STASA QC - Cycle Time Optimization in Serial Production

elfo AG, Sachseln (CH)

Part Description

Choke disk made of POM (Hostaform C9021 red), lot size: 600 000/year

Goal

The project goal was to optimize cycle time in the ongoing serial production. The quality features inner diameter, outer diameter, height and burr formation (attributive) have to be kept within their tolerances. The molding process was adjusted by an experienced tool setter. Before the optimization with STASA QC the cycle time was about 13.0s. The projected cycle time was 15.0s.

Activities and Results

Using the DoE functionality of STASA QC an experimental design has been generated, containing the following machine parameters: mass temperature, cavity temperature, holding pressure, holding pressure time, cooling time, injection velocity.

After producing parts using the 11 sets of machine parameter values in the experimental design, the qual- ity features of the corresponding parts were measured. Using this data the machine settings optimization (set point optimization) was executed with STASA QC.

STASA QC determined an optimal machine setting, which had a cycle time of only 10.7s. This resulted in a reduction of cycle time of 2.3s compared to the machine setting in serial production. Cycle time was reduced by 18%, without changing the quality of the parts.

Achieved Savings

The production costs of the choke disk has been reduced due to the cycle time optimization by about 2200 Euros / year.

Quote of Hans-Ulrich Müller, head of technology and quality management, ELFO AG, Sachseln:

"elfo AG produces many high precision plastic parts of this kind. Hence, the investments in STASA QC are returned in the first year. A further advantage is that the tool setters are able to determine and to simulate the influencing variables, turning them into results immediately."