Case Study - 13A plug

Plug body: selecting the material

From the resistivity-cost chart wood seems to be a cheaper choice for the plug body than polymers. So why isn't wood used in practice?

The plug body is a complex 3D shape. It is no good having the perfect material if we can't actually form it to the desired shape, so we need to examine the processing options for various materials.

The table shows that:
  1. Polymers can be shaped by various moulding processes.
  2. Wood can only be machined into the shape of a plug, which would not be practical for mass production.
  3. The processing options are greater for thermoplastics than for thermosets.
+ : routine
? : difficult
X : unsuitable
 Polymer Wood
ABS
(thermoplastic)		 UF
(thermoset)		 Pine
Polymer
Shaping		 Polymer extrusion + X  
Compression moulding + +  
Injection moulding + ?  
Blow moulding + X  
Machining Milling + X +
Grinding X X +
Drilling + ? +
Cutting + ? +
Joining Fasteners + + +
Solder / braze X X X
Welding + X X
Adhesives + + +

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