Electrochemical Machining

Question 1

ECM – Principle/Method

Answer 1

• Based on the chemical (or anodic) dissolution of metal by electrolysis
• Also known as the “reverse of electroplating”

Question 2

ECM- Principle/Method

Answer 2

Shaped tool (electrode) is brought close to an electrically conductive workpiece at a constant rate maintaining a gap while submerged in an electrolyte solution

Tool and workpiece are connected to a DC supply and a high density current passes through the gap and the rapidly flowing electrolyte

Electrochemical reaction deplates the metal from the anode (workpiece) and gets washed away by the electrolyte before plating on the cathode (tool) can take place

Question 3

Electrolyte solution for ECM?

Answer 3

Conductor – allow electric current to flow between the tool and the workpiece

Coolant – to keep temperature of tooling and workpiece constant as the conductivity of the fluid depends on its temperature

Flushing agent – to carry off deplated material (microscopic particles) from the gap and remove hydrogen bubbles

Question 4

Electrodes for ECM?

Answer 4

Copper, brass, stainless steel, bronze, titanium

Question 5

What are the desired properties for ECM?

Answer 5

Good (sufficient) strength not to deform by flow pressure from the electrolyte bath

Minimal electrical resistance

High chemical resistance

Question 6

List 4 different variations of ECM?

Answer 6

• Electrochemical Grinding
• Electrochemical Honing
• Pulsed Electrochemical Machining
• Electrolytic In-process Dressing(ELID) Mirror-Surface - Grinding
• Electrochemical Deburring
• Shaped Tube Electrolytic Machining(STEM)

Question 7

List 3 applications of ECM

Answer 7

• Hard or difficult to machine metal
• Difficult geometry or impossible to manufacture with conventional techniques
• Die sinking, forging dies, and other shaping tools with irregular contours
• Multiple hole drilling
• Deburring
• Micromachining

Question 8

Advantages of ECM?

Answer 8

• Can be used for any conduction material regardless of hardness can be machined; Workpiece can already be hardened
• Complex shapes and contours can be machined in one process step with excellent surface finish
• No distortion as no thermal or mechanical stress
• little surface damage to the workpiece
• No burs
• Little tool wear(only from flowing electrolyte)

Question 9

Limitations of ECM?

Answer 9

• Only conductive materials(tooling and workpiece) can be machined
• Not suited for sharp profiles(sharp square corner; and external)
• LArge forces on electrode and workpiece due to small gap and high pressure flow of electrolyte
• Workpiece must be cleaned and oiled directly after machining to avoid corrosion
• Environmental impact with the disposal of electrolytic sludge
• Expensive equipment and tooling cost