Thermosets cannot be welded, so how are the faying surfaces attached?
The thermosetting plastics are usually bonded.
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What two types of thermoplastics are there?
Amorphous and Crystalline
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Describe Amorphous Thermoplastics
Amorphous thermoplastics have no orderly structure and no defined melting temperature.
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Describe Crystalline Polymers
Crystalline have a very rigid structure and as heat is added they remain rigid until the melting point is reached and then transform to a liquid, the glass transition point is very sharp.
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Which type of thermosetting polymer is easier to weld?
Amorphous
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Why is surface preparation important for polymers during welding?
The moulding process can leave a layer of surface contaminant which must be removed and they usually need to be prepared so they will closely fit together.
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Ultrasonic Welding for Thermoplastics.
Cycle takes 1 to 2 seconds, Better with rigid plastics, Dissimilar can be welded with care, Plastic does actually melt unlike metal process.
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Friction Welding for Thermoplastics.
Joint Strength up to 90% of parent plastic strength, Can be used on dissimilar plastics, Takes between 1 and 5 seconds.
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Diffusion
Relatively slow process.
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Resistance
If the plastic altered included a conductive wire then resistance welding can be used. Implants commonly consist or copper mesh of carbon fibres.
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Laser
The technique, suitable for joining both sheet film and moulded thermoplastics, uses a laser beam to melt the plastic in the joint region.
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Thermosets cannot be welded, so how are the faying surfaces attached?
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