When you are purchasing plastic injection molds, you'll have noticed that many mold makers guarantee the lifetime for the molds they build, such as 300,000 shots, 500,000 shots etc. Mold life means the life of the mold, not yours. Injection mold life stands for the number of molding cycles that a mold can make before it needs to be replaced.

How long does a plastic injection mold last?

Any injection molds will be subject to wear. Wear will occur particularly to ejectors, gates, slides & other moving parts of the molds. Surface finishes such as high polish or sparked finish will also become less defined over time. The following factors affect how quickly wear takes place:

a) The mold material. Soft aluminium molds will incur much more wear from the plastic material than hard steel molds. Steel molds should last for millions of moldings, but not when certain plastic materials are used - see the next point.

b) The molding material. Certain materials can be very abrasive, such as glass filled nylon for example. Other materials are very corrosive and will rust normal steel molds, so aluminium alloy or stainless steel molds should be used, or the steel mold should be stainless steel or aluminium alloy plated.

c) Mold setter skill. Molds need to be set up to work in the injection molding machine correctly. Overlocking, poor tool alignment, excessive ejector stroke, overpressurisation of the plastic material, not enough lubricant on the ejectors are all examples of poor setting which wear any mould down much more quickly than necessary.

d) Mould maintenance. Good maintenance and periodic inspection go a long way to prolong mold tool life.