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Aluminum alloy die-casting mold damage analysis

In aluminum alloy die casting production, mold damage is the most often see split lines, craze. Stress is the first reason of cause mould damage.
 
In the process of die casting production
1 mold temperature
Mould in prenatal should be preheated to a certainty temperature, otherwise when chilling during high temperature liquid metal filling and incur mould inside layer temperature gradient increases, thermal stress, cracks make mould appearance, even cracking.
From time to time, in the process of producing, mould when the mould temperature overheat, incidental sticky mold, moving parts out spirit damage incur mould appearance.
Should set up the cooling temperature control system, adhere to mold task temperature within the inevitable limitations.
2 alloy filling
Metal liquid with high pressure, high speed filling, is bound to impact to mold change drastically and scour, therefore mechanical stress and thermal stress. In the process of impact, the metal, impurities, gas will with mould appearance in complex chemical effect, and accelerate erosion and the occurrence of cracks. When the liquid metal is gas, low pressure area in the cavity expansion first, when the gas pressure, blasting introversion, pull out of the cavity surface of the metal particle and formation damage, cracks occur due to cavitation.
3 mold opening mold
In core pulling, the process of open mould, when some components deformation will occur to mechanical stress.
4 produce process
In each produce aluminium alloy die casting process, because the liquid metal mould and the heat exchange between the cyclical temperature change in the mould appearance, provoking periodic thermal expansion and shorten the periodic thermal stress. Such as casting mold appearance due to heating by compressive stress, and open mold ejection after casting, mold appearance a tensile stress because it is cool. When the alternating stress repeated rebirth, make the mold is more and more big, the internal accumulation of stress when the stress beyond the data falters, limit, mould crack appearance
 
Second, the blank forging problem
1 some mould only produced the hundreds appeared split lines, and the crack to carry out soon. Capable of guaranteeing the appearance size, only when is forging and steel of the dendritic crystal, mixed carbide, loose defects such as shrinkage cavity, bubbles stretched along the processing method is extended, streamline, the streamline final quenching distortion and cracking in the future, in the process of the use of effect has enormous influence on the tendency.
2 at the end of every car, milling, planing, etc processing occurs when cutting stress, the stress can be offset through the center of annealing.
3 hardened steel grinding grinding stress, friction heat during grinding and softening, decarburization layer, decreases the intensity of heat falters, easy cause cracking, early crack. Of H13 steel after fine grinding, tolerated heated to 510-570 ℃, to one hour per 25 mm insulation thickness to eliminate stress annealing.
4 edm stress. Mould appearance in a layer of enrichment of electrode and the dielectric element of white layer of hard and brittle, the layer itself will have crack, stress. Electrical discharge machining in high frequency should be adopted, to minimize the white layer, required polishing method to remove, and tempering treatment, tempering at level 3 tempering temperature.
 
 
3. Die disposal process
Heat treatment of inappropriate and will incur mould cracking and scrapped prematurely, special is only use conditioning, not for quenching, nitriding process for appearance, in die casting for thousands of times will represent physical crack and craze.
Steel quenching stress, is in the process of the cooling of the thermal stress and phase transformation of the organization stress superposition of the consequences of quenching stress is the cause of formation of shape, craze, solid required temper to eliminate stress.
In the process of mould processing and manufacturing
1 blank forging quality problems
Some mould only produced the hundreds appeared crack, and crack in soon. Capable of guaranteeing the appearance size, only when is forging and steel of the dendritic crystal, mixed carbide, loose defects such as shrinkage cavity, bubbles stretched along the processing method is extended, streamline, the streamline final quenching distortion and cracking in the future, in the process of the use of effect has enormous influence on the tendency.
2 at the end of every car, milling, planing, etc processing occurs when cutting stress, the stress can be offset through the center of annealing.
3 hardened steel grinding grinding stress, friction heat during grinding and softening, decarburization layer, decreases the intensity of heat falters, easy cause cracking, early crack. Of H13 steel after fine grinding, tolerated heated to 510-570 ℃, to one hour per 25 mm insulation thickness to eliminate stress annealing.
4 edm stress. Mould appearance in a layer of enrichment of electrode and the dielectric element of white layer of hard and brittle, the layer itself will have crack, stress. Electrical discharge machining in high frequency should be adopted, to minimize the white layer, required polishing method to remove, and tempering treatment, tempering at level 3 tempering temperature.

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Phone:0512-52617088

Company:CHANGSHU PUJIANG MACHINERY CO.,LTD.

Address:Maoqiao supporting area, yushan industrial park, changshu city, jiangsu province

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CHANGSHU PUJIANG MACHINERY CO.,LTD.
Add:Maoqiao supporting area, yushan industrial park, changshu city, jiangsu province
Pho:0512-52617088
Mob:18962361550
Fax:0512-52617088-8688

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