TOOL DESIGN

TOOL DESIGN

MOHD FIRDAUS IBRAHIM
SYAFIRUL IKMAR SHAHARUDIN

JABATAN KEJURUTERAAN
MEKANIKAL
POLITEKNIK SEBERANG PERAI

TOOL DESIGN

MOHD FIRDAUS IBRAHIM
SYAFIRUL IKMAR SHAHARUDIN

2021
JABATAN KEJURUTERAAN MEKANIKAL

©All rights reserved. No part of this publication may be translated or reproduced in any
retrieval system, or transmitted in any form or by any means, electronic, mechanical,
recording, or otherwise, without prior permission in writing from Politeknik Seberang

Perai.

PSP eBook | TOOL DESIGN ii

All rights reserved

No part of this publication may be translated or reproduced in any retrieval
system,or transmitted in any form or by any means, electronic, mechanical,
recording, or otherwise, without prior permission in writing from Politeknik

Seberang Perai.

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Email : [email protected] Website : www.psp.edu.my
FB : politeknikseberangperai Ig : politeknikseberangperai

Perpustakaan Negara Malaysia Cataloguing-in-Publication Data

Mohd. Firdaus Ibrahim
TOOL DESIGN / MOHD FIRDAUS IBRAHIM, SYAFIRUL IKMAR SHAHARUDIN.
Mode of access: Internet
eISBN 978-967-0783-86-4
1. Tools--Design and construction.
2. Government publications--Malaysia.
3. Electronic books.
I. Syafirul Ikmar Shaharudin. II. Title.

621.9

iii PSP eBook | TOOL DESIGN

Acknowledgement

We would like to express our deepest appreciation to all those who provided us
the possibility to complete this book. A special gratitude to our head of department,
Mr Muhammad Nasir Bin Marzuki, whose contribution in stimulating suggestions and
encouragement, helped us to coordinate these work especially in writing this book.

Furthermore, we would also like to acknowledge with much appreciation the
crucial role of the staff of Mechanical Engineering Department who gave the
permission to use all required equipment and the necessary material to complete the
task. A special thanks goes to our team mate, who help us to assemble the notes and
gave suggestion about the idea in this books. Last but not least, many thanks go to
the director of Politeknik Seberang Perai, Sr. Harith Fadzilah Bin Abd Khalid whose
have invested his full effort in guiding the team in achieving the goal.

MOHD FIRDAUS IBRAHIM
SYAFIRUL IKMAR SHAHARUDIN

PSP eBook | TOOL DESIGN iv

Preface

TOOL DESIGN exposes to the knowledge of datum concept, geometric
tolerances and fundamentals to design tool based on clamping and locating principle.
The topics also covers the principle of tool applications in metal and non-metal
process. The field of tool design is one of the most diverse areas of manufacturing
engineering. From simple cutting tools and workholders to complex cutting dies,
computer software applications, and rapid prototyping, the field of tool design has
evolved into an individual discipline requiring imagination and innovation to solve
today's complex tooling conundrums.

Tool design is a specialized area of manufacturing engineering comprising the
analysis, planning, design, construction, and application of tools, methods, and
procedures necessary to increase manufacturing productivity. To carry out these
responsibilities, tool designers must have a working knowledge of machine shop
practices, tool-making procedures, machine tool design, and manufacturing
procedures and methods, as well as the more conventional engineering disciplines of
planning, designing, engineering graphics and drawing, and cost analysis.

v PSP eBook | TOOL DESIGN Pages

Table of Content 1
1
Chapter 2
CHAPTER 1 TOOL DESIGN METHOD 3
5
1.0 Basics of Tool Design 6
1.1 Design Objectives
1.2 Tool Designer Responsibilities 8
1.3 The Design Process 8
1.4 Economics of design 9
1.5 Choice on Tool Life 13
17
CHAPTER 2 TOOLING MATERIAL 19

2.0 Materials Used for Tooling 22
2.1 Physical Properties 25
2.2 Mechanical Properties 26
2.3 Ferrous Tool Materials 27
2.4 Nonferrous Tool Materials 28
2.5 Heat treatment
29
CHAPTER 3 MOULDING 30
32
3.0 Types of Moulding Processes 27
3.1 Injection Moulding 36
3.2 Injection Moulding Defects
3.3 Plastic Extrusion Moulding Process 37
3.4 Blow Moulding
3.5 Transfer Moulding

CHAPTER 4 TOOL AND DIE

4.0 The Term of Tool and Die
4.1 Types of Die Cutting Operations
4.2 Types of Die in Manufacturing Process

SUMMARY

REFERENCE



11 PSP eBook | TOOL DESIGN
CHAPTER

TOOL DESIGN METHOD

Introduction

1.0 BASICS OF TOOL DESIGN

Tool design is a specialized area of manufacturing engineering comprising the analysis,
planning, design, construction, and application of tools, methods, and procedures necessary
to increase manufacturing productivity. To carry out these responsibilities, tool designers
must have a working knowledge of machine shop practices, tool-making procedures, machine
tool design, and manufacturing procedures and methods, as well as the more conventional
engineering disciplines of planning, designing, engineering graphics and drawing, and cost
analysis.

1.1 DESIGN OBJECTIVES

The main objective of tool design is to increase production while maintaining quality and
lowering costs. To this end, the tool de signer must:

Reduce the overall cost in manufacturing a product by making acceptable parts at the
lowest cost.
Increase the production rate by designing tools to produce parts as quickly as possible.
Maintain quality by designing tools to consistently produce parts with the required
precision.
Reduce the cost of special tooling by making every design as cost-effective and
efficient as possible.
Design tools to be safe and easy to operate.

