How to select Injection mold steel? - Cars & Trucks

There are numerous reasons that may affect the quality of the plastic products in the process of plastic injection mould few are given below
Plastic materials the difficulty of plastic materials' presentation determines the complexity of the injection mould process. The performance of plastic materials differs greatly due to their different grades, varieties, manufacturers or even changed batches. Different performance parameters may lead to completely changed mouldings.
Injection Temperature is also one reason: The melt flows into the cooled cavity and losses its heat due to heat conduction. At the similar time, the melt generates heat due to shearing action, and this part of the heat may be more or less than the lost heat produced by heat conduction, which depends on the injection conditions. The viscosity of the melt becomes worse with the increasing of temperature. In this way, the higher the injection temperature is, the worse the melt viscosity becomes and the smaller the required filling pressure needs. Meanwhile, the injection temperature is also limited by the thermal decomposition temperature and degradation temperature.
Mould Temperature: The lower the mould temperature is, the faster the heat loses, due to the heat conduction; the lower the melt temperature is, the worse the mobility becomes. This phenomenon is particularly obvious when we adopt a lower injection rate.

There are many kind of steel: for long runs production, a durable mold is required, the tool steel must be selected properly; for small volume production, steel selection can be as economic as possible as long as it meet the requirement of production demands.
How to choose the injection mold steel? Important steel properties include:
Ease of machining
Dimensional stability after heat treatment
Wear resistance
Surface finish
Corrosion resistance

Mold steel we selected frequently are 1.2344, 1.2343, 1.2312, 1.1730, H13, S136, 2083, etc. Normally we categorized them as pre-harden steel or harden steel. Pre-harden steel can be machined and used directly after purchase, harden steel required heat treatment during process, the machining take longer time, injection mold made by harden steel usually have long service life.

Corrosion resistant hardened steels should be selected when conventional flame retardants are used. In the case of halogen free flame retardant DSM thermoplastics, standard steel types can be selected. Beryllium copper inserts may be used for improved cooling near hot spots. High heat conductivity is also required for gate drops in hot runner molds. Standardization of mold parts is growing, not only for ejector pins, leader pins and bushings, but also for mold plates and even complete mold bases. These standard mold bases require only machining of the cores, cavities and cooling channels and fitting of an ejection system. Advantages are:

Cost savings 3050%
Short delivery times
Interchangeability
Easy and rapid repair

Injection mold manufacturer plastic injection molding in China