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OBJECTIVES

After completing this unit, the student should be

able to:

• List the objectives of tool design.

• Identify the source of specified design data.

TOOL DESIGN

Tool design is the process of designing and developing

the tools,methods,and techniques necessary to improve

manufacturing efficiency and productivity. It gives

industry the machines and special tooling needed for

today’s high-speed, high-volume production. It does

this at a level of quality and economy that will ensure

that the cost of the product is competitive. Since nosingle tool or process can serve all forms of manufac-

turing, tool design is an ever-changing, growing

process of creative problem solving.

TOOL DESIGN OBJECTIVES

The main objective of tool design is to lower manufac-

turing costs while maintaining quality and increased

production. To accomplish this, the tool designer must

satisfy the following objectives:

• Provide simple, easy-to-operate tools for maxi-

mum efficiency.

• Reduce manufacturing expenses by producing

parts at the lowest possible cost.• Design tools that consistently produce parts of

high quality.

• Increase the rate of production with existing

machine tools.

• Design the tool to make it foolproof and to pre-

vent improper use.

• Select materials that will give adequate tool life.

• Provide protection in the design of the tools for

maximum safety of the operator.

TOOL DESIGN IN MANUFACTURING

Manufacturing for global competitiveness clearly

requires the success of concurrent engineering. Con-current engineering is a process that allows the

design team to be involved in a comprehensive plan

for product design and production. Concurrent engi-

neering allows the tool design team member to be

involved in product design and production where

their knowledge of fixtures and manufacturing

processes will result in fewer design errors. Concur-

rent engineering teams consist of product designers,

process planning engineers, tool designers, quality

control engineers, production management, and

1

SECTION I

Basic Types and Functions of Jigsand Fixtures

UNIT 1

Purpose of Tool Design

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machining technicians. Companies may vary job

titles and team compositions to suit their internal

company structure.

Team members contribute based on their area of

expertise. The product, a method for manufacturing,

tooling concepts, and a quality plan are developed that

suits the selected manufacturing facility. In this way,

problems are not discovered on the production floor,

but are corrected early in the concurrent process. This

ultimately saves time and money while speeding up

the process of getting product to market earlier. Con-

current engineering allows a company to have a dis-

tinct economic advantage in a global market.

The tool designer develops a plan for maintain-

ing the concepts developed by the team with respect

to economic guidelines. Expert computer systems

are now part of the design environment, and they

support an integrated approach for tracking time and

money allocated for the project and provide imme-

diate information at any point in the concurrent

process.

PLANNING THE DESIGN

The designer is responsible for managing information

resources that impact the tool design. Product design

changes are continuously reviewed to determine tool-

ing changes that might be necessary. Last-minute

costly changes are eliminated or minimized. The

team meets regularly to provide any necessary

updates or changes in the production plan. This is

time wisely spent and results in an efficient and cost-

effective tool design. The design process is not as lin-

ear as it used to be. Communication models between

team members include e-mail and electronic transfer

of materials and may make use of sophisticated tech-nology such as teleconferencing. Team members

may consist of customers, designers, and builders in

different locations that may take them halfway

around the world.

Part Drawings

The tool designer receives a duplicate of the part geom-

etry that will be used to make the part (Figure 1–1).

Many part prints are transmitted electronically and

may include a solid model. The solid model allows the

designer to view the three-dimensional part geometry.

The task of tool design begins with a more complete

understanding of the part. A prototype, or a single

manufactured part used for evaluation purposes, can be

made available. A prototype goes one more step

beyond the solid computer model. The prototype, a

single physical part provided prior to formal produc-

tion, is a valuable tool for understanding more com-

plex part geometries. Prototypes are manufactured

using conventional Computer Numerical Control

(CNC) machine tools or some of the newer technolo-

gies such as stereolithography or a layered object man-

ufacture, more commonly referred to as a LOM. Both

the stereolithography and LOM develop the part

geometry using a system of layering the medium and

solidifying or cutting out that layer with a laser. The

result is a solid object made one layer at a time where

the layers may be no more than .003 thick. Whether

analyzing the prototype and the part drawing or just

the part drawing, the designer must consider the fol-

lowing factors that directly influence the design choic-es. These factors are:

• Overall size and shape of the part

• Type and condition of the material used for the

part

• Type of machining operation to be performed

• Degree of accuracy

• Number of pieces to be made

• Locating and clamping surfaces

Production Plan

The production plan (Figure 1–2) is an itemized list of

the manufacturing operations and the sequence of the

operations chosen by the process planning engineer.

The production plan can take many forms, depending

on the needs of each company. At the least, it should

include a brief description of each machining operation

and the machine tool designated for these operations.

The tool designer also uses this plan to assist in the

design. The production plan can include the following:

• Type and size of machine tool specified for

each operation

• Type and size of cutters specified for each operation

2 SECTION I Basic Types and Functions of Jigs and Fixtures

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• Sequence of operations

• Previous machining operations performed on the

part

In addition to the part drawing and production plan,

the tool designer is informed of the amount of time and

money that is available to spend on the design. Using

this information and a little creativity and experience,

the tool designer begins to study the design alternatives.

Alternatives

One of the first steps in problem solving is determining

the alternative solutions. The same process is used in tool

design to ensure that the best method is chosen. During

this phase of the design, the tool designer must analyze

all important information in order to answer the follow-

ing questions:

• Should special tooling be used or existing equip-

ment modified?

• Should multiple-spindle or single-spindle machines

be used?

• Should the tool be single-purpose or multipurpose?

