A Statistical Evaluation of the Influence of Different Material and Process Parameters on the Heat Transfer Coefficient in Gravity Die Casting
Abstract
:1. Introduction
2. Materials and Methods
2.1. Experiments
- Mold inserts made of different materials, once of the standard die steel X37CrMoV5-1 and once made of the copper alloy CuCr1Zr, whereby their geometry was kept the same.
- Mold inserts once conventionally manufactured with straight temperature control channels at a distance of 15 mm from the cavity and once generatively manufactured with contour-adapted channels at a distance of 10 mm from the cavity (see Figure 2). Both made of the same steel (X37CrMoV5-1).
- In addition to the steel core, a version made of furan resin sand was also used, which, in addition to significantly different thermal properties, has other contact conditions due to its different surface properties and at least partial compressibility.
- From the investigation of various mold coatings and their respective wear behavior with regard to the heat transfer [20], to reduce the number of parameters, only a single die coating (KS 81 from Hüttenes-Albertus, Düsseldorf, Germany) was selected for the experiments underlying this work. Furthermore, some experiments were carried out with completely uncoated mold modules. The age of the coating was 2, 3, 4, 5, 6, or 7 previous castings (or set to 20 if no coating was used).
2.2. HTC Determination
2.3. Analysis of Variance (ANOVA)
3. Results
3.1. HTC at the Mold–Casting Interface
3.2. HTC at the Core–Casting Interface
4. Discussion
Comparison of the Mold-Casting and Core–Casting Interface
5. Conclusions
- For areas with gap formation, changes of the mold material show the highest impact on the HTC before the gap forms.
- After the formation of a gap, some influence can be achieved by changing the layout of the cooling channels.
- Should an increase in contact pressure be observable at the interface, the mold material again shows a strong influence on the HTC at higher temperatures, while at lower temperatures the condition of the coating increases in influence. For this last case, the overall state of the heat flow in the casting also must be considered.
- The influence of the overall temperature and heat flow distribution may be reducible by facilitating heat transport away from the mold wall using active cooling even under pressure.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Al | Si | Fe | Cu | Mn | Mg | Ti | Other |
---|---|---|---|---|---|---|---|
Balance | 7.1 | 0.1 | 0.02 | 0.05 | 0.42 | 0.09 | Sr |
Label | Description of Variable |
---|---|
tc | Target temperature in the cooling channels |
cc | Distance of the cooling channels in the mold from the interface to the casting |
km | Thermal conductivity of the mold material at the considered interface temperature |
cpm | Heat capacity of the mold material at the considered interface temperature |
wg | Width of the gap between casting and mold wall |
kair | Thermal conductivity of air at the calculated temperature in the gap |
cpair | Heat capacity of air at the considered interface temperature |
ac | Number of casts on the coated mold before the test; for tests without coating, a value of 20 casts is used |
kc | Thermal conductivity of the core material at the considered interface temperature |
cpc | Heat capacity of the core material at the considered interface temperature |
