Friday, November 13, 2009

Electrochemical Grinding

Electrochemical grinding

Electrochemical grinding is a process that removes electrically conductive material by grinding with a negatively charged abrasive grinding wheel, an electrolyte fluid, and a positively charged workpiece.[1] Materials removed from the workpiece stay in the electrolyte fluid. Electrochemical grinding and electrochemical machining are similar but a wheel is used instead of a tool shaped like the contour of the workpiece.

Process characteristics

• The wheels and workpiece are electrically conductive.
• Wheels used last for many grindings - typically 90% of the metal is removed by electrolysis and 10% from the abrasive grinding wheel.
• Decomposes the workpiece and deposits them into the electrolyte solution. The most common electrolytes are sodium chloride and sodium nitrate at concentrations of 2 lbs per gallon.

Process schematics
The wheels are metal disks embedded with abrasive particles. Copper, brass, and nickel are the most commonly used materials; aluminum oxide is typically used as an abrasive when grinding steel. A thin layer of diamond particles will be used when grinding carbines or steels harder than Rockwell C65.
Tolerance
• This kind of grinding is mostly used because it can shape very hard metals and also because it is a chemical reducing process, the wheel lasts a longer time than normal grinding wheel can.
• This type of grinding has different types of wheels so it can shape metals to whatever they need to be shaped to.
• Produces a smoother, burr-free surface and causes less surface stress than other grinding methods.

Uses

• Production of tungsten carbide cutting tools.
• Burr-free sharpening of hypodermic needles
• Grinding of superalloy turbine blades
• Form grinding of aerospace honeycomb metals
• Removal of fatigue cracks from underwater steel structures. In this case, seawater itself acts as


the electrolyte. Diamond particles in the grinding wheel remove any non-conducting organic matter, such as algae, before electrochemical grinding begins.

Disadvantages
Electrochemical grinding loses accuracy when grinding inside corners, due to the effects of the electric field.

by :- Yusrin Bin Mohd Yusof
( 06PKM09S1010)
Azlan Shah Bin Baharudin
(06PKM09S1013)

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