Simple Solutions That Work! Issue 11

Contact: DAVID C. SCHMIDT [email protected] 52 If we go to the lowest level of chemistry and the highest pouring temperature, we see that we are now predicting shrinkage areas right down in the area that the production casting was showing. In fact, simulation now shows a massive loss of density in the middle, which literally would be a hole just like we saw in the castings. A comparison of the results from the 3 sets of simulations is shown in Figure 6. So, by using the high end of the Pouring Temperature and the low end of the Chemistry Range, we are best able to predict shop floor problems. Knowing that there are going to be variations, we normally want to design the process for the worst of those conditions. So, for future simulations, what the foundry is going to do is use the lower end of the chemistry spectrum quality so that you do not have to go through these sorts of calculations manually. It is taken care of automatically when we do a simulation. Figure 5 shows a look at those results on a slice through the middle of the model. We can see that there are no predicted problems. This simulation was done using the highest levels of the chemistry and the lowest level of the pouring temperature. That clearly was not matching what was going on in the foundry. If we go to an intermediate chemistry, that is, lowering the carbon and silicon levels to the middle of the range and the middle of the expected range of pouring temperature, we see that defects are starting to occur in the simulation, but they are not really occurring in the area that we saw on the sectioned casting. Figure 5. Simulation results of a slice through the castings. Figure 6. Comparison of simulation results with shop floor results. in the higher end of the pouring temperature spectrum, because that produces the worst situation, and then design the gating and risering to attack those worst-case scenarios.