Part 1

Figure C4.2.1 provides the details of a simplified version of a bracket used to hold a strut in place on an automobile. Welded to the auto body frame, the bracket cups the strut and secures it to the frame with a single bolt and a lock washer. Proper alignment is necessary for both smooth installation during assembly and future performance. For mounting purposes the left-side hole, A, must be aligned on center with the right-side hole, B. If the holes are centered directly opposite each other, in perfect alignment, then the angle between hole centers will measure 0.00. The bracket is created by passing coils of flat steel through a series of progressive dies. As the steel moves through the press, the bracket is stamped, pierced, and finally bent into appropriate shape.

Recently customers have been complaining about having difficulty securing the bracket closed with the bolt and lock washer. The bolts have been difficult to slide through the holes and then tighten. Assemblers complain of stripped bolts and snug fit- tings. The problem-solving cycle begins with Step 1. Plan: Recognize a Problem Exists. Bracket customers have made management at WP Inc. well aware of the problem. Because management is unsure of the root cause of the problem, they proceed with the second step of problem solving and assemble a team. The team consists of representatives from process engineering, materials engineering, product design, and manufacturing. Beginning with Step 4. Plan: Clearly Define the Problem, the team has decided to brainstorm the reasons why this problem has occurred.

Assignment 1

Form a team and use the WHY-WHY diagram technique to deter- mine why the bracket may be hard to assemble.

Part 2

In conjunction with the WHY-WHY diagram for why the bracket is not easily assembled, the team has decided to develop performance measures to answer the following question: How do we know that the changes we made to the process actually improved the process?

Assignment 2

Part 3

What performance measures does your team feel are necessary to answer this question: How do we know that the changes we made to the process actually improved the process?

Continuing in the problem-solving cycle, the team proceeds with Step 5. Plan: Problem Process, Document and Analyze the team visited the customer's assembly plant to determine where the brackets were used in the process and how the assembly was actually performed. There they watched as the operator randomly selected a strut, a bracket, a bolt, and a locknut from different bins. The operator positioned the strut in place, wrapped the bracket around it, and secured it to the frame by finger-tightening the bolt and locknut. The operator then used a torque wrench to secure the assembly. While they watched, the operator had difficulty securing the assembly several times. Back at their plant, the team also created a flowchart for WP's process of fabricating the bracket (Figure C4.2.2 O). Uncoil steel Straighten steel Stamp/ pierce flat bracket Quality check Transfer to bender Bend Quality check Transfer to heat treat Delay Heat treat Quality check Pack Ship Figure C4.2.2 Flowchart of Bracket-Fabrication Process After completing the flow diagram and verifying that it was correct, the team moved on to Step 6. Plan: Determine Possible Causes. They decided to use a cause-and-effect diagram to guide their efforts in brainstorming potential root causes for the problem: difficulty securing brackets closed with bolt and locknut.

Assignment 3

Case Study 4.2 Process Improvement This case is the beginning of a four-part series of cases involv- ing process improvement. The other cases are found at the end of Chapters 40, 50, and 6 D. Data and calculations for this case establish the foundation for the future cases; however, it is not necessary to complete this case in order to complete and understand the cases in Chapters 4 10, 50, and 6 0. Complet- ing this case will provide insight into the use of problem-solving techniques in process improvement. The case can be worked by hand or with the software provided. Part 1Assignment Create a cause-and-effect diagram and brainstorm potential root causes for the problem: difficulty securing brackets closed with bolt and locknut. Part 4 Through the use of a cause-and-effect diagram, the engineers determine that the most likely cause of the problems experi- enced by the customer is the alignment of the holes.At some stage in the formation process, the holes end up off center. Combining this information with the WHY-WHY diagram conclusion that hole alignment was critical for smooth installa- tion during assembly narrows the search for a root cause. Un- fortunately, the team still doesn't know why the holes are not properly aligned. They decide to create another cause-and-ef- fect diagram that focuses on causes of improper hole alignment. Figure 04.2.1 9 provides the details of a simplied version of a bracket used to hold a strut in place on an automobile. Welded to the auto body frame, the bracket cups the strut and secures it to the frame with a single bolt and a lock washer. Proper align- ment is necessary for both smooth installation during assembly and future performance. For mounting purposes the left-side hole, A, must be aligned on center with the right-side hole, B. If the holes are centered directly opposite each other, in perfect alignment, then the angle between hole centers will measure 0.00 . The bracket is created by passing coils of at steel through a series of progressive dies. As the steel moves through the press, the bracket is stamped, pierced, and nally bent into appropriate shape. 11 mm 6 mm 22 mm 10 mm + A B - - 10 mm 45 mm 20 mm 2 mm 28 mm 60 mm Figure C4.2.1 Bracket Recently customers have been complaining about having diffi- culty securing the bracket closed with the bolt and lock washer. The bolts have been difficult to slide through the holes and then tighten. Assemblers complain of stripped bolts and snug fit-tings. The problem-solving cycle begins with Step 1. Plan: Rec- ognize a Problem Exists. Bracket customers have made man- agement at WP Inc. well aware of the problem. Because man- agement is unsure of the root cause of the problem, they pro- ceed with the second step of problem solving and assemble a team. The team consists of representatives from process engi- neering, materials engineering, product design, and manufactur ing. Beginning with Step 4. Plan: Clearly Define the Problem, the team has decided to brainstorm the reasons why this problem has occurred.Assignment Form a team and use the WHY-WHY diagram technique to deter- mine why the bracket may be hard to assemble. Part 2 In conjunction with the WHY-WHY diagram for why the bracket is not easily assembled, the team has decided to develop perfor mance measures to answer the following question: How do we know that the changes we made to the process actually im- proved the process? Assignment What performance measures does your team feel are necessary to answer this question: How do we know that the changes we made to the process actually improved the process? Part 3 Continuing in the problem-solving cycle, the team proceeds with Step 5. Plan: Problem Process, Document and Analyze the team visited the customer's assembly plant to determine where the brackets were used in the process and how the assembly was actually performed. There they watched as the operator ran- domly selected a strut, a bracket, a bolt, and a locknut from dif- ferent bins. The operator positioned the strut in place, wrapped the bracket around it, and secured it to the frame by finger-tight- ening the bolt and locknut. The operator then used a torque wrench to secure the assembly. While they watched, the opera- tor had difficulty securing the assembly several times. Back at their plant, the team also created a flowchart for WP's process of fabricating the bracket (Figure C4.2.2 0).Stamp Uncoil Straighten pierce Quality Transfer Bend steel steel flat check to bender bracket Quality check Transfer to heat treat Delay Heat treat Quality Pack Ship checkFigure C4.2.2 Flowchart of Bracket-Fabrication Process After completing the ow diagram and verifying that it was cor- rect, the team moved on to Step 6. Plan: Determine Possible Causes. They decided to use a cause-and-effect diagram to guide their efforts in brainstorming potential root causes for the problem: difficulty securing brackets closed with bolt and locknut