FITTING Introduction Fitting is assembling twe or more machined components with necessary fit by hand work skills on bench ‘or work at site. Although the assembly components are machined accurately on machines. still some hand wo'k component In position The term bench work indicates production of usable tems of product components by hand on bench In fitting and bench work large numpe! © tools and equipments are required to perform various operations, Fitter 's 4 hichly killed person to carry out the fitting and bench work Work material (a) Selection of material To shapé metallic components task, Material for aw ver carefully after stud'ing drawing to ne werk (b) Estimate of material After deciding about the e ar t he quantity of raw material can be worked out so as to Meet out Ine s work ndard tables the weight of keeping Some margin for cutting and filing. Using s raw material required can be estimated (c) Cost of material Common metals are available in the market in standard sections on weight basis The cost is worked out by weight of material and its rate per kgFitting Processes x Marking Fixing dimensions on work is known as marking. The work is carried out first preparing two adjacent surfaces as reference surface for marking and then fixing the dimensions as per drawing Keeping in view comparative flatness and smoothness, one side and adjacent one end are identified. These surfaces are then filed to make them perfectly flat and smooth Maintaining their square ness Using surface plate, scale, V-block, surface gauge the dimensions are then fixed as per drawing with reference to reference surfaces. The layout lines are then punch marked to make them to last long Chipping The process of removing thick layers of metal by mean of cold Chisels is known as chipping. The ©xcess un wanted material is cut and removed using chisels. In handling material is then removed by chipping to make the surface flat Cutting/Sawing Cutting/sawing 'S a process of Parting metal with the help of hacksaw Cutting is carried ut by setting suitable blade in hacksaw frame and adjusting the blade tension. The work piece is securely fixed in the vice ‘The cut is initiated by locating the position just Outside the line with few teeth to form nick. To saw further the hack is moved to take Cutting stroke with Proper balance and 40-50 stroke per minute The cutting is slow down at the end of cut to control the saw yo Filing , In chipping & Cutting operations 0 5-0 6 mm allowance is provided for tiling to remove the burr from the cuts and clean the face of cuts. It 's necessary to have this allowance to finish the final shape. The process of Smoothing surfaces with files is known as filing The filing is Carried out by Proper holding of work to the level of elbow in vice adjusting Position with proper footing and holding the file in correct way. In filing the file is moved € pressure to remove material Itis brought to Starting t The file is moved across the work with (a) Straight filing In straight filing the file is moved forward at right angle to length of work The technique is used to Smoothing thin pieces (b) Cross filing In cross filing the two Consecutive strokes are taken in Cross direction at angle to work to cover maximum surface area and to remove maximum material from the work. This also removes the score marks of the file (c) Draw filing — . In draw filing the file is Placed at right angle across the work by with both hand close together. The file is moved Up and down 6 length of work. Draw filing is used for smoother cutting as finishingHh Scraping Scrapin 9 is process to maki e a fine. smo form of thin slices. Scrapers are used tee oe ee nae Drilling Drilling is operation of producing circular in a metal work on a drilling machine using appropriate size of drill piece. The work is carried out Reaming For accurat finish of drill hole. The reamers re} hole first hole is made by selecting d 25 mm. It is followed by reaming with correct siz e hole, drilling Is followed by reaming to correct shape & size and surface move little material from the drilled hole For reamed rill with 0.4mm allowance for reaming up to hole of e of reamer Taping nal threads using taps. In taping first a smaller size hole , It is a operation of making inter is drilled. The size if drill can be calculated from the following formula r ISS p=T-2d D is the diameter of tap drill size. T diameter of tap and d's depth of tread FO itch of thread plug and bottom tap known as Rougher threads d = 0 61p Hand taps are made in sets of three » taper = Intermediate and Finisher respectively After drilling treads are cut using taps one by » one \ a f cuttin’ externa! threads On round rod and bolt with help of dies The ae pee Pe: ter and adjustable die to cut threads On larger OF solid die can be used for fixed diame smaller diameter work : “ ee ize are allowed to ensure imterchangeability of nas system of limits imits fits am Limits ations ins! m roduction certain var! E oon parte with certain degree of freedom This system is KNO' ce m m mension The permissible ble sizes for dimens!