Polymers - Tools, Equipments and Processes Flashcards
What would you use to marl out polymers and why
Chinagraph Pens
Spirit Based Pens
Both have the advantage of being easily removed after the part has been made
When using compasses or drilling into a polymer it is useful to place tape on the surface to precept the surface from skidding and scratching the surface
How thick is acrylic
3mm
Vary slightly and will have an effect with the laser cutter
Therefore it is better to measure the thickness of the acrylic before it is laser cut
What would you use to measure the thickness of acrylic
Venir Callipers
What is line bending
One of the most simple methods of forming a polymer sheet
Give the line bending process
The strip heater consists of a hot wren that is used to heat the acrylic to a temperature of around 160˚C
At this temperature the acrylic becomes pliable and easily to be bent into shape
The heat can be regulated to accommodate varying thicknesses of acrylic and varying radius of bends
Care should be taken to not overheat the acrylic
What is vacuum forming
Used to produce a 3 dimension complex shapes in a thermoplastic sheet
What is the material that you would use for vacuum forming
HIPS
Give some key features that are needed for the vacuum forming mould
Sloping sides (around 5˚) to ensure that HIPS can be easily removed
Rounded corners to prevent the HIPS sheet from thinking on the corner and possibly splitting
Smooth surface
Give the stages of vacuum forming
Once the mould is ready, it is placed on the table of the vacuum former and lowered int the machine
A sheet of HIPS is then clamped over the top if the machine heat is applied
After a short time the HIPS will become soft. Should not overheat as otherwise it may not form properly and webbing may occur
Mould is then raised up into the hot HIPS sheet and air is succeed out of the machine by turning on the vacuum pump
Once formed the sheet should be allowed to cool then removed from the vacuum former and tried with a gerbil cutter
What is press forming
Produces 3 dimension outcomes to vacuum forming bu is used with simpler shapes in thicker thermoplastic sheets such as 3mm acrylic
Give the press forming process
Acrylic sheet is heated up in an oven to make it soft and pliable
It is then placed between the yoke and the plug and the two parts of mould are placed together,
The mould may feature guide pins to ensure that two parts accurately align with each other
Once cool, the sheet can be removed and trimmed
What is injection moulding
Used in extensively in industry to produce many thousands of objects that we use in our everyday lives
Seats, phone cases, pens
Only used when products are made in large batches. Te initial costs are high with the machinery and dyes that ere used
However once set up it’s quick and accurate to use
Give the injection moulding process
Polymer granules are fed into hopper which in turn feeds the granules into the heating chamber
Archimendan screw then transports the polymer granolas along the heater chamber whee they gradually become molten
A hydraulic ram forces the molten polymer through a spare gate and into the mould
The mould is rapidley cool with water to set the polymer
The mould is then opened and injection moulded product is removed
What is extrusion
Very similar to injection moulding
Produces long continues length of polymer products in a uniform cross section
What is blow moulding
Simple blow moulding can be doe on a vacuum forming machine
Firstly a clamping ri ng needs to be produced. This consists of a sheet of a sheet of materials such as 3mm plywood that has a hole cut into the middle that is the same size of the diameter of the dome
The HIPS is then heated until soy=t and then blow into the dome shape
What is industrial blow moulding
Similar to injection moulding but the material is blown ad forced against the mould to produce an empty cavity such as a plastic water bottle
What is Rapid Prototyping Systems
PRS involves the manufacture of a 3D image to produce a model of a product or component
Give 3 methods of rapid prototyping
3D printing
Stereo Lithography
Laser sintering
All of these are additive processes = They add material to build a product
Describe the 3D PRINTER
Uses a filament polymer that is fed through a heater unit that converts it into a modelling state
Most common polymer used with a 3D printer are ABS and biopolymers
Once heated the polymer is extruded and follows a path to produce a 3D object by building up the shape layer by layer, with each successive layer using to the previous one.
The path is controlled by the use of three stepper motors allowing and 3D shapes to be produced
The model can be altered to be hollow solid or structured
What its a Stereolithography printer
Works similar to a 3D printer but here the tool is a laser that follow a similar path that works a bath of resin
The laser cures the resin to form a solid shape as it moves along, again buying up a model layer by layer which can be solid, hollow or contain internal structures
What is Laser Sintering
Methods of rapid prototyping is very similar to the stereolithography method but it involves the use of fine heat fusible powder
Those powder can be made form a polymer, a ceramic or a metal
Turns it into a molten state
Each successive layer fuses to the previous layer , gradually building up the 3D model
Give some ways that ensure quality control is ensured in 3D printing
Running a computer simulation of the print to see if the rafts and supports are correctly placed which also ensures that there is sufficient filament that is going to be used and the time the hob will take.
