What Should Be Reviewed When Changing Suppliers for a Custom Part?
When an existing custom part is moved to a new supplier, the review should cover more than whether the new supplier can reproduce the dimensions shown on the drawing.
Review the drawing and function-critical requirements, relevant manufacturing or inspection history, required quantity and transfer situation, and the verification needed for the new source.
The drawing defines the required part, but the previous supplier may have produced and controlled those requirements under particular manufacturing conditions. When the manufacturing source changes, those conditions may change as well.
Proven Part + Complete Drawing ≠ Automatic Source Transfer.
The manufacturing question is not simply whether another supplier can make the part, but what needs to be reproduced, controlled and verified as the part moves to a new manufacturing source.
What Should Be Reviewed When the Supplier Changes?
What Requirements Need Particular Attention?
The technical drawing remains the primary reference for dimensions, tolerances, material, surface requirements, heat treatment and other specifications.
Some requirements may also be particularly important to fit, positioning, motion, assembly, wear or another equipment function. If their importance is not obvious from the drawing alone, relevant application or assembly context can help identify where manufacturing and verification attention may be needed.
The drawing defines what the finished part needs to be. The new manufacturing source still needs to determine how those requirements will be produced, controlled and verified.
What Has Already Been Learned From Producing the Part?
An existing part may already have useful production history.
Previous inspection results, recurring production issues, sample feedback or relevant supplier comments can indicate which requirements have required particular attention.
This information does not replace the drawing, and the new supplier does not necessarily need to reproduce the previous manufacturing process. It provides evidence that may help avoid relying on assumptions during the transfer.
Does the New Supply Situation Match the Previous One?
The same part may be evaluated differently when the production situation changes.
A repeat-production part may now need a small qualification batch. A second source may initially supply a lower quantity. In other cases, the new source may need to support larger repeat quantities.
Required quantity can affect manufacturing approach, setup economics, material purchasing, secondary processes and inspection planning.
The part should therefore be evaluated for the quantity and sourcing situation that apply to the new source.
What Needs to Be Confirmed Before Repeat Supply?
Producing an acceptable sample or first batch is important, but the transfer may also require verification that relevant requirements can be controlled under the intended production conditions.
Depending on the part and project, this may involve dimensional inspection, material or treatment documentation, sample approval or other agreed verification.
The objective is not to add unnecessary inspection. It is to determine what evidence is appropriate before the new source becomes part of the repeat-supply route.
When Is a Supplier Transfer Worth a Closer Manufacturing Review?
A closer review may be useful when:
- an established part is moving to a new supplier or second source;
- the drawing is complete, but relevant production knowledge may remain with the previous source;
- the new supplier proposes a different manufacturing approach;
- the part has critical tolerances, surface requirements or function-sensitive features;
- previous production has involved recurring manufacturing or inspection issues; or
- the quantity or production stage will be different with the new source.
None of these situations means the transfer will necessarily be difficult.
They indicate that moving an existing part to another supplier may involve more than simply sending the same drawing to a new manufacturer.
What Is the Manufacturing Question During a Supplier Transfer?
A proven part already shows that the required component can be produced.
Supplier transfer creates a different question:
The drawing defines the required part. Relevant production history, quantity and manufacturing evidence can help determine what deserves particular attention during the transfer.
The purpose is not to reproduce the previous supplier's manufacturing process automatically.
A new supplier may use the same manufacturing approach or a different one. A different approach is not automatically better, and a different process does not automatically indicate a problem.
The question is whether the proposed approach can achieve, control and verify the requirements that matter for the intended part and project.
What Information Is Useful When Reviewing a Supplier Change?
The review can usually begin with two pieces of information:
When available, two additional types of evidence can also be useful:
Not every project will have all of this information.
Start with the drawing and current transfer situation. Additional evidence is useful when it helps answer a manufacturing question that could affect how the new source produces, controls or verifies the part.
Frequently Asked Questions
Is a complete drawing enough to change suppliers for a custom part?
It may provide most of the technical requirements needed to begin the review. Relevant manufacturing or inspection history can also be useful when it helps identify requirements that deserve particular attention during the transfer.
Does a new supplier need to use the same manufacturing process as the previous supplier?
Not necessarily. Different manufacturing approaches may be capable of meeting the same drawing requirements. The proposed approach should be evaluated against the part requirements, quantity and verification needs.
Should I send an existing sample when changing suppliers?
An existing production part or approved sample can be useful when available. It should support the technical drawing rather than replace the defined requirements.
What if I do not have information from the previous supplier?
The review can still begin with the technical drawing, required quantity and current transfer situation. The new manufacturer can review the available evidence and identify whether anything else needs clarification.
Have an Existing Custom Part That Needs a New Manufacturing Source?
If an established drawing-based component is moving to a new supplier or being qualified for a second source, start with the drawing and information that defines the current transfer situation.
We can review the available evidence from the manufacturing side to identify what needs to be reproduced, controlled and verified before the part is evaluated for a new manufacturing source.
Send Drawing for Manufacturing Review →