In the world of injection molding, most parts are 100% plastic. But sometimes, plastic alone isn't enough. You need the strength of metal, the conductivity of copper, or the hardness of steel — but you also need the design freedom, light weight, and corrosion resistance of plastic.
That's where Insert Molding comes in.
Insert molding is the process of placing a metal component — a nut, a terminal, a bracket, or even a complex machined part — into the mold cavity before injecting plastic. The plastic flows around the metal, solidifies, and creates a single hybrid part that combines the best of both materials.
In the world of injection molding, size changes everything. But there is an even bigger leap: moving from standard molds to the extremes.
On one end, you have Large Molds—20-ton monsters that produce car bumpers and refrigerator liners. On the other end, you have High-Precision Micro Molds—tiny blocks of steel that produce medical catheters and watch gears, often smaller than a grain of rice.
Having looked at both extremes, one thing becomes clear: Large mold making is "civil engineering." Micro mold making is "micro-surgery." They share almost nothing except the name.
Here is a practical three-way comparison.
Many mold buyers and new mold engineers confuse rotary thread mold with 2K overmold (soft rubber overmolding mold) and common fixed injection mold. Actually, plastic thread unscrewing mold is an independent rotary injection mold structure, specially designed for plastic parts with internal & external screw threads, no manual thread stripping, no obvious parting line on thread surface.
Unlike TPE overmold mold (double-color rotary mold for non-slip handle), thread rotary mold focuses on automatic thread demolding via gear rotary system, which is widely used in daily packaging, industrial plastic fittings and consumer plastic products.
In the product design phase, wall thickness is often one of the most overlooked parameters. Many product managers and designers think: "A little thicker means a stronger product" or "A local thick area doesn't matter, it won't affect the look."
This is a dangerous misconception.
Uneven wall thickness—especially locally thick or thin sections—is one of the most common causes of part rejection in injection molding. It doesn't make your product fail immediately. Instead, it triggers a chain reaction: sink marks, warpage, voids, dimensional instability — and eventually, scrap.
Today, let's break down what uneven wall thickness really does to your parts, and how to avoid these pitfalls at the design stage.
The plastic filter disc is a small but critical component, often seen in kitchen appliances, industrial equipment, and daily household products. What makes it stand out is its dense array of tiny, evenly spaced holes—each a marvel of precision engineering. Today, we break down how injection molding brings these complex filters to life, and the key techniques that make mass production possible.
READ MOREOne of the first questions you'll face when designing an injection mold is: "How many cavities should this mold have?"
The answer isn't random. It's a calculated trade-off between production volume, equipment capacity, mold cost, and part quality.
And here's something that confuses many people: there's a big difference between a multi-cavity mold (identical parts) and a family mold (different parts in one mold).
Let me break it all down for you.