© imits m: are two extreme per issl a es oe i Lin smallest size are nown as high and |ow limit respe' ly largest size : = Wy, w_ lim easonable Ti It difference between high low_limits of size. It covers olerances is ' m rf work ; impe fection IN - difference between dimension of hole and shaft for any tyP fit iffe It is " # Allowance ~~Fitting Vice Steel Scale / Steel Rule Try-square Universal Marking Block/surface gauge Surface Plate V-Block Angle Plate Specifications Width opening & depth ofjaw Common size from 65 75. 100. 125 150.200 men width Length of scale 15 30. &60cm& Accuracy 0.5 or 1 in mm 1/16 or 1/64 in inch Length ofbiade Gommon sizes nn precision 20, 25 and 30 cm “Size of base & length of sping! 750X100 mm to 1x 75 m size Grade-A 0 005 Grade-B 0 02 flatness accuracy Length & cross section By lengtn 15¢ Tools in common use Use Holding work piece or marking and measuring dimensions To check flatvess & square ness & marking For marking Drawing \nevat equired height For marking an small eces and checking 2. Do not put pu lath ‘0 support scale tc adjust height of scriber8 work for marking support work fo dailing hole support scale t adjust height of scriber& work for markin holding & supporting ibing line on etal 7 Reep gently Specific precautions 1 Keep Work surtace horizontal 8 paralle! tg 2 Keep work si mm above ja 3 use clamps & grips fo holding finishe Keep scale vertical set height of scriber Keep eye vertical to read value 7 Use edge of checks flatne 2.Keep stock 1n touch wat prepared face !o check square ness & marki Buse fitter try-square only 7 Keep gently ce plate 2-Move in touch describe 3.Adjust Hera! 1 Do not kee keeping. work piece 3 Protect from rust & dit Cle: & smeared wilh ol! oF grease after use Keep gently on surface plate 2 Move in touch with S Pt required n surface plate when usec for marking 2. Clean betore wse 1 Ensure sharpness of point 2 Maintaining angle to draw tinef 3 ‘ = ~ ok | a. | ~Guting g & chipping T “Select proper chisel for work -Maintain correct position, and angle when working Grp at proper place with adequate pressure = -Leave no chance for slip_ Select right scraper -Maintain correct position and angle when working | Gr p at proper place with adequate pressure work surtace -Select correct dritt | -Hold work in machine vice sLocate position of hole & put mark with dot punch -Grip at proper piace with adequate pressure Ensure correct location ct dail on machine Select nearest size of drill | Follow correct sequence of ubricant while cutting e Size 100 mm upwards ‘slices fro fine 4 . /. smooth surtace ~. i whi Keep « Flat/straight/twist drill For making Twist drill may be circular holes parallel shank 0 20- ao y 40mm or tapered shank 3.0t0100mm Diameter of bolt ‘ “To cut internal Set of three pieces Rougher such as in Intermediate and Finisher holes satis ag threads, "Diameter of bolt SOlid “adjustable die ‘on bars * Hand/machinelexpanding Diameter of hole to be correct size with ? _ reamed smooth finish ne enn TR hammer mainly used for’chipping & riveting ase ~~ By weight Pa Used for bending hammer | Size 022 to 01 kg stretching ‘hammering at ‘By weight Size.0.11 to .01 kg To external threads For making holes’of preening work ‘ye “Select appropiate Die Use lubricant while cutting threads -Select nearest size of drill | Keep reamer vertica! Gereral puroose # 1 Hold at nght place 2 Ensure tight ness of handle hs age. 0% ee i net rs hae a , Cone enh | Cnetres of hole work plane t | surface . Fae na toate arian a t __-bner/angular 2 Use correct combination ; 3 Place in box if not in use sy \ feet | . » Locate centre of Gee ae a alias cipieacenen, Cutting smoothing & ” | Handle carefully i fitting work 2 File show'a not touch jaw ‘ plates of vice auring filing 3.Do not store in punch Place separately 19 wooden rack 4 Do ne" strike against inetal remove onipsPe 7 Sketch Steel Scale JAW PLATE _-suioing Jaw © LD Sketch Fitting/Parallel Jaw Vice EEE® Sketch Surface Plate _ + scmicacunveD SCRAPER Neci< LG e eS Anacdil Lene __ Sketch Drill C'4 Sketch Ball Peen Hammer_¢ €-S: i SHANK +S. —sistch __seoaper Ch 9 38 Scrappers (A... Reamer (t+: 3:57 wife — Handle | Sketch Cross Pen Hammer ¢ $+ § |a BAD «<= Sqare Trimguler Rrund ee4 wOUMd ¥ | Flat ttand Kafe Eup Diamond Sketch types of files CLA: sD Sketch file operation (straight file, cross file and draw filing) | 2 8S Fi Hee. 3.) Half Round Chiese) CH-¢-s.> : lat Chieset C ch | oe SS Cross cut Chigsel iu Diamond Point Chiese! ee, == es Se ee