Die Casting Process Introduction

The setting and adjustment of the process parameters in the die-casting production directly affects the quality of the product. A parameter may cause multiple defects in the product, and the same product of the same defect may be related to a number of parameters, requiring in the test die casting production to carefully analyze the changes in process parameters on the impact of casting molding. Die-casting production enterprises are usually responsible for the design and adjustment of the machine’s process parameters.

In this paper, a die-casting machine, for example, that the main process parameters of die casting production and adjustment technology:

(1) shot time: filling the length of time with the casting wall is proportional to. For the larger quality of the casting, injection speed (shot speed) is slow, the required filling time may be appropriate to increase, generally more than 2s. At the rapid pressure injection rate (shot two speed), the punch movement time is equal to the filling time.

(2) open mode (type) time: open mode is generally more than 2s. When the die wall thickness is thin, the mold opening time is longer; the mold is more complex than the simple mold mold opening time is longer. At the beginning of the adjustment, the mold opening time can be slightly longer; and then shortened.

Note: the machine work program for the first open mode, after the opening of security doors, to prevent incomplete cooling castings splash wounding.

(3) out of the delay time: to ensure that the product is fully solidified molding, and non-stick mold under the premise of minimizing the extension of the delay time, generally more than 0.5s.

(4) back to the delay time: to ensure that the smooth removal of castings under the premise of minimizing the delay time back to the general, generally more than 0.5s.

(5) energy storage time: generally about 2s. When setting, operate the machine for automatic cycle movement, observe the energy at the end of the energy storage time can reach the set value; can meet the set pressure value under the premise of minimizing the energy storage time.

(6) thimble number: According to the mold requirements set the number of thimble.

(7) pressure parameter settings: to ensure that the machine can work properly, casting product quality can meet the requirements of the premise, to minimize the work pressure. When selecting and setting the injection pressure, consider the following factors:

1) Die Casting structural characteristics determine the pressure parameter settings.

① wall thickness factors: the thin-walled pieces, the injection than the pressure election higher; for thick-walled parts, compaction than the pressure optional higher.

② casting geometry complexity: for the complex shape of the die casting, choose a high injection and compaction than the pressure; simple shape of the casting, the pressure should be lower.

③ process rationality: a reasonable process of mold and die casting, injection and compaction than the pressure set lower.

2) the characteristics of the die-casting alloy to determine the pressure parameter settings.

① alloy crystallization temperature window: the crystallization temperature of the window of the alloy material, select the high-pressure injection and compaction of the pressure; on the crystallization temperature of the window of small alloy material, the injection ratio is set lower.

② alloy mobility: good mobility of the alloy, choose a lower injection pressure; poor mobility of the alloy, the injection pressure higher than the pressure.

③ the density of the alloy: the density of the alloy, the injection of specific pressure, compaction than the pressure should be larger; and the density of small alloy, injection pressure, pressure than the pressure are smaller.

④ casting the specific strength: the required strength of the castings, the compaction is higher than the pressure.

3) The setting of the pressure parameter determined by the pouring system.

① runner resistance: If the runner resistance, and mainly due to the long runner, turn more, in the same cross-sectional area under the runner thickness is small, the compaction than the pressure should choose a larger.

② runner cooling speed: If the runner cooling speed, the injection than the pressure election higher; the other hand, the runner cooling speed is slow, the injection pressure ratio need to set a little lower.

4) The setting of the pressure parameter determined by the spill system.

① exhaust pipe distribution: mold exhaust pipe distribution is reasonable, the injection pressure and compaction than the pressure are selected higher.

② Exhaust cross-sectional area: mold exhaust cross-sectional area is large enough, the injection pressure can choose a little higher pressure.

(8) Inner runner speed setting: If the required runner speed is high, the injection pressure should be higher.

(9) temperature setting: When the alloy melt and mold temperature difference between the larger, the injection pressure should be selected higher; the other hand, if the temperature difference is small, the injection pressure is set lower.

(10) injection speed setting: injection rate is divided into slow injection speed (also known as the speed of a material), fast injection speed (also known as injection speed) and compaction speed.

Slow injection speed is usually in the range of 0.1-0.8m / s, and the velocity is gradually increased from 0. Fast injection speed and runner speed is proportional to the general from low to high adjustment. Without affecting the quality of the casting, with a lower rapid injection speed (ie, the speed of the inner runner) is appropriate.

Compaction has a very short time. Its purpose is to compact the metal, making the casting tissue dense. Compaction speed in the regulation, the general observation of the pressure of the pressure gauge pressure gauge in the compaction of a slash was evenly increased, die-casting products can be no loose phenomenon.

(11) speed, two-speed material speed conversion sensor switch position adjustment principle:

1) The one-speed, two-speed motion of the plunger should be carried out after the plunger passes through the chamber.

2) for thin-walled small castings, the general one-speed delay time is shorter, and the second speed is longer.

3) for thick-walled castings, the general one-speed delay time is longer, and the second speed is shorter.

4) Adjust the conversion point according to the quality of the casting (such as flash, underlay, bubble, etc.).

(12) Temperature adjustment of the metal melt: The temperature of the alloy melt can be displayed and set on the machine’s electrical box panel. The pouring temperature of the various alloy melts is not the same; for the same die casting alloy and different structure products, thick-walled castings are lower than the pouring temperature of thin-walled castings.

(13) the choice of pouring amount: the selected amount of each casting should be produced by the product thickness of the product in the range of 15-25mm is appropriate, and requires each alloy melt to stabilize the amount of pouring.

(14) Mold temperature control: For different alloy melt, the mold temperature is different, generally the alloy solidification temperature of 1/2 is limited. In the die-casting production, the most important thing is the mold working temperature stability and balance – it is the impact of die casting quality and die-casting efficiency of one of the important factors.

Machine hydraulic system of the various operating parameters, such as pressure, speed, stroke, starting point and end point, the action of the time and the entire working cycle of the total time has a certain technical parameters. Require the commissioning staff must be familiar with the technical performance of the machine, according to the hydraulic system diagram, carefully analyze the structure of all components, the role of performance and debugging range, to clarify the actual location of the hydraulic components on the equipment and understand the machinery, electrical.

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