Forming processes Flashcards
(16 cards)
What are the different forming processes
Forging
Press forming
Strip heating polymers
Vacuum forming
Moulding of GFRP and CFRP composites
What is hot forging? What are some properties of forged components compared to cast ones?
Hot forging is a forming process that uses force to reshape heated material into a desired shape. Forged components are stronger and lighter than equivalent cast components.
Examples of forging
Hand forging
Industrial hot press forging
What is hand forging?
Heating steel until it can be reshaped with a hammer
Equipment for hand forging
Forge, anvil
What is press forming? What are 2 examples of press forming?
Press forming is a cold forming process that bends or shapes sheet metals into components like car body panels.q
What is dedicated tooling (press forming)
Complex 3D shapes can be formed in one operation using dedicated two piece press tools
What is general purpose tooling (press forming)
Sheet metals blanks can be formed into simple folded panels or boxes using a general purpose block and blade tool on a forming press
What is strip heating polymers?
A forming process for making simple components by making bends in thermoplastic sheets
Process for strip heating polymers
A flat blank is cut out using a laser cutter
The component is placed on the strip heater so that a fold line is directly above the heating element
The strip of material near the fold line heats up and becomes pliable
Component is folded
Component cools and becomes rigid
What is vacuum forming
Vacuum forming is used to make complex, curved, thin - walled hollow shapes from thin thermoplastic layers
Process for vacuum forming
A thin thermoplastic polymer sheet is clamped in place and is heated until it softens
The platen is raised and pushed the mould into the pliable thermoplastic sheet from below
A vacuum pump reduces the pressure under the mould, forcing the mould into the thermoplastic sheet.
As the sheet cools, it hardens into a new shape. It can now be removed and trimmed
What are GFRPS and CFRPS
GFRPS (Glass reinforced plastics) consist of strands of glass fibre held together in a polyester resin mix.
CFRPS (Carbon fibre reinforced plastics) consist of stands of carbon fibre held together in a polyester or epoxy resin mix
What is the lay up process
Release agent is applied to the surface of a mould
A resin gel coat is applied
Long strands of glass fibre are applied in layers and coated with polyester resin. A roller is used to expel air bubbles
More layers are applied to increase strength and rigidity
The finished component can be removed from the mould and trimmed once cured
What is vacuum bagging
A wax release agent is applied to the surface of a mould
Carbon fibre sheets pre - impregnated with epoxy resin are laid into the mould
This is placed into a plastic bag and air is removed with an air pump
Sheets are compressed and forced into a mould
This is placed into an autoclave where pressure an heat is applied causing it to cure
Component is left to cure and is then trimmed
What is the spray up process
Release agent is applied to the surface of a mould
A resin gel coat is applied
A mix of chopped fibres and polyester resin are applied with a spray gun in layers
A roller is used to expel air bubbles and compact the layers
One the resin is cured, the finished component is removed and trimmed
