Smart Molding International 1-2020

mold design 20 smart_molding interna ti onal 1/2020 Easier decisions in mold design using virtual molding T here are many ques ti ons that injec ti on mold manufactur- ers confront daily regarding the variety of mold materials which are available in the market. What type of steel should be used for which part of the mold? Whether it is the thermal conduc ti vity of the steel used for the cavity insert, the diameter of a suitable ejector pin or even the mechanical sta- bility of the core pins, SIGMASOFT® Virtual Molding leads to the correct decision. In SIGMASOFT® every mold material, e.g. steel, isola ti on, etc., is taken into account with its thermal and mechani- cal proper ti es. As an example, one can simulate the hea ti ng up phase or the developement of hotspots during sev- eral injec ti on cycles having the thermal conduc ti vity and speci fi c heat capacity of all the mold materials. Besides the predic ti on of shrinkage and warpage of plastic parts, SIGMASOFT® also simulates the deforma ti on of inserts and core pins during fi lling. These cal- cula ti ons are based on possible imbal- ances in the fi lling of the cavity and of course the mechanical proper ti es of the steel. SIGMA Plastic Services, Inc. (IL), the American subsidiary of SIGMA Engineering GmbH, simulated an in- teres ti ng project in coopera ti on with two companies, CAVAFORM (FL) and Cra ft s Technology (IL). In the project the deforma ti on of core pins made of di ff erent materials during fi lling of the cavity was evaluated. The investigation was done for an injec ti on mold with 16 cavi ti es, which is used to produce centrifuge tubes. In 8 of these cavi ti es, core pins made of tungsten carbide are integrated to form the inside of the tubes. 420 stain- less steel is used for the other 8 core pins. Simula ti ve analysis of the fi lling phase shows an imbalance, which comes to existence a ft er about 85% of fi lling has passed and becomes more obvious near the end of fi lling (Figure SIGMASOFT® provides a variety of methods to forecast the shrinkage and warpage of plas ti c parts. Along with this, one can also simulate the deforma ti on of inserts or core pins during fi lling. SIGMA simulates and compares the deforma ti on of core pins made of two di ff erent mold materials under equal process condi ti ons. The calcula ti ons are based on the imbalanced melt fl ow inside the cavity and the mechanical proper ti es of the two materials.