How to Choose the Right Die-Casting Machine for Production?

Type and characteristics of die casting machine

Classification of die-casting machine

Die casting machines are usually divided into hot chamber die casting machines and cold chamber dies casting machines according to the working state of their pressure chamber. The pressure chamber of the hot chamber die casting machine is immersed in the liquid metal in the heat preservation crucible, and the injection mechanism is installed above the heat preservation crucible; The pressure chamber of the cold chamber die casting machine is separated from the heat preservation furnace. During die casting, liquid metal is removed from the heat preservation furnace and injected into the pressure chamber for die casting. Cold chamber dies casting machine according to the position of the pressure chamber and injection mechanism, the pressure chamber and injection position in the horizontal position is called the horizontal cold chamber die casting machine. The pressure chamber and injection mechanism in the vertical position are called the vertical die-casting machine. A vertical die casting machine, vertical injection, and vertical direction of the die are called the full vertical die casting machine.

Characteristics of hot chamber die casting machine

Hot chamber die casting machine is simple in structure, convenient in operation, and easy to realize automatic production; No need for a pouring procedure; simple procedure with high production efficiency; Less heat loss, and less metal loss; The liquid metal is always in the closed channel, and the oxide inclusions are not easy to be involved. The liquid metal entering the cavity is clean, and the casting quality is good. The injection ratio is small; there is no pressurized section in the injection process; the Pressure chamber, punch, gooseneck, nozzle, and other hot parts have a short service life and are not easy to replace.

In the current die casting production, hot chamber die casting machine usually produces zinc, tin, lead, and other low melting point alloys and small, thin-wall magnesium alloy die casting parts; most of the clamping force is less than 160t (1.6MN), more than 400t (4MN) few. And magnesium alloy, due to its forming characteristics, using the hot chamber, cold chamber production, production of magnesium alloy hot chamber machine, the clamping force is usually less than 650t (6.5MN).

 

Characteristics of horizontal cold chamber die-casting machine

The cold-chamber die-casting machine has full specifications and models, wide adaptability to product sizes and alloy types, simple production operation, high production efficiency, and can be connected with automatic peripheral equipment to realize automatic production, easy to realize the subsection control and adjustment of the injection stroke, and good satisfaction to different requirements of the die casting process. The disadvantage is that the heat loss of the liquid metal in the injection process is large, and the contact between the liquid metal and the air is easily involved in oxidized inclusions and air. Special technology should be adopted for products with high density or heat treatment.

A horizontal cold chamber dies casting machine mainly produces aluminum, magnesium, copper, and other non-ferrous alloys. The application of ferrous metal die casting is very few. The clamping force of a cold chamber die-casting machine is tens to thousands of tons.

 

The characteristics of the vertical die-casting machine

Less gas is involved in the metal hydraulic injection process of vertical die casting machine; Convenient for central pouring system setting; Maintenance and operation trouble, there are cutting and cake pushing procedures in the production process, low production efficiency; Medium and minicomputer is the main machine, less consumption in the production process; At present, vertical die casting machine is mainly used for special products such as motor rotor die casting production. With the continuous improvement of the injection performance of the horizontal cold chamber dies casting machine, to improve the production efficiency, the horizontal cold chamber dies casting machine has been used more and more micro motor rotor production.

 

Die casting machine parameters and specifications selection

Calculate the clamping force

Please choose according to die-casting die-casting machine, a very important job is to calculate the clamping force and whether it meets the requirements of die casting machine; die-casting machine clamping force must be greater than the die-casting products of rose type force and reserve safety coefficient, higher calculation of force is with metal under pressure parts of the mold parting surface projection area multiplied by the die pressure. The die casting machine’s clamping force and swelling force shall meet the F lock requirements≥k F lock in the swelling type — the main swelling force of the product (N); k — safety factor, generally 1.15.

In the actual production situation, when calculating the clamping force and selecting the die-casting machine, attention should be paid to whether the parting surface position is special, the size of the slide core pulling projection area and the size of the deviation between the injection force center and the equipment center.

When choosing a die-casting machine, the clamping force must be considered together with the process of molding concrete structures. It is not recommended that the rising force is greater than the die-casting machine clamping force under the condition of production. Otherwise, it will produce fly expected risk and product size precision, and it isn’t easy to guarantee the quality. At the same time, adding die-casting machine moving parts wear and life of die casting machine will greatly damage.

