A Six Sigma Challenge
Situation
Felix works as an engineer at an automotive supplier company and has been promoted three times in the last year--from materials manager to quality manager to production manager. He was also put in charge of the company's lean manufacturing initiative. A customer is complaining that the "lean" initiative has not eliminated quality problems, so now Felix's company is under pressure to launch a Six Sigma initiative. Felix and two other engineers were selected to train as Six Sigma Black Belts.
During the first week of Black Belt Training, Felix discovered that a Six Sigma initiative is much more than doing projects. The company's readiness to launch a Six Sigma initiative and its selection of champions, who act as sponsors or mentors to the organization or the project team, are equally as critical to create a Six Sigma infrastructure. Felix went back to the plant with two challenges: to find a suitable Six Sigma project to tackle and to figure out how to get his company to truly support the Six Sigma concept. He made a presentation to his management team and some of them attended a Six Sigma training session.
For his first Six Sigma project, Felix focused on the customer who returned the parts because they could not be assembled correctly. In the first three meetings, the team made a process map, which is a flowchart that tracks individual production processes, and considered what actions in the process relate to the customer's problems. Because he did not have a champion to outline a project charter, Felix also had to create the charter from scratch.
Available data
After studying the assembly process, Felix and his team decided that the problem was the length of the individual pieces to be assembled. Using the process map as a guide, they collected data on length of the part at the saw operation. The first problem they discovered was that the specifications were written as 20 inches I0.015 inch, but the operators were using a gage that measured to the nearest 32nd of an inch. After finding a new gage, data were collected for two days. The data values are given in the table, "Length of Pieces after Sawing."
Questions
1. From the data Felix and his team collected, what is the behavior of the saw operation with respect to the length of the pieces?
2. What insights can be gained from the data that can help answer the customer complaints?
3. What should Felix and his team do next?
Answers to April Brain Teaser
Q: How does the current behavior of this process compare to the behavior based on the previous data? See the March 2002 Brain Teaser for the data.
A: The individuals and moving range chart, "Percent Good at First Test" (below) includes both sets of data. The average value is still 47% but the variation is less, which leads to tighter limits. However, reducing the variation around an unacceptable average does not fix the problem. The average value needs to increase dramatically.
Q: How can you use the details for the causes of rejection of instruments to determine the root cause?
A: A Pareto Chart can be used to show the relative contribution of the various causes for rejection to the total. Bad solder was the overwhelming problem identified, with 60% of all causes that were tabled.
Q: Consider the specific causes of rejections and brainstorm about what step in the process the problem is occurring.
A: For the two highest causes of rejection, bad solder can come from the soldering process or the previous step in which connections are made. The first place to investigate the incorrect connection problem is in the step in which the connections are initially made. Data from the incoming component test and the kitting process, which is the process for gathering incoming components together for a unit and placing them in a container, may provide insights into the component failure and the wrong PC board problems.
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