Every design must be created with these objectives in mind. No matter how well a tool
functions or produces parts, if it costs more to make the tool than it saves in production, its
usefulness is questionable. Likewise, if a tool cannot maintain the desired degree of
repeatability from one part to the next, it is of no value in production. The following questions
should be used as a checklist to determine if a particular tool design will meet the preceding
objectives:

PSP eBook | TOOL DESIGN 2

Does the design require the operator to work close to revolving tools?
Does the tool have a means to secure it to the machine table?
Will the fixture keys fit the table of the intended machine?
Will the tool perform with a high degree of repeatability?
Has every possible detail been studied to protect the operator from injury?
Are all sharp edges and burrs removed?
Is there any possibility of the clamp loosening or the work being pulled from the tool?
Have the human ergonomics been considered in the design?
Will coolants and cutting fluids freely drain from the tool?

1.2 TOOL DESIGNER RESPONSIBILITIES

Typically, tool designers are responsible for creating a wide variety of special tools. Whether
these tools are an end product or merely an aid to manufacturing, the tool designer must be
familiar with:

cutting tools, tool holders, and cutting fluids;
machine tools, including modified or special types;
jigs and fixtures;
gages and measuring instruments;
dies for sheet-metal cutting and forming;
dies for forging, upsetting, cold finishing, and extrusion, and
fixtures and accessories for welding, riveting, and other mechanical fastening.

In addition, the tool designer must be familiar with other engineering disciplines, such as
metallurgy, electronics, computers, and machine design as they too affect the design of tools.
In most cases, the size of the employer or the type of product will determine the exact duties
of each designer. Larger companies with several product lines may employ many tool
designers.

In this situation, each designer may have an area of specialization, such as die design, jig and
fixture design, or gage design. In smaller companies, however, one tool designer may have to
do all of the tool designs, as well as other tasks in manufacturing.

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1.3 THE DESIGN PROCESS

While the specifics of designing each type of tool are discussed in subsequent sections of this
text, a few basic principles and procedures are introduced here. The design process consists
of five basic steps:

I. Statement and analysis of the problem;
II. Analysis of the requirements;
III. Development of initial ideas;
IV. Development of possible design alternatives, and
V. Finalization of design ideas.
While these five steps are separated for this discussion, in practice, each overlaps the others.
For example, when stating the problem, the requirements also must be kept in mind to
properly define and determine the problem or task to be performed. Likewise, when
determining the initial design ideas, the alternative designs are also developed. So, like many
other aspects of manufacturing, tool design is actually an ongoing process of creative problem
solving.

I. Statement of the Problem
The first step in the design of any tool is to define the problem or objective as it exists with
out tooling. This may simply be an assessment of what the proposed tool is expected to do,
such as drill four holes. Or, it may be an actual problem encountered in production where
tooling may be beneficial, such as where low-volume production is needed to relieve a
bottleneck in assembly. Once the extent of the problem has been determined, the problem
can be analyzed and resolved by following the remaining steps of the design process.

II. Analysis of Requirements
After the problem has been isolated, the requirements, including function, production
requirements, quality, cost, due date, and other related specifics can be used to determine
the parameters within which the designer must work. Every tool that is designed must:

perform specific functions;
meet certain minimum precision requirements;
keep costs to a minimum;
be available when the production schedule requires it;
be operated safely;
meet various other requirements such as adaptability to the machine, and

PSP eBook | TOOL DESIGN 4

have an acceptable working life.
Table 1 illustrates a method of applying these criteria to the process of choosing a tool design.
Rarely, if ever, will one tool design be best in all areas. The tool designer's task in this situation
is to weigh all the factors and select the tool that best meets the criteria and the task to be
performed.
III. Development of initial ideas
Initial design ideas are normally conceived after an examination of the preliminary data.
This data consists of the part print, process sheet, engineering notes, production schedules,
and other related information. While evaluating this information, the designer should take
notes to ensure nothing is forgotten during the initial evaluation. If the designer needs more
information than that furnished with the design package, the planner responsible for the tool
request should be consulted. In many cases, the designer and planner work together in a team
environment to develop the initial design parameters.
IV. Development of Design Alternatives
During the initial concept phase of design, many ideas will occur to the designer and/or the
team. As these ideas are developed, they should be written down so they are not lost or
forgotten. There are always several ways to do any job. As each method is developed and
analysed, the information should be added to the list shown in Table 1.

Table 1: Basic pattern for tool analysis

V. Finalization of Design Ideas

5 PSP eBook | TOOL DESIGN

Once the initial design ideas and alternatives are determined, the tool designer must analyze
each element to determine the best way to proceed toward the final tool design. As stated
earlier, rarely is one tool alternative a clear favorite.
Rather, the tool designer must evaluate the strong points of each alternative and weigh them
against the weak points of the design. For instance, one tool design may have a high
production rate, but the cost of the tool may be very high. On the other hand, a second tool
may have a medium production rate and will cost much less to build. In this case, the value of
production over cost must be evaluated to determine the best design for the job.
If the job is a long-term production run, the first tool may pay for itself in increased production
volume. If, however, the production run is short or it is a one-time run, the second tool may
work best by sacrificing production speed for reduced tool cost. The best design is usually a
compromise between the basic criteria of function, production requirements, quality, cost,
due date, and other requirements.

1.4 ECONOMICS OF DESIGN

The tool designer must know enough economics to determine, for example, whether
temporary tooling would suffice even though funds are provided for more expensive
permanent tooling.
He or she should be able to check the design plan well enough to initiate or defend a planning
decision to write off the tooling on a single run as opposed to writing it off by distributing the
cost against probable future reruns. The tool designer should have an opinion backed by
economic proof of certain changes that would make optimum use of the tools.
Lastly, the following basic guidelines of economical design are important to keeping costs low
while maintaining part quality:

Keep all designs simple, functional, and uncomplicated.
Use preformed commercial materials where possible.
Always use standard pre-manufactured components.
Reduce or eliminate unnecessary operations.
Do not use overly tight, expensive tolerances.
Simplify tool drawings and documentation.

