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 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

MTBF, reliability can be express For Thus t hours R 1.00 100 .999 1000 .987 8760(1 year) .892 10000 .878 43800(5 years .566

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