hour of build capacity.
Capacity Cost
is easily determined by dividing the printer cost by the average build rate as determined in the previous article. Figure 1 compares the capacity cost of the four printers. Surprisingly, the least expensive printer has the highest capacity cost. The Voxeljet printer has the lowest capacity cost followed by the QuickCast printer.
Elements of Pattern Cost Capacity cost only measures the cost of obtaining build capacity. Operating cost is how much it costs to run the printer after acquisition. Other than labor, there are three major elements of pattern cost; the cost of materials, depreciation and the cost of maintenance. • Material Cost - For purposes of this analysis, list prices of the materials supplied by the manufacturer of the printer were used. Manufacturers often sell at a discount and aftermarket material suppliers often supply less expensive materials. Given the difficulty of determining actual average prices, manufacturers’ list prices are used.
Material cost for QuickCast patterns
varies widely with the geometry of the pattern and has four components: 1. Resin used to build the internal support structure – the volume of resin used for internal support structure is approximately 13% of the pattern volume.
2. Resin used to build the skin – the volume of resin used to build the skin of the pattern is the surface area times the skin thickness
3. Resin used to build supports – the stereolithography process builds supports which attach the part to the build platform and act as a fixture. The amount of supports required varies dramatically from pattern to pattern and can vary significantly depending on how the part to be built is oriented in the build.
4. Resin undrained from the interior of the pattern – In the build process, liquid resin is trapped within the pattern. Drain and vent holes
® Figure 2: Material Cost for the Printers
System
3D Systems ProX 800 3D Systems S Pro 230
3D Systems ProJet 3510 CPX Voxeljet VX1000 PPB
Table 2: Printer List Price
List Price $550,000 $475,000 $100,000 $735,625
Figure 3: Depreciation Cost per Cubic Inch of Patterns
allow that liquid resin to be drained out after the build is complete. Draining is further encouraged by
placing in the pattern in a centrifuge for several minutes. Nonetheless, it is virtually impossible to completely
April 2017 ❘ 17
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