Miscellaneous machining methods

Question 1

Drill types

Answer 1

• HSS twist drills
• Solid carbide drills
• Exchangeable tip drills
• Ejector drills
• Core drills

Question 2

Drilling machines

Answer 2

• Drill presses
• Radial arm drill press
• NC drilling machines
• Deep hole drilling machines

Question 3

Axial force in drilling: fomula

Answer 3

F=Dfka

Question 4

Power while drilling: formula

Answer 4

P=M*ω

Question 5

Drill selection

Answer 5

• based on hole depth, diameter and material
• best productivity with carbide twist drills with cutting fluid channels

also:

• stack drilling
• combined spotfacing or countersinking

Question 6

Spade drill

Answer 6

(Spatenbohrer)

• used for large diameter holes (40-150mm)
• same shank takes several bit sizes
• max. depth is 1,5*D

Question 7

Deep hole drilling methods

Answer 7

• ejector drilling
• BTA or STS (single tube system) drilling
• Gun drilling

Question 8

Reaming (Reiben)

Answer 8

• improve hole quality
• removing of triangularity
• improvement of dimension tolerance

Question 9

Boring (Aufbohren)

Answer 9

• 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

Question 10

Boring machines specifications

Answer 10

• spindle can be moved in axial direction but not for feed movement
• feed by table movement
• typically machining of large parts

Question 11

Gear manufacturing process

Answer 11

1. bar sawing
2. turning
3. hobbing (Walzfräsen)
4. broaching (Räumen)
5. Hardening
6. Grinding
7. Measurement

Question 12

Methods for gear manufacturing

Answer 12

• hobbing –> large gears
• form cutting/milling
• grinding (abrasive)
• shaping and scratching
• broaching –> small gears

Question 13

What is an advantage of involute profiles?

Answer 13

it can be shifted somewhat to reach an even axis distance and still standard tool can be used

Question 14

Worm manufacturing

Answer 14

• Turning
• Milling
• Whirling

Question 15

Where is whirling used?

Answer 15

large pitch thread manufacturing (ball screws, worm gears, extruder screws)

Question 16

Shaping and slotting

Answer 16

• shaping only for gears because of inefficiency

- Slotting for manufacturing one-off keyways and other internal non- symmetric cylindrical features

Question 17

Broaching (Räumen)

Answer 17

• for internal cylindrical features to holes
• also external forms
• complicated and expensive tool but long-living
• simple and fast operation
• precise, good quality

Question 18

Sawing

Answer 18

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

Question 19

Ultrasonic machining

Answer 19

• 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)

Question 20

Electric discharge machining (EDM)

Answer 20

• 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

Question 21

EDM: electrode material

Answer 21

should be easy to machine and wear little due to sparking
• Graphite
• Copper
• Other metals: Tungsten

Question 22

EDM: dielectric fluids

Answer 22

• Insulation
• Flushing
• Cooling
• Oil, water or kerosene

Question 23

Electrolytic machining

Answer 23

• low removal rate
• used by aeronautics for thin parts or small holes made of difficult to cut materials
• used in polishing and deburring (entgraten)