In this post, you learn what is Electrochemical machining, Its working principle, advantages and disadvantages and more.
Electrochemical machining is the reverse of electroplating. An electrolyte works as a current carrier, and the high rate of electrolyte flow in the tool-workpiece gap washes metal ions from the workpiece (anode) before they have a chance to plate onto the tool (cathode).
Modification of this process are used for turning, facing, slotting, tremping, and profiling operations in which electrode becomes the cutting tools. The shaped tool is made out of brass, copper, bronze, or stainless steel.
The electrolyte is an extremely conductive inorganic salt solution such as sodium chloride mixed in water or sodium nitrate. It is pumped at a high rate through the passages in the tool.
A DC power supply in the range of 5-25 volt. Maintains current densities which for most of the applications are 1.5-8 A/mm2 of the active machined surface.
Machines having current capacities as high as 40,000 A and has low has 5 AR available.
The penetration rate of the tool is proportional to the current density since the metal removal rate (MRR) is only a function of the ion exchange rate. It is not affected by the strength, hardness, or toughness of the workpiece.
Design Consideration of Electrochemical Machining
- It is not suited for producing sharp square corners or flat bottoms.
- Controlling the flow of electrolyte is difficult so irregular cavities may not be produced to desired shapes with acceptable dimensional accuracy.
- Machining of hard and brittle material is possible with excellent quality of surface finish and dimensional accuracy.
- Complex shapes can also be easily machined.
- There is almost a negligible tool wear, so the cost of tool making is only a one-time investment for mass production.
- There is no application of force, no direct contact between tool and work and no application of heat.
- Mechanical and thermal residual stresses and are absent in the workpiece.
- Very close tolerance can be obtained.
- All non-conducting materials cannot be machined.
- Tools material and workpiece material should be chemically stable with the electrolyte solution.
- Designing and marking of the tool is difficult but its life is long so recommended only for mass production.
- The accurate feed rate of tools is required.
Application of Electrochemical Machining
- This process is used to machine complex cavities in high strength materials, particularly is the aerospace industry for mass production of turbine blades, jet-engine parts, and nozzles.
- It is also used to machine forging-die cavities (die sinking) and to produce small holes.
- Can be used as a deburring process.
- There is no tool wear and it can be used to machine hard (brittle and heat resistant) materials.
- Internal finishing of surgical needles and also for their sharpening.
- Drilling of small and dipper holes with very good quality of internal surface finish.
- Used for making inclined and blind holes and finishing of conventionally machined surfaces.
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