Please answer the assignment section of Part1 and Part 2. Thanks
Q> CASE STUDY 9.2 Normal Probability Distribution This case is the rst of three related cases found in Chap- ters 9, 10, and 13. These cases seek to link information from the three chapters in order to resolve quality issues. Although they are related, it is not necessary to complete the case in this chapter in order to understand or complete the cases in the following chapters. PART 1 Max's B-B-Q Inc. manufactures top-of-the-line barbeque tools. The tools include forks, spatulas, knives, spoons, and shish-kebab skewers. Max's fabricates both the metal parts of the tools and the resin handles. These are then riv- eted together to create the tools (Figure C9.2.1). Recently, Max's hired you as a process engineer. Your rst assign- ment is to study routine tool wear on the company's stamp- ing machine. In particular, you will be studying tool-wear patterns for the tools used to create knife blades. In the stamping process, the tooling wears slightly during each stroke of the press as the punch shears through the material. As the tool wears, the part fea- tures become smaller. The knife has specifications of 10 mm : 0.025 mm; undersized parts must be scrapped. The tool can be resharpened to bring the parts produced back into specification. To reduce manufacturing costs and simplify machine scheduling, it is critical to pull the tool and perform maintenance only when absolutely necessary. It is very important for scheduling, costing, and quality purposes that the average number of strokes, or tool run length, be determined. Knowing the average number of strokes that can be performed by a tool enables routine maintenance to be scheduled. It is the plant manager's philosophy that tool main- tenance be scheduled proactively. When a tool is pulled FIGURE (29.2.1 Barbeque Tools unexpectedly, the tool maintenance area may not have time to work on it immediately. Presses without tools don't run, and if they are not running, they are not making money. As the process engineer studying tool wear, you must develop a prediction for when the tool should be pulled and resharpened. The following information is available from the tool maintenance department. I The average number of strokes for a tool is 45,000. I The standard deviation is 2,5 00 strokes. I A punch has a total of 25 mm that can be ground off before it is no longer useful. I Each regrind to sharpen a punch removes 1 mm of punch life. I The cost to regrind is 2 hours of press downtime to remove and reinsert tool, at $300 per hour 5 hours of tool maintenance time, at $65 per hour 5 hours of d0wntime while press is not being used, at $300 per hour I The average wait time for unplanned tool regrind is 15 hours at $300 per hour. I Because of the large number of strokes per tool regrind, this is considered to be a continuous distri- bution. The normal curve probability distribution is applicable. Q> ASSIGNMENT One percent of the tools wear out very early in their expected productive life. Early tool wearoutand, thus, an unplanned tool pullcan be caused by a variety of factors, including changes in the hardness of the material being punched, lack of lubrication, the hardness of the tool steel, and the width of the gap between the punch and the die. Key part dimensions are monitored using X and R charts. These charts reveal when the tool needs to be reground in order to preserve part quality. Use the normal probability distribution and the information provided to calculate the number of strokes that would result in an early wearout percentage of 1 percent or fewer. [f the plant manager wants the tool to be pulled for a regrind at 40,000 strokes, what is the chance that there will be an early tool wearout failure before the tool reaches 40,000 strokes? PART 2 Now that you have been at Max's B-B-Q inc. for a while, the plant manager asks you to assist the production sched- uling department with pricing data on a high volume job requiring knife blades for the company's best customer. As you know, it is the plant manager's philosophy to be proactive when scheduling tool maintenance (regrinds) rather than have to unexpectedly pull the tool. However, pricing will be a very important factor in selling this job to the customer. Essentially, the plant manager wants no unplanned tool pulls, but sales needs pricing cost reduc- tions. The production scheduler would like a tool regrind schedule that results in minimal inventory. Q> ASSIGNMENT You will soon be meeting with the plant manager and the managers from sales and production scheduling. They are expecting you to have an answer to the question: Given the need to balance maximizing tool use, minimizing Plant Manager Strokes before Pull 40,000 Number of 25 Pulls Production over Life of Tool Cost of Each Pull Additional Cost of an Unplanned Pull Chance of Unplanned Pulls Total Addi- tional Cost Due to Unplanned Pulls Total Cost 1,000,000 $2,425 $4,500 inventory, minimizing production disruption, and mini- mizing cost, how many strokes should you recommend to run this tool before pulling for a regrind? Create a graph that shows the number of unplanned pulls versus the number of strokes. The graph should comprise at least six data points. Next, complete the spreadsheet in Figure C922 showing the costs of each individual's plan. Using the graph and the spreadsheet, prepare a response for the question, How many strokes should the tool be run before pulling it for a regrind? Your analysis should include answers to the following questions: How will this number balance tool use, cost, inventory, and production disruption? What are the economics of this situation? Production Sales Scheduler Manager You 42,000 43,000 25 25 1,050,000 1,075,000 $2,425 $2,425 $2,425 $4,500 $4,500 $4,500 S H E1 1\"] IE] 2
