# How to choose injection mould ?

- Share

- Issue Time
- 10-17-2017

As far as i know, there are three factors must be considered when choose the **plastic injection machine** for your products.

1. Max mould length of a side must less than the space of tie bars.

how to estimate the mould dimensions for your product?

usually we can estimate the injection mould dimension as below:

length of mould: length of your product add 300mm, if the product is very big then we can add 400mm.

width of mould: width of your product add 300mm, if the product is very big then we can add 400mm.

height of mould: 2.5 times of product height, if the plastic injection mould has special demand, then we can add more, if the mould feeding type use hot runner system, then we should add runner plate thickness on.

2. The weight of product (gram) must less than theoretical shot weight (gram) of the injection machine.

if your mould is multi-cavity, then the total product weight should less than the shot weight. otherwise your product could not be make perfectly.

3. Based on upper two factors, we should also need to consider the clamping force. clamping force is difficult to estimate, we can estimate it by below:

Clamping force = projected area of product in the direction of opening and closing mould (cm²) ×the number of mold cavity×in-mold pressure (kg/cm²)

Projected area of product in the direction of opening and closing mould is generated by the product appearance size.

In-mold pressure is different with different materials, generally we can calculate it by 350-400 kg/cm².

- if you need help, pls contact me, I am Tea, my email is injectionmold2006@163.com
- whatsapp+8615958816137 skype：injectionmold2006@163.com