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1.5 CHOICE ON TOOL LIFE

The tool designer can often influence the choice of cutting-tool materials. Therefore, the tool
designer must know the tool-life economics involved.
Typical tool-life curves are shown in Figure 1.1 for high-speed steel (HSS), sintered carbide,
and oxide tools. The wear characteristics, as denoted by the n values, show that the economic
life Tc for carbide tools is shorter than that for HSS tools (Tc equals 15 minutes for carbide
versus 35 minutes for HSS). It is even more important to use higher speeds and a shorter tool
life for oxide tools, since Tc equals five minutes.
In Figure 1.2 it is evident that most economical metal removal demands high cutting speeds
and thus higher horsepower when using carbide and oxide tooling.

Figure 1.1: Tool-life comparison of various tool materials.

7 PSP eBook | TOOL DESIGN

Figure 1.2: Performance data for various tool materials.

2CHAPTER PSP eBook | TOOL DESIGN 8

TOOLING MATERIAL

2.0 MATERIALS USED FOR TOOLING

The material selected when creating a particular tool normally is determined by the
mechanical properties necessary for that tool's proper operation. These materials should be
selected only after a careful study and evaluation of the function and requirements of the
proposed tool.
For most applications, more than one type of material will be satisfactory, and a final choice
normally will be governed by material availability and economic considerations.
The principal materials used for tools can be divided into three major categories: ferrous
metals, nonferrous metals, and nonmetallic materials. Ferrous tool materials have iron as a
base metal and include tool steel, alloy steel, carbon steel, and cast iron. Nonferrous materials
have a base metal other than iron and include aluminum, magnesium, zinc, lead, bismuth,
copper, and a variety of other metals and their alloys. Nonmetallic materials include woods,
plastics, rubbers, epoxy resins, ceramics, and diamonds that do not have a metallic base.
To properly select a material, several physical and mechanical properties should be
understood to determine how they affect a tool's function and operation.

2.1 PHYSICAL PROPERTIES

The physical properties of a material control how it will react under certain conditions.
Physical properties are natural in the material and cannot be permanently altered without
changing the material itself. These properties include: density, colour, thermal and electrical
conductivity, coefficient of thermal expansion, and melting point.

 Density
The density of a material is a measure of its mass per unit volume. Density is important to
consider when the weight of a tool needs to be minimized.

9 PSP eBook | TOOL DESIGN

 Colour
Colour is the natural tint contained throughout the material. For example, steels are normally
a silver-gray colour and copper is usually a reddish brown.

 Thermal and Electrical Conductivity
Thermal conductivity and electrical conductivity measure how quickly or slowly a specific
material conducts heat or electricity. Aluminum and copper, for example, have a high rate of
thermal and electrical conductivity, while nickel and chromium have a comparatively low rate.

 Coefficient of Thermal Expansion
The coefficient of thermal expansion is a measure of how a material expands when exposed
to heat. Materials such as aluminum, zinc, and lead have a high rate of expansion, while
carbon and silicon expand very little when heated. Using materials with low coefficients of
thermal expansion is important when dimensional accuracy is critical. Specifying materials
with differing rates of thermal expansion can cause problems in constructing and using tools.

 Melting Point
The melting point is the temperature at which a material changes from a solid to a liquid state.
Materials such as tantalum and tungsten have a high melting point, while lead and bismuth
have a comparatively low melting point. The melting point is a consideration when high
temperatures are involved in the use of a tool.

2.2 MECHANICAL PROPERTIES

The mechanical properties of a material can be permanently altered by thermal or mechanical
treatment. These properties include strength, hardness, toughness, plasticity, ductility,
malleability, and modulus of elasticity.

 Strength
Strength is the ability of a material to resist deformation. The most common units used to
designate strength are pounds per square inch (psi) and kiloPascals (kPa). When designing

PSP eBook | TOOL DESIGN 10

tools, the principal categories to be most concerned with are a material's ultimate tensile
strength, compressive strength, shear strength, and yield strength.

 Ultimate Tensile Strength
Ultimate tensile strength is the value obtained by dividing the maximum load observed during
tensile testing by the specimen's cross-sectional area before testing.
A material's ultimate tensile strength is an important property to consider when designing
large fixtures or other tooling. It is of lesser importance in tools and dies except where soft-
or medium hard ferrous or nonferrous materials are used.
The tensile tests successfully made on tool steel involve the use of tempering temperatures
much higher than those typically used on tools.
Tool steels for hot work, fatigue, or impact applications are usually specified at lower hardness
levels. The tensile properties of tool steels can be obtained from data books or vendor
literature.

 Compressive Strength
Compressive strength plays an important role in tool design. It is the maximum stress that a
metal, subjected to compression, can withstand without fracture bending or bulging.
The compressive strength test is used on hardened tool steels, especially at high hardness
levels.
For all ductile materials, the specimens flatten out under load, and there is no well-marked
fracture. For these materials, compressive strength is usually equal to tensile strength.

 Shear Strength
The shear strength of a material is important to consider when designing tools that will be
subjected to shear loads or torsion loads. Shear strength is defined as the stress necessary to
cause failure in shear loading (or torsion loading). For most steels, the shear strength is
approximately 50-60% of the alloy's tensile yield strength. Shear strengths are measured in
units of lb/in. 2 (psi) or kN/m^2 (kPa).

