Many customers ask whether a single injection mold can run more than one plastic material. The short answer: it is possible, but only under strict conditions. Mold steel is one of the critical limiting factors.
READ MOREValve shut-off gates (valve gate hot runners) use a mechanical valve pin to open or close the gate on demand. Unlike open hot runners, which stay continuously open during production, valve gates provide active flow control. They are not a mandatory upgrade for every mold, but a specialized solution for specific molding challenges.
Typical scenarios where valve shut-off gates are required
When we quote an injection mold, surface finish and draft angle are two essential items that customers frequently inquire about. Mold surface treatment mainly falls into two categories: SPI polish finish and etched texture (graining). Different finishes carry different requirements for draft angle.
READ MOREMany overseas buyers ask the same question when they receive this two-shot handle sample: why one part of the handle is glossy and smooth, while the grip area delivers a fine matte soft-touch feeling?
Quite a few assume the matte texture comes from post-spray painting after injection molding. This is a common confusion in plastic surface finishing: in-mold texture vs post-treatment coating.
If you work with custom injection molded plastic parts, you have almost certainly seen a thin seam running along the edge of a component. This is the parting line (PL) — one of the most fundamental, and most misunderstood, features of injection molding.
Many buyers mistakenly think a parting line means the product is two separate pieces glued together. This is not true. The finished plastic part is molded as one single piece in one shot. The line simply marks where the two halves of the injection mold close and seal together before plastic is injected.
Plastic parts with undercuts cannot eject directly along the mold opening direction. Mold designers have three mainstream mechanical solutions: slides (side actions), lifters (angled ejectors), and collapsible cores. Many engineers confuse these three structures. This article explains their working principles, use cases, pros & cons, and selection logic for your DFM review and quoting.
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