PRESENTED TO: DR UMAR MANZOORPRESENTED BY: GROUP # 2

COURSE: SURFACE ENGINEERING AND TRIBOLOGY

SURFACE CLEANING PROCESSESE13-304SHAAF AMJADE13-311UMAIR KHALIDE13-321IMRAN HUSSAIN KHANE13-327AMEEN UR RASHEEDE13-343SYED MUSTAJAB HASSAN KAZMI1In order to ensure the efficient and lasting qualities of coating, surface treatments and various finishing. Thorough cleaning of base metal is required to achieve this objective. A metal surface during its phase of production come prone to many contaminants such as dust, oils, grease, tars, mill scales and other foreign materials. Thus various cleaning methods are adopted to ensure a clean surface of base metals for further finishing processes.

Cleaning of MetalsSo cleaning methods for metals are categorized on the basis of the contaminants involved. These categories are as follows.Chemical CleaningUltrasonic CleaningMechanical CleaningOxy-acetylene flame cleaning

Types of Cleaning TechniquesCHEMICAL CLEANINGChemical cleaning is a type of surface treatment processes which involves a metal cleaning which removes contamination usually oil and grease.The chemical cleaning process involves certain process which are stated as:

CHEMICAL CLEANINGChemical CleaningSolution, Dispersion AggregationEmuslificationSaponification Alkaline CleaningAcid CleaningSolution:In this process, contaminant are dissolved in a cleaning solution.Dispersion:A process in which surface active elements are added which remove the concentration of contamination in the cleaning solution.Aggregation:In this process, various contaminations are removed from surface in cleaning solvent and collected as a big dirt particle.Emulsification:Emulsion cleaning uses emulsifiable solvents. These emulsifiable solvents are compound which are formed by mixing organic solvent with emulsifying agent, also soluble in water. They are less toxic. Soap mixed with organic solvent make good emulsions.Saponification:A chemical reaction is occurred by reaction of animal oil or vegetable oil into soaps which is water soluble e.g detergents

CHEMICAL CLEANINGAlkaline Cleaning:It is a common industrial cleaning technique which uses an alkali to remove oils grease, wax, and many types of particles from a metallic surface. Cleaning solution consists of water soluble salts such as NaOH, KOH, Na2CO3 with dispersants and surfactants in water. cleaning is done by immersing or spraying at temperature of 50oC to 95oC. Acid Cleaning:In acid cleaning, various acid cleaners are used for pickling, deoxidizing, and bright dipping after the substances such as oil or greases that dont dissolve in acid have been removed from metal surface. Process is carried out at high temperature and done by soaking, spraying, brushing or wiping. Common acid cleaners involve HCl, HNO3 , H3PO4 ,and H2SO4.It typically removes thicker oxides, rusts and scales from metals.CHEMICAL CLEANINGMECHANICAL CLEANINGIt is the disturbance of the contamination on the metal This can be done by means of wire or brush , belt, jet, tumbling or stream jet, abrasive blasting, buffing and polishing. These techniques improves the removal of mill scale, rust and other solid contamination.

MECHANICAL CLEANINGMechanical CleaningPower BrushingTumblingAbrasive BlastingVibratory CleaningBarrel finishing involves the application of a horizontally oriented barrel of hexagonal cross sectionParts are rotated by mixing the barrel at 10-50 rev/minThe particles rise in the barrel due to rotation, followed by a tumbling down of the top layer due to gravity.Steel balls, granite chips, aluminum oxide pallets or slag are employed. TUMBLING OR BARREL FINISHINGIn this technique power brushes and fibers are driven by electrical motors are being used to remove contaminations such as heat treatment scales, weld flux and burns etc.Power brushing also help us to remove and smoothen sharp edges on metal surface during grinding or cutting.Uniform surface is attained by this technique

POWER BRUSHING

Dry Abrasive Blasting:Abrasives particles are fired by injection them into a high velocity air stream onto the metal surface through nozzleThe abrasives which are commonly used are shots, steel grits or coarse sand.Wet Abrasive GrindingSuspension of abrasives is made with the help of an agitator. Slurry is blasted with a gun through a centrifugal pump.Silica, quartz or aluminum oxide powder are being used as abrasive mediums.

ABRASIVE BLASTINGBulk finishing manufacturing technique used to deburr , radius, descale, furnish, clean, and shine a big number of relatively small jobs.Tubs or bowls are loaded with jobs and abrasive media are vibratedFrequencies ranging from 900 and 3600 cycles per minute.

VIBRATORY CLEANING

Anultrasonic cleaningis a process that usesultrasound (usually from 20400kHz) and an appropriate cleaning solvent (sometimes ordinary tap water) to clean items. In a ultrasonic cleaning process, system consists of a generator that produces high frequency electric energy being converted into high frequency sound waves by a transducer. These high frequency waves vibrate the cleaning solution as well as the component. When sound waves passes through a liquid, its cavitates or ruptures forming small vacuums pockets which then readily collapse resulting into vigorous scrubbing action. The cleaning agents may be acids, solvents and detergents.This technique is used for cleaning of aircrafts, automobiles, electronic equipment, computer precision parts, optical and magnetic parts, and jewelry and watch parts.

ULTRASONIC CLEANING

WORKING OF ULTRASONIC CLEANING SYSTEMWhen cleaning is required for large size jobs such as large plates of steel, then oxy-acetylene flame cleaning is used to remove rust or mill scale over their surfaces. Heat is provided to the scale from the flame which expands it and easily removes from the surface in the flakes form. Organic contaminants such as oil or grease also get burnt as the temperature of the flame is very high. After the oxy-acetylene flame cleaning, brushing is done in order to remove the burnt scale or remaining contaminants.OXY-ACETYLENE FLAME CLEANING:[1] J. P. KAUSHISH, MANUFACTURING PROCESSES, New Dehli: Asoke. K. Ghosh, PHI learning Private Ltd., 2010. REFERENCES:THANK YOU FOR YOUR ATTENTION