Miscellaneous machining methods Flashcards
Drill types
- HSS twist drills
- Solid carbide drills
- Exchangeable tip drills
- Ejector drills
- Core drills
Drilling machines
- Drill presses
- Radial arm drill press
- NC drilling machines
- Deep hole drilling machines
Axial force in drilling: fomula
F=Dfka
Power while drilling: formula
P=M*ω
Drill selection
- based on hole depth, diameter and material
- best productivity with carbide twist drills with cutting fluid channels
also:
- stack drilling
- combined spotfacing or countersinking
Spade drill
(Spatenbohrer)
- used for large diameter holes (40-150mm)
- same shank takes several bit sizes
- max. depth is 1,5*D
Deep hole drilling methods
- ejector drilling
- BTA or STS (single tube system) drilling
- Gun drilling
Reaming (Reiben)
- improve hole quality
- removing of triangularity
- improvement of dimension tolerance
Boring (Aufbohren)
- hole finishing method
- similar to internal turning, but here the tool is rotating
- tool can be fed radially
- tool can be adjusted/use of combination tool
Boring machines specifications
- spindle can be moved in axial direction but not for feed movement
- feed by table movement
- typically machining of large parts
Gear manufacturing process
- bar sawing
- turning
- hobbing (Walzfräsen)
- broaching (Räumen)
- Hardening
- Grinding
- Measurement
Methods for gear manufacturing
- hobbing –> large gears
- form cutting/milling
- grinding (abrasive)
- shaping and scratching
- broaching –> small gears
What is an advantage of involute profiles?
it can be shifted somewhat to reach an even axis distance and still standard tool can be used
Worm manufacturing
- Turning
- Milling
- Whirling
Where is whirling used?
large pitch thread manufacturing (ball screws, worm gears, extruder screws)
Shaping and slotting
- shaping only for gears because of inefficiency
- Slotting for manufacturing one-off keyways and other internal non- symmetric cylindrical features
Broaching (Räumen)
- for internal cylindrical features to holes
- also external forms
- complicated and expensive tool but long-living
- simple and fast operation
- precise, good quality
Sawing
Hack saw - low costs - easy - inefficient small volume
Band saw
- medium costs
- flexible, larger diam.
- thin blade
Circular saw
- most efficient
- high costs
- large volume
- diameter range limited
Ultrasonic machining
- hammering abrasive particles against the workpiece surface at a high frequency
- particle acceleration up to 15 000 g
- for hard, brittle and non-conductive materials (ceramics)
Electric discharge machining (EDM)
- wire and sinking
- tool is neg., WP is pos.
- based on electrical erosion
- in dielectric fluid
- pulsating DC
- low cutting forces
- low removal rate
- complex geometries
- precise
EDM: electrode material
should be easy to machine and wear little due to sparking
• Graphite
• Copper
• Other metals: Tungsten
EDM: dielectric fluids
- Insulation
- Flushing
- Cooling
- Oil, water or kerosene
Electrolytic machining
- low removal rate
- used by aeronautics for thin parts or small holes made of difficult to cut materials
- used in polishing and deburring (entgraten)
