Annex to the present some exercises of Total Quality Management, would you do for me, and How much for it?
Problem No. 1
The Modern Styles Furniture Company produces a line of disassembled furniture, which comes in a carton. The buyer is required to assemble the pieces into a usable object. One of the products is a two-shelf bookcase. Here is the parts list for the product:
1 – back panel , 2 – middle shelves , 1 – package of screws
1 – top shelf , 2 – side panels , 1 – cardboard carton
This problem is concerned only with the cardboard carton and its contents. The pieces of the bookcase are assumed to be satisfactory, but some may be missing in some cartons. This constitutes a simplification, of course, since it ignores the problem of defective or damaged parts. The company provides an 800 number on the carton to assist customers who experience difficulties. Recently, there has been a rash of calls concerning missing parts. The Company promptly ships the missing part(s) to the aggrieved customer.
Management is concerned about the poor reputation which the Company’s products are acquiring and about the extra expense of the shipments, which should be unnecessary. In an attempt to pinpoint the problem, some employees have been detailed to check every carton before it is sealed up and to keep a record of their findings on a check sheet. Any parts discovered to be missing are replaced before the carton is shipped. Here is a table of their findings for one week.
| Piece | Mon. | Tues. | Wed. | Thurs. | Fri. | Total |
| Back panel | 3 | 1 | 2 | 1 | 1 | 8 |
| Top shelf | 2 | 2 | 3 | 1 | 2 | 10 |
| 1 Middle Shelf | 6 | 4 | 7 | 4 | 10 | 31 |
| 2 Middle shelves | 6 | 4 | 7 | 4 | 10 | 31 |
| 1 side panel | 7 | 10 | 4 | 8 | 6 | 35 |
| 2 side panels | – | 2 | 1 | 3 | 1 | 7 |
| Screws | 3 | 4 | 5 | 5 | 4 | 21 |
| Carton | – | – | – | – | – | |
| Total | 27 | 27 | 29 | 26 | 34 | 143 |
- Fill in the totals in the Table.
- Which piece is most often omitted?
- Suggest a corrective action for the piece in b.
- Which piece is the next most often omitted?
- Suggest a corrective action for the piece in d.
- Which day is most prone to errors in packing?
- Suggest a corrective action for the worst day.
Problem 2. Using the data in Problem #1, construct a Pareto diagram for the missing pieces.
Problem 3: Assume that action has been taken to resolve the problem of the missing pieces in Problem #1, according to the suggestions in the answers to Problem #B. In order to find out whether the corrections were effective, all cartons produced in one week have been checked, producing the data in the table, below.
| Piece | Mon. | Tues. | Wed. | Thurs. | Fri. | Total |
| Back panel | 1 | 2 | 1 | 2 | 1 | 7 |
| Top shelf | 3 | 2 | 3 | 1 | 3 | 12 |
| 1 Middle shelf | – | – | – | – | – | – |
| 2 Middle shelves | 1 | 2 | 1 | – | 1 | 5 |
| 1 side panel | – | – | – | – | – | – |
| 2 side panels | 2 | 1 | 1 | 3 | 1 | 8 |
| Screws | 5 | 6 | 3 | 3 | 5 | 22 |
| Carton | – | – | – | – | – | – |
| Total | 12 | 13 | 9 | 9 | 11 | 54 |
- How much progress has been made in solving the missing pieces problem?
- Which piece is now the most often omitted?
- Suggest a corrective action for the piece in b.
Problem 4:
The Perfect Circle Company manufactures bushings. Once each hour a sample of 125 finished bushings is drawn from the output; each bushing is examined by a technician. Those which fail are classified as defective; the rest are satisfactory. Here are data on ten consecutive samples taken in one week:
| Sample no. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Defective | 15 | 13 | 16 | 11 | 13 | 14 | 20 | 25 | 30 | 45 |
a. What type of control chart should be used here?
b. What is the centerline of the chart?
c. What is the lower control limit (LCL)? The upper control I?
d. What statistic should be plotted on the control chart for?
e. Draw the control chart using Excel.
f. Is this system under control?
g. What should the quality control engineer do?
