Ejector and Drag Marks: T1 Sample Review Checklist

Virtually every molded part carries a trace of the ejection system. The buyer’s objective at the T1 trial is not to demand a traceless part, but to separate normal, stable witness marks from defects that signal tool interference, extreme ejection force, or cosmetic failure. Mark depth and location are largely determined during tool design; accepting an ambiguous mark at T1 sets it as the production standard.

Distinguishing Normal Witness from Tooling Issues

Buyers typically observe shallow circular marks at pin locations, raised or sunken outlines, linear drag scratches along the pull direction, or gloss circles telegraphing through to the opposite cosmetic face.

Over-force ejection vs. normal witness: Faint pin shadows are inherent. Deep impressions, localized whitening, or push-through gloss on the opposite face indicate that the part is being ejected before it is sufficiently stiff, or that the pins are undersized or poorly distributed, requiring excessive force.

Drag lines and interference: Linear scratches along the direction of draw typically mean the part is scraping over the steel. This points to a draft angle shortfall, a texture gripping the plastic, or a damaged cavity surface. Drag lines indicate tool wear and stress, not just a cosmetic blemish.

Pin condition: Marks that worsen over time or exhibit localized flash indicate worn pins or excessive pin-bore clearance.

Cosmetic face placement: Ejector marks located on A-surfaces generally mean the tool’s ejection layout was not reconciled with the buyer’s cosmetic specifications. At T1, relocating a pin or changing to a blade/sleeve ejector is still a viable (though costly) tooling change.

Questions to Ask the Molder at T1

When evaluating ejector marks, ask the supplier which marks they consider inherent to the tool and which they expect to improve with process tuning or polishing. If drag lines are present, ask whether they stem from texture grip, insufficient draft, or surface galling.

Determine if ejection can be staged, or cooling extended, to reduce impression depth, and establish what that would cost in terms of cycle time. If marks appear on a declared cosmetic face, request the specific tooling options available (e.g., pin relocation, polishing) to resolve it.

Evidence and Documentation to Request

Request a marked drawing or photo set that maps every visible mark on the T1 sample back to the tool’s ejection layout. Demand a written classification from the supplier dividing the marks into “inherent,” “process-tunable,” and “tooling-correctable.”

If cosmetic faces are impacted, require confirmation against the defined zones in your inspection standard. When fixes are implemented, mandate side-by-side comparisons of the post-fix samples against the T1 originals.

When to Withhold Mold Approval

Do not approve tools exhibiting drag lines or scratches without identifying the root cause; interference damages tools cumulatively. Delay approval if marks land on A-surfaces with no agreed-upon tooling remedy. Deep impressions accompanied by stress whitening or deformation signal a fundamental ejection-force issue, not a cosmetic one, and require process or tooling intervention before sign-off. Do not accept claims that a mark “will polish out” without a scheduled, verified polishing step.

Sourcing and RFQ Guidelines

To avoid late-stage disputes, declare cosmetic faces in the RFQ so the ejection layout is designed around them before steel is cut. Explicitly state that visible-face witness will be reviewed against the cosmetic standard at the mold trial. Ask bidders to detail how their tool-design review process reconciles ejector placement with defined cosmetic zones.

Disclaimer

PlasticsTechnologyAlliance.com is an independent buyer resource. It does not manufacture parts, design tooling, or certify suppliers. Which marks are inherent and which are correctable depends on the specific tool, confirm classifications and remedies with your supplier at trial.