Case study
1.0
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
Table 2. Comparison of the Capabilities of Various Sand Casting Processes Min
Volume (in3
) Vp
209.16 162.49 144.47 131.76 123.11 120.01 113.83 105.66 103.43
Surface area (in2
229.77 319.56 383.45 421.96 446.35 460.38 481.40 513.95 525.19
) Ap
# of cores Nc
0 1 2 3 4 5 6 7 8
• Quantification of part design com- plexity in cast parts using a criterion adopted from a prior study.
• Estimation of fabrication costs associated with conventionally produced molds and cores and 3-D sand printing for varied production volume.
• Analysis of fabrication costs as a function of part complexity factor values.
• Estimation of break-even costs between traditional and 3-D sand printing to determine levels of part complexity where 3-D sand printing is more cost-effective.
• Examination of the effects of changing the costs of 3D sand printing. Te criterion for measuring part
design complexity used in this study was adopted from a prior study focused on quantification of part
¦ Cores volume (in3
) Nc 0
46.67 64.69 77.40 86.05 89.15 95.33
103.50 105.74
thickness (in) Tmin
0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12
Max
thickness (in) Tmax
8.24 8.24 8.24 8.24 8.24 8.24 8.24 8.24 8.24
Length (in) L
8.24 8.24 8.24 8.24 8.24 8.24 8.24 8.24 8.24
complexity of cast parts for traditional processes. Key geometric attributes that can be determined from the CAD model of the desired part associ- ated using this complexity model are presented in Table 1. Te tooling cost is influenced by tool design and complexity which is dictated by the part design complexity. For example, the mold for a complex part design such as a train air brake may require multiple cores. Alternatively, a simpler casting might be a solid uniform cross- sectioned part without the need for a single core. Designers and tool makers observed that the tooling cost depends on the number of cores, volume and surface area of part, core volume, draw depth (i.e., the depth of tooling) and variation in section thickness. For a given part design, the cost of moldmaking for both pattern and 3-D sand printing was conducted. For
Width (in) W
6.36
6.36 6.36 6.36 6.36 6.36 6.36 6.36 6.36
Height (in) H
5.16 5.16 5.16 5.16 5.16 5.16 5.16 5.16 5.16
Draw depth (in) Dd
2.95 2.95 2.95 2.95 2.95 2.95 2.95 2.95 2.95
Complexity factor CF
19.7 41.3 50.1 55.4 58.9 60.9 63.1 65.6 66.7
conventional pattern making, tooling costs were generated using an Internet- based cost generator. Te bounding box of the part, the number of cores and the number of part features are required to generate the tooling costs. Fabrication costs of molds and cores were estimated by industry quotation method based on the size of the casting, number of cores and other factors. Te impact of part design complex-
ity, increasing the number of cores and complexity of core geometries were analyzed with respect to production cost of mold making using traditional and 3-D sand printing.
Case Study 1: Train Air Brake Te part geometries in these case
studies are derivative designs of actual castings. Each case study starts with a solid casting, and cores are sequentially added until all the desired cores are
Fig 4. Tooling costs (i.e., patterns and coreboxes) as a function of com- plexity are shown for Case Study 1.
32 | MODERN CASTING April 2017
Fig 5. Fabrication costs for Case Study 1 for 3-D sand printing costs and conventional patternmaking is shown.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60