SHEET METAL SHOP GENERAL WORKSHOP PRACTICE -2 Sa INDEX To various metal forming processes ¢ g, spinning, punching, ‘anking, cup drawing, introduction to soldering and brazing, | introduction to metal spinning process, PRACTICAL/IOBS reparation of job involving shearing, circular shearing, rolling, folding, i sending and soldering, process e.g. funnel or any other job involving above : eperations Fercise on iob brazing process Spinning a bowl/cup/saucer, i { GRADE‘a \ —_ s fry ORES ores ®, aie the various sheet metal operations : ~ 4) jveacuring and marking 2. ‘ Cleaning . Laying out 4, Culling and shearing 25, Bending + 6. Stretch forming i Ded Srawing 8. Riveting Soldering 10. Hollowing or Blocking 41. Sinking 42. Raising 43. Planishing. oR ae ae (MEASURING AND MARKING _——e— ’ The #1 : cizas of sheets-availabse in market is quiet large. But the required size of shect for making @ competent may be a smaller one. So, a standard size sheet has to be cul into several smialier pieces, each piece having sufficient area for making one such component. These smaller sizes are first decided and then these sizes are marked on the larger sheet to cut into small pieces along the marked lines. A litle allowance for cutting has to be kept to the required smaller overall sizes se that the cut pieces are not undersize. Overall dimensions, length and breadth of the required smatior pieces are marked on the large sheet with the help of marking tools, including a steel rule, a straight edge, a steel square otc. and a scribier. The sheet surface may have to be coated witha colouring media. Such as cellulose lacquer, so that the scribed lines are clearly visible. The procedure for marking straight lines, curved lines, indentation marks and transferring a pattem is as follows : . sgt soprano 4. Marking straight lines “Tie straight‘edg® or steel Square is used to draw straight lines. When straight edge or steel square is used, a sharp pointed seriber is held in one hand at an angle against the edge of the straight edge of steel square, then the lines are drawn by applying a ite pressure tothe seriber. 2. Marking circles and arcs “The circles and ares are marked on the surface of a sheet metal with the help of a divider ora tramme point, One leg of the divider is placed at the centre of @ circle or arc, the other enis moves with a little pressure on the divider to mark the circle of arc. 3, Marking irregular curves Curves are drawn with the help of a French curve. The French curve is set in such a way that at least three points coincide with the curve, itis then moved to c curves may also be drawn by a flexible rule made of spring steel. 4, Miarking indentation marks \cide next three points. The irreguar Ths indentation marks for drilling are made with a centre punch, whereas marks for centres to divide: Iocetio of punch is marked with two intersecting li of tiie punci is given a light blow with the help of hammer 6. Transferring a pattern are mathed by metimes a prick punch and ine harp pointed pen while transferring a pattern, the ends of the fines the patter ane join the lines by a scriber in proper mann raww the cult of the paper patiern ona sheet or s.iiber is used for metal pattern. ov for transferring a pattern etc. are made with a prick punch, While using punches, first th . then the punch is held at that point anit hess use0= Cutting off £ ¢ This means severing a piece forma strip with a cut along a single line. , Parting : Parting signifies that scrap'is removed between the two pieces to part them. » ‘Blanking Blanking mieans to cut a whole required piece from sheet metal. - Punching Punching means to make circular holes on a sheet with the help of a punch and die. Piercing Piercingis similar to punching but in punching, circular holes are produced in a sheet where as in piercing; holes oiher than circular are produced in a sheet. Stitting When shearing is conducted between rotary blades, the process is referred to as slitting. It cuts the sheet metal lengthwise. In this way, strips of small