Polymers Flashcards
what are stock forms
standard sizes for a material, component or product
examples of stock forms
- sheets (acrylic)
- granules (Polypropylene)
how can polymers be fixed
with nuts,bolts, screws and rivets
what is additive manufacturing
a method of shaping a form by building on top of a material
what is subtractive manufacture
a method of shaping a form by the removal of a material
what is a filament
a material in thread like form
what do some polymer based fibres contain
different wood carbon and metal fibres
what is a bespoke product
a one off product that matches the client requirements exactly
what is a chinagraph pencil and what’s it used for
used to mark on the high gloss surface of acrylic
- if not available, an alcohol based permanent marker can also be used
how can acrylic be cut
- coping saw
- hacksaw
- file
what temperature does acrylic need to be heated to to be able to bend without cracking
150 - 170
what is a vacuum former
a machine that heats a polymer so that it is malleable enough to be pulled over a former with a vacuum
how does a vacuum former work (use HIPS in the example)
- HIPS is heated
- once hot, the solid former is pressed into the HIPS from a bed that can rise
- the vacuum is turned on, removing all the air from around the former
- the HIPS takes the form of the solid former
what is talc
a clay mineral that can be dusted in the former so that it drops out of the mould with ease
why should a former have a draft angle
so that it doesn’t fr stuck in the mould
how else can polymers be shaped
- press moulding
- drape formung
how does injection moulding work
- granular plastic is held in a hopper
- it’s moved via an Archimedean screw, along a heated tube called the heating chamber
- once the polymer has been melted, it’s pushed into a mould with a hydraulic ram
- the mould is then cooled so that the moulded plastic can be removed
why does the mould have a hydraulic ram in injection moulding
to make sure just enough material is injected into the mould each time
how does extrusion work
- first two steps the same as injection moulding
- once the polymer has been melted, it is pushed through a die mould, which will form the shape of the extrusion
- because there is no hydraulic ram, molten plastic can be fed through the die continuously
how to apply a finish on a polymer
- file can be used to remove some of it
- abrasive paper then used to remove file marks, known as “rubbing down”
- once the file marks are removed, a fine abrasive paper can be used to achieve a matt finish
- it an electric buffer or car body can give it a glossy finish
how are polymers made
from crude oul
what is a digital vernier calliper
a digital device for measuring accuracy