11 PSP eBook | TOOL DESIGN

 Yield Strength
The yield strength of a material is often the most important property to consider when
selecting an alloy for a specific application. Measured in units of lb/in. 2 (psi) or kN/m^2 (kPa),
yield strength is the stress level at which an alloy will show permanent elongation after the
stress has been removed. A typical yield strength reported is 0.2%, which indicates that the
stress produced 0.2% elongation in a 2-in. (50.8-mm) test specimen. Therefore, if permanent
deformation is not acceptable for a given application, the stresses that a component is
subjected to must be below the yield strength of the alloy. Heat treatments can be used to
increase or decrease the yield strengths of alloys.

 Hardness
Hardness is the ability of the material to resist penetration or withstand abrasion. It is an
important property in selecting tool materials.
However, hardness alone does not determine the wear or abrasion resistance of a material.
In alloy steels, especially tool steels, the resistance to wear or abrasion varies with alloy
content.
Hardness scales have been developed, each covering a separate range of hardness for
different materials.

 Rockwell Hardness
Rockwell hardness is the most widely used method for measuring the hardness of steel. The
Rockwell hardness test is conducted by using a dead weight that acts through a series of levers
to force a penetrator into the surface of the metal being tested. The softer the metal being
tested, the deeper it will be penetrated with a given load. The dial gage does not directly read
the depth of penetration, but shows scales of Rockwell numbers instead. A variety of loads
and penetrators can be used, each designated by a different letter and the relative hardness
or softness measured.
Two types of penetrators are used in Rockwell hardness testing: a diamond cone, known as a
brale, for hard materials such as tool steel, and a hardened steel ball for soft materials.

PSP eBook | TOOL DESIGN 12

 Brinell Hardness
The Brinell hardness method of measurement is much older than the Rockwell method. It
operates similarly to the Rockwell ball-test principle.
In the Brinell machine, a 10 mm (.39 in.) steel ball is forced into the material being tested
under a load of up to 3,000 kg (6,600 lb). Instead of measuring the penetration, the diameter
of the impression in the test piece is measured using a small hand microscope with a lens
calibrated in millimeters. The measured diameter is converted into a Brinell hardness number
by using a table.
The Brinell hardness measurement is most useful on soft and medium-hard materials. On
steels of high hardness, the impression is so small that it is difficult to read; therefore, the
Rockwell test is used more commonly for such materials.

 Toughness
Toughness is the ability of a material to resist fracture when subjected to impact loads
(sudden rapid loads). Materials that have high toughness must have a combination of high
strength and high ductility. Those with high strength but little ductility have low toughness.

 Plasticity
Plasticity is the property of a material that allows it to be extensively deformed without
fracture. Two general categories of plasticity are ductility and malleability.
• Ductility is the property of a material that allows it to be stretched or drawn with a tensional
force without fracture or rupture.
• Malleability is the property of a material that permits it to be hammered or rolled without
fracture or rupture.

 Modulus of Elasticity
The modulus of elasticity is a measure of the elastic stiffness of a material. It is a ratio of the
stress to the strain in the elastic region of a tensile test. The modulus of elasticity determines
how much a material will elastically deflect under an applied load. For alloys within the same
family, the modulus of elasticity does not vary (for example, the modulus of all steels is 30 ×
10^6 psi; the modulus of all aluminum alloys is 10.5 × 10^6 psi). The modulus of elasticity is
not affected by heat treatment.

13 PSP eBook | TOOL DESIGN

2.3 FERROUS TOOL MATERIALS

Many ferrous materials can be used for tool construction. Typically, materials such as carbon
steels, alloy steels, and cast irons are widely used for jigs, fixtures, and similar special tools.
These materials are supplied in several different forms.
The most common types used for tools are hot rolled, cold-rolled, and ground.
When steel is hot-rolled at a mill, a layer of decarburized slag, or scale/oxide, covers the en
tire surface of the metal. This scale/oxide should be removed when the part being made is to
be hardened. If, however, the metal is to be used in an unhardened condition, the scale/oxide
may be left on. When ordering hot-rolled materials, the designer must make allowance for
the removal of the scale/oxide.
Cold-rolled steels are generally used for applications where little or no machining or welding
is required. Cold-rolled bars are reasonably ac curate and relatively close to size. When rolled,
these steels develop internal stresses that could warp or distort the part if it were extensively
machined or welded. A cold-rolled bar is distinguished from a hot-rolled bar by its bright,
scale-free surface.
Steels are also available in a ground condition. These materials are held to close tolerances
and are available commercially in many sizes and shapes. They are normally used where a
finished surface is required without additional machining. The two standard types of ground
materials are "to-size" and "oversize." To-size materials are ground to a specific size, such as
.25 in. (6.4 mm), .50 in. (12.7 mm), or any similarly standard size.
Oversize materials are normally ground .015 in. (0.38 mm) over the standard size.

2.3.1 Carbon Steels
Carbon steels are used extensively in tool construction. They contain mostly iron and carbon
with small amounts of other alloying elements, and are the most common and least expensive
types of steel used for tools. The three principal types are low-carbon, medium-carbon, and
high-carbon steels. Low-carbon steel contains 0.05-0.30% carbon; medium-carbon steel
contains 0.30-0.70% carbon; and high-carbon steel contains 0.70-1.50% carbon. As the carbon
con tent is increased in carbon steel, the maximum strength and hardness also increase when
the metal is heat-treated. Figure 2.1: Example of carbon steels.

