model, 2D drawing (PDF), reference photo (if any)Filling this in takes 15 minutes and saves two weeks.
What a good injection molding quote contains
| Line | Required | Why |
|---|---|---|
| Tooling cost, separate | Yes | One-off, must be visible |
| Cavitation and machine tonnage | Yes | Explains the price |
| Cycle time assumed | Yes | Checkable |
| Material grade and part weight | Yes | Checkable |
| Piece price at 3 volumes | Yes | e.g. 10k / 50k / 200k |
| MOQ | Yes | And what happens below |
| Lead time: tool | Yes | Separately from production |
| Lead time: production | Yes | — |
| Payment terms | Yes | 30/70, L/C, etc. |
| Packaging cost | Yes | Export carton is real |
| Tool ownership clause | Yes | Buyer-owned is standard |
| Quote validity | Yes | Resin prices move |
A one-line quote is not a quote. Ask for the breakdown — a supplier who will not provide one either does not know their own costs or is planning to recover margin later.
Common mistakes that delay quotes
| Mistake | Consequence |
|---|---|
| Sending only a photo | Supplier quotes a guess, then revises upward |
| Sending an STL | Geometry approximated, quote provisional |
| Saying "high quality" | No measurable requirement |
| No volume stated | Tooling amortised over an assumed number |
| No material grade | Supplier picks cheapest, part fails later |
| No cosmetic definition | Dispute at first article |
| No Incoterm | Price not comparable |
| Asking five suppliers with different info | Five incompatible quotes |
Timeline
| Scenario | Time to quote |
|---|---|
| Complete package, standard part | 24 – 48 hours |
| Complete package, complex tool or tight tolerance | 3 – 5 days |
| Missing 2D drawing | +3 – 5 days |
| Missing material or volume | +2 – 5 days |
| No 3D model | 1 – 2 weeks (design must be created) |
Our guides to injection molding cost explain how the numbers are built, mold cost covers the tooling side, common injection molding materials covers grade selection, supplier auditing covers due diligence, and writing an RFQ covers the documentation side.
Quote practice in this guide follows standard procurement workflow, with test and tolerance references from ASTM International and ISO, material data cross-checked against MatWeb and Engineering Toolbox, and processing practice reflecting Plastics Technology and PLASTICS industry standards, with material characterisation through SPE and NIST reference data.
What do I need to send to get an injection molding quote?
A STEP model, a 2D drawing with tolerances, the material grade, annual and monthly volume, cosmetic requirements, tool life, delivery terms and destination. With those, most suppliers quote in 24 to 48 hours.
Can I get a quote from a photo or a sample?
You can get an indication, but not a firm price. Without a 3D model the supplier must estimate geometry, and without a drawing they must assume tolerances. Expect the number to move once real data arrives.
What file format is best for quoting?
STEP (.stp) is the standard. IGES and Parasolid also work. STL is faceted geometry — acceptable for a rough indication only. PDF drawings are needed in addition to the model, not instead of it.
Why do suppliers ask so many questions?
Because each answer changes the price. Material grade, volume, tool life, tolerance and cosmetic requirements each move the tooling cost or the piece price by 10 to 50 percent. A quote without them is a guess.
How long should a quote take?
24 to 48 hours for a complete package on a standard part, three to five days for complex tools, and one to two weeks if the enquiry is missing drawings, material or volume.
What should a quote include?
Tooling as a separate line, cavitation and tonnage, cycle time, named material and part weight, price at three volumes, MOQ, lead times, payment terms, packaging and a tool ownership clause. A single number is not a quote.
Conclusion
A quote is a function of information: ten items in the first email and the price comes back in two days and holds; five items and it takes two weeks and moves twice. The template above is the whole method.
At Rui Cheng we quote from a STEP model plus a 2D drawing within 48 hours, with tooling and piece price separated, at three volumes, and with the resin grade and cycle time stated. Send the package and we will come back with a costed breakdown rather than a number.
