Common Mistakes Before Sending a Product to Manufacturing
Quick Answer The most common mistakes before sending a product to manufacturing are: skipping a DFM review, using inconsistent or missing tolerances, choosing materials without checking manufacturer capability, underestimating assembly complexity, and sending incomplete drawing packages. Catching these issues before tooling starts can save weeks of delay and thousands of dollars in rework. |
Sending a product to manufacturing is a one-way door in many respects. Once tooling is cut, a production run is scheduled, or a supplier commits machine time to your part, changes become expensive and slow. Almost every costly manufacturing mistake follows a recognizable pattern - and nearly all of them are preventable with a structured review before files leave your desk.
Mistake 1: Skipping a Design for Manufacturability (DFM) Review
A DFM review checks whether a design can actually be produced efficiently with the intended process. Many companies skip this step because the design "looks finished" in CAD. But CAD software does not flag manufacturing constraints: undercuts that need expensive side-actions in a mold, wall thickness variations that cause sink marks, or machining features that require a fourth axis your supplier does not have.
Mistake 2: Inconsistent or Missing Tolerances
Drawings with tolerances specified on some dimensions but not others, or tolerances tighter than the function requires, both cause problems. Missing tolerances leave the supplier guessing; unnecessarily tight tolerances increase machining cost and reject rates without improving function.
Mistake 3: Choosing a Material Without Checking Manufacturer Capability
A material that performs perfectly on paper can become a sourcing problem if your chosen manufacturer does not regularly work with it, or if it requires a minimum order quantity that does not match your production volume. Confirm material availability with your manufacturer before finalizing the specification.
Mistake 4: Underestimating Assembly Complexity
A design that looks straightforward as an exploded CAD view can be unexpectedly difficult to assemble on a production line - parts that are hard to orient correctly, fasteners that require awkward tool access, or sub-assemblies that must be built in a specific, non-obvious sequence.
Mistake 5: Sending an Incomplete Drawing Package
Manufacturers quote and produce parts based on what is explicitly specified in the drawing package. Missing surface finish callouts, undefined critical dimensions, or absent material certification requirements all lead to either an inaccurate quote or a part that technically matches the drawing but does not meet the actual requirement.
Mistake 6: Not Building a Pre-Production Prototype to Validate the Final Design
Some companies move directly from CAD to full production tooling, skipping a final validation prototype after the last round of design changes. Even small late-stage modifications can introduce new fit or tolerance issues. A single pre-production sample is the last checkpoint before committing to tooling.
A Simple Pre-Manufacturing Checklist
DFM review completed for the intended manufacturing process
All critical dimensions toleranced, with a stack-up check on key assembly interfaces
Chosen material confirmed available at your required volume and lead time
Assembly sequence physically tested, even with a rough prototype
Drawing package includes 3D model, dimensioned drawings, BOM, and finish specifications
Final pre-production sample built and checked against the latest design revision
FAQ
What is the biggest cause of manufacturing delays?
Incomplete or inconsistent documentation is the most common cause - when a drawing package leaves dimensions, tolerances, or material specifications open to interpretation, manufacturers either pause to ask clarifying questions or proceed with assumptions that may not match what you need.
Can a DFM review be done after the design is finished?
Yes - the ideal time is after the design is functionally complete but before drawings are finalized and tooling is ordered. At this stage, changes are still relatively inexpensive to make.
Do small-batch or prototype runs need the same level of review?
The review can be lighter for small batches, but the core checks - tolerancing, material availability, and a complete drawing package - still prevent wasted time and cost even at low volumes.
Comments