Leakages of Die Casting Parts
Features: Water or gas leakages occur on the die casting part after testing.
Causes of leakages
1. The boost pressure is insufficient.
2. The design of the pouring system is unreasonable.
(1) Being far away from the leakage area make internal quality poor.
(2) The metal flow is not well fused, resulting in cold shuts.
(3) The cross-sectional area of the inner gate is small. The pressure transfer is not well and the distal end forms gas porosity or shrinkage porosity.
3. Alloys are not selected properly and fluidity is poor, which is not suitable for die casting production.
4. Partial defects such as gas porosity, shrinkage porosity and cold shuts appear due to poor exhaust.
5. The die casting design is unreasonable. The wall thickness is uneven or too thick and there are hot junctions, resulting in defects such as gas porosity, shrinkage porosity and cracks and seriously affecting the air tightness.
6. The die casting is processed much, destroying the dense oxidation layer on the surface or thinning the wall thickness, especially the double sided processing part.
7. The alloy melting temperature is too high. The holding time is long, and the wall thickness is prone to shrinkage porosity and shrinkage cracks during die casting.
8. The paint has a large amount of gas and is easy to produce gas porosity.
9. Failures occur for pressure inspection equipment.
10. The sealing surface is damaged or does not meet the roughness requirements. For example, the machined surface has scratches, indentations, etc., or roughness of the non-machined sealing groove is poor due to cracks.
11. The deformation of the die casting causes the sealing surface to warp.
12. Aluminum sticks to the surface of the product, and the dense layer on the surface is destroyed.
Measures
1. The pressure at the distal end of die casting or wall thickness part is not insufficient, increasing the specific pressure.
2. The pouring system can be improved reasonably according to simulation filling or actual sample debugging analysis.
3. Choose a good alloy.
4. In the hot mold stage, analyze whether there are gas entrainment and poor alloy flow fusion in the partial die casting part, and reasonably add a slag bag and an exhaust duct.
5. Use X-ray flaw detection to find the hot junction. If the heat junction is indeed a leakage point, you can negotiate with the customer's engineer to change the structure and reduce the wall thickness. In addition, a secondary extrusion process can be used to solve the leakage at the hot junction.
6. Try to avoid processing or use the smallest processing allowance as much as possible.
7. Use the X-ray flaw detection to check internal quality of die castings. Lower the melting temperature appropriately.
8. Use the X-ray detection to check the die casting quality. Use paint with low gas release volumes.
9. Use qualified die castings to identify pressure test equipment. Maintain and inspect equipment.
10. The pressure test should be performed. Strengthen process protection and repair molds in time.
11. Flatness inspection should be performed. To control the production process, the holding time must be sufficient. At the same time, prevent squeezing, crushing and falling of the product during the process operation.
12. Strictly control the sticking of aluminum on the product surface. Adjust the cooling water to control the mold temperature. Adjust the spray position and polish the surface of the mold.
Causes of leakages
1. The boost pressure is insufficient.
2. The design of the pouring system is unreasonable.
(1) Being far away from the leakage area make internal quality poor.
(2) The metal flow is not well fused, resulting in cold shuts.
(3) The cross-sectional area of the inner gate is small. The pressure transfer is not well and the distal end forms gas porosity or shrinkage porosity.
3. Alloys are not selected properly and fluidity is poor, which is not suitable for die casting production.
4. Partial defects such as gas porosity, shrinkage porosity and cold shuts appear due to poor exhaust.
5. The die casting design is unreasonable. The wall thickness is uneven or too thick and there are hot junctions, resulting in defects such as gas porosity, shrinkage porosity and cracks and seriously affecting the air tightness.
6. The die casting is processed much, destroying the dense oxidation layer on the surface or thinning the wall thickness, especially the double sided processing part.
7. The alloy melting temperature is too high. The holding time is long, and the wall thickness is prone to shrinkage porosity and shrinkage cracks during die casting.
8. The paint has a large amount of gas and is easy to produce gas porosity.
9. Failures occur for pressure inspection equipment.
10. The sealing surface is damaged or does not meet the roughness requirements. For example, the machined surface has scratches, indentations, etc., or roughness of the non-machined sealing groove is poor due to cracks.
11. The deformation of the die casting causes the sealing surface to warp.
12. Aluminum sticks to the surface of the product, and the dense layer on the surface is destroyed.
Measures
1. The pressure at the distal end of die casting or wall thickness part is not insufficient, increasing the specific pressure.
2. The pouring system can be improved reasonably according to simulation filling or actual sample debugging analysis.
3. Choose a good alloy.
4. In the hot mold stage, analyze whether there are gas entrainment and poor alloy flow fusion in the partial die casting part, and reasonably add a slag bag and an exhaust duct.
5. Use X-ray flaw detection to find the hot junction. If the heat junction is indeed a leakage point, you can negotiate with the customer's engineer to change the structure and reduce the wall thickness. In addition, a secondary extrusion process can be used to solve the leakage at the hot junction.
6. Try to avoid processing or use the smallest processing allowance as much as possible.
7. Use the X-ray flaw detection to check internal quality of die castings. Lower the melting temperature appropriately.
8. Use the X-ray detection to check the die casting quality. Use paint with low gas release volumes.
9. Use qualified die castings to identify pressure test equipment. Maintain and inspect equipment.
10. The pressure test should be performed. Strengthen process protection and repair molds in time.
11. Flatness inspection should be performed. To control the production process, the holding time must be sufficient. At the same time, prevent squeezing, crushing and falling of the product during the process operation.
12. Strictly control the sticking of aluminum on the product surface. Adjust the cooling water to control the mold temperature. Adjust the spray position and polish the surface of the mold.
