Simple Solutions That Work! Issue 14

47 of having a sand supply that can be controlled between a pH of 6.8 and 7.4 in order to control the foundry process. The sand supplier should be able to demonstrate how they control the pH of their product. The next quality to scrutinize when choosing the proper silica sand is the ADV or sand grain cleanliness. Most foundry sand is washed, but it is most beneficial to be washed at least three but preferably 4 times to remove the natural impurities that stick to the sand grain surface. The material that remains on the sand grain can result in the need for additional binders or catalyst to activate the binder. The ADV should be 1.0 or under in order to guarantee the efficient use of your binders. If the foundry is using reclaim sand it is always a good practice to measure the ADV of that material, because all of the various materials used in casting production (sand additives, risers, cores, etc.) can significantly raise the ADV of your reclaimed sand. Another important factor to use for silica sand evaluation is the distribution of the material. Foundry experts around the world continue to proclaim that the best sand for metal casting is a product with a 3 or 4 screen bell curve distribution. This will provide the best mold or core compaction to improve near net shape and surface finish, as well as the highest permeability. Permeability is critical to getting gas to move away from the mold to metal interface. Each sand grade and application require a proper level of 140M to increase mulling/ mixing efficiency, maintain system moisture levels or increase tensile strengths. The proper distribution is also extremely critical to the operation of the modern sand printer to ensure the sand flow and prevent clogging of the printer heads. The proper distribution will also impact the next important factor, which is the lack of dust. Providing silica sand with extremely low levels of material on the 200M, 270M and Pan will keep dust generation to a minimum. The reduction in dust generation will not only help reduce overall binder consumption, but it will also reduce the airborne silica, improving the working environment inside the casting facility. The final criterion used to evaluate your silica sand choice is the sand conductivity. A lower sand conductivity enables an easier transfer of energy, which means the sand will mull in or mix quicker, requiring less energy. This can be extremely beneficial to the efficient coating of the sand grains in any process and minimize binder consumption. To effectively compete, the modern foundry must operate at the lowest possible cost while using advanced manufacturing solutions to provide the highest possible quality casting. To accomplish this objective, one critical piece of the puzzle is choosing the correct silica sand and controlling any sand variations to achieve optimum process performance. Tightly controlled raw materials will increase the effectiveness of your advanced manufacturing solution and optimize the quality of your end product. DEFECT PREVENTION ADVANCED MANUFACTURING SOLU I NS Contact: KYLE GRAHN [email protected]