Manufacturing Tooling Design and Economics

Tech 3113
Manufacturing Tooling
Nageswara Rao Posinasetti

1. Introduction
December 2, 2015Nageswara Rao Posinasetti2

 Reduce the overall cost of manufacturing a product by
producing acceptable parts at lowest cost.
 Increase the production rate by designing tools that will
produce parts as quickly as possible.
 Maintain quality by designing tools which will 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 that will be safe and easy to operate.
Objectives of tool design

 Cutting tools, tool holders and cutting fluids
 Machine tools
 Jigs and fixtures
 Gages and measuring instruments
 Dies for sheet metal cutting and forming
 Dies for forging, cold finishing and extrusion
 Fixtures for welding, riveting and other
mechanical fastening
Responsibilities of tool designer

 Statement and analysis of the problem
 Analysis of the requirements
 Development of initial ideas
 Development of design alternatives
 Finalization of design ideas
The Tool Design Process

 Problem without tooling
 What the tool is supposed to do?
 Drill four holes
 Bottleneck in assembly
 Low productivity with out tooling
Statement of the problem

 Must perform certain functions
 Must meet certain minimum precision
requirements
 Must keep the cost to a minimum
 Must be available when the production schedule
requires it
 Must be operated safely
 Must meet other requirements such as
adaptability to the machine tool, etc.
Analysis of the requirements

Estimating cost of tooling

 Cost of material
 Cost of manufacturing
 Cost of assembling
 Cost of standard parts
 Cost of tryout
What is tool cost?

 Estimate the volume and mass - CAD
 Steel – 7.843 g/cm3
Cost of material

 It includes
 Cost of machining
 Cost of heat treatment
Cost of manufacturing

Making a Cost Estimate
 This ability comes by experience
 Cost estimating procedures depends on
the source
 Purchase finished component
 Have a vendor produce the component
 In house manufacture

The Cost of Machined Components
 Control factors that determine the cost of
machined components are:
 From what material is the component
produced?
 Cost of material
 Cost of scrap
 Ease with which the material can be removed
(machined)

 What type of machine is used to manufacture
the component?
 Lathe, horizontal mill, vertical mill, and so on.
 Cost of machine tool, tools and fixtures used
 What are the major dimensions of the
component?
 Size of the machine required
 That determines the machine overhead cost

 How many machined surfaces are there,
and how much material is to be removed?
 Gives a good estimate of time required for
machining
 How many components are made?
 Fixturing requirements
 Setting times and costs

 What tolerance and surface finishes are
required?
 Tighter tolerances are more expensive
 What is the labor rate for machinists?

Thumb rules for estimation

 This is relatively easier part.
 Check with vendor.
Cost of standard parts

 Drilling and fitting time and costs
 Depends on
 Number of parts
 Complexity
 Precision required
 Skill of the operator and judgment
 Prefers a rule of thumb rather than
sophisticated analysis
Cost of Assembling and Tryout

 Using the listed alternatives, prepare a comparative
analysis for the following tooling problem: A total of 950
flange plates require four holes accurately drilled 90
degrees apart to mate with a connector valve. Which of the
listed alternatives is the most economically desirable?
A. Have a machinist who earns $20.00 per hour lay out and
drill each part at a rate of 2 minutes per part.
B. Use a template jig, capable of producing 50 parts per hour
and costing $50.00, in the production department, where
an operator earns $10.00 per hour.
C. Use a duplex jig, which costs $500.00 and can produce a
part every 26 seconds, in the production department,
where an operator earns $10.00 per hour.
Tooling Economics

 Option a: Cost per piece = 20/30 = $0.67
 Option b: Production rate = 60/1.2 = 50 per hour
 Cost per piece = 50/950 + 10/50 = 0.05 + 0.20 = $0.25
 Option c: Production rate = 3600/26 = 138 per hour
 Cost per piece = 500/950 + 10/138 = 0.53 + 0.07 =
$0.60
 Cost per piece = 500/5000 + 10/138 = 0.10 + 0.07 =
$0.17 (If 5000 pieces are to be produced)
Tooling Economics

