Injection mold cavity

Injection mold cavity definition solution

  • Plastic product precision

For the accurate plastic product, normally it is single cavity, no more than 4 cavity.

  • The injection maximum volume of injection molding machine: 

The volume of the total injection mold cavity should be lower than the injection maximum volume, the best is to lower than 80% of  the injection maximum volume.  For example if one  plastic cap weight is 30g and it is four cavity mold. The injection mold cavity volume is 30*4=120g. The plastic injection molding machine maximum volume should be more than 120/0.8=150g

  • The maximum clamping force

P=Kp x S

P=The maximum clamping force(Ton)

Kp=The clamping force constants(t/cm2)

S=The vertical projection area of plastic injection mold cavity (cm2)

General Kp for common plastic injection molding resin

Nylon 0.32  0.64~0.72(t/cm2)
PE 0.32(t/cm2)
POM 0.64~0.72(t/cm2)
PP 0.32(t/cm2)
Resin with glass fiber  0.64~0.72(t/cm2)
ABS 0.30~0.48(t/cm2)
The other engineering resin 0.64~0.8(t/cm2)

  • Economical efficiency

It is how much you can spent on the mold and how many parts you would like to produce the plastic product as well as how long your lead time it is.

For example, you need 300,000 pcs plastic cap in five years, every year you need to order 60000pcs, then you can consider to have 4 cavity mold,  if the injection cycle is 30 s, 20 working hours each day for production. We can produce 2400pcs plastic cap each day.  Then our lead time for 60000pcs plastic cap is 25days; but if you just need 5000pcs plastic in five years and you need 1000pcs each year, then you just need to have single cavity mold.

Plastic injection mold cavity quantity and layout

Injection mold cavity divide to single cavity and multiple-cavity

Multiple cavity devide Same product multi-cavity and different product multi-cavity(Family mold)

Multi cavity according to the arrangement of gating system is divided into: balance and non balance layout

Plastic injection mold multiple-cavity

Plastic injection mold multiple-cavity


About Hedy Yeh

Major in machinery and tooling in university from 2001 to 2004; Worked for plastic mold design, mold manufacturing and mold and production project management from 2003 to 2008; Working for mold marketing and mold project management from 2008 till now My facebook page