Why the drawing decides the quotation
A foundry prices exactly what the drawing defines. When an item is missing, each supplier fills the gap with its own assumption, and the offers stop being comparable. The eight items below are what JK Casting checks during drawing review; putting them on the drawing first shortens that review.
1. Material grade and its standard
Write the full designation with its standard, for example “EN-GJS-450-10 per EN 1563”, “ASTM A216 WCB” or “HT250 GB/T 9439”, and the heat-treatment condition if one is needed. “Cast iron” or “steel” on its own cannot be quoted. Wrought grades such as 1045 on a cast part need a decision on the cast grade that replaces them. The gray iron, ductile iron and cast steel grade charts list common equivalents.
2. Machined surfaces and as-cast surfaces
Mark every machined surface with a machining symbol and state that all other surfaces stay as-cast. If you also have a raw casting drawing, keep it on the same revision as the finished drawing. Say whether you want raw castings for your own machining line or finished parts; JK Casting machines only the castings it supplies.
3. Datums
Show the datum features that locate the part, and use the same datums on the raw and finished drawings. The first machining operation locates on as-cast faces, so name the cast surfaces that may serve as starting datums.
4. Draft and fillets
Cast walls need draft so the pattern can be withdrawn from the mould, and internal corners need radii. Either specify draft angles and fillet radii, or add a note that they may be added by the foundry and show the faces where draft must not change a fit. If the drawing shows only the finished part, the draft, fillets and machining stock are proposed during drawing review and agreed with you before tooling is made.
5. Critical dimensions and tolerances
Mark the dimensions that control fit or function, and give a general tolerance note for the remaining as-cast dimensions. Tolerances are reviewed against the casting route and the machining plan before quotation, and the drawing governs.
6. Surface requirements
State the as-cast surface acceptance, the roughness of machined faces where it matters, any coating or galvanizing standard with its masking zones, and part marking.
7. Inspection and records
Name the dimensions to report on the first article, the material certificate required (for example EN 10204 3.1 when agreed for the order), any additional tests the part needs, and the records to send with each batch. The first article approval guide shows how these records are reviewed.
8. Quantity
Give the first batch, the expected annual demand and the repeat batches. Quantity decides the tooling, so it belongs on the RFQ with the drawing. One- or two-piece orders are rarely economical because a casting needs tooling first.
Drawing checklist
- Part number, drawing revision and date
- Material grade with its standard, and heat-treatment condition
- Machined surfaces marked; all other surfaces as-cast
- Datum features, the same on raw and finished drawings
- Draft and fillet radii, or a note on who adds them
- Critical dimensions and a general tolerance note
- Surface, coating and marking requirements
- Inspection, first article report and material certificate
- First batch, annual demand and repeat batches
Send the drawing for review, or prepare a housing enquiry with the machined housing RFQ worksheet.
Frequently asked questions
Can you quote from a drawing that is missing some of these items?
Yes. The first review can start from an incomplete drawing. The missing items are listed as open questions, and the quotation states any assumptions until they are confirmed.
Do you need a 3D model as well as the 2D drawing?
A 3D model helps the review, but the 2D drawing with its tolerances and notes governs. Send both if you have them, with the same revision.
Who adds draft and machining stock to the drawing?
If the drawing shows only the finished part, the draft, fillets and machining stock are proposed during drawing review and agreed with you before tooling is made.
What if I only have a sample and no drawing?
JK Casting can scan a sample and prepare a drawing for your approval before tooling is made. Critical fits are confirmed against the mating parts rather than copied from worn surfaces.