1.5-Polymer finishes

Question 1

Why are polymer self finishing

Answer 1

-they require no additional finishing process once manufatured

Question 2

What is overmoulding+what are the two methods

Answer 2

moulding a second polymer over specific parts of a product
-TPE often used
-overmouldings provide areas of grip or texture
-overmouldings can highlight different colours for differet component parts
Two methods- two injection moulding, twin shot injection moulding

Question 3

Overmoulding- two injection moulding moulds

Answer 3

• one mould for product and one for grip areas
• product is injection moulded, then placed into a second mould where the overmoulding polymer is injection moulded onto the body

Question 4

Overmoulding- twin shot injection moulding

Answer 4

-injection moulding machine has a mould designed to produce the product in one cycle
-mould has two separate component cavities
-main product part created in first mould cavity
-mould opens slightly and rotates 180 degrees to secondary position
-mould closes and second injection applies the overmould
fast continuous process

Question 5

Why might designers use acrylic spray paints

Answer 5

• fast drying and water soluble so becomes water resistent
• improves aesthetics and can provide additional protection against the effects of UV light and weathering
• used for mass customisation, particularly in the automative industry, such as colour bumpers and wing mirrors on cars
• items could be pigmented but this is impractical and not cost effective for manufacture to change the granules on an injection moulder

Question 6

Why might designers add pigments to the polymer

Answer 6

• to provide colour
• these can be added during the manufacturing process of during manufacture of polymer stock form
• smart pigments e.g. thermocromic can be added producing ready finished smart polymer products
• pigments added to gel coats when laying up GRP