ch08-intro methods engrg

Work Systems and the Methods, Measurement, and Management of Workby Mikell P. Groover, ISBN 0-13-140650-7.

©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Methods Engineering

Chapters:

8. Introduction to Methods Engineering and Operations Analysis

9. Charting Techniques

10.Motion Study and Work Design

Part II



Introduction to Methods Engineering and Operations Analysis

Sections:

1. Evolution and Scope of Methods Engineering

2. How to Apply Methods Engineering

3. Basic Data Collection and Analysis Techniques

4. Automation and Methods Engineering

Chapter 8



Methods Engineering

Analysis and design of work methods and systems, including the tooling, equipment, technologies, workplace layout, plant layout, and work environment



Other names for methods engineering:

Work study Work simplification Methods study Process re-engineering Business process re-engineering

Methods Engineering is often associated with work measurement.



Objectives in Methods Engineering

Increase productivity and efficiency

Reduce cycle time

Reduce product cost

Reduce labor content

Improve motivation and morale



Other Objectives

Improve customer satisfaction

Improve product and/or service quality

Reduce lead times and improve work flow

Increase flexibility of work system

Improve worker safety

Apply more ergonomic work methods

Enhance the environment (both inside and outside the facility)



Operations Analysis

Study of an operation or group of related operations for the purpose of analyzing their efficiency and effectiveness so that improvements can be developed

Objectives in operations analysis Increase productivity Reduce time and cost Improve safety and quality

Same basic objectives as methods engineering

Methods engineering places more emphasis on design. It is broader than operations analysis.



Evolution and Scope of Methods Engineering

Initial research (late 19th century) - Frank Gilbreth: Motion study

Scientific management (late 19th century-early 20th century)- Frederick W. Taylor: Motion and time study (first principle of the five principles)

Primary concern: manual physical labor

Today: methods engineering is applied to areas such as indirect labor, logistics, service operations, office work, and plant layout.



Methods Engineering

Can be divided into two areas:

1. Methods analysis

2. Methods design



Methods Analysis

Concerned with the study of an existing method or process break the method (process) down into work elements or

basic operations examine the details of the elements: a systematic (=

purposefully regular, methodical) search to improve the process

This involved checklists of questions and suggestions for improvements

Objectives : Eliminate unnecessary and non-value-adding work

elements Combine elements and operations Rearrange elements into more logical sequence Simplify remaining elements and operations

In your project



Methods Design

Concerned with either of the following situations:

1.Design of a new method or process Required for new product or service and there

is no existing precedentMethod must be designed from scratch, using

best existing practice for similar operations

2.Redesign of an existing method or process based on a preceding methods analysis



Systematic Approach in Methods Engineering

1. Define the problem and objectives

2. Analyze the problem

3. Formulate alternatives

4. Evaluate alternatives and select the best solution

5. Implement the best method

6. Audit the study (follow-ups)

IE 407-IE 408

A systematic approach is more likely to yield operational improvements than an undisciplined approach



Step 1: Define the problem and objectives

Problem: the reason for needing a systematic approach to determine its solution low productivity, high cost, inefficient methods, the

need for a new method/operation

Objective: the desired improvement or new methods design that would result from the project. Increase productivity, reduce labor content, improve

safety, develop a new method

The problem definition and the objectives must be specific to the problem under investigation.



Step 2: Analyze the problem

Data collection and analysis.

Kind of activities involved Identify the basic function of the operation Gather background information Observe existing/similar processes Collect data Construct experiments on the process Develop/utilize a mathematical model of the process Perform a computer simulation of the process Use charting techniques



Step 3: Formulate Alternatives

There are multiple ways to perform a task or accomplish a process.

Some of them are more efficient and effective than others

Formulate all feasible alternatives



Step 4: Evaluate alternatives and select the best

Methodical assessment of the alternatives with respect to the original problem definition and the objectives.

Selecting the best one with respect to the objective (but this is not a simple task)



Step 5: Implement the best method

Install the selected solution

Introduce/institute changes proposed in the existing method

Pilot studies and trials of the new (revised) method

Documentation of the revised method



Step 6: Audit the study

Continuous improvement (follow-ups)

Fine-tune the organization’s problem solving and decision making skills How successful was the project in terms of

the original problem definition and the objectives?