 

Confirm relevant parameters of die casting machine

After choosing the die locking force of the die casting machine, it is usually necessary to confirm the following parameters of the die casting machine according to the die scheme of the product.

(1) Whether the thickness of the die-casting mold is within the adjustment range of the effective die-casting machine thickness.

(2) Whether the die casting machine’s die opening stroke can ensure the normal removal of products.

(3) Whether the distance of the guide column of the die casting machine can meet the installation of the outer contour size of the mold, whether the mold is within the effective range of the T-shaped groove of the mold plate, and special attention should be paid to confirm whether the core pulling or other protruding parts of the mold interfere with the Golin column of the die casting machine and other affiliated institutions.

(4) According to the fixed die thickness of the die casting mold, confirm whether the push distance of the die casting machine can meet the following of the product cake.

(5) Confirm whether the die casting machine’s ejection distance can ensure the product launch’s needs.

(6) According to the product’s pouring weight, calculate the pressure chamber’s filling degree and select the diameter of the pressure chamber. The FILLING DEGREE IN PRODUCTION SHOULD BE LESS THAN 75%, even if the volume OF the pouring metal is less than 75% of the volume of the pressure chamber, so that the pouring mouth will overflow before the punch seals it. Normally, it is a standard with a maximum of 60%. In the production, the selection pressure chamber filling rate is conducive to the indoor gas discharge pressure; we also want to consider the loss of liquid metal filling kinetic energy. When the pressure chamber is full of degrees higher, the high-speed filling period is longer because the liquid metal produces very big resistance through the gate. The punching movement was slow, leading to after-filling parts of the energy shortage. The end of the product is prone to flow defects. Hence, the filling rate of the medium pressure chamber in current production is generally 30%-50%.

Check whether the injection performance of die casting machine meets the needs of the products

The injection performance of the die-casting machine is a key factor affecting product quality. For some large products with high-performance requirements, it is necessary to analyze the characteristics of the injection system P-Q diagram to determine whether the die gate area matches the die-casting machine’s injection capacity. Under the condition that the energy of the injection system meets the requirements of compact and pressure-resistant castings, the injection system is required to have good low-speed performance, acceleration performance, and pressurization performance, and the products with high requirements of thin wall or appearance are required to have good high-speed and acceleration performance. According to the calculation of the above parameters, the type of die-casting machine can usually be selected.

 

Optional die-casting machine auxiliary function

In recent years, with the requirements of product precision and lightweight, die casting as an efficient precision forming technology has been more widely used in different production environments, the die casting put forward higher requirements, such as no pores, welding, heat treatment, etc. To adapt to the needs of products, die-casting machine, injection performance, automation control system, and auxiliary process aspects had a very major development; some of these new technologies belong to the standard configuration of the die-casting machine, some belong to the selected device, when choosing a die-casting machine, need according to the actual needs of enterprises and products, these functions are selected.

Rapid die exchange system

Adapting to the needs of multi-variety, small batch production, and large mold exchange greatly reduces mold exchange time and improves production efficiency.

(1) Mould rapid pressing device

The hydraulic automatic locking system is used to replace the original mold plate bolt locking mechanism . The die-casting machine below 1250t (12.5MN) generally adopts the form of a hydraulic locking plate, and the die-casting machine above 1600t (16MN) generally adopts the form of a hydraulic locking pin.

(2) The Golin column extraction device can pull out one or two Golin columns on the upper side when the mold is exchanged. For large molds with hydraulic cylinder core extraction or horizontal width beyond the distance of the Golin column, it can be easily loaded without disassembly and installation of hydraulic cylinders. 

(3) Mold placement and positioning device

In the mold installation process, the die-casting machine is installed on the mold placement platform or V-shaped guide rail bracket to achieve the mold’s rapid positioning, pressure chamber flange, and mold plate. 

(4) C plate clamping device

Through the displacement movement of the C plate driven by the die casting machine’s hydraulic cylinder, the die casting machine’s push-out plate and die are realized.

Compared with the tie rod bolt connection, the time is greatly shortened. 

