When requesting quotations from die-casting suppliers in China, sending a 2D drawing and 3D model does not necessarily mean every supplier will quote on the same basis.
Does the quotation include machining? Is leak tightness required? Are there special cosmetic requirements? Is a new die required, or will an existing tool be transferred? If these conditions are unclear, different suppliers may make different assumptions.
A quotation that initially appears less expensive can therefore change during trial production when machining, inspection, tooling changes or additional operations are identified.
The purpose of a technical RFQ is not to fill the document with as many standards and numerical requirements as possible.
Its purpose is to define the conditions that materially affect manufacturability and quotation, so suppliers are evaluating the same scope.
The following sections explain the technical information worth defining before requesting a quotation for die-cast parts from China.
1. An RFQ Is More Than a Drawing Package
A quotation for a die-cast component depends on more than part geometry.
Typical information includes:
| RFQ Item | What to Define | Why It Matters |
|---|---|---|
| Part definition | 2D drawing, 3D data, revision | Geometry, dimensions and document control |
| Material | Alloy designation and applicable specification | Material and casting requirements |
| Manufacturing scope | Die casting, machining, finishing and other operations | Process and supplier scope |
| Functional requirements | Leakage, pressure, appearance or special characteristics | Process and inspection planning |
| Tooling | New/existing tool, ownership, maintenance and change responsibility | Tooling cost and production conditions |
| Quality & inspection | Critical characteristics, measurement and required submissions | Inspection and quality planning |
| Volume & logistics | Annual volume, lot size, packaging and delivery terms | Production and logistics assumptions |
Not every project requires every item.
The required information depends on the part, drawing and customer-specific requirements. The objective is to identify what matters for that particular quotation.
2. Align the 2D Drawing, 3D Data and Revision
A 3D model is useful for understanding geometry, but it may not communicate every manufacturing and inspection requirement.
A 2D drawing may define critical dimensions, datums, geometric tolerances, surface requirements and machining instructions that cannot be determined from geometry alone.
Before issuing an RFQ, check whether:
- the 2D drawing and 3D data are at the same revision;
- critical and functional dimensions are identified;
- machining datums are clear;
- as-cast and machined surfaces can be distinguished; and
- special cosmetic or surface requirements are defined.
When GD&T or casting tolerances are required, the objective is not simply to name a standard. The supplier needs to understand what the drawing actually requires.
Where a casting-tolerance specification such as ISO 8062-3 is applicable, the tolerance class should not be selected from the casting process alone. Drawing requirements, manufacturing method, subsequent machining and inspection conditions all need to be considered during the supplier’s feasibility review.
3. Define Both Material and Manufacturing Scope
“Aluminum die casting” by itself is not a complete material or manufacturing specification.
The RFQ should identify the alloy designation and applicable material specification required by the drawing or customer specification.
Materials from different standards should not automatically be treated as equivalent simply because their names or typical applications appear similar. Any proposed substitution requires project-specific review of composition, mechanical properties, functional requirements and downstream processes, together with customer approval where required.
The manufacturing scope also needs to be explicit.
For example, determine whether the quotation includes:
- tooling;
- die casting;
- trimming and deburring;
- shot blasting;
- machining;
- cleaning;
- surface treatment;
- assembly;
- inspection; and
- packaging.
This is particularly important when sourcing from China.
A casting-only quotation and a quotation for a finished component including machining and surface treatment are not directly comparable, even when both refer to the same drawing.
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4. Define Functional Requirements Through Actual Test Conditions
For pressure-tight housings and fluid-related components, requirements such as “no leakage” or “leak tight” are usually not sufficient by themselves.
Where applicable, define:
- test medium;
- test pressure;
- holding conditions;
- allowable leakage;
- sealing locations;
- the production stage at which testing is performed; and
- whether remedial processes such as impregnation are permitted.
These conditions depend on the application. There is no single universal leakage criterion or test pressure that can be applied to every die-cast component.
The same principle applies to cosmetic surfaces, finishing requirements and other special characteristics.
Whenever possible, the RFQ should make the acceptance condition understandable before quotation.
If the definition of an acceptable part is unclear, suppliers may differ not only in price but also in their assessment of manufacturability.
5. Define Tooling Scope Separately from Part Price
When a new die is required, tooling scope is part of the quotation and should be reviewed separately from the piece price.
Relevant questions can include:
- Is the project using a new or existing die?
- What is included in die design and manufacture?
- Is a specific die material required?
- Are there special slide, core or insert requirements?
- Which spare parts are included?
- Who owns the physical tool?
- Who is responsible for storage and maintenance?
- How are repairs and modifications handled?