PSP eBook | TOOL DESIGN 14

Low-carbon steels are soft, tough steels that are easily machined and welded. Due to their
low carbon content, these steels cannot be hardened except by case hardening. Low-carbon
steels are well suited for tool bodies, handles, die shoes, and similar situations where strength
and wear resistance are not critical.
Medium-carbon steels are used where greater strength and toughness are required. Since
medium-carbon steels have higher carbon content, they can be heat-treated to make studs,
pins, axles, and nuts. Steels in this group are more expensive as well as more difficult to
machine and weld than low-carbon steels.
High-carbon steels are the most hardenable type of carbon steel. They are used frequently
for parts with which wear resistance is an important factor. Other applications where high-
carbon steels are well suited include drill bushings, locators, and wear pads. Since the carbon
content of these steels is so high, parts made from them are normally difficult to machine and
weld.

Figure 2.1: Example of carbon steels

2.3.2 Alloy Steels
Alloy steels are basically carbon steels with additional elements added to alter their
characteristics and bring about a predictable change in their mechanical properties. Not
normally used for most tools due to their cost, some alloy steels have found favour for special
applications. The alloying elements used most often in steels are manganese, nickel,
molybdenum, and chromium. Below are example of alloy steels in figure 2.2.

15 PSP eBook | TOOL DESIGN

Figure 2.2: Example of alloy steels

Alloying elements
There are around 20 alloying elements that can be added to carbon steel to produce various
grades of alloy steel. These provide different types of properties. Some of the elements used
and their effects include:

 Aluminium – can rid steel of phosphorous, sulfur and oxygen
 Chromium – can increase toughness, hardness and wear resistance
 Copper – can increase corrosion resistance and harness
 Manganese – can increase high-temperature strength, wear resistance, ductility and

hardenability
 Nickel – can increase corrosion, oxidation resistance and strength
 Silicon – can increase magnetism and strength
 Tungsten – can increase strength and hardness

Another type of alloy steel frequently used for tooling applications is stainless steel. Stainless
steel is a term used to describe high-chromium and nickel-chromium steels. These steels are
used for tools that must resist high temperatures and corrosive atmospheres. Some high-
chromium steels can be hardened by heat-treatment and are used where resistance to wear,

PSP eBook | TOOL DESIGN 16

abrasion, and corrosion are required. Martensite stainless steel is sometimes preferred for
plastic injection moulds.
Here, the high chromium content allows the steel to be highly polished and prevents
deterioration of the cavity from heat and corrosion.

2.3.3 Tool Steels
Tool steels are alloy steels produced primarily for use in cutting tools. Properly selecting tool
steels is complicated by their many special properties. The five principal properties of tool
steels are:

I. Heat resistance,
II. Abrasion resistance,
III. Shock resistance,
IV. Resistance to movement or distortion in hardening, and
V. Cutting ability.

Because no single steel can possess all of these properties to the optimum degree, hundreds
of different tool steels have been developed to meet the total range of service demands.
Frequently, hardness is proportional to wear resistance, but this is not always the case
because wear resistance usually increases as the alloy content and, particularly the carbon
content, increases.
The toughness of steels, on the other hand, is inversely proportional to their hardness, and
increases markedly as the alloy or carbon content is lowered.

2.3.4 Cast Iron
Cast iron is essentially an alloy of iron and car bon, containing from 2-4% carbon, 0.5 to about
3% silicon, 0.4 to approximately 1% manganese, plus phosphorus and sulphur. Other alloys
may be added depending on the properties desired.
The high compressive strength and ease of casting gray irons are utilized in large forming and
drawing dies to produce such items as auto mobile panels, refrigerator cabinets, bathtubs,
and other large articles. Conventional methods of hardening result in little distortion. Alloying
elements are added to promote graphitization and improve mechanical properties or develop
special characteristics.

17 PSP eBook | TOOL DESIGN

2.4 NONFERROUS TOOL MATERIALS

Nonferrous tool materials are used to some degree as die materials in special applications,
and generally for applications with limited production requirements. On the other hand, in jig
and fixture design, some nonferrous materials are used extensively where magnetism or tool
weight is important. Another area where nonferrous materials are finding increased use is for
cutting tools. Alloys and compositions of nonferrous materials are used extensively to
machine the newer, exotic, high-strength metals.

2.4.1 Aluminum
Aluminum has been used for special tooling for a long time. The principal advantages to using
aluminum are its high strength-to-weight ratio, nonmagnetic properties, and relative ease in
machining and forming. Pure aluminum is corrosion resistant, but not well suited for use as a
tooling material except in limited, low-strength applications. Aluminum alloys, while not as
corrosion resistant as pure aluminum, are much stronger and well suited for many special
tooling applications. Aluminum/copper (2000 series), aluminum/magnesium and silicon
(6000 series), and aluminum/zinc (7000 series) are the alloys most frequently used for tooling
applications. Depending on composition, some aluminum alloys are weldable and some can
be heat-treated. Example of aluminum in figure 2.3.
One form of aluminum alloy finding increased use is aluminum tooling plate. This material is
available in sheets and bars made to close tolerances. Aluminum tooling plate is useful for a
wide variety of tooling applications. From sup ports and locators to base plates and tool
bodies, aluminum tooling plate provides a lightweight alternative to steel.

Figure 2.3: Example of aluminum

PSP eBook | TOOL DESIGN 18

2.4.2 Magnesium
Magnesium, like aluminum, is a lightweight yet strong tooling material. Lighter than
aluminum, magnesium has a good strength-to-weight ratio. Magnesium is commercially
available in sheets, bars, and extruded forms. The only disadvantage in using magnesium is
its potential fire hazard. When specifying magnesium as a tooling material, make sure those
who are to make the various parts are well acquainted with the pre cautions that must be
observed when machining this material. Below in figure 2.4 is the example of magnesium.