(5) Fast fixed mold unloading device

When the die casting die is disconnecting, it is difficult for the die to fall off from the die casting machine’s fixed formwork because the holding cup’s flange is coordinated with the mold. Two sets of unloading hydraulic devices are designed for the new die-casting machine in the fixed formwork. After the die is released from the die-casting machine, the die is quickly detached from the fixed formwork by the hydraulic unloading device. 

(6) Quick connection of core-pulling hydraulic cylinder interface

Die casting machine and die core-pulling hydraulic cylinder circuit and oil pipe interface adopt quick joint docking.

The above devices, except for the connection of the mold hydraulic cylinder, are all connected with the die-casting machine’s control system, and the mold exchange operation can be achieved through the operation panel. Using the above rapid die exchange system, the exchange time of the complex die casting machine can be shortened to less than 10min, and the effect of increasing the operating rate of the equipment is remarkable.

Display and automatic injection curve

At present, the injection curve control of die casting machine mainly has the following three forms:

(1) open-loop control form

Injection stroke usually involves 3 (slow injection, fast shot, and pressurization) or 4 (injection and slow fast injection, secondary fast shot, and pressurization) injection by electric adjustment or manually adjusting the handwheel velocity and pressure of paragraphs, parameters, and injection curve reached according to display or process engineering experience and revise manual adjustment.

(2) Semi-closed-loop control form

Through the control system of injection pressure, speed, schedule, and set parameters, the control system through the sensor and the displacement of the encoder test the actual parameters of the injection process, according to the actual parameters and injection curve, and to compare the measurements with the set value, when the next die casting cycle by adjusting valve opening to modify die casting parameters, make it close to the target. The injection stroke is controlled by three or more sections (including the final section deceleration function) to make the actual injection curve closer to the set curve.

(3) real-time control form

The injection stroke is controlled by multiple segments (foreign high-performance die-casting machines have achieved 20 segments of control, including terminal deceleration), and the parameters of different stroke segments can be programmed. Due to the high precision servo valve used, improved response speed and feedback correction are detected (can reach about 5 ms); in the process of the injection of pressure and velocity, information detection and feedback correction unceasingly make up for the production fluctuation on the effects of injection parameters, make each cycle and value accord highly with the actual injection curve, So that die casting production with high stability and reliability, to meet the needs of high performance die casting process.

Overspeed injection performance

The air injection speed of the traditional die casting machine is usually 4.5-6m/s, and the air injection speed of the ultra-high-speed die casting machine can reach 8m/s or even 10m/s, which can not only realize the sharing of magnesium alloy and aluminum alloy but also shorten the filling time because of the high filling speed. At the end of filling, the liquid metal temperature is higher, which is conducive to the transfer of pressurization pressure. The internal porosity of die casting is highly diffused, which improves the internal quality and appearance of products.

Ultra-low speed die casting machine can be set in the low-speed range of 0.05-0.70m /s to achieve laminar flow filling of products, reduce the internal gas content, can produce T6 treatment of high performance die casting, generally suitable for the product structure is relatively simple, thick wall dies casting, the internal gate cross-sectional area is large, It is usually used in conjunction with a hot pressure chamber, mold temperature control, and other technologies.

Local pressure compaction pin device

It is mainly used in parts with large local wall thickness and is easy to produce shrinkage porosity and defects. Compact die casting is obtained by pressurizing and compacting the parts from the end of the injection to the solidification of the products. It is widely used in automobile connectors with higher mechanical properties, such as engine support, steering wheel pillar, and other products.

 

Core pulling spray function

Usually, the core pulling action of the die-casting machine is in the extraction position when spraying, and part of the core is buried in the mold cavity at this time and can not be sprayed. Especially for the core pulling with long forming size and poor cooling effect, it is especially easy to cause adhesion strain of the product and shorten the life of the core. When the core pulling and spraying function is used, the core pulling control signal is connected to the spray machine signal. The core hydraulic cylinder can be pushed out after the product is removed and before the spray action. The core pulling can return after the spray to improve the molding and cooling effect of the core pulling.

 

Vacuum die casting function

Due to the die casting under dynamic load, and often having a sealing function, have a higher request for internal porosity, now with the development of the automotive lightweight, more and more automobile part USES the aluminum alloy die-casting and T6 treatment, and the quality of die casting internal proposed the more stringent requirements, vacuum die casting offers mold vacuum system control interface, through the vacuum die casting machine program, The opening and closing of mold vacuum valve can be synchronized with the circulation of die casting machine.

