Chapter 23 Machining Processes Used to Produce Round Shapes: Turning and Hole Making R. Jerz 1 2/24/2006
Processes Turning (outside surface) straight, taper, facing, contour, form, cut-off, threading, knurling Boring (internal holes) taper, form, drilling, threading, reaming Drilling (internal) Reaming (internal) R. Jerz 2 2/24/2006
Machining Surface Roughness R. Jerz 3 2/24/2006
Drilling Holes R. Jerz 4 2/24/2006
Drilling Operations Various types of drills and drilling and reaming operations. R. Jerz 5 2/24/2006
Drilling Video R. Jerz 6 2/24/2006
Drilling Machines Figure 23.24 (a) Schematic illustration of the components of a vertical drill press. (b) A radial drilling machine. Source: (b) Courtesy of Willis Machinery and Tools. R. Jerz 7 2/24/2006
Various Types of Drills R. Jerz 8 2/24/2006
Drills R. Jerz 9 2/24/2006
Reamers Figure 23.26 (a) Terminology for a helical reamer. (b) Inserted-blade adjustable reamer. R. Jerz 10 2/24/2006
General Capabilities of Drilling Feed, f Speed, V Depth of cut, d Diameter, D RPM, N R. Jerz 11 2/24/2006
Speeds and Feeds in Drilling R. Jerz 12 2/24/2006
Drilling Design Considerations Design for clamping Flat surfaces preferred Tolerances requirements Machinability of materials Allowance for tool Depth of hole (walking) Diameter of hole R. Jerz 13 2/24/2006
Boring Process Characteristics Single point tool Enlarges or straightens an existing hole Produces accurate holes (better tolerances than drilling) Able to produce large internal holes Can be performed on a lathe, boring mill, or jig bore machine tools R. Jerz 14 2/24/2006
Boring R. Jerz 15 2/24/2006
Boring and Boring Mill R. Jerz 16 2/24/2006
Boring Design Considerations Through holes, not blind holes Greater length to diameter more difficult Avoid intermittent cuts R. Jerz 17 2/24/2006
Turning Process Creates cylindrical external or internal shapes Creates flat surfaces on part ends (faces) Uses a single point tool Wide variety of shapes The machine tool is called a lathe R. Jerz 18 2/24/2006
Lathe CAD Video R. Jerz 19 2/24/2006
Video Lathe/Turning R. Jerz 20 2/24/2006
Lathe Cutting Operations Turning: produces straight, conical, curved, or grooved workpieces Facing: produces flat surfaces at the end of the part and perpendicular to its axis. Also used to produce grooves. R. Jerz 21 2/24/2006
Lathe Cutting Operations Parting or Cutting Off: cuts a piece from the end of a part Threading: produces external or internal threads Knurling: produces a regularly shaped roughness on cylindrical surfaces, as in making knobs R. Jerz 22 2/24/2006
Lathe Cutting Operations Form tool: produces axisymmetric parts Boring: enlarges a previous hole or to produce circular internal grooves Drilling: produces a hole R. Jerz 23 2/24/2006
Cutting Screw Threads R. Jerz 24 2/24/2006
Lathe Figure 23.2 General view of a typical lathe, showing various components. Source: Courtesy of Heidenreich & Harbeck. R. Jerz 25 2/24/2006
NC Lathe and Turret R. Jerz 26 2/24/2006
Parts Made on Lathes R. Jerz 27 2/24/2006
Turning Operation Figure 23.3 Schematic illustration of the basic turning operation, showing depth-ofcut, d; feed, f; and spindle rotational speed, N in rev/min. Cutting speed is the surface speed of the workpiece at the tool tip. R. Jerz 28 2/24/2006
Tool R. Jerz 29 2/24/2006
Turning Formulas R. Jerz 30 2/24/2006
Turning Parameters R. Jerz 31 2/24/2006
Turning Feeds & Speeds R. Jerz 32 2/24/2006
Feeds & Speeds for Tool Materials R. Jerz 33 2/24/2006
Cost Elements Equipment Tooling Setup time Load/unload time Direct labor Indirect labor Cycle time, idle time Overhead rate R. Jerz 34 2/24/2006
Safety Factors Rotating parts or tools Hot, sharp chips Eye and skin irritation from cutting fluids R. Jerz 35 2/24/2006
Example from Book A 6-in long, 0.5 in diameter 304 stainlesssteel rod is being reduced in diameter to 0.48 in by turning on a lathe. The spindle rotates at N=400 rpm, and the tool is traveling at an axial speed of 8 in/min. Calculate, the cutting speed, material removal rate, cutting time, and power. R. Jerz 36 2/24/2006