- How are engineering changes costed and approved?
- What happens if the tool later needs to be transferred?
Tool life should also not be reduced to one universal number. It depends on factors such as part geometry, die construction, alloy, casting conditions, thermal load and maintenance.
Clarifying these responsibilities during quotation reduces the risk of discovering later that an expected tooling activity was outside the original scope. What the buyer should verify before authorizing tool manufacture is covered in what buyers should verify before tool release.
6. Define Quality Requirements Through Actual Acceptance and Inspection Needs
Listing ISO 9001, IATF 16949, PPAP or CMM in an RFQ does not by itself define product acceptance.
For critical characteristics, consider defining:
- which characteristics require specific control;
- at what production stage they are measured;
- the agreed measurement method;
- what evidence is required for initial approval;
- what records are required during production; and
- where process-capability evidence is required, what project or customer criterion applies.
Using a CMM does not itself guarantee product quality. Drawing datums, measurement strategy, measurement locations and evaluation methods need to be aligned.
Similarly, PPAP requirements should reflect the customer and project rather than assuming the same submission level for every component.
The objective is therefore not to list the largest number of quality standards.
It is to define what needs to be verified and under what conditions.
7. Volume, Lot Size and Logistics Also Affect the Technical Quotation
Annual volume is not only a commercial input.
Depending on the project, volume can influence decisions involving:
- die-casting machine selection;
- cavity strategy;
- automation;
- machining equipment;
- inspection approach;
- packaging; and
- production planning.
Where possible, the RFQ should therefore provide:
- expected annual volume;
- order or lot-size assumptions;
- prototype quantity;
- target start of production;
- delivery destination;
- packaging requirements; and
- applicable commercial terms such as Incoterms.
If volume is still uncertain, requesting quotations at more than one volume scenario can be more useful than forcing the project into one unsupported forecast.
8. What to Define — and What Not to Assume Universally
This distinction is one of the most important parts of a technical RFQ.
| Define or Confirm in the RFQ | Do Not Assume Universally |
|---|---|
| Alloy designation and applicable material specification | Automatic equivalence between different material standards |
| Critical dimensions, datums and drawing tolerances | A fixed CT grade based only on casting process |
| Actual leakage-test requirements | A universal test pressure or leakage limit |
| Required capability evidence for identified critical characteristics | One Cpk threshold for every project |
| Tooling scope and responsibilities | Universal die life, hardness or maintenance conditions |
| Required inspection and submission evidence | Mandatory CMM, X-ray or PPAP for every component |
| Volume, lot size and delivery assumptions | Comparing unit prices quoted under different volume assumptions |
With this distinction in place, the RFQ becomes more than a request for price. It becomes a common technical basis for evaluating manufacturability, scope and quotation assumptions.
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Conclusion
Reducing rework in China die-casting sourcing is less about sending more documents and more about defining the conditions that materially affect manufacturability and quotation.
A practical sequence is:
drawing and material → manufacturing scope → functional requirements → tooling → quality and inspection → volume and logistics
This makes missing information and differences in supplier assumptions easier to identify before quotations are compared.
It is equally important not to fill undefined customer or drawing requirements with generic numerical values simply because they are commonly seen elsewhere.
X-Diecasting Tech draws on approximately 20 years of die-casting production-engineering experience at a Japanese Tier-1 manufacturer, including mass-production launch, equipment introduction, tooling and fixtures, quality improvement and supplier support. In China, support can cover supplier verification, clarification of technical requirements, quotation review, and technical follow-up through trial and mass production. See how we support projects in China.
If you need China-side technical verification of RFQ requirements or manufacturing scope for a die-cast and machined-part quotation, you can share the drawing, annual volume, alloy, required secondary operations and the issues you would like to clarify. You can then discuss a drawing or sourcing project.
Frequently Asked Questions
Do I need both a 2D drawing and 3D data for a die-casting RFQ?
It depends on the project. A 3D model is useful for geometry, while critical dimensions, datums, geometric tolerances and machining instructions may be defined on the 2D drawing. The important point is that the supplier has enough controlled information to evaluate both manufacturing and inspection requirements.
How much should tolerance and leakage requirements be defined at the RFQ stage?
Requirements that materially affect function, manufacturability or quotation should be defined as early as practical. However, avoid selecting a fixed casting-tolerance class solely from the process or copying a generic leakage-test value. Requirements should come from the drawing, customer specification and actual product function.
Should tooling requirements be defined separately from the part quotation?
Yes, when new tooling is required. Clarifying die scope, ownership, maintenance, spare parts, engineering changes, repair and transfer responsibilities makes it easier to distinguish tooling assumptions from the quoted part price.