Analysis of Erosion Damage Mechanism of Low Pressure Die Casting Mold (LPDC) Gate Sleeve | Maintenance Plan for Gravity Casting Mold Gate Sleeve
Low pressure die-casting mold (LPDC) sprue sleeve erosion damage, 64% of which is caused by the synergistic effect of high-speed aluminum liquid erosion and melting, shortening the overall service life of the mold.
The flow rate of aluminum liquid passing through the sprue sleeve is greater than 480mm/s, resulting in a significant increase in surface erosion shear force and a 71% increase in wear rate of the nitride layer.
The coaxial deviation between the sprue sleeve and the riser is greater than 1.6mm, and the aluminum flow continues to impact the inner wall of one side, doubling the local melting rate.
The sprue sleeve is made of ordinary H13 without nitriding. After continuous casting for 1600 cycles, obvious grooves appear on the inner wall, and after nitriding, it can reach 5200 cycles.
The polishing pattern on the inner wall of the sprue sleeve is perpendicular to the flow direction of the aluminum liquid, and the adhesion tendency of the aluminum liquid is increased by 37%. The adhesive aluminum layer is repeatedly peeled off and takes away the substrate material.
The distance between the cooling water channel of the sprue sleeve and the inner wall is less than 9mm, and the local mold temperature is too high. The infiltration and erosion effect of aluminum liquid is enhanced, accelerating the damage of the mold cavity.
Low pressure die-casting molds (LPDC) and counter pressure casting molds (CPC) gate sleeves are subjected to continuous aluminum liquid erosion, with a higher loss rate than gravity casting mold gate sleeves. Motorcycle wheel hub casting molds, wheel hub differential pressure casting molds, wheel hub low-pressure casting molds, structural component casting molds, aluminum alloy wheel hub molds, aluminum casting forming molds, low-pressure casting tooling molds, and sprue sleeves are vulnerable inserts that can be replaced separately without the need to scrap the entire set of molds. Zhejiang Xinfeng Machinery statistics on mold maintenance cases show that the sprue sleeve is the most frequently replaced insert. Many customers wait until the erosion groove is very deep before replacing it, which accumulates aluminum slag in the groove and causes burrs every time the mold is opened, increasing the polishing cost. Some manufacturers have designed the sprue sleeve to be a one-piece non removable structure, which can only be welded and repaired as a whole after partial damage, increasing maintenance costs by three times and extending delivery cycles. The initial processing cost of the replaceable sleeve structure has increased by 14%, but the maintenance cost has significantly decreased in the later stage, making it more suitable for long-term mass production customers overseas. The rounded corner R5 or above at the entrance of the sprue sleeve can disperse the direct impact of aluminum liquid, reduce local flow velocity peaks, and decrease erosion speed by 40%. If the iron impurity content in the aluminum liquid is higher than 0.18%, it will reduce the activation energy of aluminum liquid infiltration, intensify the melting corrosion of the sprue sleeve, and the control of aluminum alloy raw materials will also affect the service life of the insert. Many overseas foundries do not purchase spare parts for sprue sleeves separately, and the shipping cycle for spare parts is long. Damaged sprue sleeves directly cause the entire production line to shut down. On B2B platforms, inquiries for sprue sleeve spare parts are scattered and suitable for layout together with supporting mold content to capture the flow of spare parts procurement.
FAQ
1. Question: What is the alert threshold for the flow rate of aluminum liquid in the sprue sleeve?
Answer: If the flow rate of aluminum liquid is greater than 480mm/s, the erosion and wear will rapidly intensify.
2. Question: What is the upper limit of coaxial deviation between the sprue sleeve and the riser?
Answer: The coaxial deviation control for docking should not exceed 1.6mm to avoid bias current.
3. Question: What are the regular service mold numbers for non nitrided H13 sprue sleeves?
Answer: Non nitriding treatment generally results in grooves after about 1600 cycles.
4. Question: What is the direction for optimizing the polishing pattern on the inner wall of the sprue sleeve?
Answer: The pattern follows the flow of aluminum liquid, reducing the probability of aluminum liquid adhesion.
5. Question: What is the minimum distance between the sprue sleeve waterway and the inner wall?
Answer: The distance between the cooling water circuit and the inner wall should not be less than 9mm.
6. Question: What is the recommended fillet value for the inlet of the sprue sleeve?
Answer: Entrance rounded corner R5 or above, dispersed aluminum liquid impact.
