Post on 17-Jul-2016
description
Lesson Outcomes
By the end of this lessons, students should be able to:
• The concept of lathe and different lathe operations
• Calculating machining parameters in lathe
operations
• Lathe machine components and lathe cutting tool
• Design and operating guideline for lathe
operations as well as troubleshooting
• Current developments in lathe machining
Lathe concept
Lathe: A machining process whereby a cutting
tool is fed into a rotating workpiece
Turning-Cutting primarity
along axial direction
Lathe-Cutting primarily
along radial direction
Lathe / turning
workpiece
Cutting
tool
workpiece
Cutting
tool
Types of lathe operations
Pls read & understand descriptions of each operation in 674-676
Types of lathe operations
1. Turning: to produce straight, conical, curved, or grooved workpieces such as shafts, spindles, and pins.
2. Facing: to produce a flat surface at the end of the part and perpendicular to its axis useful for parts that are assembled with other components.
3. Cutting with form tools: to produce various axisymmetric shapes for functional or aesthetic purposes.
4. Boring: to enlarge a hole or cylindrical cavity made by a previous process or to produce circular internal grooves.
5. Drilling: to produce a hole which may be followed by boring to improve its dimensional accuracy and surface finish.
Types of lathe operations
6. Parting: also called cutting off, to cut a piece
from the end of a part, as is done in the
production of slugs or blanks for additional
processing into discrete products
7. Threading: to produce external or internal
threads
8. Knurling: to produce a regularly shaped
roughness on cylindrical surfaces, as in making
knobs
Roughing & Finishing
1. Perform rough cut: high f,d high MRR.
Why?
2. Perform finishing cut: low f,d low
MRR. Why?
Lathe machine components
Bed: supports all other major components. Heavy & rigid. Ways allows carriage to slide.
Carriage: consists of cross-slide, tool post, and apron. Cutting tool is mounted on tool post.
Cross slide: moves radially and in/out.
Headstock: Contains motors & gearing to supply power to spindle.
Spindle: hollow so that a workholding device (chuck or collet can be mounted)
Tailstock: Slides in the ways to support the other end of the workpiece. Dead/live center or drill can be mounted here.
High speed machining
• High speed: V=600-1800 m/min
• Very high speed: V=1800-18000 m/min
• Ultra high speed: V>18000 m/min
• Heat is removed along with chips low
thermal distortion
• High productivity Low unit cost
Ultra precision machining
• For precision manufacturing of electronic,
nuclear energy and defense applications
• Cutting tool is a single crystal diamond
• Tool radius is at nanometer (10-9) level
• Surface finish is at nanometer level
• Very stiff machines with temperature
stability
Summary
• Lathe is a process whereby a cutting tool is fed into a rotating workpiece. A number of lathe processes allows the machinist to machine a great variety of cylindrical shapes
• Calculations for Material removal rate, cutting speed, cutting time, torque and power are important before any lathe operation
• Components should be designed with machining limitations in mind
• Troubleshooting can be performed by identifying the appropriate machining parameter to change and modifying it in the correct amount
• High speed machining and precision machining are becoming increasingly important to lower production cost and produce precision components