First Year, Mechanical Engineering Dept., Faculty of Engineering, Fayoum University Dr. Ahmed Salah Abou Taleb 1 Manufacturing Processes 1 (MDP 114)

2 Machining Operations & Machine Tools Machine TurningMillingDrillingShaperBroacherSaw Screw Thread GearsPlanner

Classifications of Machined Parts 3 1.Rotational - cylindrical shape 2.Non-rotational (also called prismatic) – block or plate Machined parts are classified as: (a) rotational, or (b) non-rotational,

4 Part Geometry Each machining operation produces a characteristic part geometry due to two factors: 1.Relative motions between the tool and the workpart. Generating – part geometry is determined by the feed trajectory of the cutting tool. 2.Shape of the cutting tool. Forming – part geometry is created by the shape of the cutting tool.

5 Part Geometry Generating shape: (a) straight turning, (b) taper turning, (c) contour turning, (d) plain milling, (e) profile milling

6 Part Geometry Forming to create shape: (a) form turning, (b) drilling, and (c) broaching

7 Part Geometry Combination of forming and generating to create shape: (a) thread cutting on a lathe, and (b) slot milling

Turning/Lathe Machine 8

Definition Turning/Lathe is a single point cutting tool machine, which removes the metal from a rotating piece of work to generate the required cylindrical shape &size. 9

Engine Turning/Lathe: The most common form of lathe, motor driven and comes in large variety of sizes and shapes. Bench Turning/Lathe: A bench top model usually of low power used to make precision machine small work pieces. Tracer Turning/Lathe: a lathe that has the ability to follow a template to copy a shape or contour. Types of Turning/Lathe 10

Automatic Turning/Lathe: A lathe in which the work piece is automatically fed and removed without use of an operator. Cutting operations are automatically controlled by a sequencer of some form Turret Turning/Lathe: lathe which have multiple tools mounted on turret either attached to the tailstock or the cross-slide, which allows for quick changes in tooling and cutting operations. Computer Controlled Turning/Lathe: A highly automated lathe, where both cutting, loading, tool changing, and part unloading are automatically controlled by computer coding. 11 Types of Turning/Lathe

Turning/Lathe Machine 12

13 Turning/Lathe Machine

Bed Head Stock Tail Stock Carriage Feed/Lead Screw 14 Turning/Lathe Machine

Size of Turning/Lathe Machine Workpiece Length Swing 15

Example: Lathe Maximum Diameter of Workpiece that can be machined = SWING (= 300 mm) Maximum Length of Workpiece that can be held between Centers (=1500 mm) 16 Size of Turning/Lathe Machine

Turning: produce straight, conical, curved, or grooved workpieces Facing: to produce a flat surface at the end of the part or for making face grooves. Drilling: to produce a hole by fixing a drill in the tailstock Lathe Operations 17

Boring: to enlarge a hole or cylindrical cavity made by a previous process or to produce circular internal grooves. Threading: to produce external or internal threads Knurling: to produce a regularly shaped roughness on cylindrical surfaces Lathe Operations 18

Contouring: tool follows a contour that is other than straight, thus creating a contoured form. Chamfering: Cutting edge cuts an angle on the corner of the cylinder, forming a "chamfer". Cut-off: Tool is fed radially into rotating work at some location to cut off end of part. Lathe Operations 19

Threading: Pointed form tool is fed linearly across surface of rotating workpart parallel to axis of rotation at a large feed rate, thus creating threads. Face Grooving: Taper Turning: Cutting with a form Tool: Lathe Operations 20

21 Methods of Holding the Work Holding the work between centers. Chuck. Mandrel. Collet. Face plate.

Centers Work holding Devices 22

Chucks Three jaw Four Jaw Workholding Devices.. 23

Three jaw chuck This is dependant chuck has three jaws for holding cylindrical shapes, which are adjusted collectively. Four-Jaw Chuck This is independent chuck generally has four jaws for holding square and rectangle shapes, which are adjusted individually on the chuck face by means of adjusting screws 24 Chucks Work holding Devices.

Mandrels Workpiece (job) with a hole Work holding Devices. 25

Collet Work holding Devices. 26

Face Plate Work holding Devices. 27

Operating/Cutting Conditions 1.Cutting Speed v 2.Feed f 3.Depth of Cut d 28

Relative tool travel in 1 rotation = πD Peripheral speed S = πDN 29 Operating/Cutting Conditions

The Peripheral Speed of Workpiece past the Cutting Tool =Cutting Speed D – Diameter (mm) N – Revolutions per Minute (rpm) ν = πDN/1000 m/min 30 Operating/Cutting Conditions

Fed (f) – the distance the tool advances for every rotation of workpiece (mm/rev) Fed rate (f r ) – linear travel rate (mm/min) f r = f N 31 Operating/Cutting Conditions

