How to avoid corrosion and deformation of the mold cavity during the storage and long-term sealing of LPDC molds?
The shutdown and sealing of molds is a common scenario encountered in cross-border projects, and improper storage can cause corrosion and stress deformation of the mold cavity.
1、 Quantitative standards for cleaning and rust prevention treatment before sealing
Before production shutdown and sealing, the mold cavity, exhaust groove, and top rod gap must be cleaned of aluminum shavings and release agent residue. The residual release agent salt can induce pitting corrosion in humid environments, and about 51% of long-term mold damage comes from residual pollutants.
The anti rust coating is made of high-temperature resistant mold specific anti rust oil, with a film thickness controlled at 15-25 μ m. The thin coating is evenly applied, and the thick oil layer is difficult to clean when the mold is opened again, which can easily lead to porosity defects in the mold cavity.
Sealed packaging combined with desiccants, the humidity inside the packaging box is controlled at 40% -60% RH, and the environmental humidity is higher than 70% RH, which increases the risk of corrosion of H13 steel by four times.
The movable surfaces of the top rod and slider are separately coated with anti rust grease to ensure that the sliding pair does not get stuck. The slider needs to be locked and fixed to prevent self weight sliding and collision with the mold cavity.
Xinfeng Machinery provides English version of mold sealing and unpacking instructions simultaneously during delivery, which is suitable for overseas customer warehouse management.
2、 Storage support and anti deformation measures
The mold must use equally high cushion blocks to support the parting surface, with the cushion blocks 80-120mm away from the edge of the mold cavity. It is forbidden to directly place the mold cavity flat and let it hang in the air. The self weight will cause the template to bend and deform, with a deformation amount of 0.03-0.06mm.
The stacking layer of large LPDC molds should not exceed 2 layers, and the weight of the upper mold will squeeze the lower template, causing deformation of the positioning pin and guide column.
The optimal temperature for long-term storage is 10-30 ℃, with temperature fluctuations exceeding ± 15 ℃. The material undergoes repeated thermal expansion and contraction, resulting in slow release of residual stress and drift in cavity size.
3、 Differentiated solutions for storage environments in different overseas regions
Due to the prolonged high humidity during the rainy season in Southeast Asia, it is necessary to strengthen sealing and drying agents. Some customers may choose additional gas-phase rust proof bags.
Due to the large temperature difference in inland warehouses in North America, priority should be given to storing in temperature controlled warehouses to reduce stress release and deformation caused by temperature fluctuations.
The European standardized warehouse has a complete humidity control system, and conventional rust proof packaging can meet the sealing requirements for 6-12 months.
The temperature difference between day and night in the Middle East warehouse is extremely large, and it is dry but dusty. It is important to focus on dust-proof sealing to prevent sand particles from entering the mating surface and scratching.
4、 Inspection items before unpacking and resuming production
After opening the box, clean the rust proof oil first, use specialized cleaning agents, prohibit strong corrosive solvents, and avoid corroding the nitride layer.
Check the flexibility of the guide column and slider movement, confirm that there is no jamming, retest the key dimensions of the mold cavity, and confirm that there is no deformation.
Test run the empty mold opening and closing machine 30-50 times, confirm that the ejection and core pulling actions are synchronized, and then put it into aluminum liquid trial production.
5、 Long tail traffic layout ideas
Sealing, rust prevention, and warehousing belong to the long tail keywords of mold maintenance, which are suitable for the operation and maintenance of existing customers.
Keywords: LPDC mold long term storage protection, how to prevent casting mold rust;
Problem class: Rust prevention for H13 LPDC die during storage;
Tutorial class: LPDC mold pre storage checklist.
Placed in the maintenance manual section, it undertakes the retrieval traffic of overseas factory mold management.
6、 Common misconceptions in the industry
Misconception 1: Long term storage can be achieved by applying thick anti rust oil. If the oil film is too thick, it is difficult to clean and can cause gas production in the mold cavity during production, resulting in porosity defects.
Myth 2: The mold is directly stored on the ground, the cavity is suspended without support, the self weight of the template is bent, and the key dimensions are permanently offset.
Misconception 3: After sealing, there is no need to check regularly. If the desiccant fails in a high humidity environment, corrosion will still occur.
FAQ
Q: What is the recommended humidity range for mold sealing?
A：40%–60% RH， The risk of corrosion significantly increases above 70%.
Q: What is the recommended film thickness range for rust proof oil?
A：15–25μm， Balancing the anti rust effect and the difficulty of resuming production and cleaning.
Q: How to arrange the mold support pad?
A: Distance from the edge of the cavity is 80-120mm, with equal height support to avoid suspension.
Q: What is the upper limit for stacking large molds?
A: No more than 2 layers to prevent deformation of the lower formwork under pressure.
Q: What are the key points of Southeast Asian rainy season storage?
A: Gas phase rust proof bag+sufficient desiccant to isolate humid air.
Q: What is the first step in resuming production and unboxing?
A: Clean the rust proof layer, retest key dimensions, and conduct an empty mold trial run.
Q: Where is the key protection for warehouses with large sandstorms?
A: The precise matching positions of sliders, guide columns, exhaust slots, etc. are dust-proof.
Q: Why does residual release agent induce rust?
A: Salt containing residues form electrochemical pitting corrosion in humid environments.
