Selection of Metal Removal Processes - Initial Steps - Process Planning and Process Industrial Engineering

Lesson 67 of Industrial Engineering ONLINE Course.

Lesson 68. Fixturing and Clamping the Work Piece - Process Planning and Process Industrial Engineering

6. Forming by Metal Removal

https://books.google.co.in/books?id=tcHxCAAAQBAJ  - Preview

Basic Types of Material Removal Processes

The planner has the classify the shape as per part drawing to:

a. Round symmetrical
b. Prismatic

Above the basic shape there will be special features like holes, threads, slots, and flats.

Processes used for Round symmetrical parts: Turning, Grinding, Honing, Lapping, Polishing
Processes used for Prismatic parts: Milling, Grinding, Honing, Lapping, Polishing (Shaping, Planing)
Holes: Drilling, Boring, Reaming, Milling, Grinding, Broaching, 
Threads: Tapping, Thread Milling

Selection machining technology from the possible technology set is primarily dependent on surface finish.

Turning provides surface finish in the range of 0.8 microns to 25 microns Ra.
Grinding provides surface finish in the range of 0.1 microns to 1.6 microns Ra.

In the book by Gideon Halevi, Table 4 gives the surface roughness range of basic machining processes.

The actual value of the surface finish, from given range depends on factors like cutting speed, feed rate, too condition, and machine rigidity etc.

A basic process is selected first. In case of round symmetrical parts, turning is the basic process. If the basic process does not meet the surface roughness specification, an additional machining process is to be added, in addition to the first basic process. Then check the geometric tolerances (for parallelism, perpendicularity, concentricity and angularity). If the last machining process meets the required geometric tolerances the job can be completed. If it does not meet the specification, one more machining process has to be added.

When more than one machining process is used, part drawings have to be prepared for each one.  The working drawing or operation drawings are needed because the material to be left for the subsequent process has to be clearly indicated. Also the cutting parameters will be different for each operation.

Some guidelines in multiple operations;
1. In the first basic process you can specify the maximum capability value of the process as surface roughness.
2. In case of external dimension, increase the basic dimension  to 10 times of the equivalent tolerance possible with the  surface roughness specified above. (This modified dimension provides material for removal by the process.

http://www.cnctrainingcentre.com/cnc-turn/cnc-turning-surface-finish/

https://www.kennametal.com/in/en/resources/engineering-calculators/turning-calculators/surface-finish.html

https://www.meadinfo.org/2009/06/surface-finish-roughness-ra.html

Surface roughness/finish obtained in various machining operations from a machine design book
https://books.google.co.in/books?id=hKlfEB8tkcAC&pg=PA121#v=onepage&q&f=false



Machine Design
Jindal U. C.
Pearson Education India, 2010 - Electronic books - 892 pages

Machine Design is a text on the design of machine elements for the engineering undergraduates of mechanical/production/industrial disciplines. The book provides a comprehensive survey of machine elements and their analytical design methods. Besides explaining the fundamentals of the tools and techniques necessary to facilitate design calculations, the text includes extensive data on various aspects of machine elements, manufacturing considerations and materials.

https://books.google.co.in/books?id=hKlfEB8tkcAC


Gillespie L.K., (1988); Troubleshooting Manufacturing Processes,, SME, Dearborn, Michigan

Wierda, L.S., (1991); Linking Design, Process Planning and Cost Information by Feature Based Modeling, Journal of Engineering Design, Vol.2, No.1, pp.3-19.

Countersinking Handbook

LaRoux Gillespie

Industrial Press Inc., 2008 - Technology & Engineering - 353 pages

This unique handbook provides total coverage of issues related to countersinking and chamfering holes, including history of their use, design reasons, and basic cutter design. It features "how-to-use" details of the most used tools and techniques and complete information on the subject of countersinking holes of any size, including those over 10 inches in diameter. Its detailed approach to illustrating over 100 different tools designs is unparalleled in technical literature and is sure to be found useful by manufacturing engineers, shop foremen, and experienced users.

Provides discussions of all cutter material variations and options, feeds, speeds and coolants, tool holders, and applications--including plastics, metals, wood, composites, ceramics, glass, and dental materials.

Discusses side effects of countersinking, including stress risers.

Includes optimum applications for specific tool use, gaging countersinks, economics, pressworking countersinks, non-traditional countersinking methods, and references to standards and other published works.

Contains case histories, practical tips, and information to make process selection easier.

https://books.google.co.in/books?id=esWtCQuLWtIC

Updated on 27.12.2020
First published on 19.7.2020