Depth of cut (d) perpendicular distance between machined surface and uncut surface of the Workpiece d = (D 1 – D 2 )/2 (mm) 32 Operating/Cutting Conditions

33 Operating/Cutting Conditions

Material Removal Rate (MRR): Volume of material removed in one revolution MRR =  D d f mm 3 Job makes N revolutions/min MRR =  D d f N (mm 3 /min) In terms of v MRR is given by MRR = 1000 v d f (mm 3 /min) 34 Operating/Cutting Conditions MRR = D d f N  (mm)(mm)(mm/rev)(rev/min) = mm 3 /min

Machining Time (T m ): required time to machine one pass. Job length (L) mm, Feed (f ) mm/rev, speed (N) rpm, outer diameter (D 0 ) mm, cutting speed (v) mm/min, feed rate (f r ) mm/min 35 Operating/Cutting Conditions

Manufacturing Time: the overall time to produce the product. Manufacturing time= Machining Time + Setup Time + Moving Time + Waiting Time 36 Operating/Cutting Conditions

Workpiece Material Tool Material Tool signature Surface Finish Accuracy Capability of Machine Tool 37 Operating/Cutting Conditions

Operations on Lathe Turning Facing knurling Grooving Parting Chamfering Taper turning Drilling Threading Operations on Lathe.. 38

Turning Operations on Lathe.. Cylindrical job 39

Turning.. Cylindrical job Operations on Lathe.. 40

Turning.. Excess Material is removed to reduce Diameter Cutting Tool: Turning Tool a depth of cut of 1 mm will reduce diameter by 2 mm Operations on Lathe.. 41

Facing Flat Surface/Reduce length Operations on Lathe.. 42

Facing.. machine end of job  Flat surface or to Reduce Length of Job Turning Tool Feed: in direction perpendicular to workpiece axis – Length of Tool Travel = radius of workpiece Depth of Cut: in direction parallel to workpiece axis Operations on Lathe.. 43

Facing.. Operations on Lathe.. 44

Eccentric Turning Operations on Lathe.. 45

Knurling Produce rough textured surface – For Decorative and/or Functional Purpose Knurling Tool  A Forming Process  MRR~0 Operations on Lathe.. 46

Knurling Operations on Lathe.. 47

Knurling.. Operations on Lathe.. 48

Grooving Produces a Groove on workpiece Shape of tool  shape of groove Carried out using Grooving Tool  A form tool Also called Form Turning Operations on Lathe.. 49

Grooving.. Operations on Lathe.. 50

Cut Off Cutting workpiece into Two Similar to grooving Parting Tool Hogging – tool rides over – at slow feed Coolant use Operations on Lathe.. 51

Cut Off Operations on Lathe.. 52

Chamfering Operations on Lathe.. 53

Chamfering  Beveling sharp machined edges  Similar to form turning  Chamfering tool – 45°  To Avoid Sharp Edges Make Assembly Easier Improve Aesthetics Operations on Lathe.. 54

Taper Turning Taper: Operations on Lathe.. tan α = D 1 – D 2 / 2L 55

Taper Turning.. Methods Form Tool Swiveling Compound Rest Taper Turning Attachment Simultaneous Longitudinal and Cross Feeds Operations on Lathe.. Conicity K = D 1 – D 2 / L 56

Taper Turning.. By Form Tool Operations on Lathe.. 57

Taper Turning,, By Compound Rest Operations on Lathe.. 58

Drilling Drill – cutting tool – held in TS – feed from TS Operations on Lathe.. 59

Process Sequence How to make job from raw material 45 long x 30 dia.? Operations on Lathe.. Steps: Operations Sequence Tools Process 60

Process Sequence.. Possible Sequences TURNING - FACING - KNURLING TURNING - KNURLING - FACING FACING - TURNING - KNURLING FACING - KNURLING - TURNING KNURLING - FACING - TURNING KNURLING - TURNING – FACING What is an Optimal Sequence? Operations on Lathe.. X X X X 61

Simple Problems Problem -1 A mild steel rod having 50 mm diameter and 500 mm length is to be turned on a lathe. Determine the machining time to reduce the rod to 45 mm in one pass when cutting speed is 30 m/min and a feed of 0.7 mm/rev is used. 62 Solution Given data: D = 50 mm, L j = 500 mm v = 30 m/min, f = 0.7 mm/rev Substituting the values of v and D in V = Π DN/1000 M/min Required spindle speed as: N = 191 rpm

Simple Problems Problem -2 Determine the angle at which the compound rest would be swiveled for cutting a taper on a work piece having a length of 150 mm and outside diameter 80 mm. The smallest diameter on the tapered end of the rod should be 50 mm and the required length of the tapered portion is 80 mm. Solution Given data: D1 = 80 mm, D2 = 50 mm, Lj = 80 mm (with usual notations) tan  = (80-50) / 2  80 or  = The compound rest should be swiveled at o 63