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Recycling - A Guide to Continuous Regrind Process. More than just Waste???. More than just Waste???. Example 1: Using 1000kg/month of Acetal (£2.84/Kg). Weight of the runner system is 100Kg (10% of Part weight), which means you are throwing away £284/month and £3408/year .
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More than just Waste??? • Example 1: Using 1000kg/month of Acetal (£2.84/Kg). Weight of the runner system is 100Kg (10% of Part weight), which means you are throwing away £284/month and £3408/year. • Example 2: Using 5000kg/month of PP (£0.95/Kg). Weight of the runner system is 1000Kg (20% of Part weight), which means you are throwing away £950/month and £11,400/year. Don’t forget Storage cost, Handling cost, Collection cost, Transportation cost, Tax liability?
Feeder (Dryer) Runners Grinder Virgin resin Parts Continuous Regrind Process
% portion of resin that has been moulded x times 70 30% regrind 50% regrind 80 50 60 40 21 25 20 13 6 3 6 2 3 0 2 > 1 1 > 1 1 5 6 3 4 2 1 6 4 5 7 8 3 2 Times passed through the machine Melt Quality Regrind For example, if 30% regrind is used in a continuous operation, only 2% of the regrind has passed through the machine 4 times and less than 1 % has passed through the machine 6 times or more.
Example: Delrin* Acetal Resin Homopolymer Copolymer Degradation-1500 free molecules Degradation-40 free molecules + 2 shorter chain segments
Example: Sarlink* TPR Require grinders with properly adjusted, very sharp knives and may need considerable cooling, especially for the softer grades.
Properties (%) 115 Tensile strength 110 Elongation 105 Unnotched Charpy 100 95 Flex-modulus 80 0% 10% 20% 30% 40% 50% 60% Regrind level Example: Zytel* GR Nylon 6.6 Glass fibre reinforced materials shows higher sensitivity to recycling, due to the breakage of fibres during the regrinding process. Ideally ground hot to minimise glass fibre breakage.
Example: FR Plastics This includes, but is not limited to, the restricted use of regrind thermoplastic material to amounts less than 25% unless specified in the individual Recognitions.
Keep in Mind • Higher the quality of the regrind, higher the quality of the finish part. • Treat the regrind as if it’s virgin material. • Maintain a constant ratio of virgin resin to reground material. • Particle size of reground material to be uniform and similar to the virgin material. • Make sure the grinder blades are kept sharp and properly set to minimise fines. • Clean grinders and regrind containers frequently. Finally, MUST establish the proper ratio of virgin material to regrind, to give the right performance for your particular application.