Ja Parkash Mukand Lal Innovative Engineering & Technology Anstitute, Chota Bans, Radaur (Yamuna Nagar) Manufacturing Processes Workshop Lab Manual MACHINE SHOP INTRODUCTION In.amachine shop, metals are cut to shape on different machine tools. A lathe is used to cut and shape the metal by revolving the work against a cutting tool. The work is clamped either in a chuck, fitted on to the lathe spindle or in-between the centers. The cutting tool is fixed in a tool post, mounted on a movable carriage that is positioned on the lathe bed. The cutting tool can be fed on to the work, either lengthwise or cross-wise, While turning, the chuck rotates in counter-clockwise direction, when viewed from the tail stock end. Principal parts of a Lathe Figure 4.1 shows a center lathe, indicating the main parts. The name is due to the fact that work pieces are held by the centers. Bed Itis an essential part of a lathe, which must be strong and rigid. It carries all parts of the machine and resists the cutting forces. The carriage and the tail stock move along the guide ways provided on the bed. It is usually made of cast iron. Head stock 1t contains either a cone pulley or gearings to provide the necessary range of speeds and feeds. It contains the main spindle, to which the work is held and rotated. Tail stock Itis used to support the right hand end of a long work piece. It may be clamped in any Position along the lathe bed. The tail stock spindle has an internal Morse taper to receive the dead center that supports the work. Drills, reamers, taps may also be fitted 'nto the spindle, for performing operations such as drilling, reaming and tapping Carriage or Saddle "is used to control the movement of the cutting tool. The carriage assembly consists of 49Jai Parkash Mukand Lal Innovative Engineering & Technology Institute, Chhota Bans, Radaur (Yamuna Nagar) aaa Manufacturing Processes Workshop Lab Manual the longitudinal slide, cross slide and the compound slide and apron. The cross slide | \ moves across the length of the bed and perpendicular to the axis of the spindle. This movement is used for facing and to provide the necessary depth of cut while turning, The apron, which is bolted to the saddle, is on the front of the lathe and contains the longitudinal and cross slide controls.- Jai Parkash Mukand Lal Innovative Engineering & Technology ™ i Institute, Chota Bans, Radaur (Yamuna Nagar) Manufacturing Processes Workshop Lab Manual 1 Compound Fig :1 Parts of a center Lathe © = & Fig:2 three jaw and four jaw chuck ivi ig: 5 calipers Fig :4 lathe dog and driving plate Fig: 5 calips 49:3 face plate Fig:3Compound Rest itsupports the tool post. By swiveling th e ig the compound re ny Be ted 10 any desined ante Pound test on the cross sli Tool Post The tool post, holds the tool holder or the tool, w hhich may be Lead Screw Adjusted to any working positon, Iisa long threaded shaft, located in front of the carriage, running from the head-stock tothe tail stock. It is geared to the spindle and controls the movement of the tool, ether for automatic feeding or for cutting threads Centers There are two centers known as dead center and live center, The dead center is positioned in the tail stock spindle and the live center, inthe head-stock spindle. While turning between centers, the dead center does not revolve with the work while the live center revolves with the work. WORK-HOLDING DEVICES L Three jaw chuck ltis a work holding device having three jaws (sell-centering) which will close or open c wn in figure. It is used for with respect to the chuck center or the spindle center, as shown in figure. It is holding regular objects like round bars, hexagonal rods, ee Face plate Cer types of work that Itis a plate of large diameter, used for turning operations. Certain typ isa plate lp of various accessories. held in chucks are held on the face plate with the help © cannot be hel d driving plate san data toe to drive a Work piece that is held between cet! These are Use ters. These are provided ail, the tail of the dog is «to receive and clamp the work piece and dog tl he ng. with an opem™r= pin P! k piece. rovided in the driving plate for driving the work Piearkash Muk, 7 and Lal Innovative Engineering & Technology ~~) Ay | Institute, Chhota Bans, R; ‘adaur (Yamuna Nagar) Acturing Processes W orkshop L Manual H ase — Tool feed Tool feed 1 Mark in chuck 2. Work between centr 3. Facing (External jaws) zw Si lathe cig: 7 operations on Fig: “alipers both outside and inside Pe srument with which both out » ins! utile 4 vers’ r r provision fo ps ely. These instruments may have provision for wecurately “cnire caliper r b ay casurements emer pth measure™LATHE OPERATIONS 1. Turning Cylindrical shapes, both external and internal, are prog » are produced by \uming operation, Turning atravey raversing cutting tool, trom the isthe process in which the material is removed by surface of a rotating workpiece. The oper: mused for machin ning internal surfac often called the boring operation in which a hole pre ee eviously drilled is enlarged. For s tuming long work, first it should be faced and cer r supported by means of the tail-stock centre. 