Sunday, June 28, 2015

Operation Analysis - Explanation by Stegemerten and Demmler in Maynard Handbook - Second Edition

They gave 10 primary points of analysis. I made them twelve  by writing Motion Analysis as a separate point and adding Jigs and Fixtures.

Purpose of Operation
Design of Part and Assembly
Tolerances and Inspection Requirements
Material Specification
Process of Manufacture
Equipment Analysis
Tools and Speed, Feed, and Depth of Cut
Jigs and Fixtures
Workplace Layout
Plant Layout
Material Flow
Motion Analysis

Many of the above points were covered in the book Operation Analysis by Maynard. But some points were convered in a different way and they are covered in this note.

Maynard and Stegemerten gave the following items for Operation Analysis in their book.

1. Purpose of operation.

2. Complete survey of all operations performed on part.

3. Inspection requirements.

4. Material.

5. Material handling.

6. Setup and tool equipment.

7. Common possibilities for job improvement.

8. Working conditions.

9. Method.

Material Specification

In a rapidly developing technology environment, the materials originally specified in the design may no longer be the most suitable. Designers may not review each and every part of a product on a continuous basis. Therefore, the industrial engineering analysts who has taken up the responsibility of improving the efficiency of the product and the process has to check the material specification periodically in his analyses.  The cost of materials keep changing also and processes that can be used on various materials keep changing. The industrial engineer has to keep familiar with developments in the field so that he may recognize materials that have become unsuitable and suggest more appropriate materials.

In the years. 1950s, the authors highlighted developments in plastics as something important for the IE to keep note of. They said, some plastics can acts as bearings without requiring lubrication.  Some plastics can resists acids and alkalis at much less expense than metals. Sheet steel may be coated with plastic. They also mention development of more easily machined metals.

They suggest the following questions.

1. Is a new material available to provide needed properties at lower cost.
Others are covered in the book

Process of Manufacture

Similar to the material specification, the manufacture process specified by the production engineering department originally may not the cost effective process now.  It becomes the responsibility of industrial engineering analyst to ensure that the best cost process is employed during his analysis project.

The authors gave example of epoxy adhesives. The wide availability of extruded sections of many materials, shell molding techniques etc. are also mentioned.  The appearance of less expensive numerically controlled machine tools, assembly devices (robotic hands), and assembly assits devices like part-orienting vibratory feeding devices are mentioned.  It is emphasized that the industrial engineer doing operation analysis work must keep abreast of developments in  the manufacturing area if he is going to produce results.

Equipment Analysis

When analyzing equipment, the industrial engineer must consider the machine capability. Routines for creating a machine-capability index are available and industrial engineer has to make sure that machine capability is calculated for various machines. This is required as time goes, machines lose the ability to produce to close tolerances. Hence, the machines are not used for high quality work after some time.

The questions suggested from machine capability or process capability angle.

1. Does the machine specified on the operation sheet have the capability to produce quality parts at the specified speed, feed, and depth of cut.

Tools and Speed, Feed, and Depth of Cut

The cutting tool manufacturers are doing research and development and coming out with tool bits that can give higher metal removal rates and also provide superior finished surface. Machine tools manufacturers are also coming out with machines having higher horsepower and rigidity.

The authors mentioned as examples, ceramic cutting tools, metal bonded diamond wheels, and new capabilities in tool grinding. Industrial engineers have new choices to increase productivity by employing higher cutting speeds, feeds and depths of cut.

Questions suggested.

1. Have the best possible speeds, feeds, and depth of cut been specified?

Updated 28 June 2015
First published 1 June 2015

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