The problems in aluminum alloy die casting



Causes of possible problems in aluminum alloy die casting are analyzed as follows:

The problems in aluminum alloy die casting

Causes of possible problems in aluminum alloy die casting are analyzed as follows:

1, geometric shortcomings: die casting appearance, specifications and design need to be offset; Gauge deviation, tensile strain, deformation, etc.

Surface defects: the appearance of the poem is not good, with lines, air marks, cold separation, spot, lack of flesh, raw edges, shrinkage marks, contusions, etc.

Internal structural shortcomings: air vent, shrinkage, casting defects, cracks, mixed, internal structural mechanism, physical properties do not meet the requirements.

2. Factors

(1) Die casting machine causes: the characteristics of die casting machine, the kinetic energy provided can not meet the required injection standards: injection force, injection rate, clamping force is enough. The selection and control of die casting process indicators are suitable, including working pressure, speed, time, stroke stroke, etc.

(2) Caused by die casting mold

Stamping die: die design, gating system specifications and parts, small chain and reasonable layout, refrigeration system.

Mold manufacturing: mold surface roughness, dimensional accuracy, strength.

Mold application: temperature control, surface cleaning, maintenance.

(3) die casting design scheme

Die casting thickness, mold Angle, drawing inclination, hot joint, deep concave, etc.

(4) Caused by actual operation of die casting

Aluminum alloy casting environment temperature, smelting environment temperature, construction paint painting amount and actual operation, production time, etc.

(5) caused by aluminum alloy material

Ingredients of raw materials and return charges, cleanliness level, preparation, smelting and processing technology, etc. The incorrectness of any of the above elements may cause defects.

Can be directly discernible: the surface quality of the workpiece can be analyzed with the eyes, for the lines, scratches, concave, deformation, cold separation, fading, stains and so on can be visualized, can also be used to magnify the magnifying glass to about 5 times larger for detection.

The important technical properties of aluminum alloy die casting steel are as follows:

1. High resistance to fire and gas, heat and cold fatigue

The die-casting die of aluminum alloy produced continuously in large quantities should always maintain high toughness under certain conditions, and do not stick to the die, and do not produce oxide layer.

Therefore, the mold should have good oxidation resistance and tempering stability. The surface layer of aluminum alloy die-casting mold is constantly heated and cooled, continuously swelling and closing, forming alternating changes of internal stress, exceeding the elastic limit of the mold steel, constantly plastic deformation, resulting in thermal fatigue.

2. It has sufficient compressive strength, strength, plasticity and temperature resistance

Aluminum alloy die casting mold is very easy to deform and even crack because of the high temperature, high voltage and internal stress when the molten metal is injected. Therefore, the die material should have sufficient high temperature strength ductility, high toughness and temperature resistance at the working environment temperature.

3. Good heat transfer

Aluminum alloy die casting mold must have good heat transfer performance to ensure the long-term use of other characteristics in the high temperature environment of 600-700℃.

4. Excellent damage resistance to molten metal

With the replacement of imported die casting machine equipment, the working pressure of die casting has increased. From low voltage 20-30mpa to high pressure 150-500mpa, continuous high temperature and high pressure casting will also produce obvious melting damage, and the mold should have more resistance.

Therefore, the die steel should have relatively high temperature compressive strength, little attraction to molten metal, indicating that the surface roughness of the die is small, there is a moderate mold air oxidation, nitride treatment layer and other protective layer, no decarbonization layer.