cpwc | Heat capacity of the core material at the considered interface temperature normalized to the weight of the core |
Parameter Set | Temperature Control (°C) | Cooling Channel Distance (mm) | Mold Material | Core Material | Age of Coating |
---|---|---|---|---|---|
1 | 300 | 15 | copper | steel | 2 |
2 | 200 | 15 | copper | steel | 3 |
3 | 100 | 15 | copper | steel | 4 |
4 | 30 | 15 | copper | steel | 5 |
5 | 300 | 15 | copper | sand | 6 |
6 | 30 | 15 | copper | sand | 7 |
9 | 300 | 15 | steel | steel | 2 |
13 | 300 | 15 | steel | sand | 6 |
14 | 30 | 15 | steel | sand | 7 |
18 | 200 | 10 | steel | steel | 3 |
19 | 100 | 10 | steel | steel | 4 |
23 | 300 | 15 | copper | steel | 20 |
24 | 200 | 15 | copper | steel | 20 |
25 | 100 | 15 | copper | steel | 20 |
26 | 30 | 15 | copper | steel | 20 |
27 | 300 | 15 | copper | steel | 20 |
32 | 300 | 15 | steel | steel | 2 |
33 | 200 | 15 | steel | steel | 3 |
34 | 100 | 15 | steel | steel | 4 |
35 | 30 | 15 | steel | steel | 5 |
(°C) | 460 | 480 | 500 | 510 | 520 | 530 | 540 |
---|---|---|---|---|---|---|---|
tc | 0.00397 | 8.05 × 10−5 | 9.21 × 10−5 | 0.00638 | 0.00468 | 0.00235 | 0.00228 |
cc | 0.15946 | 0.13673 | 0.13674 | 0.15133 | 0.12693 | 0.11288 | 0.11301 |
km | 0.04582 | 0.86318 | 0.86317 | 0.84228 | 0.86839 | 0.88477 | 0.88464 |
cpm | 0.01923 | 3.49 × 10−7 | - | - | - | - | - |
wg | 0.07403 | - | - | - | - | - | 1.41 × 10−5 |
kair | 0.68357 | - | - | - | - | - | - |
cpair | 0.00769 | - | - | - | - | - | - |
ac | - | - | - | - | - | - | - |
kc | 0.0051 | - | 1.14 × 10−7 | - | 1.18 × 10−7 | - | - |
cpc | - | - | - | - | - | - | - |
cpwc | - | - | - | - | - | - | - |
(°C) | 460 | 480 | 500 | 510 | 520 | 530 | 540 |
---|---|---|---|---|---|---|---|
tc | 0.03315 | 0.00108 | 0.00106 | 0.00016 | 0.00447 | 0.00274 | 0.00325 |
cc | 0.02637 | 0.03179 | 0.03025 | 0.03746 | 0.03395 | 0.03052 | 0.03078 |
km | 0.0006 | 0.01744 | 0.01756 | 0.00817 | 0.0013 | 1.59 × 10−5 | - |
cpm | 0.11193 | - | 0.12014 | 0.09652 | 0.10867 | 0.12018 | 0.07945 |
wg | 0.10746 | 0.07517 | 0.045 | 0.09289 | 0.16115 | 0.17403 | 0.24973 |
kair | 0.003 | 0.02283 | 0.00644 | 0.00107 | 0.01014 | 0.00852 | 0.04854 |
cpair | 0.20356 | 0.00245 | 0.00065 | 0.00965 | 0.01701 | 1.96 × 10−5 | 0.03928 |
ac | 0.42709 | 0.00062 | 0.13448 | 0.14493 | 0.10168 | 0.0622 | 0.03847 |
kc | 0.08677 | 0.84993 | 0.64426 | 0.60903 | 0.56154 | 0.60163 | 0.51035 |
cpc | 4.10 × 10−5 | 0.00013 | - | - | - | - | - |
cpwc | 1.25 × 10−5 | 7.76 × 10−5 | - | - | - | 0.00011 | - |
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Wolff, N.; Zimmermann, G.; Vroomen, U.; Bührig-Polaczek, A. A Statistical Evaluation of the Influence of Different Material and Process Parameters on the Heat Transfer Coefficient in Gravity Die Casting. Metals 2020, 10, 1367. https://doi.org/10.3390/met10101367
Wolff N, Zimmermann G, Vroomen U, Bührig-Polaczek A. A Statistical Evaluation of the Influence of Different Material and Process Parameters on the Heat Transfer Coefficient in Gravity Die Casting. Metals. 2020; 10(10):1367. https://doi.org/10.3390/met10101367
Chicago/Turabian StyleWolff, Nino, Golo Zimmermann, Uwe Vroomen, and Andreas Bührig-Polaczek. 2020. "A Statistical Evaluation of the Influence of Different Material and Process Parameters on the Heat Transfer Coefficient in Gravity Die Casting" Metals 10, no. 10: 1367. https://doi.org/10.3390/met10101367