Part Buyers Authority Issue #2

16 PART BUYERS A U T H R I T Y Contact: FRANÇOIS AUDET [email protected] How to challenge your foundry? Here are three effective ways to challenge the foundry you’re working with or seeking to work with: 1. Request to see the casting simulation results on the mold design to see how the liquid metal you buy fills the mold and solidifies to avoid porosity defects. 2. Request to see the thermal analysis measurements on the melt quality that will fill your molds, to review how consistent the melt quality is to avoid defects. 3. Ask an impartial foundry process engineer to work with you, the machining shop and the foundry as a team for long-term follow-up and success. Audits once a year don’t work; invest in a closer relationship. 4. For sand molding, require data regarding sand properties and the controls that are in place. Predictive Simulation Sometimes the foundry needs a little push from the OEM to adopt a new technology. For example, OEMs need to see newer technologies that can prevent these defects such as casting simulation and thermal analysis to support their in-house experts. You as an OEM will end up with more consistent castings delivered more quickly by participating in the process and being up to date on current technologies. Foundries do their best to be current in the latest technologies, however as castings become more complex, the dynamics change. Your particular project may be that situation where a collaborative environment yields the highest results for all of you. Figure 5: shows a thermal analysis sample taken from a final ductile iron melt. That’s what the foundry was pouring into the molds. As predicted, castings from that melt exhibited casting defects especially due to low nodularity and gas. The mold design was improved to reduce turbulence, however, the thermal analysis results indicated the metallurgical properties of the molten metal were not right. In this particular case study, the analysis was conducted and problem solved because the OEM took the lead and hired an expert to bring this resources at a critical time. The OEM has this consultant as part of their internal team, exactly for this purpose. In conclusion, stop working in silos; start working as a team with the machine shop, foundry, and your own team of experts. You’ll save time, prevent defects, and overall save money. Therefore, before you order any castings, challenge the foundry first by asking to review the predictive simulation and thermal analysis processes they have in place to prevent these porosity defects. Figure 4: Cut plane showing porosity defects as predicted by simulation in the cast steel impeller for mold design #1; no porosity predicted on the improved mold design #2 to produce the same impeller with success. (image courtesy of Finite Solutions Inc. www.finitesolutions.com ) Figure 5: Ductile iron 80k thermal analysis sample with bad nodularity and gas bubble as the sample solidifies, while shrinkage porosity test passed. (image courtesy of MeltLab™ Systems, www.meltlab.com ) How to collaborate successfully Casting buyers and machine shops need to talk the same language that the foundry uses, or frustration awaits. While you can rely on the foundry to be your experts – challenging their team with your expert team will bring you the most value.