Heat Staking

Heatstaking (or heat staking) is a method of joining two or more parts, where at least one is made out of plastic. The bond is made by partially de-forming the plastic part to fix the other. Heatstaking is the most efficient way to  bond metal to plastic, and is commonly used in high volume/low cost applications in the automotive, telecom and appliance industries.

The process works by heating the plastic to a temperature above the glass transition temperature via the use of super-heated air or a thermode, and then applying pressure in order to deform it and create the stake. The plastic is then cooled down again – under constant pressure – below the glass transition temperature, ensuring good fixation of the parts. This cooling can be done with compressed air if using a thermode, or with a cold, preformed tool if super-heated air is used.

Heatstaking design guidelines:

• Plastic material with glass fiber filling
• The % of glass fibers is typically between 10-40%, where 40% is the most abrasive to the tooling in the system
• A keep-out zone of 1.5mm – 2mm around each heatstake pin is ideal
• Average heatstake applications use a force of 22lbs – 34lbs but can vary depending on the pin diameter

Types of plastic to use:

• Materials that can be processed:
  • PA66 GF30 (Glass filling 30%)
  • PPA GF33 (Glass filling 33%)
  • POM
  • PBT + 20% FV – VO (Glass filling 20%)
  • PPS GF40 (Glass filling 40%)
• Glass filling up to maximun 40%
  • Higher glass filling will reduce thermode lifetime
• All plastic materials used for injection moulding can be used for Heatstake Technology
• Rubber (EPDM) and Silicon Materials are no good for Heatstake process

 

 

For more information, read our Fundamentals of Heatstaking paper