Don’t be deceived by the simplicity of the humble ring!
The US military required a critical high precision ring to separate the propellant in a Surface to Air Missile (SAM) from the payload. They were using a component machined from metal with a cost of close to US$600 each. A combination of PEEK and carbon fibre (probably the most expensive and hyped combination you could put together) was trialled but failed to meet the demanding performance requirements.
Long fibre thermoplastics were then introduced. After some clever MFA, fibre orientation and FEA analysis combined with a gating design and part modification the desired result was achieved. This gave rise to the correct fibre orientation and weld lines were shifted away from critical fastening points.
Dr Raj Mathur, VP of Technology and Business Development for Plasticomp: “Although it is deceptively simple, a ring is the most difficult part because the melt flow has to meet at some point in the circle, creating weak points. So, this is a story of how long fibre can overcome the weakness of weld line. LFT gave it the narrowly prescribed/needed stiffness and strength. The Army guys fell in love with us when they visited and saw these rings popping out of the press every 20 seconds!“
