From First Sample to Steady Supply
What the prototype stage is actually for
A prototype sample answers three questions at once: whether the cavity geometry fits the product and its tolerances, whether the chosen thickness and density protect the unit through handling, and whether the insert presents the product the way the unboxing or kitting process expects. A sample approved on looks alone tends to surface fit problems later, so the sample round should be handled with the real product in hand, not a mock block.
Drawings should state the material type, thickness, cavity depths and corner radii explicitly. When those values live only in an email thread, the production tool is reproducing an interpretation rather than a specification, and small drift between sample and run is almost guaranteed.
Handoffs that keep the run consistent
Between sample approval and production, three handoffs matter. First, the signed-off sample itself should be kept as the physical reference both sides compare against. Second, any change to the product enclosure — even a port move of a few millimetres — should trigger a drawing revision before the next batch, because cavities do not forgive unannounced revisions. Third, reordering should reference the approved sample number or revision, not a photo.
On recurring orders, receiving inspection can be light but should not be zero: check cavity positions against the master sample periodically and note compression set if foam has been stored long before use. Catching drift early costs a phone call; catching it at final assembly costs a line stop.
FAQ
Why approve a foam prototype with the real product?
Cavity fit, presentation and handling all depend on the actual enclosure dimensions and weight. Approving against a mock block hides fit problems that only appear at assembly.
What should a foam insert drawing specify?
Material type, thickness, cavity depths, corner radii and the revision number. If these values are only in emails, production is reproducing an interpretation instead of a specification.
When should an insert drawing be revised?
Whenever the product enclosure changes, even slightly. A moved port or added boss can make an otherwise correct cavity unusable.
How do we keep repeat orders consistent?
Reference the approved sample and revision on every reorder, keep the signed sample as the master, and periodically compare incoming batches against it.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.