• Will the savings justify the cost of the tool?

• What type of gauge, if any, should be used to

check each operation?

Answering these questions and others related to the

specific task, the tool designer develops alternative solu-

tions. From these alternative solutions, the most effi-cient, dependable, and cost-effective design is chosen.

CHALLENGES TO THE TOOL DESIGNER

The tool designer has many manufacturing responsi-

bilities. In addition to technical design duties, the tool

designer may be responsible for obtaining materials,

toolroom supervision, and tool inspection. The tool

designer should understand the extent of these addi-

tional duties.

UNIT I Pupose of Tool Design 3

Figure 1–1 Part drawing.

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Figure 1–2 Production plan.

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Design

In this phase, the tool designer is responsible for

developing the drawings and sketches of the tool

design ideas. Design drawings are usually subject to

approval by a chief designer. However, in smaller

companies, the tool designer often makes the tooling

decisions.

Supervision

The extent of a tool designer’s supervision is normally

determined by the size of the company (Figure 1–3).

Supervision for a single section, such as design or

toolmaking, or for the entire tooling department, may

become the tool designer’s responsibility. In either

case, the ability to lead others is helpful.

One resource a tool designer may often use to

help resolve design problems is the group of skilled

people in the toolroom. The toolroom is the area in a

shop where the machine tools and the skilled work-

force are found. These skilled trades employees arecapable of taking the prints for the individual compo-

nents of a tool and manufacturing them, assembling

the parts, and verifying their accuracy. A variety of

machine tools including manual mills, lathes,

grinders, jig mills, machining centers and in some

cases their CNC counterparts might be found in a

typical toolroom. Regardless of the level of skill a

designer possesses, these skilled toolmakers can

often see solutions that may not be obvious to the

designer. For this reason, it is always a good idea to

build a good working relationship with your toolmak-

ers. In tool design, a cooperative relationship between

the designer and the toolmakers is essential. Not only

does working together make the task at hand easier,

but also using the available expertise makes moresense than trying to do the job alone.

Procurement

Often a tool designer is responsible for obtaining the

materials to make the tool. In these situations, the tool

designer normally relies on vendors or salespeople to

supply materials and parts that meet the design speci-

fications. When selecting a vendor, a good practice is

to choose the company that offers the most service to

its customers. Services such as design assistance and

problem solving, where their product is involved, are

important factors to consider before making a final

selection. Another point to consider is whether thevendor can supply special parts or components when

necessary. Generally, the specialty vendors can fur-

nish special items for much less than those items cost

to make in-house. Since most specialty vendors offer

these services, the decision should be made on a basis

of which vendor can meet the designer’s needs in the

most timely, efficient, and dependable manner.


Figure 1–3 The tool design departments in most manufacturing organizations use a combination of drawingboards (A) and computer-aided design (CAD) workstations (B) to create the necessary tool design drawings(Photo courtesy of Advanced Technologies Center ).

A B

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Inspection

Many times the tool designer is required to inspect

the finished tool to ensure that it meets specifications.

This inspection, or functional tryout, is normally con-

ducted in two phases. First, the tool itself is inspected

for compliance with the tool drawing. Second, several

test parts are produced with the tool and are carefullychecked to ensure that they conform to the specifica-

tions shown on the part print. After the tool has been

turned over to the production department, the tool

designer should make periodic checks during produc-

tion to ensure that the specified tolerances are main-

tained (Figure 1–4).

• Electronic communication skills

• Geometric dimensioning and tolerancing

SUMMARY

The following important concepts were presented in

this unit:

• Tool design is the process of designing and devel-

oping tooling devices, methods, and procedures to

aid in improving overall manufacturing efficiency

and productivity.

• The primary objective of tool design is lowering

manufacturing costs while maintaining consis-

tent quality and increased production.

• The tool design function is a well-integrated

position within the concurrent engineering team,

requiring skills in computer technology and mul-

tiple communication mediums.

• Tool designers use part drawings and produc-

tion plans in developing alternative design solu-

tions for efficient, dependable, and cost-effective

tool designs.

• Tool designers, in addition to designing tooling,

may also be responsible for toolroom supervi-

sion, procurement, and tool inspection.

• To become a tool designer, an individual must be

able to make mechanical drawings and sketches,

understand manufacturing techniques and tool-

making methods and equipment, have a creative

mechanical ability, and have a working knowl-

edge of shop mathematics through practical

trigonometry.

REVIEW

1. List the seven objectives of tool design.2. Determine the source of the following data by

indicating 1 for the part drawing, 2 for the pro-

duction plan, and 3 for additional instructions.

a. Time allocation

b. Overall size and shape of the part

c. Required accuracy

d. Sequence of operations

e. Type and size of machines used

f. Money available


Figure 1–4 The tool designer consults the machinistto determine how well the jig or fixture performs.

REQUIREMENTS TO BECOME A TOOL DESIGNER

To perform the functions of a tool designer, an indi-

vidual must have the following skills:

• The ability to make mechanical drawings andsketches

• An understanding of modern manufacturing meth-

ods, tools, and techniques

• A creative mechanical ability

• An understanding of basic toolmaking methods

• A knowledge of technical mathematics through

practical trigonometry

• CAD drafting skills

• File management

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g. Number of pieces

h. Previous machining

i. Locating surfaces

j. Material specifications

k. Type of cutters needed

l. Type of machining required

3. What does the term concurrent mean and how is

it applied to the design of tooling?

4. Describe a toolroom.

5. List the skills of a tool designer.


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