What were the implementation issues? What should be done differently in the next

study?



The Techniques of Methods Engineering

The following techniques are mostly accociated with the analysis step in the methods engineering.

Charting and diagramming techniques

Motion Study and Work Design

Facility Layout Planning

Work Measurement Techniques

New approaches



Charting & Diagramming Techniques

They are available mainly for collecting, displaying and analyzing data

Network diagrams

Traditional industrial engineering charting techniques Operation charts Process charts Flow diagrams

Other (alternative) diagrams Block diagrams Process maps

Next week



Motion Study and Work Design

Concerned with basic motions of a human worker while performing a given task

17 basic motion elements, like reach, grasp, move, release

“Principles of motion economy”- guidelines for work design Use of human body in developing the standard

method (e.g., design the work so that both hands are fully utilized)

Workplace layout Design of tooling used in the task



Motion Study and Work Design -Objective

Unnecessary motions can be eliminated.

Some of the motion elements can be combined.

The method can be simplified.

In your project

2 weeks later



Facility Layout Planning

Facility layout refers to: Size and shape of a facility Arrangement of the different departments and

equipment within the facility

The layout plays an important role in determining the overall efficiency of the operations

Problem area includes: Design of a new facility Installing new equipment, retiring old equipment Expanding (or contracting) an existing facility

IE 302 and IE 407



Work Measurement Techniques

Four basic work measurement techniques:

1. Direct time study

2. Predetermined motion time systems (PMTS)

3. Standard data systems

4. Work sampling They can be used in methods engineering to

make improvements in the work methods

3 weeks later



New Approaches

Lean productionBased on the Toyota production systemEmbraced by U.S. companies due to its success at Toyota

Six Sigma and other quality-focused programsWidely adopted in industry for improving quality of work processes

5S: The 5-step work organization:Seiri (Sort), Seiton (Set in order), Seiso(Shine), Seiketsu (Standardize), Shitsuke (Sustain)

Most of the tools used are adaptations of the old IE principles.



Selecting Among Alternative Proposals

Need for a systematic procedure to decide among alternative proposals

To begin, list the technical features and functional specifications for the application Must features

Some features and specifications that should be guaranteed at the minimum level.

Desirable features Not must features

Criteria matrix to evaluate alternatives Proposals are evaluated against the features and

specifications Eliminate candidates that do not satisfy “must features” Develop scores for desirable features



Evaluation of Robots for Welding

Industrial Robot Candidates

Model A Model B Model C Model D

Must features:

Continuous path control OK OK OK OK

Six-axis robot arm OK OK Not OK OK

Walkthrough programming OK OK OK OK

Desirable features:

Ease of programming (0-9) 6 4 6

Capability to edit program (0-5)

4 2 5

Multi-pass features (0-4) 2 2 2

Work volume (0-9) 5 8 6

Repeatability (0-5) 5 2 4

Lowest price (0-5) 4 5 3

Delivery (0-3) 1 1 3

Evaluation of vendor (0-9) 6 5 8

Totals: 33 29 37



Evaluation of Robots for Welding Industrial Robot Candidates

Model A Model B Model C Model D

Must features:

Continuous path control OK OK OK OK

Six-axis robot arm OK OK Not OK OK

Walkthrough programming OK OK OK OK

Desirable features:

Ease of programming (0-9) 6 4 6

Capability to edit program (0-5)

4 2 5

Multi-pass features (0-4) 2 2 2

Work volume (0-9) 5 8 6

Repeatability (0-5) 5 2 4

Lowest price (0-5) 4 5 3

Delivery (0-3) 1 1 3

Evaluation of vendor (0-9) 6 5 8

Totals: 33 29 37 Eliminate C because, it doesn’t satisfy one of the must

features

Select D because, it has the highest score among desirable features.



