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Lathe Practice & Milling

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Presentation on theme: "Lathe Practice & Milling"— Presentation transcript:

1 Lathe Practice & Milling

2 Introduction Lathe is a machine, which removes the metal from a piece of work to the required shape &size

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

4 Automatic 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 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 Lathe A highly automated lathe, where both cutting, loading, tool changing, and part unloading are automatically controlled by computer coding.

5 Component Description

6 Lathe Operations 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. Boring: to enlarge a hole or cylindrical cavity made by a previous process or to produce circular internal grooves. Drilling: to produce a hole by fixing a drill in the tailstock Threading: to produce external or internal threads Knurling: to produce a regularly shaped roughness on cylindrical surfaces

7 Lathe Operations

8 Cutting Tools Single point cutting tool

9 Work Holding in Turning: 1. Three jaw chuck
- For holding cylindrical stock centered. - For facing/center drilling the end of your aluminum stock

10 2. Four-Jaw Chuck - This is independent chuck generally has four jaws , which are adjusted individually on the chuck face by means of adjusting screws

11 3. Collet Chuck Collet chuck is used to hold small work pieces

12 Collets Types Fig : (a) and (b) Schematic illustrations of a draw-in-type collets. The workpiece is placed in the collet hole, and the conical surfaces of the collet are forced inward by pulling it with a draw bar into the sleeve. (c) A push-out type collet. (d) Workholding of a part on a face plate.

13 4. Magnetic Chuck Thin jobs can be held by means of magnetic chucks.

14 Milling Milling is one of the basic machining processes.
Milling is a very versatile process capable of producing simple two dimensional flat shapes to complex three dimensional interlaced surface configurations.

15 The milling process: Typically uses a multi-tooth cutter Work is fed into the rotating cutter Capable of high MRR Well suited for mass production applications Cutting tools for this process are called milling cutters

16 Classifications Milling operations are classified into two major categories: Peripheral (side) Generally in a plane parallel to the axis of the cutter Cross section of the milled surface corresponds to the contour of the cutter Face Generally at right angles to the axis of rotation of the cutter Milled surface is flat and has no relationship to the contour of the cutter Combined cutting action of the side and face of the milling cutter

17

18 Straddle milling - milling two parallel surfaces using two cutters spaced apart on an arbor.

19 Operating Parameters Rpm Feed rate
Cutting Speed converted into Rpm based on cutter diameter Feed rate Feed per tooth Table feed rate Feed direction -- Conventional vs. Climb Conventional milling Most common method of feed Feed work against the rotation of the cutter

20 Workholding Devices Vise Chucks Rotating tables Angle plates
Special fixtures Universal dividing head Modular fixturing systems Clamp work to table

21 Vices

22

23 Simple formula v = πNDo (v = cutting speed mm/min, N = rotational speed rev/min, Do = original diameter, ft or mm) Do-Df = 2d (d = depth of cut, mm) fr = Nxf (f = feed in mm/rev, fr = feed rate in mm/min) Tm = L/fr (L = length of work piece, Tm = machining time in min or sec MRR = Material Removal Rate = v x f x d, MRR in mm3/min

24 Example 1: A cylindrical work part 125 mm in diameter and 900 mm long is to be turned in an engine lathe. Cutting conditions are: v = 2.5 m/s, f = 0.3 mm/rev, and d = 2.0 mm. Determine: (a) cutting time, and (b) metal removal rate.

25 Example 2: A workbar with 5
Example 2: A workbar with 5.0 in diameter and 48 in length is chucked in an engine lathe and supported at the opposite end using a live center. A 40.0 in portion of the length is to be turned to a diameter of 4.75 in one pass at a speed = 400 ft/min and a feed = in/rev. Determine: (a) the required depth of cut, (b) cutting time, and (c) metal removal rate.


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