Electrochemical honing

Electrochemical Honing

Prepared by: Rahil Patel (11BIE026)

Yagnik Savaliya (11BIE027)

Vaibhav Chhajer(11BIE028)

Vishal Derashri (11BIE030)Pandit Deendayal Petroleum University

Introduction- Honing

• Honing is an abrasive machining process that produces aprecision surface on a metal workpiece by scrubbing anabrasive stone against it along a controlled path.

• Honing is primarily used to improve the geometric form of asurface, but may also improve the surface texture.

• Hone tool has a combined motion of rotation andtranslation

Pandit Deendayal Petroleum University

Application

• Cylinders for internal combustion engines, air bearingspindles and gears.

• There are many types of hones but all consist of one ormore abrasive stones that are held under pressure againstthe surface they are working on.

• In terms of sharpening knives, a honing steel does notactually hone knives, but simply realigns the metal along theedge.


Automatic Honing Machine- Cylinder honePandit Deendayal Petroleum University

Different Types Of Honing Tools


Honing Stone

• The hone is composed of abrasive grains that are boundtogether with an adhesive.

• Generally, honing grains are irregularly shaped and about 10 to50 micrometers in diameter (300 to 1,500 mesh grit).

• Smaller grain sizes produce a smoother surface on theworkpiece.

• A honing stone is similar to a grinding wheel in many ways, buthoning stones are usually more friable so that they conform tothe shape of the workpiece as they wear in. To counteracttheir friability, honing stones may be treated with wax or sulfurto improve life; wax is usually preferred for environmentalreasons.

• Any abrasive material may be used to create a honing stone,but the most commonly used are corundum, silicon carbide,cubic boron nitride, or diamondPandit Deendayal Petroleum University

Electrochemical Machining(ECM)

• It is a method of removing metal by an electrochemicalprocess.

• It is normally used for mass production and is used forworking extremely hard materials or materials that aredifficult to machine using conventional methods.

• Its use is limited to electrically conductive materials.

• ECM is often characterized as "reverse electroplating," inthat it removes material instead of adding it. It is similar inconcept to electrical discharge machining (EDM)

• In ECM there is no tool wear. The ECM cutting tool is guidedalong the desired path close to the work but withouttouching the piece.


Electrochemical Machining(ECM)

• High metal removal rates are possible with ECM, with nothermal or mechanical stresses being transferred to thepart, and mirror surface finishes can be achieved.

• In the ECM process, a cathode (tool) is advanced into ananode (workpiece). The pressurized electrolyte is injected ata set temperature to the area being cut. The feed rate is thesame as the rate of "liquefaction" of the material. The gapbetween the tool and the workpiece varies within 80-800micrometers (.003 in. and .030 in.).

• As electrons cross the gap, material from the workpiece isdissolved, as the tool forms the desired shape in theworkpiece. The electrolytic fluid carries away the metalhydroxide formed in the process.


Electrochemical Machining ProcessPandit Deendayal Petroleum University

Electrochemical Honing

• It is a process in which it combines the high removalcharacteristics of Electrochemical Dissolution(ECD) andMechanical Abrasion(MA) of conventional Honing.

• It has much higher rates than either of honing & internalcylindrical grinding.

• Cathodic tool is similar to the conventional honing tool, withseveral rows of small holes so that electrolyte could enterdirectly into interelectrode gap.

• Electrolyte provides electron through the ionization processwhich acts as coolant and flushes away the chips that areformed off by mechanical abrasion and metal sludge thatresults from electrochemical dissolution action.


Electrochemical Honing-Process

• Tool is inserted inside the worked hole or a cylinder.

• Mechanical abrasion takes place first by the stones/hones.

• Oxides formed due to working from previous process will beremoved by it and clean surface will be achieved.

• Now the clean surface will be in contact with electrolyte andthen Electrochemical Dissolution will remove the desiredmaterial.

• Same procedure is continued till the required cut is made.

• To control surface roughness Mechanical Abrasion isallowed to continue for a few seconds after the current hasbeen turned off.


Electrochemical Honing-Process

• Majority of the material is removed by the ECD phase.

• Abrading stones remove enough material to generate around, straight, geometrically true cylinder.

• Mechanical abrasion just removes the surface oxides thatare formed on the work surface due to ECD.

• Removal of oxides enhances the performance of ECD as itcould directly remove the required material and freshsurface is obtained for each ECD phase.


Process Characteristics

• Abrasive stones are used to maintain the gap size of 0.075to 0.250mm.

• Surface finish ranges from: 0.2 to 0.8µm.

• Electrolyte temperature is nearly maintained at 38-40 0C.

• Pressure of 1000kPa.

• Flow Rate: 95 L/min.

• DC Current is Used.

• Voltage gap of 6 to 30V is kept accordingly.

• Current Density of 465 A/cm2 .


Process Characteristics

• Cross-Hatched Cut surface is obtained after machiningwhich is most desired after any load bearing surface.

• Tolerance can be achieved is as low as ±0.003mm.

• Material removal rate is 3 to 5 times faster thenconventional honing and 4 times faster than that of internalcylindrical grinding.


Applications• Due to rotating and reciprocating honing motion, the

process reduces the errors in roundness through the rotarymotion.

• Taper and waviness errors can also be reduced


Advantages• Low tolerances.

• Good surface finish is achieved.

• Small Correction on workpieces is possible.

• Shaping and surface finishing is done in one process.

• Light stone/hone pressure is used in the process, heatdistortion is avoided.

• Due to Electrochemical Dissolution phase, no stress isaccumulated and it automatically deburrs the part.

• It can be used for hard and conductive material that aresusceptible to heat and distortion.


Disadvantages

• Machinery cost is high.

• Machining cost per piece increases as it is an additionprocess.


Thank You..!!


Electrochemical honing

Business

Transcript of Electrochemical honing