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Process Simulation in Elastomer Applications: Identifying “non-productive” times pays off

Using the process-oriented approach of SIGMASOFT® makes it possible to consider all of the molding times present in an actual injection molding cycle. In the injection molding simulation of elastomeric applications, SIGMASOFT® not only considers the filling and curing times, but also the non-productive times between each production cycle while the mold is opened and closed. If the simulated process considers the influence of multiple consecutive molding cycles, the accuracy of the simulation is dramatically improved.

Figure 1 – Temperature distribution in a metallic component over-molded with rubber. Left: without consideration of the mold opening time; right: considering a mold opening time of 60 seconds, where significantly lower temperatures and long curing times are observed.

Figure 1 – Temperature distribution in a metallic component over-molded with rubber. Left: without consideration of the mold opening time; right: considering a mold opening time of 60 seconds, where significantly lower temperatures and long curing times are observed.

Even though it is not necessary to include them to complete an injection molding simulation, the “non-productive” times have a major influence on the mold temperature and thus on the process and on the part quality. With the Process Simulation Software SIGMASOFT®, from SIGMA Plastic Services, Inc. (Schaumburg, Illinois), all the non-productive times can also be included into the simulation of multiple consecutive production cycles and a substantial improvement in the accuracy of the results predicted can be achieved.

Considering the times in which the mold opens and closes, the times in which the mold is heated or cleaned, as well as handling times in which the inserts are placed or the parts removed, makes it possible to exactly describe the real multi-cycle production process. The interaction between all components present in the mold is considered with the local temperature dependent material properties, along with the heat that escapes the mold into the environment while it is both opened and closed and the exact timing of each event are coupled together inside of SIGMASOFT® to provide a comprehensive understanding of a very complex system. In this way, even factors that influence the part quality, such as the mold temperature and curing degree, can be predicted before the mold is ever built.

An example is presented in Figure 1. In this case, the mold temperature drops significantly while it is in the open position because heat radiates from both heated mold surfaces. If this time and open condition are not considered in the simulation, the mold temperature calculation will be higher than actual; resulting in a faster curing reaction and a shorter cycle time than what is actually possible. Other events will also be incorrectly calculated such as curing degree during filling and required injection pressure.

In SIGMASOFT®, non-productive times can be defined and individually modified in the simulation. For this reason, it is also possible to optimize the entire production process or mold design simultaneously. Through this simulation, it is possible to decide if changes in the process definition will solve production problems, or if the mold has to be modified to achieve the desired quality and productivity goals.

For more information:

Matt Proske

SIGMA Plastic Services, Inc.

10 N. Martingale Road, Suite 425

Schaumburg, IL 60173

Phone: 847-558-5600

Email: contact@3dsigma.com

Web: www.3dsigma.com

SIGMA® (www.3dsigma.com) is 100% owned by MAGMA® (www.magmasoft.com), the world market leader in casting process simulation technology based in Aachen, Germany. Our SIGMASOFT® process simulation solution optimizes the manufacturing process for injection molded plastic, thermoset, rubber, and MIM/CIM components. SIGMASOFT® combines the 3D geometry of the parts and runners with the complete mold assembly and temperature control system and incorporates the actual production process to develop a turnkey injection mold with an optimized process.

At SIGMA® and MAGMA®, our goal is to help our customers achieve required part quality during the first trial. The two product lines – injection molded polymers and metal castings – share the same 3D simulation technologies focused on the simultaneous optimization of design and process. SIGMASOFT® thus includes a variety of process-specific models and 3D simulation methods developed, validated and constantly improved for over 25 years. A process-driven simulation tool, SIGMASOFT®, with its comprehensive simulation approach, provides a tremendous benefit to production facilities. Imagine your business when every mold you build produces required quality the first time, every time. That is our goal. This technology cannot be compared to any other conventional “design” simulation approach employed in plastics injection molding.

New product success requires a different communication between designs, materials, and processes that design simulation is not meant for. SIGMASOFT® provides this communication. SIGMA® support engineers, with 450 years of combined technical education and practical experience, can support your engineering goals with applications specific solutions. SIGMA® offers direct sales, engineering, training, implementation, and support, by plastics engineers worldwide.