How to reduce aluminum adhesion in LPDC mold release agent selection and spraying?
The release agent forms an isolation film on the surface of the mold cavity, which is a key consumable solution to suppress aluminum liquid welding and reduce casting strain.
1、 The influence of spray thickness and dilution ratio of release agent on isolation effect
The conventional dilution ratio of water-based die-casting release agent is 1:8 to 1:12, and the spray dry film thickness is controlled at 8-15 μ m. Under this parameter, the isolation is stable, and the aluminum adhesion defect rate can be controlled within 3%. The dilution concentration is too high, the film layer is too thick, and the erosion residue accumulates in the exhaust groove, inducing porosity; Excessive dilution leads to discontinuous film layer, and the probability of local welding and aluminum adhesion increases to 26%.
The spraying distance is controlled at 200-300mm, the atomization pressure is 0.2-0.3MPa, the atomization is sufficient, the film layer is uniform, and local accumulation is reduced.
The optimal spraying range for the mold cavity temperature is 220-320 ℃. When the temperature is below 180 ℃, moisture cannot quickly vaporize and the mold cavity accumulates water; When the temperature is above 380 ℃, the release agent is instantly burned and cannot form a film.
Oil based release agents have stronger isolation capabilities, but they emit large amounts of smoke. Due to strict environmental regulations in Europe, their use is limited and they are mostly used for small-scale trial production.
Xinfeng Machinery synchronously provides reference parameters for demoulding agent spraying during the trial stage, facilitating customer debugging.
2、 Spraying strategies corresponding to different casting structures
The wheel hub has a large area of smooth cavity, and uniform thin spraying is used, with a focus on spraying the rounded corners of the spokes and the hot spot area near the sprue.
The deep inner wall of the motor housing is prone to material accumulation, and segmented spraying is used to ensure film formation at the bottom of the inner wall and avoid aluminum sticking and tearing at the bottom.
Thin walled heat dissipation ribs have narrow joints and higher atomization requirements to prevent mold release agents from accumulating and blocking the joints.
The thick and large hot spot position and high temperature of the aluminum liquid make the isolation film more prone to erosion, so it is necessary to increase the spraying frequency appropriately.
3、 Selection differences brought by environmental regulations in overseas markets
The environmental control in Southeast Asia is loose, and both water-based and oil-based release agents are used. Customers prioritize the unit price of consumables.
The North American market has control over VOC emissions, and the use of oil-based release agents is restricted. The vast majority of factories uniformly use low VOC water-based models.
The EU REACH regulation restricts certain additives, and the formulation of release agents needs to comply with certification. Import customs clearance will verify MSDS documents.
There are significant differences in ventilation conditions among factories in the Middle East, and low smoke water-based release agents are given priority to reduce the accumulation of smoke in the workshop.
4、 Chain defects caused by improper spraying
Excessive accumulation of release agent, high-temperature decomposition produces gas, which is wrapped by aluminum liquid to form pores. The root cause of many pore defects is not the exhaust groove, but the release agent.
Insufficient spraying frequency, failure of isolation film at the hot spot position, tearing of aluminum welding cavity and casting surface, and damage to the cavity surface caused by aluminum erosion.
Poor atomization, large droplets adhering to the mold cavity, water vaporization and explosion, forming pitting and bubble pits on the surface of the casting.
5、 Long tail traffic layout ideas
Release agents and adhesive aluminum belong to the category of workshop operation and maintenance search, and the target audience is on-site process workers and production line supervisors.
keywords LPDC mold release agent spraying parameter、low pressure casting sticking aluminum；
Problem class: Best solution ratio for water-based LPDC release agent;
Comparison class: Oil based vs Water based Release Agent for LPDC die.
Suitable for operation and maintenance guide blog posts, undertaking production fault retrieval traffic.
6、 Common misconceptions in the industry
Misconception 1: The more mold release agent sprayed, the better. Excessive dosage can produce gas, block exhaust, and significantly increase porosity defects.
Misconception 2: The higher the temperature, the more suitable it is for spraying. If the mold cavity temperature is too high, the release agent will burn out instantly and cannot form an isolation film.
Misconception 3: Oil based release agents are always more effective than water-based ones. Environmental regulations in Europe and America restrict oil based release agents, and there are obvious smoke hazards.
FAQ
Q: What is the standard dilution ratio for water-based release agents?
A：1:8~1:12， Fine tune according to cavity temperature and casting structure.
Q: What is the optimal spraying temperature range for the mold cavity?
A: 220-320 ℃, ensuring stable film formation and rapid evaporation of moisture.
Q: What defects can excessive release agent cause?
A: The decomposition of the medicine produces gas, forming pores that block the exhaust duct.
Q: What are the difficulties in spraying deep tube shells?
A: Insufficient atomization at the bottom of the inner wall can easily lead to local film breakage and aluminum adhesion.
Q: What are the EU's regulations on release agents?
A: Need to comply with REACH, provide MSDS, and restrict harmful additives.
Q: What is the recommended setting for atomization pressure?
A：0.2–0.3MPa， Balancing atomization fineness and spraying efficiency.
Q: Is it useful to directly thicken and spray after sticking aluminum?
A: Short term improvement, prioritize investigating the temperature of the mold cavity and the wear status of the nitride layer.
Q: Where are the key areas for spraying wheel hub molds?
A: Hot spots are concentrated near the sprue and the rounded corners of the spokes.
