Prior to mull to energy, batch mullers had to have set mixing times that were long enough to properly coat sand grains. While this approach is effective, it cannot properly account for the changing conditions in the sand system such as core loading, sand to metal ratio changes, etc. and causes sand batches to be either over mulled (mulled past the clay’s temper point) or under mulled (not mulled long enough for clay to reach its peak strength). Over/under mulled batches contribute to inconsistent sand properties and can be found by tracking the energy dose added to each batch. The graph below is taken from a batch muller energy study and shows the variability of energy dose in each batch.
As you can see the energy dose (measured in KWS) can fluctuate wildly from batch to batch. When tracked over a three day study, we can see even more variation from the muller. The graph below shows the quantity of batches with each energy dose over the 3 day study. Note that the graph shows which batches are over mulled and which are under mulled.
With mull to energy we can stabilize sand coming from the muller by controlling the energy dose per batch. This helps keep the sand properties consistent from batch to batch while lowering the energy bill for the muller. In most cases we have also seen a reduction in the muller utilization and some have had an increase in through put as well. To learn more about the benefits of mull to energy and how it can help your foundry contact us.