Figure 2.4: Example of magnesium
2.4.3 Bismuth alloys
Bismuth alloys have several different uses in special tools. One of the principal advantages of
bismuth alloys is their comparatively low melting temperature. Many alloy compositions will
melt in boiling water. In addition to acting as a reusable nesting material, it can be applied as
a matrix material for securing punch and die parts in a die assembly, and as cast punches and
dies for short-run forming and drawing operations.
Another frequent application of these alloys is for cast workholders. In this case, the material
is melted and poured around the part and, once cool, the part is removed and the cast nest
is used to hold subsequent parts for machining.
Low-melt alloys are also useful when machining parts with thin cross-sections, such as turbine
blades. In these applications, the material is cast around the thin sections and acts as a
support during machining. Once the machining is complete, the material is melted off the part
and can be reused.

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2.4.4 Carbides
Carbides are a family of tool materials made from the carbides of tungsten, titanium,
tantalum, or a combination of these elements. They are powder metals consisting of the
carbide with a binder, usually cobalt, hot-pressed and then sintered into desired shapes. The
most common carbide material used for special tools is tungsten carbide. All carbides are
characterized by their high hardness values and resistance to wear. This makes them an
excellent choice for cutting tools. Generally, there is a tradeoff between hardness and
toughness, but micrograin carbides provide greater hardness and toughness together.
Example of carbide is in the figure 2.5.

Figure 2.5: Example of carbides

2.5 HEAT TREATMENT

Heat treatment is the process of heating metal without letting it reach its molten, or melting,
stage, and then cooling the metal in a controlled way to select desired mechanical properties.
Heat treatment is used to either make metal stronger or more malleable, more resistant to
abrasion or more ductile.

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All heat treatments involve heating and cooling metals, but there are three main differences
in process: the heating temperatures, the cooling rates, and the quenching types that are
used to land on the properties you want. In a future blog post, we’ll cover the different types
of heat treatment for ferrous metals, or metal with iron, which consist of annealing,
normalizing, hardening, and/or tempering. Figure 2.6 shown the example of heat treatment
process.
Stages of Heat Treatment
There are three stages of heat treatment:

 Heat the metal slowly to ensure that the metal maintains a uniform temperature
 Soak, or hold, the metal at a specific temperature for an allotted period of time
 Cool the metal to room temperature

Figure 2.6: Heat treatment of steel forging

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3CHAPTER

MOULD

Molding is a manufacturing process that involves shaping a liquid or malleable raw material
by using a fixed frame; known as either a mold or a matrix. The mold is generally a hollow
cavity receptacle, commonly made of metal, where liquid plastic, metal, ceramic, or glass
material is poured. The figure 3.1 below is the example of mould design in making a plastic
fan propeller.

Figure 3.1: Mould design in making a plastic fan propeller

3.0 TYPES OF MOULDING PROCESSES

Molding is primarily used during the manufacturing process of plastic. Plastic is a synthetic
material, and to form it into the desired shape different molding processes are used. Each

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process requires the manipulation of molten plastic, and then leaving it to set. Thermoplastics
can then be melted down and reformed if necessary, however thermoset plastics cannot be
reheated.
Examples of molding processes are injection moulding, transfer moulding, extrusion, and
blowing moulding. Figure 3.2 show the comparison between all plastic moulding processes.

Figure 3.2: Plastic molding comparison

3.1 INJECTION MOULDING

Injection Moulding Process is a manufacturing process used for producing parts or
components by injecting molten material into the mould cavity. Injection molding can be
performed with only one of these materials like glass, plastics, etc. and most commonly,
thermoplastic polymers are used. Injection Moulding Machine was invented by John Wesley
Hyatt, patented in 1872. Below in figure 3.3 are the example of injection moulding machine.

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Figure 3.3: Injection moulding machine
The parts of Injection Moulding Machine in figure 3.4 are as follows.

1. Reciprocating Screw
2. Granules
3. hopper
4. heater
5. Nozzle
6. Fixed Pattern
7. Mould cavity
8. Moving Pattern
9. Final Product

Figure 3.4: Parts of Injection Moulding Machine

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Explanations of the parts of Injection Moulding Machine are as follows.
1. Reciprocating Screw:
The reciprocating screw rotates by means of motor and the reciprocating motion is provided
by hydraulic system.
2. Granules:
The thermoplastic granules are to be used in the Injection Moulding Machine to create solid
components.
3. Hopper:
By the use of hopper, the plastic granules are to be poured into the moulding machine.
4. Heater:
It acts as a source of heat for heating the plastic granules to the molten state.
5. Nozzle:
A nozzle of required size is to be placed at the end of heating zone so that, molten material
enters from it and acquire the required shape.
6 and 8. Fixed Pattern and Moving Pattern:
These are the two patterns which are placed side by side so as to form a mould. Among the
two patterns, one is the fixed pattern and the other is the movable pattern.
During Solidification, the molten metal present in between these patterns can stay for some
time and after that, the moving pattern moves aside, and thereby final product is obtained.
7. Mould Cavity:
It is the place where solidification takes place between the fixed pattern and moving pattern
and the formation of the component takes place.
9. Final Product:
Thus the final product will be obtained after cooling.

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Working Principle of Injection Moulding Machine:
The reciprocating screw rotates by means of a motor and its reciprocating motion is
provided by the hydraulic system.
The Plastic granules are to be poured into the hopper and they will be pass through
the chamber due to the rotation of the screw.
The Heater heats the granules to its critical temperature.
The thermoplastic molten liquid is pressurized (by the hydraulic system) outside the
Assembly and allowed to travel through a nozzle of small diameter with high velocity
and low pressure into the space between the molds.
The liquid will fill the mold with uniform compaction among the atoms and thereby
density is uniform.
After filling the liquid in the mold, by the cooling process, it will be solidified.
Any shape and any size of the component can be produced with uniform density.
Density can be controlled by varying the pressure in the pressure line and thereby
production rate is high and wastage is recyclable.
The component can be produced any number of times till it achieves the required
shape.

