ELECTRO CHEMICAL MACHINING PPT.......

USED FOR ENGINEERING STUDENTS..................

1. polayya chintada

2. Introduction Non-conventional machining system in which metal is removed by electrochemical process Characterized as ‘Reverse Electroplating’ means it removes metal instead of adding it Normally used for mass production and for hard materials that are difficult to machine using conventional processes Both external and internal geometries can be machined

3. We can use both electrical energy and chemical energy to remove the material ECM can be depends on faradays laws of electrolysis process For removing of material electrolyte will play essential role Here ,DC power supply is used i.e. 3-30 V Here, gap between tool and work piece is 0.5 mm Tool is -ve and work piece is +ve MRR is 1600 mm3/min Accuracy is +- 0.02mm and surface finish 0.4mm

4. Principle Faraday’s law of electrolysis : The Weight of the substance produced during electrolysis process is directly proportional to the current which passes 2.the length of time of process 3.The equivalent weight of the material Two dissimilar metals are in contact with an electrolyte and anode loses metal to cathode

5. Anode : Workpiece Cathode : Tool Electrolyte : An electrically conductive fluid

6. Process parameters

7. P r ocess

8. Main subsytem Power Supply Electrolyte Tool The Control system work piece

9. Power Supply A constant voltage has to be maintained and high density is required Type: direct current Voltage: 2 to 35 V Current: 50 to 40,000 A Current density: 20 A/cm 2 to 300 A/cm 2

10. Electrolyte Common electrolytes used are sodium chloride, sodium nitrate, sodium hydroxide, sodium fluoride, sodium chlorate, potassium chloride and sulphuric acid. These solution on reaction produce an insoluble compound in the form of sludge. Essential for electrolytic process It cools the cutting zone which becomes hot due to the flow of high current Electrolyte solution is pumped between the tool/work piece gap at about 2.5 N/mm 2 and 30 m/s

11. Electrolyte The main functions of an electrolyte in ECM are: It carries the current between tool and work-piece. I t r e mo v es th e p r o d u cts o f machin i ng and other insoluble products from the cutting region. It dissipates heat produced in the operation. The essential characteristics of electrolyte includes: Good electrical conductivity. Non-toxicity and chemical stability. Non-corrosive property. Low viscosity and high specific heat .

12. T ool The most commonly used tool material are copper, brass, titanium, copper tungsten and stainless steels when electrolyte is made of salts of sodium and potassium. Titanium has been found to be the most suitable tool where the electrolyte has the tendency to anodize the tool as in case of sulphuric acid. The other tool materials are aluminium, graphite, bronze, platinum and tungsten carbide. The accuracy of tool shape directly affects the work- piece accuracy. Electro-forming and cold forging are two methods of tool shaping.

13. T ool Requirements of Tool For ECM : Good thermal conductivity Strong enough to withstand high pressures It should be easily machined It should be conductor of electricity . It should be chemically inert to the electrolyte. Outer insulation material : Vinyl, Teflon, epoxy, enables or high temperature varnish

14. The control system Control Parameters include Voltage Inlet and outlet pressure of electrolyte Temperature of electrolyte The current is dependent on above parameters and feed rate

15. Work-piece (anode): Work-piece should be conductor of electricity. So it is almost limited to metals only . Work piece is made anode Material of the work piece is removed due to anodic dissolution

16. Further specialized Applications Die Sinking Profiling and contouring Trepanning Grinding Drilling Micro-machining Pulsed ECM

17. Economics & Products The process is economical when a large no. of complex identical products are to be made Large cavities are more economical on ECM and can be made in 1/10 th time in EDM Two most common products : Turbine/compressor blades Rifle barrels

18. Advant a ges ECM is well suited for the machining of complex two-dimensional shapes Delicate parts may be made Difficult-to machine geometries Poorly machinable materials may be processed Little or no tool wear Disadvantages Initial tooling can be timely and costly Environmentally harmful by-products Complicated tool design Large power c onsumpt i on

19. References Electrochemical machining – nptel Science Direct – ECM Wikipedia – electrochemical machining Wendt – electrochemical machining & miccromaching

20. Thank You … yours… polaiah chintada …