Case Studies

Case studies

Case study #1 – Improve factory yield

Case study location: A successful hi-tech manufacturing factory

Problem description:

1. The Factory was not able to sustain its long term process yield goals

2. It took too long to implement process improvements.

The Goal:  Achieve sustainable high yield and fast implement process improvements.

Method used: TOC TP

The process:

Step 1:  A team of representatives from each major function of the factory was formed.

Step 2:  Each member of the team listed down the Un Desirable Effects (UDE‘s) from their prospective. We generated a Current Reality Tree

) and found the root cause.

Step 3:  We used the ” Cloud ” technique to identify the conflict  and the assumption  behind each branch of the Cloud.

It was found that everyday engineering and manufacturing departments dealt with a permanent firefighting. The scene was the morning management meeting where the previous day indicators where presented and discussed. The result of this meeting was a list of actions that should be taken immediately to solve the problems in the line. One of the “hidden assumption” that was found in the Cloud analysis process was the fact that those who solved the problems (that came out of the morning meeting) received the appreciation of the upper management. It was also found that in some cases engineers and manufacturing people did not make efforts to solve problems on the spot but rather escalate them to the morning management meeting (“If I raise a problem it means I am here..”). When problems were solved the person received management appreciation.

Step 4: Generate solutions. We created ” Injections ” to the conflict (Solutions).

1 . The responsibility for the daily indicators moved from upper management to the middle management (supervisors and engineers).

2 . The morning management meeting was canceled; indicators were distributed over the network.

Results : Short time after implementing the Injections, the factory yield increased to goals and was sustainable high,  the time it took to implement process improvements significantly shortened.

Case study #2 – improvement of Test fixture (Jig) for electronic components

System description:  Test fixture is used in automatic testing machine, to measure high frequency surface mounted electronic components (couplers, filters etc). Components are measured, and packed or discarded to the defect bin per measurement result. During measurement the components are placed on the springy contacts of the test fixture printed circuit. Printed circuit is a three-layer sandwich – epoxy glass covered from both sides with thin metal layers. Measure rate is about 5 components per second.

Test fixture is shown in diagram

The problem:  The printed circuit is very sensitive to “strikes” during measurement. Metal layers tend to cracks and result in an inaccurate measurement. This failure appears after 20-30 thousands measurements. The expensive test fixture should be removed from the testing machine and repaired. Repair operation requires special equipment, highly qualified repair personnel, takes much time and is very costly. What can be done?

Solution idea was generated based on TRIZ  principles:

Printed circuit is turned from sandwich of three layers firmly connected to each other into a sandwich with layers that are not connected each other . This design eliminates strains that are causing metal layers cracks due to repeat contact bending during measurement.

Results:  The test fixture is ten times cheaper, reliable for millions of measurements and easy to repair.