Note:
The thermoplastic molten liquid has low viscosity and thereby it can flow easily.
In the case of thermoset liquids, the viscosity is high and thereby it is difficult to flow from the
nozzle and that's the reason, thermoplastics will be used in Injection Moulding Machine.

3.2 INJECTION MOULDING DEFECTS

The defects of Injection Molding, figure 3.5 are as follows.
Flash
Short Shots
Vacuum Voids
Sink Marks
Burn Marks

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Weld Lines
Surface Delamination
Warping
Jetting
Flow Lines

Figure 3.5: Defects of Injection Molding

3.3 PLASTIC EXTRUSION MOULDING PROCESS

Figure 3.6: Example of Plastic Extrusion Molding Process
Extrusion molding such as in the figure 3.6, is another method of manufacturing plastic
components. Extrusion molding is very similar to injection molding and is used to make pipes,
tubes, straws, hoses and other hollow pieces. Plastic resin is fed into a barrel where it is
liquefied. A rotating screw propels the liquefied plastic into a mold, which contains a tube-

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shaped orifice. The size and shape of the tube determines the size and shape of the plastic
piece. The liquefied plastic then cools and is fed through an extruder, which flattens the
plastic and forms the piece into its final shape.

3.4 BLOW MOULDING

Blow molding is a process used for making hollow objects such as piping or milk bottles. In
the blow molding plastic manufacturing process, plastic is heated until molten. The liquid,
molten plastic is injected into a cold mold. The mold has a tube set within it, which has a
particular shape when inflated. While the plastic is molten, air is blown into the tube and the
plastic is formed around the tubing. The plastic is left to cool and removed from the mold.
Blow molding is identical to the production of wood-plastic boards up to the point that the
HDPE drains from the sitting troughs. It is kept in an air-tight heated tank, where a valve puts
measured dollops of it onto the heads of a series of air compressors. Each compressor fits
into a metal mold shaped like a bottle. While the compressor pours air into the mold,
ballooning out the HDPE into the mold, another compressor functions to pump air out of the
mold so the HDPE fits perfectly. A circular razor cuts the excess plastic from the head of the
air compressor, which then undergoes an acid bath and a separate water bath to clean it of
any remaining residue for the next use. Figure 3.7 shown blow molding processes

Figure 3.7: Blow molding processes

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The end of the cooling HDPE, which by now has the consistency of putty, is stamped in the
shape of the bottle’s mouth and screw top. When it’s cooled entirely, the mold splits in half
to drop the plastic bottle into a hopper, where live workers clean it and buff off any edges or
imperfections on the bottle. Figure shown the blow molding processes.

3.5 TRANSFER MOULDING

In this process, a thermosetting charge is loaded into a chamber immediately ahead of the
mold cavity, where it is heated; pressure is then applied to force the softened polymer to flow
into the heated mold where curing occurs. There are two variants of the process, illustrated
in Figure 3.8: (a) pot transfer molding, in which the charge is injected from a ‘‘pot’’ through a
vertical sprue channel into the cavity; and (b) plunger transfer molding, in which the charge
is injected by means of a plunger from a heated well through lateral channels into the mold
cavity. In both cases, scrap is produced each cycle in the form of the leftover material in the
base of the well and lateral channels, called the cull. In addition, the sprue in pot transfer is
scrap material. Because the polymers are thermosetting, the scrap cannot be recovered.

Figure 3.8: (a) Pot transfer molding, and (b) plunger transfer molding. Cycle in both
processes is: 1) charge is loaded into pot, (2) softened polymer is pressed into mold cavity

and cured, and (3) part is ejected.

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4CHAPTER

TOOL AND DIE

4.0 THE TERM OF TOOL AND DIE

The terms “tool” and “die” are used interchangeably to the point that many machinists refer
to the field broadly as “tool and die”, regardless of their specific expertise. In general, this
practice is completely appropriate—there is little functional difference between a tool and a
die, if any, and most machinists who fabricate tools also create dies. However, there are some
nuances to the terms in industry, so it’s worth breaking down the slight distinctions. Figure
4.1 shown the example of tool and die

Figure 4.1: Example of tool and die
The easiest way to think of the difference between a tool and a die is simply that dies are a
subset of tools—all dies are tools, but not all tools are dies. In metal stamping, a tool can be
almost any mechanical device used to cut, form, support, or mold metals. By that definition,
jigs and fixtures are tools, as are drills and cutting blades. Dies, on the other hand, are only

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those tools that functionally change the shape of the metal. Dies are typically the female
components of a larger tool or press.

4.1 TYPES OF DIE CUTTING OPERATIONS

A major advantage of die cutting is its versatility as a fabrication method. Since the process
depends upon the shape and configuration of an interchangeable die, manufacturers can
perform multiple operations using a single cutting machine by replacing the die itself.
Specialized dies may be used for specific projects, such as those involving bending, coining, or
curling. There are many different types of dies, and, generally, the name of the die operation
is signified by the type of die used in it.

i) Blanking
Blanking is a way of cutting flat material by trimming it from its exterior edge. The
blanking die usually compresses uniformly, creating a precise degree of flatness.

ii) Cut Off
When excess material needs to be trimmed from a finished part, the process is
usually performed by a cut off die. These dies are also used to cut or shorten a
piece of material by a predetermined length to prepare it for further tooling or
machining processes

iii) Coining
Coining is a type of stamping procedure used to punch circular holes through a
material (usually metal). The cut is made via pressurized force clamping a punch
and die. This process can result in highly intricate or precise product features.

iv) Notching
It is an operation in which a specified small amount of metal is cut from the edges.
Lancing: It is an operation of cutting a sheet metal through a small length and then
bending this cut portion.

v) Lancing
Lancing is a piercing operation in which the work piece is sheared and bent with
one strike of the die. A key part of this process is that there is not reduction of

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material, only a modification in its geometry. This operation is used to make tabs,
vents, and louvers.