 C = Initial cost of the fixture
 I = interest rate on investment, say 6%
 M = maintenance cost of fixture, say 10%
 T = tax requirement on fixture investment,
say 4%
 D = depreciation of fixture, say 50%
 Make depreciation 100% if the cost is to be
recovered in one year.
 S = setup cost per year = setup cost per
batch * setup cost
Tooling Economics

 t = time saved because of the fixture,
hours
 a = Labor hourly cost
 A=Cost of saving due to fixture = a * t
 Y=Yearly cost of fixture = S +
C*(I+M+T+D)
 n = Annual production rate
 N = Pieces to be made per
year to justify fixture =
 It is necessary n > N December 2, 2015Nageswara Rao Posinasetti23
Tooling Economics
A
Y

 Economical cost of fixture,
 Number of years for fixture to pay itself
Tooling Economics
DTMI
S-taN

C
T)M(IC-S-taN
C

Years

 The Initial cost of a fixture is $ 500. Given that the
interest rate on investment as 6%, maintenance
cost of fixture is 10%, tax requirement on fixture
investment is 4% and the depreciation of fixture is
to be taken as 50% per year. Setup cost of the
fixture is about $10 per single setup. If the time
saved because of the use of fixture is about 0.03
hours with a labor hourly cost of $10, calculate the
number of parts to be produced per year to offset
the cost of the fixture. If the cost of the fixture is to
be recovered in the first year, what should be the
production volume required? If the economical
batch size of manufacture for the parts is 1000,
how many batches should be produced per year to
offset the cost of the fixture?

Q5
C = Initial cost of the fixture $ 500.00
I = interest rate on investment 6%
M = maintenance cost of fixture 10%
T = tax requirement on fixture investment 4%
D = depreciation of fixture 50%
S = setup cost $ 10.00
Y=Yearly cost of fixture = S + C*(I+M+T+D) $ 675.00
t = time saved because of the fixture, hours 0.03
a = Labour hourly cost $ 10.00
A=Cost of saving due to fixture = a * t $ 0.30
Number of pieces to be made per year 2,250
Make depreciation 100% if the cost is to be recovered in one year. 100%
Yearly cost of the fixture if the cost is to be recovered in one year. $ 800.00
Number of pieces to be produced if the cost is to be recovered in
one year. 2,667
Economical batch size of manufacture 1000
Number of batches 3
Setup cost per year = setup cost per batch * Number of batches $ 30.00
Y=Yearly cost of fixture = S + C*(I+M+T+D) $ 3,175.00
Number of pieces to be made per year 10,583

Design alternatives
Create Analyze in terms of these criteria
Alternatives Function Quality Cost Date Auxiliary
A
B
.
.

 Temporary tooling
 Permanent tooling
Economics of Design

 Break-even charts are perhaps most
widely used to determine profits based on
anticipated sales.
 They have other uses, however, such as
for selecting equipment or for measuring
the advisability of increased automation.
Break-Even Charts

 To determine which of two machines is
most economical, the fixed cost and
variable cost of each machine are plotted
 The total cost is composed of the sum of
the fixed and variable costs.
Break-Even Charts

 Fixed cost, which relates to the initial
investment on the equipment and tools
required for the process.
 Variable cost on the other hand varies with
the actual number of objects made.
 The total cost is the sum of both fixed and
variable cost.
Break Even Analysis

 TC = total cost
 FC = fixed cost
 VC = variable cost per piece
 N = production quantity
NVC+FC=TC 

NCV+CF=NCV+CF 2211 
CV-CV
CF-CF
=N
21
12
N = Break even quantity

Permanent mould
casting, ($)
Die casting
($)
Tooling 3600 7000
Setup cost 6.8 17.0
Labor cost 0.50 0.33
Material cost 0.50 0.25
An aluminum canopy can be obtained by either permanent
mould casting or die casting process. The costs in dollars in
either case are
Find out the break-even quantity of production
from 1000 to 15 000 pieces.

