Potting & Encapsulation

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The applications and machine requirements for this are as diverse as the products themselves. Our machine range has covered from dispensing shots ranging from 0.02ml to 50Kg +, using filled and unfilled Epoxy, Polyurethane or Silicone, often needing to be stirred, heated, or de-gassed etc. They are being used in simple manual and robotic applications, with single or multiple dispensing heads.

When selecting the correct machine from our range, the process of actually potting the component has to be considered. If you are making the transition from manual to machine application, there are some general guides that can apply to this process.

  1. The time taken to fill a component is dependant on how quickly the component will accept the encapsulant, often machines can dispense this quicker than the component can accept it.
  2. Therefore, it is often easier to encapsulate in stages, allowing the first stage to settle, before dispensing the next.
  3. Filling time can be reduced by heating the encapsulant (Epoxy & P.U.) which will reduce the viscosity and help flow, but this will also reduce the gel time and if filled increase the risk of filler settlement. Therefore if heating also consider stirring.
  4. The volume of encapsulant required can often vary due to the dimensional tolerance on the components being potted.
  5. Try to ensure the component has an adequate flow path for the encapsulant to go in and for the air to come out. For example, a PCB heavily populated on both sides and designed to be a tight snap fit into a moulded case.
  6. Machine dispensing can allow components to be filled from the bottom up thus pushing air out, rather than filling top down which tends to trap air.
  7. Unlike hand mixing, most metering and mixing machines do not entrain air to any degree during the mixing process. Thus air free material going in to machine will come out air free, therefore you may not you need to de-gas. Also, although degassing is often requested, if the material is poured in atmospheric conditions when air can be trapped by the component itself, is it really necessary?
  8. If you have been hand mixing the material before, it may have been bought in small kits, whereas with a machine you may be able to use the material in larger, cheaper containers and size the machine reservoirs to the supply.
  9. Try to use non abrasive fillers, when pumping grinding paste expect wear.
  10. Remember the ‘Potting’ process normally takes place at a stage where most of the product build cost has been incurred, but unlike earlier stages if the process go wrong it is very unlikely that anything will be retrievable. Moreover, it may take a days’ production to find out.
  11. It may seem to be agricultural and messy, but often rather than potting directly from the machine it is more efficient to use a simple metering and mixing machine to back fill a syringe with mixed material and then use the syringe to pot the part.

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This programmable stepper/ballscrew driven Iota C is used to dispense a 12gm shot of 4:1 PU at a slow, controlled varying rate over a 30 seconds cycle to prevent air entrapment in the component.

Because of the diversity of processing requirements and shots sizes, sometimes the need for multiple cycles, we offer use both piston and continuous delivery gear pumps for metering. For example, we have used 6 different types of machine for potting transformers. Therefore while there is not a definitive ‘Potting’ machine, we can provide the definitive machine for your specific application requirements, albeit the simple small shot Iota R or a high output rate MasterCaster gear pump machine with degassing and heating.