01 hoffman ch01
TRANSCRIPT
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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
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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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4 SECTION I Basic Types and Functions of Jigs and Fixtures
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.
UNIT I Pupose of Tool Design 5
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
6 SECTION I Basic Types and Functions of Jigs and Fixtures
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.
UNIT I Pupose of Tool Design 7
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