Sheet metal cutting and forming Flashcards
1
Q
Thermal cutting methods
A
- Flame cutting
- Laser cutting
- Plasma cutting
- Water jet cutting
- Marking
2
Q
Flame cutting
A
- min. 8mm thickness
- low costs (operation and invest)
- thickness barely affects speed
- slow
- only ferrous materials (Eisen)
- 1-4mm groove
- starting from middle not ideal
3
Q
Powder cutting
A
- flame cutting with iron powder fed in the flame to increase temperature
- cutting of stainless steel and cast iron
- only alternative for thickness of 100mm and higher
4
Q
Plasma cutting
A
- high speeds (1-6m/min)
- smaller details possible as in flame cutting
- gases: air, nitrogen, argon, hydrogen, oxygen
- best for thickness <50mm
- slow for thick materials
- groove V-shaped
- high costs for invest and nozzle
5
Q
Laser cutting
A
- oxygen or air for steel
- argon for titanium
- nitrogen for others
–> blow away molten material
- fast for thin steels (20m/min)
- high quality
- narrow groove (o,2-0,4mm)
- easy
- high costs
- slow >6mm
- poor efficiency + gas –> costs
6
Q
Water jet cutting
A
- high pressure beam with abrasives (70-400 MPa)
- nozzle 0,1-0,6 mm
- metallic, non-metallic and organic materials
- many materials
- no heat affects
- narrow groove (0,1-0,4mm)
- good quality
- limited thickness
- wetting
- invest costs
- noise, abrasive dust
7
Q
Factors affecting cutting method selection
A
- Material
- Sheet thickness
- dimensions
- quality
- quantity
- Costs
8
Q
Forming methods
A
- rolling
- (deep) drawing (ziehen)
- extrusion
- forging (pressen)
9
Q
What is springback in bending?
A
- elastic material in sheet bends back a little
- plastic deformation remains
- smaller when material is soft and radius small
10
Q
Design tips for bending
A
- radius should not be defined too exactly
- too sharp corner may break
- 180° bend should not be completely flat
- large radius increases springback
- bends should be in same direction
- ends not inclined
11
Q
Drawing (Ziehen)
A
Drawing ratio:
β=D/d
D-blank diameter
d-drawn cup diameter
Clearance (mm):
ν=s+ksqrt(s10mm)
s-thickness
k-coefficient (0,07 for steel, 0,02 for alu, 0,04 for others)
