1.2 Non-traditional 3D machining

Question 1

Advantages of Electric Discharge Machining

Answer 1

Advantages
- cuts any conducting material regardless of hardness.
-It cuts with a spark, so there are low cutting forces to distort
the workpiece or damage fragile workpieces.
-It can be used for the holes in fuel injectors.
-Can machine at shallow entrance angles as the spark jumps the shortest distance and there is no force to displace
the tool.
-Can machine complex cavities, producing a negative image of cutting tool. It produces a good surface finish which is good enough for moulds for glass

Question 2

Limitations of Electric Discharge Machining

Answer 2

-Low metal removal rate
-Rapid toolwear
-Difficult to compensate for overcut and wear
-Workpiece must be conducting
-Heat effected layer 0.004 to 0.38 mm

Question 3

Why use chemical blanking?

Answer 3

Prototype Manufacture & short production runs
⚫ No costly tooling
⚫ complexity limited by the artwork
Making precision parts from thin sheets
⚫ Retaining the metallurgical properties
⚫ Parts are as flat as original stock
⚫ For hard materials

Question 4

Limitations of chemical blanking?

Answer 4

⚫ Metal Removal rate is low
Metal thickness⚫ Max 2 mm
⚫ Min 1.5μm
⚫ Min. hole or slot 1.5 x metal thickness
⚫ Min. land 2 x depth of cut
⚫ Tolerances 10% metal thickness

Question 5

Electrochemical Machining Advantages

Answer 5

⚫ no metallurgical damage
⚫ machines hard materials
⚫ good surface finish
⚫ roughness < 5m
⚫ no tool wear
⚫ no direct cutting forces

Question 6

Electrochemical Machining Disadvantages

Answer 6

⚫ high Machine tool costs
⚫ high power
requirements
⚫ 150 x conventional
⚫ high loads due to
pressure of electrolyte
⚫ corrosive fumes