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Name: Ansari Kaushar Ali

CLASS: 1042. Name: Ansari Kaushar Ali. Subject: Plant Maintenance & Safety. Department: Mechanical. Semester : 4th sem . Enrolment No: 106470319130. COLLEGE: S.T.B.S COLLEGE OF DIPLOMA ENGINEERING, SURAT. TYPES OF WEAR. Definition of wear:

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Name: Ansari Kaushar Ali

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  1. CLASS: 1042 Name: Ansari Kaushar Ali Subject: Plant Maintenance & Safety • Department: Mechanical Semester: 4thsem Enrolment No: 106470319130 COLLEGE: S.T.B.S COLLEGE OF DIPLOMA ENGINEERING, SURAT

  2. TYPES OF WEAR Definition of wear: Due to utilization of machines and equipments the reduction takes place in the dimension of part slowly & continuosly as the change in shape and surface finishing is known as wear. Three type of wear: 1) Mechanical wear 2) Molecular wear 3) Corrosive wear

  3. Mechanical Wear Definition: When two mating surface are in contact and have relative motion than friction is developed between the mating surfaces. The surface layer gets sheared off under the effect of friction is known as mechanical wear. • Example of mechanical wear: • -wearing of gear teeth. • - wearing of piston rings and cylinder lines. • wearing of belt & pulley in belts drive. • wearing of chain in a chain drive. • wearing of balls & races in a ball bearing. • wearing of screw threads of a lead screw. • - wearing of key and key way grove.

  4. Tool wear • Forms: • -crater wear • -flank wear • -chipping • Causes: • -abrasion • -adhesion • -diffusion • -plastic deformation

  5. Molecular wear Definition: when parts in contact are having motion and moving under the effect of high pressure or load than molecular wear takes place. The surface of the parts jammed under pressure resulting into localized welding is known as seizure. Such seized parts are causing wear on the of surface of one-another during their relative motion is called the molecular wear

  6. Corrosive wear The surface of metal gets oxidised when comes in contact with the moisture and oxygen. The oxide layer formed due to oxidation of metal on the surface of metallic parts is termed as corrosion. The oxide layer known as corrosion is brittle in nature and hence breaks away causing the wear of part surface having relative motion due to breaking of the surface layer the dimensions of the parts reduces. The wear takes place due to this phenomenon is known as corrosive wear. The metal surface becomes spongy under the effects of processes like oxidation and sulphurisation and hence the surface layer becomes brittle. The formation of holes in pipe due to cavitation hole formation in oil tank scaling of water tank sheets and scaling of the silencer pipes are examples of the corrosive wear

  7. Causes of wear -faulty design -insufficient lubrication -improper lubrication -insufficient clearance between surface -overload -misalignments -bad workmanship -use of improper tools -contact with dust and metal particles -effect of temperature -effect of water & chemical

  8. Effects & Reduction Of Wear Effects of wear: -overheating -vibration -quality reduction -lowered efficiency -noisy operation Wear Reduction Methods: -improved lubrication -increasing the surface hardness of the parts -proper surface treatment or surface coating -improving the surface finishing -maintenance of proper clearances -surface protection against dirt,dust and metal particles

  9. The Causes Of Mechanical Wear -improper material for parts -Misalignments of the parts -clearance between the parts in insufficient -overloading of parts -uses of improper lubrication for lubrication of parts -insufficient lubrication -maintenance and repairing work not done -poor surface finish of mating surface of the parts -ingrate of dirt,dust and metal chips & particles between the mating surface -bad workmanship in part manufacture -use of improper tools

  10. The Causes Of Molecular & Corrosive Wear The causes the molecular wear: -parts fitted under high pressure -parts rubbing with high pressure and velocity -lubrication of part is insufficient The causes the corrosive wear: -contact with air,water and chemicals -change of atmospheric temperature -electrochemical reaction taking place -oxidation of the surfaces -presence of corrosive gases in the air -wear resistance layer of the wearing surface is poor -parts are made from impure materials -Parts surface finishing is poor -insufficient cleaning of the parts

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