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What is called hard mold?

2016/11/2 11:09:51

As customer’s quality awareness for the product improving, many manufacturers  have high requirements for the mold and mold material. Hard mold collectively  refers to plastic die/mold core and cavity with hardness over 50HRC. Generally,  allowed hardness is about 50HRC, and now more common domestic die/mold hardness  are in 48-52HRC. Hard plastic molded products are mainly small products, such as  our most common thin-walled mold, disposable cutlery mold, nylon plastic mold,  wine box mold etc.

The biggest characteristic of hard mold is its high hardness which ensures  longer life. Universally hard mold life can reach more than 1 million shots. It  is relatively very cost-effective for some big products. It can be used to  improve plastic parts profit by improving the mold production.

The process for hard mold is different from other plastic mold. Considering its  hardness is about 50 HRC which is very difficult for machining, the first step  is to rough machining and remain a few millimeters allowance for the surface.  After rough finish, it is heat treatment. The common technique is vacuum  hardening. To make the plastic mold hardness reach to 50 HRC. Because the steel  has deformation after heat treatment, we need air cooling three days before  starting fine machining work. Due to the high hardness, it is very difficult for  finishing, especially for CNC milling tool, while the plastic mold processing  progress will be slower. We will give priority to spark discharge machining.

Since there has some scrap rate for the mold heat treated, it is high risk to  make hard mold than make a common mold in a general way. But need to decide  according to actual situation. For plastic hard mold/die, the most common steels  are mainly H13, S136, 2344 and so on.

Tags: injection mould maker, plastic mould maker,