Page 35 - Injection Molding Advanced Troubleshooting Guide

16 1 Troubleshooting Methodology

Another thing to think about is adding both subject area “experts” as well as out-
siders. Often times the outsiders will ask questions that can spark non-traditional
thinking which in turn may lead to the true solution.
Alex Osborn is known as the originator of brainstorming and the basic rules he
established are:
1. Do not criticize.
2. Wild ideas are welcome.

3. Go for quantity.
4. Build on others’ ideas.

1.4.7.5„ Design of Experiments (DOE)
DOE is a tool that creates an intentional set of experimental conditions that will
help determine the impact of problems. The power of DOE is that it combines con-
ditions in a way so as to limit the total number of experiments conducted during a
trial. By utilizing DOE it is possible to capture interactions between process condi-
tions and see what the major contributing factors are. There are numerous soft-
ware packages on the market that can help develop DOE and analyze the data.
Specifics on DOE are beyond the scope of this book, but it should be considered as
a troubleshooting tool.
Sometimes simple full factorial DOE is the ticket to finding a solution. In a full
factorial DOE there is no simplification of the number of experiments to be run. An
example of a full factorial DOE may be looking at the influence of mold tempera-
ture and second-stage pressure on part dimensions. A full factorial DOE in this
case would require the following runs:
1. Cold mold, low second-stage pressure
2. Warm mold, low second-stage pressure
3. Cold mold, high second-stage pressure
4. Warm mold, high second-stage pressure

These four experiments will determine the impact of these two factors. Adding a
third factor would increase the number of experiments resulting in more time
required to conduct the trials.