Metal Forming Flashcards
Disadvantages with work hardening
- Reduced ductility
- mechanical properties are less easy to predict
- always occur in cold working
what are the three working temperatures
- cold working
- warm working
- hot working
advantages of cold working
- increases strength and hardness
- no heating of work required
- better accuracy and tolerances
- better surface finish
disadvantages of cold working
- high forces and power required for deformation
- sometimes metal is simply not ductile enough to be cold worked
advantages of warm working
- lower forces and power
- more intricate geometries possible
- no need for heat treatment or may be reduced
disadvantages of warm working
- workpiece must be heated which increases time and cost
- increased risks to operators due to increase temperature
advantages of hot working
-increased ductility-
less power and force
-metals that fracture in cold can be working in the hot
-no work hardening occurs
disadvantages of hot working
- lower-dimensional accuracy e.g. shrinkage occurs
- higher energy is required due to increased thermal energy to heat the qworkpiece
- work surface oxidation can occur
- shorter tool life
types of bulk metal forming
- Rolling
- forging
- Extrusion
- Wire and bar drawing
types of rolling
- flat rolling
- shape rolling
- thread rolling
- ring rolling
disadvantage of rolling mills (Rollers lined up)
- equipment is massive and is expensive
- high compressive forces requierde
- temperature control required
- fast rolling speeds
what is thread rolling
Where threads are formed on parts by cold rolling them between two dies
advantages of thread rolling
- higher production rates
- less waste material
- strong threads and better fatigue resistance
advantages of impression die forging
- higher production rates
- less waste material
- greater strength
disadvantages of impression die forging
- not capable of close tolerances
- further machining may be required
