The traditional troubleshooter documents the process inputs, which are machine-specific parameters that are entered into the machine. The scientific troubleshooter documents the process outputs, which are the results of the process when acceptable parts are produced. Many of these parameters are the same as the process input, but each of these parameters would be consistent from one machine to another.

 

Examples of machine-independent process parameters include melt temperature, coolant temperature entering and leaving the mold, coolant flow, first-stage fill time, first-stage fill weight, second-stage packing time, second-stage plastic pressure, gate-seal time, cooling time, plastic backpressure, screw recovery time, overall cycle time, final part weight, clamp tonnage, and dewpoint. You can also document any important information such as photographs, observations, and quality information.

 

 

 

STEP 3—RULE OUT OBVIOUS CAUSES

Once a non-conformance occurs, the first thing to do is to thoroughly inspect the part to make sure that other defects are not present. If any aspect of the process, mold, machine, or material is obviously suspect, then this should be investigated first.

 

For example, let’s suppose a part may have flash. With only this information, the traditional troubleshooter might investigate the clamp tonnage, transfer position, packing pressure, or barrel temperatures. Now, let’s assume further inspection by the scientific troubleshooter, which determines that the part also has splay. With this additional information, it may be possible to suppose that both the flash and splay could be the result of moisture in the material.

 

 

 

STEP 4—ACTUAL VS. ‘IDEAL’ PROCESSES

Once obvious causes are ruled out, the next logical step is to compare the current process with the documented standard. Since a well-documented process contains a variety of parameters, it is best to start by reviewing the parameters that most likely relate to your defect. As you compare the documented standard to the current process, you will determine which aspects of the process have deviated from the standard. A scientific troubleshooter can use this information to help make educated decisions about what parameters need to be changed to bring the process back to the documented standard.