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Operation Analysis Human Factors R. Z. Angila

If

Methods Engineering

Focuses Primarily on improving productivity though (re)design of: Organizational structure

Motivation: Incentives/rewards Work Process

Work operations

Tools (Products) Work environment

Then

Operations Analysis

Focuses Primarily on improving productivity though (re)design of: Organizational structure

Motivation: Incentives/rewards Work Process

Work operations

Tools (Products) Work environment

The 9 Primary Approaches to Operation Analysis

1.

2.

3.

4.

5.

Operation Purpose Part Design Tolerances and Specs Material Manufacturing Sequence and Process 6.

Setup and Tools 7.

Material Handling 8.

Plant Layout 9.

Work Design Also consider: management and reward changes

Simultaneously consider many ways of making improvements!

1. Operation Purpose

Ask:   “Does this operation serve a useful purpose?” “Is this operation really needed?” Try to:  Eliminate operations  Combine operations As many as 25% of operations in American Industry can be eliminated.

Example 1: Operation Elimination

 Many stores have dropped the requirement that customers sign their credit slip for small totals: less than $15 - $50.

 This makes the payment transaction

very fast

!

– E.g. in coffee shop study, Average payment transaction time: 27 sec

Example 2: Operation Elimination Outsource operations

 Ask: “Can a

supplier

an operation more economically than we can

in-house

?”  Operation : pack ball bearings in grease  Modification: purchase sealed bearings from supplier.

Example 3: Operation Elimination

Eliminate re-work Coffee shop worker: 1.

2.

Worker pours milk into stainless steel beaker, Steams milk, pours into cup.

3.

Runs out of milk – must pour and steam more while customer waits impatiently.

Solution:  Add measuring lines to inside of beaker so worker does not have to estimate how much milk to pour.

2. Part Design

Design for manufacturing and life-cycle  Reduce parts – simplify designs  Reduce processing operations  Utilize better material  Loosen tolerances where possible  Design for manufacturing: choose an

easy

to manufacture shape over a

difficult

one.

Minimum cost design

 It helps designers if they understand processes such as: casting, molding and punching, bending, etc.

 Example: instead of: – Four bends in sheet metal to make part, – Make lower cost extrusion with 4 bends already in it.

 This type of thinking is called “Design for Manufacturing”

3. Tolerances and specifications

 Designers tend to incorporate tolerances that are

more rigid than necessary

 Why? To be

extra sure

in all situations.

that product will function  It is perceived to

reduce risk

, but it can add much

unnecessary cost

,  Need to consider risk/cost

trade-off

.  Taguchi (86) methods develop quality products

and

reduce cost.

4. Material

 Incorporate better, more economical material in designs: – – Less expensive Easier to process – – Use materials more economically Use supplies and tools more economically, – – Standardize materials Find best vendor: price, stock. Can achieve 10% to 15% reductions by shopping around, sometimes every year.

Example: New material

 Substitute glass tubing for Micarta spacer bar in transformer. ( Micarta is a glass cloth, epoxy resin laminate material )  less expensive

and

better cooling  Replace stamped gear with plastic gear in assembly.

 saved $0.13 per unit, $10,000 per year.

Keiretsu : (Japanese term) interlocking relationship between manufacturers and suppliers.

5. Manufacturing Sequence and Tools

      Re-sequence operations Group operations that can share common fixturing Mechanize manual operations where economically feasible (see section on setup) Use more efficient facilities (see section on layout) Example, substitute Super automatic cappuccino machines for old style.

Manufacture near-net shape.

Use Robots (where economically feasible – usually for long product runs, small product variability)

Example: re-sequencing

Original sequence: 1.

2.

3.

Paint part 1 Paint part 2 Paint part 3 4.

5.

Paint part 4 Rivet parts together New sequence: 1.

2.

Rivet parts together Paint

one

assembly

6. Setup, Tools and Fixtures

 Carefully consider economic trade-offs: – Will the setup, fixtures, or tools be used enough to justify their expense?

 Prevalent mistake of tool makers and planners: – Too much specialized tooling and fixturing

Example: Tooling

 Good choice: Tooling that saves 10% on each job and is used frequently.

 Poor choice: Tooling that saves 90% on each job but is used only twice a year. (Will not recover expense of creating and storing tooling).

7. Material Handling

The best way to handle material is NOT to handle it.

 Moving, storing, positioning, tracking.

 Insuring that materials get

where

they need to be

when

they are needed.

 Material Handling Institute survey says 35 to 85% of the cost of getting a product to market is associated with material handling.

Better material handling:

 Reduces cost, time  Increases safety, health and well being of workers: – 40% of plant accidents happen during material handling – 25% are caused by lifting and shifting material

Approach to reducing material handling time

 Reduce time spent picking up material  Use mechanized of automated equipment (where economically feasible)  Make better use of existing handling facilities  Handle material with greater care  Consider

bar coding

8. Plant Layout

   Poor layout can result in major costs through increased travel time, increased material handling, etc.

Two types of layouts for plants: –

Product layout

: machines placed in the order used in the manufacturing process. –

Advantage

: reduces travel time

Process layout

: machines grouped by type: e.g. all lathes together, all drill presses together, etc.

Advantage

: makes training easier.

Later we will discuss Muther’s Systematic Layout Process (SLP).

9. Work Design

 Eliminate operations,  Re-sequence, re-design operations Many of our remaining chapters focus on many different types of work design!

Muther’s (1973) Systematic Layout Process (SLP) Goal : identify how to rearrange space to make it more effective for a task.

1.

2.

3.

Chart out relationships between areas based on magnitude of material handling, Establish space requirements, Make activity relationship diagrams 4.

5.

6.

Space relationship layout Evaluate alternative layouts Select best layout, plan installation.

Decision Matrices

A

performance parameter

is whatever is important to the decision maker in the situation,

“Goodness” score

for each option i is Σ (importance weight j * performance score i j )

importance (1 least, 10 most) Option 1 Option 2 Option 3 Performance Parameters Renovation Cost Material handling cost Use of Space Aesthetics Goodness Score 8

3 4 2

10

3 3 4

5

4 4 3

7

2 1 3

88 89 92

Performance score, where 4 = best, -1 = unacceptable

6. Select the

best

layout for your purposes

1.

 Choose the Layout with the highest “score” from your decision matrices

2.

88 89

3.

92

Best!