The thickness of the cake is too poor, and the product is easy to form defects such as under-casting, cold separation (soup back), pores, blackening, lack of meat in the gate layer, looseness, shrinkage, and degradation of product mechanical properties.
The size specification of the thickness of the cake
1. In general, the thickness of the cake is: Φ50 is 16±5mm, Φ60 is 18±5mm, Φ70 is 20±5mm, Φ80 is 22±5mm, Φ90 is 24±5mm, and Φ100 is 26±5mm.
2. When the pore requirements of the product are relatively strict, the thickness of the cake should be appropriately thickened by 2～5mm, namely: Φ50 is 20±5mm, Φ60 is 22±5mm, and Φ70 is 25±5mm.
3. When the sprue sleeve and shunt cone of the mold does not need to be cooled by water, the thickness of the cake should be appropriately reduced by 2～3mm, namely: Φ50 is 4±5mm, Ф60 is 16±5mm, Ф70 is 18±5mm, etc.The material composition of the material cake is composed of aluminum water with lower temperature around the material cylinder, poor fluidity, impurities poured into the surface of the aluminum water in the press chamber, oxide scale, and a part of alloy with good high-temperature fluidity. The high-temperature molten aluminum has better fluidity and generally flows at the front; the molten aluminum with lower temperature and poor fluidity is at the back.
The effect of too thin cake thickness on product quality. The cake is too thin. There is no high temperature, good fluidity, and flowable molten aluminum in the cake, and there is no molten aluminum that can transfer pressure to the cavity. Products are prone to defects such as under-casting, cold separation, pores, blackening, porosity, shrinkage, and degradation of product mechanical properties.
The reasons are as follows:
1. The molten aluminum in the cavity cannot accept the pressure of injection and pressurization, and the molten aluminum cannot be crystallized under high pressure, and a large amount of fine internal grain structure is not formed. The internal structure of the product is coarse and loose, the structure is not dense, the mechanical strength is low, and it is easy to break.
2. The aluminum water in the runner cannot be pressed into the cavity for feeding, and the aluminum water in the cavity cannot be solidified and contracted under pressure. The thicker part of the product cannot receive pressure when it solidifies and shrinks, and shrinkage and porosity are prone to appear, which increases the porosity of the product.
3. The molten aluminum in the cavity is not solidified under pressure, and the hydrogen precipitated when the molten aluminum is cooled and solidified will expand without pressure and form larger pores.
4. If the material cake is too thin due to too little pouring amount when the aluminum water is not filled with the runner and the high-speed injection is started, the gas in the runner and cavity is not well removed, and the product is easy to form pores, suffocation, and surface Defects such as soup back (cold compartment) and blackening. If the thickness of the cake is too thin due to the flying material and the pressure is lost, the product will have defects such as pores, looseness, shrinkage, and decreased mechanical properties of the product.the adverse effects of too thick cake thickness
1. Waste aluminum melt, increase the number of recycled materials and increase material loss.
2. The cake is easy to burst and explode, one is to hurt people, and the other is to fly out of molten aluminum and stick to the mold or product.
3. The high-speed die-casting starts after part of the molten aluminum has flowed into the cavity at low speed. The molten aluminum that first flows into the cavity at low speed will be cooled to form a soup and pattern.
4. The molten aluminum flowing into the inner gate at low speed will be cooled and solidified first, and these materials that have cooled and solidified first will block the inner gate and affect the filling. The material that is cooled and solidified at the inner gate will layer with the high-speed filling product, and the fracture will be bright after trimming, and the product will lack meat.
Therefore, every detail of high-quality die-casting products must be strictly observed.