Production management system and remote diagnosis function

The present die casting machine can provide production management, product process parameter storage, fault display, and quality management functions: can record the batch and production quantity of products; Store process parameters of different products (molds) for the next production to ensure the consistency of production and reduce the adjustment time; Real-time display of die-casting machine and surrounding equipment information (warning, fault, status, error) and provide service and maintenance tips; According to the deviation between the actual casting parameters and the set parameters, record the suspicious or bad information of the product. The foreign real-time control die-casting machine can provide users with timely reference information in the production process and have the function of remote diagnosis.

Fully automatic die-casting island

Die casting automatic die casting island is the automatic soup feeding, spray, take parts, and other peripheral equipment control system and die casting machine control system integrated into one, easy to operate, can realize automatic production. In recent years, servo industrial robots have been widely used in the peripheral equipment of die casting. The automatic spray machine using servo robots has the memory of spray curves and the control of multi-point spray quantity. Because of the six-axis rotation, it can adapt to the spray requirements of complex molds, and the consistency and reliability of spray operation are greatly improved. The SERVO ROBOT PICKUP MACHINE can separate the qualified and unqualified products and put them in the designated station according to the comparison information of the deviation between the actual injection parameters and the set target value of the control system. Due to the application of a servo robot, the integrated control degree of the die-casting machine and peripheral equipment control system is getting higher and higher. The current die-casting automation production unit has been able to achieve the automatic uncrewed operation of the whole die-casting process, product testing, cutting edge, burring, and surface treatment, and the production efficiency and stability have been well guaranteed.

Choose the right die-casting machine, mainly looking at the following factors

1.the weight of the die casting. There are many kinds of die castings, some lightweight, some heavyweight, and different weights of die castings need to choose different equipment models.

2.Material of die casting machine. The materials used to produce die castings include zinc, lead, tin, copper, aluminum, magnesium, etc. No single piece of equipment can process all these materials, and the materials processed by different equipment are different.

3.The external dimension of the die casting. The external dimensions of die castings are inconsistent, so customers need to choose equipment according to the external dimensions of die castings.

4.Precision and internal quality of die-casting parts. The performance of the injection system is important when considering accuracy and internal quality. There are four parameters to consider when selecting an injection system:

(1) Injection force. The injection force is an important driving force to promote the movement of the injection piston, so when choosing, we should understand the diameter of the injection cylinder and choose according to the injection tonnage we need.

(2) Start time of pressurization. When the equipment is being flown, the time between the top of the punch and the start of pressurization should be less than 0.02s.

(3) Pressure building time: when the pressure reaches the set value, the time used should be less than 0.02s.

(4) Pressurization time: The pressurization time is calculated from the starting time of pressurization, plus the pressure building time, which should be less than 0.04s.

When choosing a die-casting machine, if you can consider the above aspects, you can choose the suitable equipment for yourself.

 

 

 

The conclusion

Die casting machine type selection is one of the most important aspects of the die casting production preparation; it is a very strong comprehensive technical work between various enterprises, and product demands, process configuration, and management are not the same, the selection of die casting machine considering the focus is different also, want to combine actual situation, make a careful consideration, usually follow the following principles.

(1) to understand the types and characteristics of the die casting machine, by the requirements of enterprise products to choose to die casting machine, both to ensure that it meets the requirements of product performance and to have a certain degree of rich, balancing the new requirements of the product development direction, and ensure the qualified rate, production efficiency and the stability of the satisfaction, use as broad as possible the process condition of production.

(2) if you have many sets of die-casting machine, the die-casting machine needs to be considered models (mainly clamping force) has a certain gradient, has compatibility, and should not only meet the needs of the production and reduce die-casting machine type and the Numbers as far as possible, if there are different brands of die casting machine, consider the compatibility of different brand die-casting machine mold installation size, to facilitate the organization of production.

(3) According to the enterprise’s current situation, automatic peripheral equipment should be configured as far as possible to ensure the stability and production efficiency of die-casting production. Automatic soup feeding and spray machines are recommended for medium-sized and above die-casting machines. In addition, under the premise of ensuring die-casting performance, careful consideration of the die-casting machine cost performance, reliability, operability, maintainability, and safety factors.

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