4.2 TYPES OF DIE IN MANUFACTURING PROCESS

There is a wide dictionary of terms used to classify dies, some broader than others. At the
highest level, dies can be separated by their function of either cutting or forming the stock
material. Any die that removes, cuts, or shears material can be called a cutting die, regardless
of its mechanism, while a die that doesn’t remove anything is a forming die.

i) Simple Dies
A simple die, as its name suggests, only performs one cutting or forming action per
stroke. These specialized machines can be cost-effective for simple designs, but
they are far less efficient where multiple forming actions are necessary.

ii) Compound Dies
Compound dies are designed so that a single stroke accomplishes multiple cutting
and forming actions. Although combining operations can slow down the stroke,
compound dies are more efficient over the course of the tool manufacturing
process and minimize the chance of errors when transferring a work piece
between multiple stations. These dies are generally less costly than progressive
dies.

iii) Progressive Dies
Progressive dies offer one of the most efficient methods of accomplishing multiple
operations on a single blank. Rather than performing operations simultaneously,
however, the modifications occur at separate stations as a feeding mechanism
continuously pushes metal into the die.

iv) Transfer Dies
Transfer dies resemble progressive dies, but they begin with pre-cut blanks that
must be mechanically transferred between stations rather than using one
continuously-fed strip of metal. Conveyor belts or transfer fingers often provide
the transfer action. A transfer die allows for heightened efficiency even when

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working with larger parts or more complex parts that aren’t compatible with
progressive die cutting.
v) Multiple Dies / Combination Die
A gang press or multiple die press is unique in that it creates multiple components
with every stroke of the press. Typically, this requires several identical dies to be
linked to the same control mechanism so that they can operate in sync with one
another.

4.3 PARTS OF A DIE

Though there are differences across categories especially between cutting and forming dies
most dies consist of a similar set of components: Part of die is like in the figure 4.2.

Figure 4.2: Parts of a Die
1) Die block. The die block is comparable to a mold in that it has holes and indentations

that correspond to the desired shape of the component. The punch or press depresses

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the piece into the die block to achieve the desired shape. In most cases, this is the
female portion of the die.
2) Die holder. A die holder supports the die block, and the holder itself is supported by a
bolster plate. These pieces are attached to the upper or lower die shoe.
3) Punch plate. The punch plate attaches the actual punching component to the ram,
which propels its movement.
4) Punch. The punch is the male portion of the die which actually descends onto the work
piece to force a conformational change.
5) Stripper plate. The stripper plate helps separate the work piece from the punch after
each stroke.
6) Guide pin. Guide pins are essential to precisely align the upper and lower halves of a
die.
7) Pressure plates/back-up plates. Various pressure plates are installed in the die to
distribute the extreme pressure applied by the punch

Figure 4.3: Male Dies

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Figure 4.4: Female Dies
4.3.1 Difference Between Male and Female Dies
We’ve repeatedly referred to male and female dies, but it can be helpful to clarify exactly
what that means especially since dies show so much diversity.
As in electronics, the male component is the protruding component, while the female is the
depression or indentation. Example of male and female dies is in figure 4.3 and figure 4.4.
In the context of metal stamping, the male punch is driven into the die block to cut or form
the work piece (or both, as discussed above).
The corresponding female part defines the shape of the component and includes the die block
indentations into which the work piece is pressed. The female portion is not always composed
of solid cavities, however, and holes can be useful to allow sheared or drilled metal to be
cleared easily.

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Except in instances where the operation uses only a simple die, the male portion will likely
comprise multiple steel cutting or forming punches with the female portions matching the
male pattern.

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Summary

Typically, tool designers are responsible for creating a wide variety of special tools. Whether
these tools are an end product or merely an aid to manufacturing, the tool designer must be
familiar with:

 cutting tools, tool holders, and cutting fluids;
 machine tools, including modified or special types;
 jigs and fixtures;
 gages and measuring instruments;
 dies for sheet-metal cutting and forming;
 dies for forging, upsetting, cold finishing, and extrusion, and
 fixtures and accessories for welding, riveting, and other mechanical fastening.

In addition, the tool designer must be familiar with other engineering disciplines, such as
metallurgy, electronics, computers, and machine design as they too affect the design of tools.

In most cases, the size of the employer or the type of product will determine the exact duties
of each designer. Larger companies with several product lines may employ many tool
designers. In this situation, each designer may have an area of specialization, such as die
design, jig and fixture design, or gage design. In smaller companies, however, one tool
designer may have to do all of the tool designs, as well as other tasks in manufacturing.

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References

(2010). Fundamentals of Tool Design. 6th Edition. Society of Manufacturing
Engineers.

Curry, D. T. (1980). Designers Guide to Machine Tools. Machine Design. Reprinted
with permission from Machine Design magazine, copyright Penton Media,
Cleveland, OH.

Goodship, V. (2007). Introduction to Plastics Recycling.

Jones, P. Types of Molding Processes (2018, May 29). sciencing.com. Retrieved
September 16, 2021, from https://sciencing.com/types-molding-processes-
7651143.html.

Mastanamma, C., Rao, K. P. & Rao, M. V. (2016). Design and Analysis of Progressive
Die. IJERA.

Suchy, I. (2006) Handbook of Die Design. 2nd edition. McGraw-Hill.

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