Simple Solutions That Work! Issue 13

T he old adage that metal casting is a blend of art and science certainly rings true. At virtually every stage of the process there are opportunities to create what will ultimately become a defect in the part you are making. In many cases, the defect may have been created much earlier in the process than where it ultimately manifests itself, which is a recipe for spending extra money on what is already a bad part. If it were simple to avoid doing this, we’d all be doing it, and no one would generate any scrap and all of us would have extra cash coming out of our ears. So, like most things it is a question of focusing on the right elements of the process so that we can eliminate defects when and where they are most likely to occur and then maintain the process across time and production runs. By way of lessons learned having worked on this for many years, here are some concepts and examples that I hope can be of value and applied more broadly to situations specific to your operations. START AT THE BEGINNING Ultimately, we will see the defect in the final product. We will be out of spec with a material or dimension or have porosity that provides a leak path or leads to structural concerns. The key to effective elimination of the defect is to determine at what point is it occurring and why. For that reason, we have to start at the beginning of the process in order to eliminate root causes and avoid the potential for compounding effects downstream. An example of this would be an alloy that includes contaminants that are getting through to the final stages of the process. If you are only focused on the end of the process, you can waste lots of time and money trying to fix the problem when the root cause is far upstream. We have been able to address this issue as part of our filtered launder transfer system so that these contaminants are filtered out of the process, effectively eliminating the root cause early in the process. By filtering the metal using ceramic foam filters that can be selected based on the specifics of the alloy and the potential contaminants, we can be sure that we are sending clean metal downstream to the casting machine. LOOK AT EACH STEP It is always tempting to skip ahead in life, and in the world of molten metals, this is always a mistake. Following along with the process from our example above, it would be easy to think that we’ve solved our problem and can now skip down to the end of the process. While it may be that we have indeed solved the problem, it is more likely there are other process steps that will impact the metal in a way that can reintroduce a defect. A good example of this might be how the metal gets transferred downstream to the next 16 JEFF KELLER CEO MOLTEN METAL EQUIPMENT INNOVATIONS ARTICLE TAKEAWAYS: • Defect prevention is a multilevel proposition, start at the beginning • Introduce quality improvements at the optimal point in the process • Defect-free outcomes require a system approach MMEI Filtered Launder Transfer System with Rotary Degasser DEFECT PREVENTION IN MOLTEN METAL PROCESSING