2.Boring Boring is enlarging a hole and is used when correct size drill is not available, However. it should be noted that boring cannot make a hole. 3.Facing Fe 2 is a machining operation, performed to make the end surface of the work piece, flat and perpendicular to the axis of rotation. For this. the work piece may be held ina chuck and rotated about the lathe axis. A facing tool is fed perpendicular to the axis ofthe lathe, The tool is slightly inclined towards the end of the work piece. 4.Taper Turning Ataper is defined as the uniform change in the diameter of a work piece measured along itstength, Ie is expressed as a ratio of the difference in diameters to the length. It is also half the included (taper) angle, Taper turning refers to the expressed in degrees of “juetion of a conical surface, on the work piece on 8 lathe. Short steep tapers may be production o} yy swiveling the compound rest to the required angle. Here, cut on a lathe b} he cutting tool ‘utona Jd slide feed handle. The work piece is rotated in a chuck ‘ans of the compoun is fed by means © or face plate or between centers caer axially located in cylindrical parts are produced by drilling operation. using por this, the work piece is rotated in a chuck oF face plate. The tail stock «a dil : anit sjandard taper. The drill it i fited into the tail stock spindle directly or a spindle 1 56| Jai Parkash M ukand Lal Innovati Makand Mnstitute, Chhota Bans Nnovative Engineering & Technology Radaur (Yamuna Nagar ur (Yam Manufacturing Processes Wo rkshop Lab Manual through drill chuck. The t: h : Uhe tail stock is then moved over the bed ind clamped red and clamped on it near the ork, When the job r fi work by turing the a ie ob rotates, the drill bit is fed into the work by ti h Wy turning thi wheel. ail stock hand «Knurling {tis the process of embossing a diamond shaped regular pattern on the surface of a work piece using a special knurling tool. This tool consists of a set of harder ed steel rollers in a holder with the teeth cut on their surface ina d finite pattern. The tool is held rigidly on the tool post and the rollers are pressed against the revolving work piece to squeeze the metal against the multiple cutting edgy s. The purpose of knurling is to provide an effective gripping surface on « \vork piece to prevent it from slipping when operated by hand 7.Chamfering itis the operation of beveling the extreme end of a work pices Chamifer is provided for etter Look, to enable nut to pass freely on threaded work piece, to remove burrs and protect the end of the work piece from being damaged ‘Threading Threading is nothing but cutting helical groove on & work piece. Threads may be cut cither on the internal or external cylindrical surfaces. A spet ally shaped cutting tool. mown as thread cutting took, is used For this purpose Thread cutting in a lathe is performed by traversing the cutting tool at a definite rate, in proportion to the rate at erfor y shich the work revolves: “f10N irroPl a I os an important aspect of relative move inv int between cutting tool and workJai Parkash Mukan Mukand Lal Innovative Engineering & Technolo ey e. In machine tools this is accom, wi work i ols this is act fi is 18 accomplished by either moving the tool with respect to wor jeve or vice versa, In order to define re Maited to be defined. a ative motion of two objects, reference dire: are ining motion of tool | work ginary coordinate system on the machine tool, A program Sa Mine eek Piece in this coordinate system is known as a part program nes are taken for case study but other machine tools like CNC grinding. (NC Hobbing, CNC filament windi i sande sete winding machine, etc. can also be dealt with in the same manner. part programming requires establ ishment of some reference poi fere cither set by manufacturer or user. ee a eat 2) Machine Origin The machine origin is a fixed point set by the machine tool builder. Usually it cannot be changed. Any tool movement is measured from this point, The controller always remembers tool distance from the machine origin ») Program Origin Iti also called home positior its motion while executing a prograr point within the workspace of the tool whi lathe itis a point where tool change is carried out of the tool. Program origin is point from where the tool starts for mm and returns back at the end of the cycle. This can he any I which is sufficiently away from the part. In ease of CNC at any point inside the machine's electronie grid system Establishing sino shift, work shift, floating zero or datum. Usually part allows the relocation of the part igure | and Figure The part origin can be set the part origin is also known 2s origin Miceds to be defined for each new Seth Zero shifting «is affected by the location of the part origin. F the part accuracy is aff