Manoogian Metal Products John Manoogian started Manoogian Metal Products as a way of avoiding boredom after...

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Manoogian Metal Products John Manoogian started Manoogian Metal Products as a way of avoiding boredom after his retirement from Lockheed Corporation. John worked for Lockheed for thirty years, starting as a laborer and working up to become a skilled. machinist, and then eventually machine shop foreman. Upon his retirement at age fifty-five, John still felt the need to be involved in something productive, so he and two friends pooled their resources and used John's metalworking experience to open a small machine shop in a rented building, The tech- niques John had learned at Lockheed for working with exotic metal alloys turned out to be useful, and Manoogian was able to develop contracts with several aerospace companies to provide specialty machining services. Manoogian Metal Products started out with some used equipment bought at auction from a company that had gone bankrupt. The equipment was not really modern, but was still in good condition and came at a very reasonable price. As Manoogian's business grew, the company gradually replaced some of the equipment that was wearing out, although much of the old equipment still remained. Manoogian recently built a new facility and has had to forgo some new equipment pur- chases until its financial position improves as business grows. But now John is worried that some equipment may have to be replaced sooner due to defects that are showing up in some of the parts. Two of these parts are #1057 and #1058, shown in the illustration at the top of page 757. Part #1057 has a groove cut in its top, whereas part #1058 has a ledge on it, The ledge of part #1058 must fit into the groove on part #1057 so that the holes in each part line up for a shaft to go through. Dimension A is 375" .0001", dimensionB is 1.25" .0001", and dimen- sion C is .625 .0001". The hole diameter is .5" .00002". Based on these tolerances, the two holes can have a maximum misalignment of .0002". Any more than that and the shaft will not fit. Side view Side view End view End view However, the following defects have been found after machin- ing the two parts in a batch of 1,000 units: PROBLEM Hole in #1057 out of spec. Hole in #1058 out of spec. Misalignment of holes Other NUMBER 34 45 127 23 To try to identify the cause of this problem, the following data were collected regarding each of the dimensions by taking samples of size five every hour: A B Sample X R X R 1 .37502 .00023 1.25002 .00003 2 .37510 .00018 1.25003 .00005 3 .37505 .00021 1.24997 .00002 4 .37498 .00015 1.24999 .00001 5 37507 .00015 1.25001 .00004 6 .37499 .00020 1.24995 .00005 7 .37496 .00003 9 10 860 .00017 1.24998 37503 .00023 1.25001 .00002 .37501 .00012 1.25000 .00007 37496 .00017 1.25004 .00004 C D Sample X R X R 1 .62504 .00013 .50001 .00003 2 .62499 .00008 .49998 .00002 3 .62497 .00012 .50003 .00003 4 .62505 .00010 50000 00002 5 .62509 .00020 .50001 .00001 6 .62499 .00009 .50000 .00004 7 .62491 .00013 .50001 .00003 880 .62498 .00018 49999 .00002 9 .62507 .00002 50000 .00001 10 .62501 .00009 .49999 .00003 1. According to this information, where is the problem occur- ring? 2. Does it appear that the process capabilities are sufficient to meet the specifications? 3. What procedure might Manoogian Metals take in the short run to alleviate this problem? 4. How could this problem have been detected earlier? Should the company's procedures be changed? 5. Can you suggest a change in machining practices that might help avoid the problem? Manoogian Metal Products John Manoogian started Manoogian Metal Products as a way of avoiding boredom after his retirement from Lockheed Corporation. John worked for Lockheed for thirty years, starting as a laborer and working up to become a skilled. machinist, and then eventually machine shop foreman. Upon his retirement at age fifty-five, John still felt the need to be involved in something productive, so he and two friends pooled their resources and used John's metalworking experience to open a small machine shop in a rented building, The tech- niques John had learned at Lockheed for working with exotic metal alloys turned out to be useful, and Manoogian was able to develop contracts with several aerospace companies to provide specialty machining services. Manoogian Metal Products started out with some used equipment bought at auction from a company that had gone bankrupt. The equipment was not really modern, but was still in good condition and came at a very reasonable price. As Manoogian's business grew, the company gradually replaced some of the equipment that was wearing out, although much of the old equipment still remained. Manoogian recently built a new facility and has had to forgo some new equipment pur- chases until its financial position improves as business grows. But now John is worried that some equipment may have to be replaced sooner due to defects that are showing up in some of the parts. Two of these parts are #1057 and #1058, shown in the illustration at the top of page 757. Part #1057 has a groove cut in its top, whereas part #1058 has a ledge on it, The ledge of part #1058 must fit into the groove on part #1057 so that the holes in each part line up for a shaft to go through. Dimension A is 375" .0001", dimensionB is 1.25" .0001", and dimen- sion C is .625 .0001". The hole diameter is .5" .00002". Based on these tolerances, the two holes can have a maximum misalignment of .0002". Any more than that and the shaft will not fit. Side view Side view End view End view However, the following defects have been found after machin- ing the two parts in a batch of 1,000 units: PROBLEM Hole in #1057 out of spec. Hole in #1058 out of spec. Misalignment of holes Other NUMBER 34 45 127 23 To try to identify the cause of this problem, the following data were collected regarding each of the dimensions by taking samples of size five every hour: A B Sample X R X R 1 .37502 .00023 1.25002 .00003 2 .37510 .00018 1.25003 .00005 3 .37505 .00021 1.24997 .00002 4 .37498 .00015 1.24999 .00001 5 37507 .00015 1.25001 .00004 6 .37499 .00020 1.24995 .00005 7 .37496 .00003 9 10 860 .00017 1.24998 37503 .00023 1.25001 .00002 .37501 .00012 1.25000 .00007 37496 .00017 1.25004 .00004 C D Sample X R X R 1 .62504 .00013 .50001 .00003 2 .62499 .00008 .49998 .00002 3 .62497 .00012 .50003 .00003 4 .62505 .00010 50000 00002 5 .62509 .00020 .50001 .00001 6 .62499 .00009 .50000 .00004 7 .62491 .00013 .50001 .00003 880 .62498 .00018 49999 .00002 9 .62507 .00002 50000 .00001 10 .62501 .00009 .49999 .00003 1. According to this information, where is the problem occur- ring? 2. Does it appear that the process capabilities are sufficient to meet the specifications? 3. What procedure might Manoogian Metals take in the short run to alleviate this problem? 4. How could this problem have been detected earlier? Should the company's procedures be changed? 5. Can you suggest a change in machining practices that might help avoid the problem?