widths are sheared from the standard size sheets, which is having larger width than the required amount of width, Nibbiing/Nibbing Nibbing is a process of continuous cutting along a specified contour, which may be a straight {ine or an irregular profile. The machines used in this operation are known as Nibblers. Trimming Teimining is the operation of cutting away excess metal ina flange or flash from a piece. part way across 2 strip, So this operation leaves a tab without removing any srofariel. Someticnes lensing means that cutis made along the three sidas and then the cutting part ic bend towards the fourth side. : _ Hotching I: isa process of removing metal to the desired shape from the side or edge of a sheet or strip Sometimes notching operation is also performed to prevent overlapping of metal where the corners ‘come together. A very good example is covering a book with a paper, Now suppose paper is sheet metal and the various cutting operations are performed to remove the sheet openings (square notch etc.) thal operation is known as notching.ren GLeANING | “Jaw alos the blank surfaces need proper cleaning betore being processed ‘his requirement \-ig inere rredominent in cabo of non-ferrous metal sheets, like those of copper, brass and silver. For esning the surfaces of these blanks pickling method is used. In pickle method we dip the blank tina picklo bath, which consists of 1 part dilute sulphuric acid and 20 parts of water, This bath fod and thie blanks are thorughly washed in a stream of water and then it is kept to dry. is heat Tcanne our] oy Le | While doing the marking of development of tite suriace of the component on the sheet, certain material for various allowances (such as overlapping, culling, bending etc.) are added. Such a layout when madé on the sheet is called laying out process. CUTTING AND SHEARING | * Cutting means to separate a sheet piece into two pieces. The term shearing stands for cutting cot het metal by two parallel cutting edges moving in opposite directions. This can be done either manually by using hand shears or snips or by means of machines called shearing machines. The "selection of a particular method and means of culting will depend on several factors, like thickness of the sheet, sizes of blanks to be cut, amount of cutting required to be done, number of blanks to” be cul; type of production-jobbing, lot (batch) or mass production, available means of cutting, etc. SOLDERING It is the process of joining two or more pieces of metal sheets by means of an alloy of tin and lead. Soi solder consists of 50% tin and 50% lead and other solder consists of 60% tin and 40% lead. For this operation, soldering iron, furnace or blow torches are used to heat the copper bit of solgering iro, solder and a flux. HOLLOWING OR BLOCKING i * — Hollowing means to bert the sheet and give ita particular shape like that of a sauce pan, lid or bow. This operation is performed on a block. Which is hollow in shape. The block may either be of wood or of cast iron. The metal is placed over a suitable hole and metal is beaten with a hammer: See fig.6.88 ; waACkeT ‘SHEET i Gas SAND BAG (A) HOLLOWING BLOCK — (8) METHOD OF HOLLOWING ——_(C) HOLLOWING METHOD ON SAND BAG ' FIG. HOLLOWING OR BLOCKING SINKING {t is a method of thinning metal to make a siallow tray. See fig. 6.89 a. ee eee FIG: SINKING (Sinking a ty on wooden blook)er { Itis the process of denting the metal down to shape over a tool witha raising hammer or'nalle. | so in this process sheet metal is,beaten and induced to blow into the required shape, Sbe fig.6..1¢ (A) POSITION OF BAT FACE WHEN RAISING (8) RAISING ‘STAGES s FIG.” “ . RAISING . . PLANISHING Tis the careful hammering operation by’ done to remove any small mails or indent raising etc. See fig. 6.91 ich exact shape and good surface is obtained. It is y ()POSTONOF HAMMER (B)ACOLLECT BEING PLINSHED (CP AMISHING A RAISED SHAPE WHEN PLANISHING WITH A COLLECT HAMMER. Fig..." PLANISHING Rr IG Itis.a process of joining the two pieces of sheet metal permanently