Question

Harnswell Sewing Machine Company

Phase 1: For more than 40 years, the Harnswell Sewing Machine Company has manufactured industrial sewing machines. The company specializes in automated machines called pattern tackers that sew repetitive patterns on such mass-produced products as shoes, garments, and seat belts. Aside from the sales of machines, the company sells machine parts. Because the company’s products have a reputation for being superior, Harnswell is able to command a price premium for its product line.

Recently, the operations manager, Natalie York, purchased several books related to quality. After reading them, she considered the feasibility of beginning a quality program at the company. At the current time, the company has no formal quality program. Parts are 100% inspected at the time of shipping to a customer or installation in a machine, yet Natalie has always wondered why inventory of certain parts (in particular, the half-inch cam rollers) invariably falls short before a full year lapses, even though 7,000 pieces have been produced for a demand of 5,000 pieces per year.

After a great deal of reflection and with some apprehension, Natalie has decided that she will approach John Harnswell, the owner of the company, about the possibility of beginning a program to improve quality in the company, starting with a trial project in the machine parts area. As she is walking to Mr. Harnswell’s office for the meeting, she has second thoughts about whether this is such a good idea. After all, just last month, Mr. Harnswell told her, “Why do you need to go to graduate school for your master’s degree in business? That is a waste of your time and will not be of any value to the Harnswell Company. All those professors are just up in their ivory towers and don’t know a thing about running a business, like I do.”

As she enters his office, Mr. Harnswell invites Natalie to sit down across from him. “Well, what do you have on your mind this morning?” Mr. Harnswell asks her in an inquisitive tone. She begins by starting to talk about the books that she has just completed reading and about how she has some interesting ideas for making production even better than it is now and improving profits. Before she can finish, Mr. Harnswell has started to answer: “Look, everything has been fine since I started this company in 1968. I have built this company up from nothing to one that employs more than 100 people. Why do you want to make waves? Remember, if it ain’t broke, don’t fix it.” With that, he ushers her from his office with the admonishment of, “What am I going to do with you if you keep coming up with these ridiculous ideas?”

a. Based on what you have read, which of Deming’s 14 points of management are most lacking at the Harnswell Sewing Machine Company? Explain.

b. What changes, if any, do you think that Natalie York might be able to institute in the company? Explain.

Phase 2: Natalie slowly walks down the hall after leaving Mr. Harnswell’s office, feeling rather downcast. He just won’t listen to anyone, she thinks. As she walks, Jim Murante, the shop foreman, comes up beside her. “So,” he says, “did you really think that he would listen to you? I’ve been here more than 25 years. The only way he listens is if he is shown something that worked after it has already been done. Let’s see what we can plan together.”

Natalie and Jim decide to begin by investigating the production of the cam rollers, which are precision-ground parts. The last part of the production process involves the grinding of the outer diameter. After grinding, the part mates with the cam groove of the particular sewing pattern. The half-inch rollers technically have an engineering specification for the outer diameter of the roller of 0.5075 inch (the specifications are actually metric, but in factory floor jargon, they are referred to as half-inch), plus a tolerable error of 0.0003 inch on the lower side. Thus, the outer diameter is allowed to be between 0.5072 and 0.5075 inch. Anything larger is reclassified into a different and less costly category, and anything smaller is unusable for anything other than scrap.

The grinding of the cam roller is done on a single machine with a single tool setup and no change in the grinding wheel after initial setup. The operation is done by Dave Martin, the head machinist, who has 30 years of experience in the trade and specific experience producing the cam roller part. Because production occurs in batches, Natalie and Jim sample five parts produced from each batch. Table below presents data collected over 30 batches (stored in Harnswell).

a. Is the process in control? Why?

b. What recommendations do you have for improving the process?

Phase 3: Natalie examines the X and R charts developed from the data stored in Harnswell.xls from Phase 2. The R chart indicates that the process is in control, but the chart X t reveals that the mean for batch 17 is outside the LCL. This immediately gives her cause for concern because low values for the roller diameter could mean that parts have to be scrapped. Natalie goes to see Jim Murante, the shop foreman, to try to find out what had happened to batch 17. Jim looks up the production records to determine when this batch was produced. “Aha!” he exclaims. “I think I’ve got the answer! This batch was produced on that really-cold morning we had last month. I’ve been after Mr. Harnswell for a long time to let us install an automatic thermostat here in the shop so that the place doesn’t feel so cold when we get here in the morning. All he ever tells me is that people aren’t as tough as they used to be.”

Natalie is almost in shock. She realizes that what happened is that, rather than standing idle until the environment and the equipment warmed to acceptable temperatures, the machinist opted to manufacture parts that might have to be scrapped. In fact, Natalie recalls that a major problem occurred on that same day, when several other expensive parts had to be scrapped. Natalie says to Jim, “We just have to do something. We can’t let this go on now that we know what problems it is potentially causing.” Natalie and Jim decide to take enough money out of petty cash to get the thermostat without having to fill out a requisition requiring Mr. Harnswell’s signature. They install the thermostat and set the heating control so that the heat turns on a half hour before the shop opens each morning.

a. What should Natalie do now concerning the cam roller data? Explain.

b. Explain how the actions of Natalie and Jim to avoid this particular problem in the future have resulted in quality improvement.

PHASE 4: Because corrective action was taken to eliminate the special cause of variation, Natalie removes the data for batch 17 from the analysis. The control charts for the remaining days indicate a stable system, with only common causes of variation operating on the system. Then, Natalie and Jim sit down with Dave Martin and several other machinists to try to determine all the possible causes for the existence of oversized and scrapped rollers. Natalie is still troubled by the data. After all, she wants to find out whether the process is giving oversizes (which are downgraded) and undersizes (which are scrapped). She thinks about which tables and charts might be most helpful.

a. Construct a frequency distribution and a stem-and-leaf display of the cam roller diameters. Which do you prefer in this situation?

b. Based on your results in (a), construct all appropriate charts of the cam roller diameters.

c. Write a report, expressing your conclusions concerning the cam roller diameters. Be sure to discuss the diameters as they relate to the specifications.

PHASE 5: Natalie notices immediately that the overall mean diameter with batch 17 eliminated is 0.507527, which is higher than the specification value. Thus, the mean diameter of the rollers produced is so high that many will be downgraded in value. In fact, 55 of the 150 rollers sampled (36.67%) are above the specification value. If this percentage is extrapolated to the full year’s production, 36.67% of the 7,000 pieces manufactured, or 2,567, could not be sold as half-inch rollers, leaving only 4,433 available for sale. “No wonder we often have shortages that require costly emergency runs,” she thinks. She also notes that not one diameter is below the lower specification of 0.5072, so not one of the rollers had to be scrapped.

Natalie realizes that there has to be a reason for all this. Along with Jim Murante, she decides to show the results to Dave Martin, the head machinist. Dave says that the results don’t surprise him that much. “You know,” he says, “there is only 0.0003 inch variation in diameter that I’m allowed. If I aim for exactly halfway between 0.5072 and 0.5075, I’m afraid that I’ll make a lot of short pieces that will have to be scrapped. I know from way back when I first started here that Mr. Harnswell and everybody else will come down on my head if they start seeing too many of those scraps. I figure that if I aim at 0.5075, the worst thing that will happen will be a bunch of downgrades, but I won’t make any pieces that have to be scrapped.”

a. What approach do you think the machinist should take in terms of the diameter he should aim for? Explain.

b. What do you think that Natalie should do next? Explain.

Answer 1