Формы для литья под низким давлением (LPDC)
Формы для гравитационного литья
Формы для литья под противодавлением (CPC)
Structural Parts Casting Mold
Форма для литья ступиц мотоциклетных колес
Форма для литья под давлением ступицы колеса с диф
Форма для литья под действием силы тяжести ступицы
Форма для литья под низким давлением ступицы колес
Full process investigation of porosity in aluminum alloy die-casting parts, from melting, mold, machine to process
Pores are the most frequent defect in die-casting, with scattered sources. Many engineers only focus on the exhaust of the mold, ignoring upstream melting and injection parameters. Xinfeng Machinery has established a complete investigation chain.
1、 Category 1: Dissolved hydrogen pores (melting end)
The hydrogen content in the aluminum liquid exceeds the standard, and hydrogen gas is released during solidification. The inner walls of the pores are smooth, circular, and dispersed. Causes: Moisture in the recycled material, insufficient degassing, moisture absorption in the insulation furnace, and water in the pouring spoon. RPT depressurization samples can quickly determine whether hydrogen exceeds the standard, which is the first step in troubleshooting. The sensitivity of A356 wheel hub components to hydrogen gas holes is much higher than that of ADC12 ordinary shell.
2、 The second category: Rolling air holes (injection and mold)
Aluminum liquid is filled with air at high speed, and the shape of the pores is irregular and distributed along the direction of the material flow. Causes: Unreasonable sprue design, excessive sprue speed, blocked exhaust groove, insufficient overflow groove capacity, and disordered filling timing. CAE filling simulation can predict areas with high incidence of gas entrapment. The position of the alloy wheel mouth spokes is prone to air entrapment.
3、 The third category: Gas producing pores (mold release agents, lubricants)
Release agent and ejector pin lubricant decompose and vaporize at high temperatures, accompanied by carbon deposition and blackening of pores. Features: Concentrated in areas with excessive spraying, appearing in batches at the same location. Insufficient blowing and excessive spraying are the most common causes.
4、 Standardize the inspection sequence to avoid blindly changing the mold
First, conduct RPT sample hydrogen testing → check spraying and blowing → verify injection speed and filling timing → check if the exhaust groove is blocked with silicon slag → evaluate the sprue and overflow capacity, and finally modify the mold structure. A large number of customers directly changed the mold, only to find that the aluminum liquid degassing failed, wasting the cost of mold modification.
5、 Logical differences in porosity during low-pressure casting
Low pressure casting has a gentle filling speed and low risk of gas entrapment; Most of the air holes come from hydrogen absorption in the insulation furnace and leakage in the riser, which is different from the mechanism of high-pressure die-casting gas entrapment. Google's "aluminum die casting porosity troubleshooting checklist" is a high-frequency search term for overseas quality engineers.
FAQ
How to distinguish between hydrogen gas pores and rolled gas pores on X-ray?
Hydrogen pores are round and isolated; The shape of the air pockets is irregular and continuous.
How long is the cleaning cycle for the exhaust duct?
ADC12 has a lot of silicon slag, and the exhaust needs to be checked and cleaned every few hundred molds.
Can enlarging the overflow groove solve the problem of hydrogen porosity?
No, the overflow tank only solves the problem of air entrainment and cannot remove dissolved hydrogen.
4. Does the faster the injection speed, the more air holes there are?
Exceeding the critical speed, the vapor rises sharply; The speed is too low and the filling is poor.
Can pores be covered by infiltration?
Just sealing the leakage, the hole is still visible under X-ray.
6. What is the priority to check for repeated air holes at the same location?
Prioritize checking spraying and blowing, then checking exhaust.
7. What are the main sources of low-pressure wheel hub air holes?
Aluminum liquid hydrogen absorption and liquid lifting tube sealing failure.
Can the filter plate solve the problem of air holes?
The filter plate removes impurities and cannot directly remove dissolved hydrogen.
Формы для литья под низким давлением (LPDC)
Формы для гравитационного литья
Формы для литья под противодавлением (CPC)
Формы для литья конструкционных деталей
Форма для литья ступицы колеса мотоцикла
Форма для литья ступицы колеса под дифференциальным давлением
Форма для гравитационного литья ступицы колеса
Форма для литья ступицы колеса под низким давлением
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