28.1 Introduction
28.2 Simulation
28.2.1 Geometry
-
(a) Filter position HF: The filter lies horizontally in the runner and is flowed through from top to bottom (falling).
-
(b) Filter position V: The filter stands vertically in the runner.
-
(c) Filter position HR: The filter lies horizontally in the runner and is flowed through from bottom to top (rising).
-
(d) Filter position HFS: The filter is located horizontally below the sprue and the flow is from top to bottom (falling).
28.2.2 Filter
28.2.3 Melt
28.2.4 Particle
Type | Density [g/cm3] | Size [µm] | Percentage [%] | Quantity [number] |
---|---|---|---|---|
Al2O3 (Alumina) | 3.95 | 25 | 45 | 7875 |
35 | 30 | 5250 | ||
45 | 7.5 | 1313 | ||
MgAl2O4 (Spinel) | 3.5 | 45 | 7.5 | 1312 |
55 | 5 | 875 | ||
80 | 5 | 875 |
28.2.5 Further Boundary Conditions
Simulation number | Variables | |||
---|---|---|---|---|
Position filter chamber | Filter length [mm] | Filter porosity [ppi] | Surface roughness (µm) | |
1 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 20 | 1,7 |
2 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 30 | 1,7 |
3 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 20 | 1,7 |
4 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 30 | 1,7 |
5 | HR
A symbol for filter position H R. It lies horizontally with flow from bottom to top.
| 22 | 20 | 1,7 |
6 | HR
A symbol for filter position H R. It lies horizontally with flow from bottom to top.
| 22 | 30 | 1,7 |
7 | HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 22 | 20 | 1,7 |
8 | HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 22 | 30 | 1,7 |
9 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 20 | 7,3 |
10 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 30 | 7,3 |
11 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 20 | 7,3 |
12 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 30 | 7,3 |
13 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 44 | 30 | 1,7 |
28.3 Results of the Simulation
Filter position | 20 ppi efficiency (%) | 30 ppi efficiency (%) | Percentage increase (%) |
---|---|---|---|
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 27.9 | 36.8 | 31.9 |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22.7 | 33.2 | 46.3 |
HR
A symbol for filter position H R. It lies horizontally with flow from bottom to top.
| 23.4 | 29.5 | 26.1 |
HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 20.8 | 33.2 | 59.6 |
28.3.1 Influence of Particle Size on Filtration Efficiency
28.3.2 Influence of Particle Type on Filtration Efficiency
Filter position | Filter porosity [ppi] | Alumina particles 45 µm | Spinel particles 45 µm |
---|---|---|---|
Filtration efficiency [%] | Filtration efficiency [%] | ||
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 20 | 27.9 | 27.7 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 30 | 37.9 | 34.5 |
HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 20 | 19.8 | 19.4 |
HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 30 | 32.8 | 32.9 |
28.3.3 Deposition of Particles in the Filter
Filter plane | |||||||
---|---|---|---|---|---|---|---|
Filter position | Filter porosity [ppi] | 1 | 2 | 3 | |||
Fraction of filtered particles [%] | Δ | Fraction of filtered particles [%] | Δ | Fraction of filtered particles [%] | Δ | ||
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 20 | 44.2 | 0.4 | 31.4 | 0.1 | 24.4 | 0.3 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 30 | 43.8 | 31.5 | 24.7 | |||
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 20 | 35.0 | 0.6 | 36.0 | 1.8 | 29.0 | 1.3 |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 30 | 35.6 | 34.2 | 30.2 |
28.3.4 Influence of the Surface Roughness of the Filter on the Filtration Efficiency
Filter | Filtration efficiency [%] | |||
---|---|---|---|---|
Position | Surface roughness [µm] | Filter porosity [ppi] | Total | Δ |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 1,7 | 20 | 27,9 | −3,1 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 7,3 | 20 | 24,8 | |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 1,7 | 30 | 36,8 | −2,5 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 7,3 | 30 | 34,3 | |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 1,7 | 20 | 22,7 | −1,4 |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 7,3 | 20 | 21,3 | |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 1,7 | 30 | 33,2 | −0,7 |
V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 7,3 | 30 | 32,5 |
28.3.5 Influence of Filter Length on Filtration Efficiency
Filter | Filtration efficiency [%] | |||
---|---|---|---|---|
Position | Filter length [mm] | Filter porosity [ppi] | Total | Δ |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 30 | 36,8 | +13,7 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 44 | 30 | 50,5 |
Filter position | Filter length [mm] | Filter plane | ||
---|---|---|---|---|
1 | 2 | 3 | ||
Fraction of filtered particles [%] | Fraction of filtered particles [%] | Fraction of filtered particles [%] | ||
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 43,8 | 31,5 | 24,7 |
HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 44 | 47,0 | 30,1 | 22,8 |
28.4 Summary of the Simulations
Simulation number | Variables | Filtration efficiency [%] | |||
---|---|---|---|---|---|
Filter position | Filter length [mm] | Filter porosity [ppi] | Surface roughness (µm) | ||
1 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 20 | 1,7 | 27,9 |
2 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 30 | 1,7 | 36,8 |
3 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 20 | 1,7 | 22,7 |
4 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 30 | 1,7 | 33,2 |
5 | HR
A symbol for filter position H R. It lies horizontally with flow from bottom to top.
| 22 | 20 | 1,7 | 23,4 |
6 | HR
A symbol for filter position H R. It lies horizontally with flow from bottom to top.
| 22 | 30 | 1,7 | 29,5 |
7 | HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 22 | 20 | 1,7 | 20,8 |
8 | HFS
A symbol for filter position H F S. The filter is located horizontally below the sprue with flow from top to bottom.
| 22 | 30 | 1,7 | 33,2 |
9 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 20 | 7,3 | 24,8 |
10 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 22 | 30 | 7,3 | 34,3 |
11 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 20 | 7,3 | 21,3 |
12 | V
A symbol for filter position V. The filter stands vertically with flow from left to right.
| 22 | 30 | 7,3 | 32,5 |
13 | HF
A symbol for filter position H F. It lies horizontally with flow from top to bottom.
| 44 | 30 | 1,7 | 50,5 |
28.5 Casting Trials
28.5.1 Geometry
28.5.2 Filter
28.5.3 Melt with Foreign Particles
28.5.4 Execution of the Casting Trials
28.5.5 Metallographic Examinations of the Filter
28.6 Results of the Casting Trials
28.7 Conclusion
-
The highest filtration efficiency is achieved when the filter is placed horizontally in the runner and the flow is from top to bottom.
-
In all filter positions where the filter lies horizontally in the runner, deposition of inclusions occurs primarily in the first third of the filter. If the filter is positioned vertically in the runner, deposition tends to occur more uniformly along the length of the filter. This could also be proven with real casting trials.
-
The simulations have shown that the roughness of the filter surface has a minor influence on the filtration efficiency. The filtration efficiency decreases slightly when the roughness of the filter surface increases.
-
By doubling the filter length from 22 to 44 mm, a 37% increase in filtration efficiency can be achieved for Al2O3 particles with a size of 20 µm. Nevertheless, 47% of the particles are deposited in the first 15 mm of the 44 mm long filter, so that the use of longer filters is not advised from a foundry technology point of view [17].