Quality Toold

IE 135 Problem Set/Case Study. Quality Control Tools and Variable Control Charts

Written report to be submitted and to be presented in class (Wednesday, August 14, 2013)

1. Southwest Wood Treating has been getting many complaints from its major customer, Home Station, about the quality of its shipment of pressure-treated products. Rick Summers, the plant manager, is alarmed that a customer is providing him with the only information the company has on shipment quality. He decided to collect information on defective shipments through a form he asked his drivers to complete on arrival at customers’ stores. The forms for the first 284 shipments have been turned in. They show the following over the last 8 weeks:

Table 1. Defect Data

Week | No. of Shipments | No. of Shipments with Defects | Reasons for Defective Shipment |

| | | Incorrect Bill of Lading | Incorrect Truckload | Damaged Product | Trucks Late |

1 | 23 | 5 | 2 | 2 | 1 | |

2 | 31 | 8 | 1 | 4 | 1 | 2 |

3 | 28 | 6 | 2 | 3 | 1 | |

4 | 37 | 11 | 4 | 4 | 1 | 2 |

5 | 35 | 10 | 3 | 4 | 2 | 1 |

6 | 40 | 14 | 5 | 6 | 3 | |

7 | 41 | 12 | 3 | 5 | 3 | 1 |

8 | 44 | 15 | 4 | 7 | 2 | 2 |

Even though Rick increased his capacity by adding more workers to his normal contingent of 30, he knew that for many weeks he exceeded his regular output of 30 shipments per week. A review of his turnover over the last 8 weeks shows the following:

Table 2. Turnover

Week | No. of New Hires | No. of Terminations | Total No. of Workers |

1 | 1 | 0 | 30 |

2 | 2 | 1 | 31 |

3 | 3 | 2 | 32 |

4 | 2 | 0 | 34 |

5 | 2 | 2 | 34 |

6 | 2 | 4 | 32 |

7 | 4 | 1 | 35 |

8 | 3 | 2 | 36 |

a. Develop a scatter diagram using total number of shipments and number of defective shipments. Does there appear to be any relationship?

b. Develop a scatter diagram using the variable “turnover” (number of new hires plus number of terminations) and the number of defective shipments. Does the...