Permanent mould casting
($)
Die casting
($)
Tooling 3600 7000
Setup cost 6.8 17.0
Fixed cost 3606.80 7017.00

Permanent mould casting
($)
Die casting
($)
Tooling 3600 7000
Setup cost 6.8 17.0
Fixed cost 3606.80 7017.00
Labor cost 0.50 0.33
Material cost 0.50 0.25
Variable cost 1.00 0.58

Prod
quantity
Permanent mould
casting, ($)
Die casting
($)
1000 4606.80 7580.00
5000 8606.80 9917.00
10,000 13,606.80 12,800.00
15,000 18606.80 15717.00
Break even quantity =
= 8119.52
58.000.1
80.36067017



 Draw and dimension with due consideration for
someone using the drawing to make the item in
the tool room.
 Do not crowd views or dimensions.
 Analyze each cut to be sure it can be done with
standard tools.
 Use only as many views as necessary to show
all required detail.
Tool Drawings

 Surface roughness must be specified.
 Tolerances and fits peculiar to tools need special
consideration.
 It is not economical as a rule to tolerance both details
of a pair of mating parts as is required on production
part detailing.
 In cases where a hole and a plug are on different
details to be made and mated, the fit tolerance should
be put on the male piece and the hole should carry a
nominal size.
Tool Drawings

 The stock list of any tool drawings should
indicate all sizes required to obtain the
right amount for each detail.
 As far as possible, stock sizes known to be
on hand should be used, but in all cases,
available sizes should be specified. A proper,
finished detail is dependent upon starting with
the right material.
Tool Drawings

 Use notes to convey ideas that cannot be
communicated by conventional drawing.
Heat treatments and finishes are usually
identified as specification references
rather than being spelled out on each
drawing.
Tool Drawings

 Secondary operations such as surface
grinding, machining of edges, polishing,
heat treating, or similar specifications
should be kept to a minimum.
 Only employ these operations when they are
important to the overall function of the tool;
otherwise these operations will only add cost,
not quality to the tool.
Tool Drawings

 Apply tolerances realistically. Overly tight
tolerances can add a great deal of
additional cost with little or no added value
to the tool.
 The function of the detail should determine
the specific tolerance, not a standard title
block tolerance value.
Tool Drawings

 Layout the part in an identifying color (red
is suggested).
 Layout any cutting tools. Possible
interference or other confining items
should be indicated in another identifying
color (blue suggested). Use of the cutting
tool should not damage the machine or the
fixture.
Tooling Layout

 Indicate all locating requirements for the
part. There are three locating planes: use
three points in one, two points in the
second, and only one point in the third
plane.
 This is called the 3-2-1 locate system. Do not
locate on the parting line of castings or
forgings. All locators must be accessible for
simple cleaning of chips and dirt.
Tooling Layout

 Indicate all clamping requirements for the
part.
 Be careful to avoid marking or deforming
finished or delicate surfaces.
 Consider the clamping movements of the
operator so injury to the hands or unsafe
situations are eliminated.
 Be sure it is possible to load and unload
the part.
Tooling Layout

 Layout the details with due considerations
to stock sizes, so as to minimize
machining requirements.
 Use full scale in the layout if possible.
 Indicate the use of standard fixture parts
(shelf items) whenever possible.
Tooling Layout

 Identify each different item or detail of any
design by the use of balloons with leaders
and arrows pointing to the detail in the
view that best shows the outline of the
item. These should not go to a line that is
common to other details.
Tooling Layout

 Safety should be designed into the tooling.
 Cutting should never be performed against a
clamp, because of vibration and tool chatter.
Instead, parts should be nested against pins in
order to take the cutter load.
 Rigidity and fool proofing should always be built
into the tooling.
Safety as Related to Tool Design

 Make drill jigs large enough to hold without
the danger of spinning.
 Small drill jigs should always be clamped
in a vise or against a bar or backstop.
 Install plexiglass guards around all milling
and fIycutting operations where chips
endanger workers or work areas.
Safety as Related to Tool Design

Questions?

Manufacturing Tooling Design and Economics

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