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Environmentally Conscious Design & Manufacturing. Class 27: Quality & ECDM. Prof. S. M. Pandit. Quality. Questions: What are the possible quality constraints in Environmentally Conscious Design and Manufacturing (ECDM) How does “Total Quality” relate to ECDM
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Environmentally Conscious Design & Manufacturing Class27: Quality & ECDM Prof. S. M. Pandit
Quality • Questions: • What are the possible quality constraints in Environmentally Conscious Design and Manufacturing (ECDM) • How does “Total Quality” relate to ECDM • Quality issues in Product & Process design
Quality ‘Type’ Quality of DESIGN Quality of a manufactured product Quality of CONFORMANCE Quality of PERFORMANCE Variables Quality characteristics Attributes
cost value Quality of performance Customer Need Design Quality Quality of conformance • Influencing factors • Type of product • Cost • Profit policy • Product demand • Product availability • Product safety Prevention Degree to which product satisfies the customer Defect Finding Analysis & rectification
Quality of conformance Design Quality Quality of performance
Quality characteristics Structural Sensory Time oriented Ethical Examples - Strength of a beam - Viscosity of fluid Examples - Reliability - Maintainability
Examples of Quality Constraints Product: Switchgear Example = Dimensional Accuracy Type = ? Comment on the consequences of dimensional inaccuracy and the remedy Type = Design Example = ? Product: Tire Example = Elasticity Type = ? Type = Performance Example = ?
Total Quality & Quality Function Deployment Objective Statement Customer Requirements ‘Whats’ Customer assessment of competition Relationship Matrix Importance Rating Technical Competitive assessment of ‘hows’ (to become the benchmark)
Objective function(s) - examples:- Maximize profit - Improve ‘quality’ Customer requirements - examples:- Increase reliability Technical Competitive Assessment of ‘How’ - Multi- disciplinary team - Product design and development - Marketing, Sales, Accounting, finance, … - Process Design - Manufacturing
++ - H - 2 H - 3 H - 4 H - 1 Strong positive correlation between H - 1 and H - 3 (I H - 1 then H - 3
Relation between ‘how’ and ‘what’ h12 h13 h11 h14 w1 w1h11 w2 h22 h23 h21 h24 h32 h33 w3 h31 h34 h44 w4 h41 h42 h43
Example 1 - Reliability * A module o a satellite monitoring system has 500 components in series. The reliability of each component is 0.999. Find the reliability of the module. If the number of components in series is reduced to 200, what is the reliability of the module?
Rs With 500 components in series, the system reliability is; Rs = 0.999500 = 0.606 With only 200 components in series, Rs = 0.999200 = 0.819 n
Reliability Evaluation Reliability of component with exponential failure distribution: :the constant failure rate for the component Mean Time to failure: Reliability of a system with two independent components in series is : Reliability of a system with n independent components in series is :
Example 2 - Reliability An auto - focus unit in a camera has 10 components in series. If the system reliability is to be 0.95 after 2000 hours of operation, what would be the mean time to failure of the individual components if they have identical failure rate ?
Rs = exp [-(1+2+. . . +10) t]= exp [-(st] Therefore, 0.95 = exp [- s (2000)] and, s = 0.0000256 / h {Failure rate of the focus unit} Since 1=2=. . . =10=c, c=s/10= 0.00000256 / h MTTF of each component: MTTFc = 1/ c = 389,915 h
Homework #9 1. A reclamation center produces two products, A and B. The sales volume for produce A is at least 60 % of the total sales of the two products. Both products use the same raw material, of which the daily availability is limited to 100 lb. Products A and B use this raw material at the rates of 2 lb/unit and 4 lb/unit, respectively. The sales price for the two products are $20 and $40 per unit. Formulate the problem as a linear programming problem.
Homework #9 2. For the data given in the last problem of midterm exam, reproduced in slide # 14 of class 26, does the actual observation lie within: i) 68 % probability interval on the observation? ii) 90 % probability interval on the observation? iii) 99 % probability interval on the observation? 3. Use slide 24 of class 8 (3/22/00) to write down a model for the feedback loop of X2t as the output and X4t as the input.
Homework #9 4. For the auto-focus unit reliability example of class 27, determine the component MTTF if the number of components is reduced to 5. What will the component reliability be after 2000 hours of operation? (Answer: MTTFc:194,957 h; Rc=0.98979)