Kistler Instrumente GmbH

Kistler and STASA develop an automatic method for the prognosis of injection molded part quality

Swiss company Kistler Instrumente AG of Winterthur is the leading international supplier of
sensors and systems for in-line cavity pressure-based quality monitoring of injection molding
processes. German specialist Steinbeis Angewandte Systemanalyse GmbH (STASA) with
headquarters in Stuttgart has many years of experience in the development of process models,
online prognosis of quality features based on characteristic process values as well as the
application of complex mathematical methods and models to industrial processes. This expertise
is based on scientifically corroborated methods such as the design of experience
(DoE) and the generation of models, and can be reliably applied to injection molding.

The implementation of approved Kistler systems into process-related quality monitoring of
injection molding processes based on process profile characteristics such as the properties
and tolerances of the cavity pressure curve is already widely established. Kistler and STASA
have now joined forces to develop an enhanced quality monitoring method for injection
molding processes that allows the direct quality monitoring and definite prognosis of the
quality of the currently molded part by using the quality models of the STASA QC program.
Based on the process models and measured process parameters, the final dimensions of the
molded part can be predicted online, i.e. while the part is being produced. Immediately after
injection molding, this approach provides information on whether the part will meet specified
dimensional tolerances when it is used.

The new concept has many benefits for manufacturers and OEMs of injection molded products:
they will receive information on the tolerance limits directly from the part specification
and can use this criterion as a parameter of the process monitoring system. This technique
significantly enhances in-line quality monitoring of injection molding processes: the limits of
monitoring parameters such as pressure maxima, pressure integrals and other values need
no longer be defined and evaluated. Instead, the relevant correlations between process
profiles and quality criteria are acquired during mold sampling and are then used for process
monitoring. The DoE used during mold sampling has beneficial side effects, because the
injection molding process can be optimized automatically and ideal parameters for meeting
the required quality criteria can be defined within the process latitude.

This combination of process and quality monitoring with quality prognosis has long been
requested by molders of high-quality, extremely sensitive, hard-to-assemble moldings such
as producers of medical parts and pharmaceutical components. This technology is integrated
into Kistler CoMo Injection process monitoring systems as an optional module. Quality
prognosis will become available as a high-end option for the CoMo Injection during the
course of 2011.

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Background: Quality Assurance with Mold Cavity Pressure
The cavity pressure curve is considered to represent a fingerprint of the injection molding
process. It is the most informative characteristic for evaluating the quality of the part. Deviations
from the optimum curve are clear indications of process fluctuations that lead to part
defects ranging from incomplete mold filling to flashing or dimensional discrepancies.
As the supplier with the largest and widest range of sensors for all methods of injection
molding, simple connection technology and intuitively easy to operate, networkable systems,
Kistler is the only manufacturer to offer complete monitoring of injection molding
from a single source. Kistler is the world's leading manufacturer of pressure and temperature
sensors for use in the plastics processing industry

Kistler Group
Kistler’s core competence is the development, production and use of sensors for measuring
pressure, force, torque and acceleration. Kistler’s know-how and electronic systems can be
used to prepare measuring signals for use in analyzing physical processes, controlling and
optimizing industrial processes, improving product quality in manufacturing and improving
performance in sports and rehabilitation.
Kistler offers a comprehensive range of sensors and systems for engine development, automotive
engineering, plastics and metal processing, installation technology and biomechanics.
A worldwide sales presence in the form of 25 group companies and 30 distributors ensures
customer proximity, application support on an individual level and short lead times.
With a staff of about 1 000, the Kistler Group is one of the world’s leading providers of dynamic
measuring instrumentation. The Kistler Group achieved turnover of 166 million Swiss
Francs in the 2009 financial year.

STASA Steinbeis Angewandte Systemanalyse GmbH
STASA Steinbeis Angewandte Systemanalyse GmbH was founded by Prof. Dr. Günter Haag
and is a member of the Steinbeis network. The specialist’s objective is the utilization of useful
innovations on the leading edge of research and development in order to keep industrial
customers abreast of the competition by leveraging their expertise. A selected team of
highly qualified experts is providing solutions to complex tasks in the area of applied analysis,
model development and simulation of technical systems. The integration of innovative
statistics and physical methods is one the specialist’s core competencies. The STASA QC
application won the do-it Software Award.