Simple Solutions That Work! Issue 14

45 Continued on next page ADVANCED MANUFACTURING SOLUTIONS KYLE GRAHN AF Gelhar Co., Inc. ARTICLE TAKEAWAYS: • Selecting the proper silica sand and controlling any sand variations will help you to achieve optimum process performance • Controlling your raw materials will help you increase efficiency and optimize quality • Learn the eight critical criteria to evaluate or determine the proper silica sand for your process CHOOSINGTHE CORRECT SILICASAND FORADVANCEDMANUFACTURING SOLUTIONS INTHE FOUNDRY T he customer driven metal casting quality demands placed on the foundry industry are rapidly transforming the level of technology required to produce saleable castings at a competitive price. These market demands require viable companies to constantly search for sustainable advanced manufacturing solutions for their foundry operations to meet and exceed these requirements. These advanced manufacturing solutions require tighter process controls and higher quality, tightly controlled raw materials, and it doesn’t matter if the foundry process being utilized to create the casting is green sand, no-bake, shell, conventional cores or 3D printing. Therefore, it is necessary for the raw material supplier to apply tighter controls on their process to deliver products that enable the metal caster to meet the finished product demands of their customer base. When choosing the proper silica sand for an advanced manufacturing solution in the foundry, there are eight critical criteria that should be monitored and used to evaluate or determine the proper silica sand for your process: 1. Sand Grain Shape (Round) 2. Sand Grain Hardness 3. Chemical Composition 4. pH Control 5. ADV (Sand Grain Cleanliness) 6. Sand Distribution 7. Lack of Dust 8. Conductivity The sand grain shape is critical to most foundry applications because it controls the surface area to be coated by the binder and it’s also critical to mold or core density. Regardless of your process a round sand grain has less surface area, requiring a lower binder content to adhere grain to grain, which also significantly reduces the amount of gas produced once the molten metal is introduced to the mold or core surface. A chemical binder addition at just 1% of sand weight requires about 4.5 grams to one pound of sand. If a foundry were using a 70 AFS GFN sand, it is the equivalent of painting almost 63 square feet with 12 to 14 drops of resin in a continuous mixer with around five seconds of retention time. With the cost of chemical binders, a reduction of just 0.1% in the binder content can provide very significant savings reflected in the