1 Electrochemical Machining (ECM)

2 Electrochemical Machining Uses an electrolyte and electrical current to ionize and remove metal atoms Can machine complex cavities in high-strength materials Leaves a burr-free surface Not affected by the strength, hardness or toughness of the material

3 Operating Principle As the tool approaches the work piece it erodes the negative shape of it. Thus complex shapes are made from soft copper metal and used to produce negative duplicates of it. This process is called electrochemical sinking As the tool approaches the work piece it erodes the negative shape of it. Thus complex shapes are made from soft copper metal and used to produce negative duplicates of it. This process is called electrochemical sinking

Operating Principle 4AUC - MENG

13/05/2002 5AUC - MENG Electrochemical Machining

6 Main Subsystems The power supply. The power supply. The electrolyte circulation system. The electrolyte circulation system. The control system. The control system. The machine. The machine.

7 ECM Components (Power) The power needed to operate the ECM is obviously electrical. There are many specifications to this power. The power needed to operate the ECM is obviously electrical. There are many specifications to this power. The current density must be high. The current density must be high. The gap between the tool and the work piece must be low for higher accuracy, thus the voltage must be low to avoid a short circuit. The gap between the tool and the work piece must be low for higher accuracy, thus the voltage must be low to avoid a short circuit. The control system uses some of this electrical power. The control system uses some of this electrical power.

8 ECM Components (electrolyte circulation system) The electrolyte must be injected in the gap at high speed (between 1500 to 3000 m/min). The electrolyte must be injected in the gap at high speed (between 1500 to 3000 m/min). The inlet pressure must be between MPa. The inlet pressure must be between MPa. The electrolyte system must include a fairly strong pump. The electrolyte system must include a fairly strong pump. System also includes a filter, sludge removal system, and treatment units. System also includes a filter, sludge removal system, and treatment units. The electrolyte is stored in a tank. The electrolyte is stored in a tank.

9 ECM Components (control system) Control parameters include: Control parameters include: Voltage Voltage Inlet and outlet pressure of electrolyte Inlet and outlet pressure of electrolyte Temperature of electrolyte. Temperature of electrolyte. The current is dependant on the above parameters and the feed rate. The current is dependant on the above parameters and the feed rate.

10 ECM Components (Machine) The machine is a major subsystem of the ECM. The machine is a major subsystem of the ECM. It includes the table, the frame, work enclosure (prevents the electrolyte from spilling), the work head (where the tool is mounted) It includes the table, the frame, work enclosure (prevents the electrolyte from spilling), the work head (where the tool is mounted) The tools (electrodes) are also part of the machine system The tools (electrodes) are also part of the machine system

11 Products The two most common products of ECM are turbine/compressor blades and rifle barrels. Each of those parts require machining of extremely hard metals with certain mechanical specifications that would be really difficult to perform on conventional machines. The two most common products of ECM are turbine/compressor blades and rifle barrels. Each of those parts require machining of extremely hard metals with certain mechanical specifications that would be really difficult to perform on conventional machines. Some of these mechanical characteristics achieved by ECM are: Some of these mechanical characteristics achieved by ECM are: Stress free grooves. Stress free grooves. Any groove geometry. Any groove geometry. Any conductive metal can be machined. Any conductive metal can be machined. Repeatable accuracy of ”. Repeatable accuracy of ”. High surface finish. High surface finish. Fast cycle time. Fast cycle time.

12 Products

13 Advantages There is no cutting forces therefore clamping is not required except for controlled motion of the work piece. There is no cutting forces therefore clamping is not required except for controlled motion of the work piece. There is no heat affected zone. There is no heat affected zone. Very accurate. Very accurate. Relatively fast Relatively fast Can machine harder metals than the tool. Can machine harder metals than the tool.

14 Disadvantages More expensive than conventional machining. More expensive than conventional machining. Need more area for installation. Need more area for installation. Electrolytes may destroy the equipment. Electrolytes may destroy the equipment. Not environmentally friendly (sludge and other waste) Not environmentally friendly (sludge and other waste) High energy consumption. High energy consumption. Material has to be electrically conductive. Material has to be electrically conductive.

15 Applications The most common application of ECM is high accuracy duplication. Because there is no tool wear, it can be used repeatedly with a high degree of accuracy. The most common application of ECM is high accuracy duplication. Because there is no tool wear, it can be used repeatedly with a high degree of accuracy. It is also used to make cavities and holes in various products. It is also used to make cavities and holes in various products. It is commonly used on thin walled, easily deformable and brittle material because they would probably develop cracks with conventional machining. It is commonly used on thin walled, easily deformable and brittle material because they would probably develop cracks with conventional machining.

16 Economics The process is economical when a large number of complex identical products need to be made (at least 50 units) The process is economical when a large number of complex identical products need to be made (at least 50 units) Several tools could be connected to a cassette to make many cavities simultaneously. (i.e. cylinder cavities in engines) Several tools could be connected to a cassette to make many cavities simultaneously. (i.e. cylinder cavities in engines) Large cavities are more economical on ECM and can be processed in 1/10 the time of EDM. Large cavities are more economical on ECM and can be processed in 1/10 the time of EDM.

17 Safety Consideration Hydrogen gas emitted is very flammable, so it should be disposed of properly and fire precautions should be taken. Hydrogen gas emitted is very flammable, so it should be disposed of properly and fire precautions should be taken. The waste material is very dangerous and environmentally unfriendly (metal sludge) so it must be recycle or disposed of properly. The waste material is very dangerous and environmentally unfriendly (metal sludge) so it must be recycle or disposed of properly. Electrolyte is highly pressurized and worker must check for minor cracks in piping before operating. Electrolyte is highly pressurized and worker must check for minor cracks in piping before operating.