Using the 5 "Why" in the case study
Description of the problem:
More bad soldering on the PCB were found in the post-wave control.
1. Why - there are bad solder joints in the panel?
Because the wave soldering is not working properly (the raw panel error-free and complies with the specification).
2. Why - the machine is not working properly?
Because the profile of the machine is incorrect.
3. Why - the Profile is incorrect?
The conveyor speed is to slow based to the specification.
WE RECOGNIZED THE SYMPTOMS
4. Why - the band running too slowly?
Because the belt engine running unevenly, and the rate does not correspond to the actual setting.
5. Why - the conveyor belt engine work unevenly?
Because the internal brushes of the motor are worn.
WE RECOGNIZED THE REAL CAUSE OF THE ERROR