Simple Solutions That Work! Issue 9

To properly compact a mold only takes 15–20 seconds, but the return on this short amount of time may be one of the highest among all foundry processes. From this short amount of time, a better casting with reduced cleaning requirements will be achieved. • Faster Shakeout and More Effective Reclamation Shakeout is faster due to reduced resin levels, which also reduces binder costs. The LOI reduction through the reclamation system will also be improved based on the reduced resin level input. • Reduced Casting Defects Defects are reduced because less binder is needed. Gasses are created when molten metal contacts the binder and must be properly vented out of the mold in order to prevent gas related casting defects. Reduced binder levels obviously result in less gas to be vented. There is an old adage in the foundry that says “ vent , vent , and then vent some more” – while this is true in order to make a quality casting , it takes time and labor to not only make these vents, but to remove vents that are filled with metal such as risers but also to simply drill the vents. Vents that are set up as loose pieces on the pattern must be removed and returned to the box when it gets back to the molding station, maintained, and kept with the mold box when it is returned to storage and then back to molding. • Reduced Casting Cleaning Compaction reduces the time to clean your castings. After casting quality, reduced casting cleaning is the second more important reason to properly compact your molds. With today’s labor market, it is very difficult to staff a cleaning JACK PALMER President PALMER MANUFACTURING & SUPPLY, INC. ARTICLE TAKEAWAYS: • Increase casting quality and reduce cleaning with compaction • Difference between vertical and rotary vibrators • Understanding when to compact IMPORTANCE OF COMPACTION 38 Proper compaction results in: • Better Surface Finish As the sand grains are as close to one another as possible, this keeps metal from getting between the grains which results in a better surface finish. • Greater Mold Strength Less binder is often required because the grains are as close together as possible. This means that a well compacted mold will be stronger than a poorly compacted mold at the same resin level. If a poorly compacted mold provides sufficient strength, then a well compacted mold with the same strength can be achieved with less resin addition, allowing for a reduction in resin costs.