by means of rivets. These rivews are made of soft iron and are usually coated with tin. In order to join the two pieces of sheet metal, first a hole is drilled in the pieces. The hole should be of correct size. Then the rivet will be inserted in the hole. After that the rivet head will be placed on some metal bar or stake. Joint will be produced by hammering the shank of the rivet ie;head is also formed on the other side. In this way, riveting operation is performed. See fig 6.84 HEAD Te T T° al | sHafie] “| HENGTH ROUND HEAD COUNTERSUNK w+ Ff T PANHEAD FLAT HEAD (A) RIVET (5) RIVET HEADS (C) RIVETING FIG.” RIVETS AND,RIVETINGDitferent types of notches are : ‘Straight Notch : Straight notch is prepared by making straight cut where wo have 4 ' bend the sheet. Soo fig. 6.70 ° if SLITS ! FIG. STRAIGHT NOTCH ‘Square Notch : The square notch ié used for making either a square box or a rectangular 2. box. See fig. 6.71 METAL TO BE : REMOVED MO INANE oe bees FIG. <::7 SQUARE NOTCH | 3. Bending : Bending means to bend the bars rods, wires, tubes and sheet metal to any | type of shapes with the help of dies. See fig. 6.72 ANGLE‘OF BEND { BEND ALLOWANCE TENSION SIDE ( "DEEP DRAWING | Drawing is a process by which hollow shapes are formed from the sheet. Die and Punch are used in drawing operation. See fig. 6.83 (“4pa ie ye Te TIF (ae8— SPINWING p> Bowe. To9e. _ shaaight sup, Courvieck Smurf, stood Rul " ovicler, conten pumel, vio velar hello Rowrnol “slalst™ Bll fro Horn men, MATERIAL Gl SHEET EGALVEN/ SED Ren) ‘ 2a Sieg PROCEDURE | x. Cut Un ar sheet place. a math Un conler on carne te corner Aime with glok Rut amd senther. 3. Punching Jy Hue comtern uth comber parrlr ond fermnower. y. mnardy Lit Rewnel uneulest oS pr BrawrMy size sthh the half of chiuerler ancl clecl » puke. Ss after am anhaiy cutting sheet i Rourne! hope uth ty wh of counuerl snif. \ é apie cecdibring for wooed halle utiang & cif Process wilh mateck wna Brmel in arc t cli-menéions ar anclr *e get derinedl Ahep raf ys femal Preckecct. fre cauttorg | 1 vse hap B06é gmp PLAY chk Peo pegy 2. ay ANGULAR Cutting, pLobtety 4 op PUM ISH wordy, malleeye" , UTI TY iT Eam. FUuNwEl ALL OIMENSLONS.. FRE in MimJOR MOSHLETY TRAM CFUNNEL) Qing * se Size GP Toxeowir MN. : om MATERIALL- Gf. Sheet Toul — Snipy Ateol Ante, Scribe ; Halls Punch, Horr Divider, Rivet Og PROCEOURE I}. Cut tHe Aheot as por atten : a Le in AI2e . 4 Develop Ate Avafece On the Given er by the help 6 a tpalvitle. take. a paittewn of funnet. - face the patteien on the bheet anol mak it. Ahe COlicr . fe fut dhe Line Sama fisen & oe aeot for Single Seam | joint by gavill on beef ingle seam joint: 1. Mate dhe joint with sotclering Leon, solblesky Ot. 2 gin wptha tone of alia. g7owlamm. ave Aoldoung Ahe sone PRECAUTIONS bd, Aa Ahect Hotel slop edges « & holdt Aavalle Ht wea carefully offowsiie it may drywi oto ~iile Rivebting clack ake havea of Ka Snip A kefat j gE om offer, ACLS tebe. Af home se hege 9" 4a ca % LL YERCISE ON Inve uiniG BRAD G BRALING ALL DIMENSIONS ARE IN. MoMyale! On ps sinvobloty brazivg iss Vie ial has / Apelor . (DRY - rls 4. shear Cutter 2. hever dSheartep mack 4. Cisel 5 Coloves 6 A 4. Cro, od grate? . file £0. ape guveler pen arn ore RoCEDURE 1. \ : do be Se eae satel poeta ams 222 a: Beard Eredive or 4 ltr. 1) ten Apreral over He suifen . toge thor ath ie flea: - &. The ports pre then dampect or hele! together Ay 50-6 offer suttable means & heated . ‘+, “The apedter together with tHe flux, melts vol Sab contacting sue fced , unites atth thee oir Lion it solidifies on coblig 40 for Ae sol - PRaCALTIOME 1~ Ont eats opperopurate catty tools of machines anust 22 4 dosed bn he thickves 9 material ¢o be cut: % tools .owndl Qe Gince a sheet prota wok wise, ode A : Ly wart sharp cutidy ooffes grat pce » Unvelwedl so vey spillec! abou. us wuedl » : 2. bia albwance must 42 provideel an the Bheeks 40k! cuttig G0 that Ahe finisheol product MA of coutect size anol Atvash- 4, Aves Auinf ao tut ef aoe - hommer ane Ab alise tools «hore edged ar« blurt 4