Basic Data Collection & Analysis Tools

1. Histograms

2. Pareto charts

3. Pie charts

4. Check sheets

5. Defect concentration diagrams

6. Scatter diagrams

7. Cause and effect diagrams



Histogram

A statistical graph consisting of bars representing different values, in which the length of each bar indicates the frequency or relative frequency of each member

A useful tool because the analyst can quickly visualize the features of the data, such as: Shape of the distribution (theoretical form, Normal,

Gama etc.) Any central tendency in the distribution (single or

multimodal) Approximations of the mean and mode (numerical

value of the centre) Amount of scatter in the data (variance or risk)



Number of individual parts



Histogram for Data Display

Normal distribution



Pareto Chart

Special form of histogram in which attribute data are arranged according to some criterion such as cost or value

Based on Pareto’s (XIXth century economist who was trying to analyze the distribution of wealth in Italy) Law: “the vital few and the trivial many” also known as 80%-20% rule 80% of a nation’s wealth is owned by 20% of the

population 80% of sales are accounted for by 20% of the SKUs

(stock keeping unit or items in stock)



Pareto Distribution



Pareto chart as a cumulative frequency distribution



Pareto cumulative distribution

Can be modeled by

where

y=cumulative fraction of the value variable (e.g., wealth, inventory value, revenue),

x=cumulative fraction of the item variable (e.g., population, inventory items, customers)

A is a constant determines the shape of the distribution (shape parameter).

10 and 10for

1

xyxA

xAy



(1 )

x yA

y x

To determine A:



Example: Pareto Cumulative Distribution

Given: 20% of the total inventory items in a company’s warehouse accounts for 80% of the value of the inventory.

Determine: (a) The parameter A in the Pareto cumulative

distribution equation. (b) Given that the relationship is valid for the

remaining inventory, how much of the inventory value is accounted for by 50% of the items?



Example: Solution

a) x=0.2, y=0.8

A=(0.20(1-0.8))/(0.80-0.20)=0.06667

b) y=(1+0.06667)(0.5)/(0.06667+0.5)=0.941

50% items in inventory account for 94.1% of the value of the inventory

(1 )

x yA

y x

10 and 10for

1

xyxA

xAy



Pareto Chart



Pareto Principle in Turkey

80% of the academic publications are affiliated to 20% of the universities.

78% of the earnings are derived from 96 export items, which makes the 20% of all export items.

In 2007 elections, three parties (20% of the political parties) won the 84% of the votes.

Three highest grossing movies in last November, i.e., Harry Potter, New York’ta Beş Minare, Saw 3D (only 20% of the movies) makes 80% of the total gross revenues.



Pie Charts

Example: Annual sales revenues and customer distributions for two years



Check Sheet

Not check lists

Data collection tool generally used in the preliminary stages of a study of a quality problem To recogize the trends Diagnose the problem Identify areas of further study

Data often entered by worker as check marks in a given category

Examples: Process distribution check sheet - data on process variability Defective item check sheet – types and frequencies of

defects on the product Defect location check sheet - where defects occur on the

product



It is clear from the check sheet that the third shift is reponsible for much of the variability in the data.

Make an investigation to determine the causes of this variability



The average daily production rate for the third shift is below the daily rate for the other two shifts.



Defect Concentration Diagram

A drawing of the product (all relevant views), onto which the locations and frequencies of various defect types are added

Useful for analyzing the causes of product or part defects

By analyzing the defect types and corresponding locations, the underlying causes of the defects can possibly be identified




•Case study involving final assembly of refrigerators

•Four views of refrigerator showing locations of surface defects

Defects here




•The defects were clearly shown to be concentrated around the middle section of the refrigerator.

•Upon investigations, it was learned that a belt was wrapped around each unit for material handling purposes.

•The defects were caused by the belt.

•The necessary correction action was taken.

Defects here



Scatter Diagrams

An x-y plot of data collected on two variables, where a correlation between the variables is suspected

It is useful to identify a possible relationship that exists between two processes.

The data are plotted as pairs; for each xi value, there is a corresponding yi value

The shape of the collection of data points often reveals a pattern or relationship between the two variables



Scatter Diagram

Effect of cobalt content on wear resistance for a cemented carbide cutting tool

Negative correlation: As cobalt increases wear resistance decreases.



Cause and Effect Diagram

A graphical-tabular chart used to list and analyze the potential causes of a given problem

Can be used to identify which causes are most consequential (related) and how to take corrective action against them

Also known as a “fishbone diagram” or “spray diagram”




Six general categories of causes 5M + 1P

Machines Equipment, tools etc.

Materials

Mother nature Enviromental factor such as air temperature, humadity etc.

Methods Procedures, sequence of activities etc.

Measurement Validity and accuracy of the data collection procedure

People

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