Do You Know The Five Key Characteristics of Injection Molds?

The Five Key Characteristics of Injection Molds – Do You Know Them?

1. Cavity and Core with Complex 3D Surfaces

The external and internal shapes of plastic parts are directly formed by the cavity and core. These complex 3D surfaces are difficult to machine, especially for blind hole inner surfaces in cavities. If traditional machining methods are used, not only are high-level technical skills required from workers, but also a large number of fixtures, tools, and longer processing cycles.

2. Specialized Division of Labor with Dynamic Collaboration

Mold production usually involves small batches — often one-off productions — yet molds require numerous standard components, ranging from mold bases to ejector pins. It is neither practical nor efficient for a single manufacturer to produce all these parts independently. The manufacturing process is complex, and the use of conventional and CNC equipment is often imbalanced.

3. High Precision, Surface Quality, and Long Service Life Requirements

Currently, general plastic parts have dimensional tolerances of IT6–7 and surface roughness of Ra0.2–0.1μm. Correspondingly, injection mold components must achieve tolerances of IT5–6 and surface roughness below Ra0.1μm. For laser disc recording surfaces, the roughness must reach mirror-level finish (0.02–0.01μm), which requires mold surface roughness to be below 0.01μm. Long-life injection molds are essential for improving efficiency and reducing costs, with current requirements typically exceeding 1 million mold cycles. High-precision molds require rigid mold bases, increased plate thickness, and additional support pillars or conical alignment elements to prevent deformation under pressure, where internal pressure can reach up to 100 MPa. The ejection system significantly affects part deformation and dimensional accuracy, so optimal ejection points must be selected to ensure uniform demolding. High-precision molds mostly adopt insert or fully assembled) structures, which demand higher machining precision and interchangeability of mold components.

4. Remote Design and Manufacturing

Mold making is not an end product itself. Instead, users provide final part designs, based on which mold manufacturers design and produce the molds. In most cases, the actual injection molding of the parts is carried out at different factories. This leads to situations where product design, mold design and manufacturing, and part production take place in different locations.

5.Long Process Flow with Tight Manufacturing Schedules

Injection-molded parts are often used together with other components to form a complete product. Frequently, other components are already completed while waiting for the arrival of the injection-molded parts. Due to strict shape and dimensional accuracy requirements, as well as differences among resin materials, repeated mold trials and adjustments are necessary after mold completion. As a result, development and delivery schedules tend to be very tight.