Transcript Chapter 5 Concept Evaluation

Chapter 9 Product Evaluation for
cost, Manufacturing, Assembly,
and Other Measure
9.1 Introduction
9.2 Cost Estimation in Design
9.2.1 Determining the Cost of a Product
9.2.2 Making of Cost Estimation
Purchasing parts
Manufacturing
9.2.3 The cost of machined Components
1, from what material is the component to be machined?
2. What type of machine is used to manufacture the
component?
3. What are the major dimensions of the component?
4. How many machined surfaces are there, and how
much material is to be removed.
5. How many components are made?
6. What tolerance and surface finishes are required?
7. What is the labor rate for machinist?
Example:
9.2.4 The Cost of injection Molded
Components
9.3 Value Engineering
worth of feature , com ponent, or assem bly
Value 
cost of it
Step 1 For each feature of the component ask the question , what does it
do?
Step 2 Identify the life cycle cost of the feature.
Step 3 Identify the worth of the function to the customer.
Step 4 Compare worth to cost to identify features that have low relative
value
9.4 Design for Manufacturing
Establishing the shape of components to
allow for efficient, high quality
manufacturing
9.5 Design for assembly evaluation
9.5.1 evaluation of the overall assembly
Guideline 1 overall component count should
be minimized
Guideline 2 Make minimum use of separate
fasteners
Guide line 3 Design the product with a base
component for locating other components
Guideline 4: do not require the base to be
repositioned during assembly
Guideline 5: make the assembly sequence efficient.
• Affords assembly with the fewest steps.
• Avoids risk of damaging components
• Avoid awkward, unstable, or conditionally
unstable positions for the product and the
assembly personnel and machinery during
assembly.
• Avoids creating many disconnected
subassemblies to be joined later
Step 1 list all the component and processes involved in the
assembly process
Step 2 List the connections between components and
generate a connections diagram
step 3 select a base component
Step 4 recursively add the next component
Connection 3 must preced connection 4
Connection 1 must precede connection 5
Step 5 identify subassemblies
[2,[3,4],1,5]
Or [button, body, [head, tube, ink], cap]
9.5.2 Evaluation of component
retrieval
Guideline 6: Avoid component characteristics that
complicate retrieval
9.5.3 Evaluation of component
handling
Quideline 8
design all
components for
end to end
symmetry
• Guideline 9 design all components for
symmetry about their axes of insertion
• Guideline 10 design components that are
not symmetric about their axes of insertion
to be clearly asymmetric
9.5.4 evaluation of component mating
Guideline 11: design components to mate
through straight line assembly
Guideline 12:
make use of
chamfer, leads,
and
compliance to
facilitate
insertion and
alignment
• Guideline 13: Maximize component
accessibility
9.6 Design for reliability
• 9.6.1 Failure-potential analysis
Step 1 identify the function affected
Step 2 identify the Effecte of failure on other
parts of the system
Step 3 identify the failure modes effecting
the function
Step 4 identify the corrective action
• 9.6.2 reliability
MTBF, reliability can be express
R(t )  e Lt
For
R(t )  e0.000013t
Thus
t hours
R
0
1.00
100
.999
1000
.987
8760(1 year)
.892
10000
.878
43800(5 years
.566
Rproduct  Rbearing1Rbearing 2 Rbearing 3 Rbearing 4
Failure rate:
9.7 design for test and
maintenance
• Step 3A: For each error; is it possible to
identify the parameters that could cause
the failure?
9.8 design for the environment
Guideline 1: be aware of the environmental effects of
the materials used in product
Guideline 2: design the product with high seperabikity
Make fastener accessible and easy to release
Avoid laminating dissimilar materials
use adhesives sparing and make them water soluable if
possible
Guideline 3 design components that can be reused to
be recycled
Guideline 4: be aware of the environmental effects of
the material not reused or recycled