Specific Gravity Measurement and Cost Comparison Program (Revision A) Price: $45 US
How many parts you can make out of a pound of material depends on its specific gravity - the lower the SG, the more parts per pound. Measuring the specific gravity of molding material is extremely easy, once you know how. All it takes is a beaker, a gram scale, some water and this program.
Material suppliers specify the SG of their materials, but they all have an "acceptable" range. You can purchase "identical" material from different vendors and more than likely they will have slightly different SG values. This is particularly true for materials with fillers or additives, such as glass, mineral, calcium carbonate, etc. If you buy a lot of material, a small difference in SG can mean a significant amount of unrealized profit.
Or you might decide to mold a part out of a material such as PVC due to it's relatively low cost. But PVC has a fairly high SG of 1.4. A more "expensive" material with a lower SG might actually result in a lower part cost.
The Cost Comparison portion of this program quickly shows you the true cost of one material as compared to another, as well as the true cost of the "same" material from two different vendors.
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