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Stationery — pen bodies, caps, clips, sharpeners, correction-tape shells — is small precision molding at very high volume. Economics live on cycle time, cavitation and color consistency.
Pen caps and clips run in 16-64 cavity molds on high-speed machines. At that cavitation, one second of cycle time is worth thousands of pieces per shift — the same logic as thin-wall packaging.
| Issue | Cause | Control |
|---|---|---|
| Shade drift between shifts | Mixer time, temperature variation | Consistent dosing; stable barrel temperature |
| Streaks | Poor masterbatch dispersion | Mixing elements; back pressure |
| Contamination | Purging discipline | Written changeover procedure |
PS, PP and ABS dominate stationery. Small shot sizes demand precise injection control — a machine that is oversized for the shot runs unstable at tiny doses, which shows up as weight variation across the cavity set.
Stationery parts assemble without fasteners: snap fits, threads and press fits molded in. Tolerance across the whole cavity set matters — cavity-to-cavity variation shows up as caps that fit on some cavities and not others, which is a mold-steel and process-stability question.
Pen caps and clips commonly run 16-64 cavity molds on high-speed machines; at that cavitation, seconds of cycle time translate to thousands of pieces per shift.
Masterbatch dosing inconsistency and barrel-temperature variation. Consistent dosing and stable temperature control keep shades aligned across shifts.
An oversized machine at a tiny shot dose runs near the bottom of its control range. Matching the machine size to the shot weight stabilizes small-part molding.