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       MSE 5090: Case Studies in Material Selection

      Week 11 - Manufacturing Aspects of Design

      Read this entire document before starting the assignments.
       
      1. Objectives
      2. Reading assignment
      3. Properties and Processes in Design
      4. Discussion questions
      5. Lecture Topics
      6. Week 11 assignments:  CS 1st Draft   CS Contact Summary
      7. Reference Material


      Objectives:
      Determine how specifications determine process options
      Review case study of a new type of Ice Axe
      Review contacts and case study performance indices
      Study how to use longer case studies into student case studies
      This week we will have the midterm on Monday, and then discuss the Ice Ax case study. Beginning this week we will focus on Case Study related topics. In addition, as time permits, some optimization and statistical topics will be added as these are increasingly considered necessary tools for an engineer.



      Reading Assignment:
      ASM pages 669 - 686, 716 - 723, 762 - 772, and 820 - 827


      Properties and Processes in Design:
      This figure, and the four following it, is taken from The ASM handbook text , 509 , M.Farag," Properties needed for Static Structures". It describes the linking of processing and properties in a design. This linking should at least be acknowledged in a case study.
       
       


      Fig. 1. Factors that should included in a  component design.



      Fig. 2 Factors that should be in considered in anticipating the behavior of material in the component.

      This is taken from Farag, opcit, and relates model, from which the performance indices are taken, to materials properties , geometry and fabrication.


          This figure is Table one from Farag , op cit page 510, and shows how component shape will reduce safety margins throughout the inclusion of stress concentration points.



          This figure , Farag op cit page 511 shows poor and good design practice for mechanical components.


      Fig. 3 Design guide lines for reducing the deleterious effects of stress concentration. See text for discussion.
      Source: Ref. 1



          This figure, opcit Farag, page 511 shows how variations in the load on  and the strength in a material combine to result in a finite failure probability even when the nominal load is a safety factor less  than the nominal strength of the component.


      Fig. 4 Effect of variations in load and strength on the failure of components.



          This table , and the one below it , are taken from the ASM textbook , G.Dieter, Overview of Materials Selection Process, P247. The top figure describes the nine classes of manufacturing process. However, the micro fabrication processes that are beginning to pervade much high technology would probably want their own category rather than being lumped in with "special methods".


      Fig. 4 The nine classes of manufacturing  processes. The first row contains the primary forming (shaping) processes. The processes in the vertical column below are the secondary forming and finishing. Source: Ref 21



          This is an important figure, again taken from Dieter , ibid., page 247. It is , in essence, a sanity check wherein the selection of a material and processing technique can be checked for compatibility. Alternatively, if a company has a particular process in house, that will tend to limit the materials that can be chosen for a given application.



      Fig. 5 Buildup of cost elements to establish selling price.
      This figure is Dieter opcit fig2. page 300. It shows how price is developed from cost by adding factors such as production overhead (atop of factory cost) and sales and distribution costs and profit. In many cases the final cost is a factor of 3-5 times the labor and materials costs. Not shown is the financial component involving write-off of research and development , taxes, and the cost of capital. In addition , there are inventory costs and various aftermarket costs involving customer support and product servicing.



      Discussion Questions:
      How is manufacturing different than processing?
      How are engineering and end user requirements integrated into new product design?
      How are Ashby material/process selection techniques integrated with other techniques in  student case studies?


      Lecture Topics:
      Monday Midterm Exam 1 hr, closed book
      Wednesday Review midterm, manufacturing and processing compared
      Friday Review Ice Ax case study, update student case study progress, preview chemical process industry case study



      Week 11 Assignments:

      First Draft Case Study  (Due 11/25/98)
      Subject: Week 11 - Case Study 1st draft
       The case study first draft is due just before Thanksgiving, so it is time to start integrating the parts you have previously prepared.

      Presentation of Case Study: Summaries of discussions with external sources (Class period 11/13/98)
          During this Friday's class one or two of you will discuss the interactions with external sources you have had in the course of preparing your case study.



      Reference Material:
      This is a site which reviews materials selection for the NASA space shuttle
      http://www.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_sys.html#sts-rcc

      This site is  a great starting point for information on Composite materials
      http://composite.miningco.com/

      Since environmental factors are key extrinsic factors in a case study , this site provides an outstanding entree point for environmental issues.
      http://www.lib.uidaho.edu:70/docs/egj07/schrode.htm
       
       
       

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      Last update 8-14-98