High pressure die casting proces s: the key to building quality metal parts

In today’s metal processing field, high pressure die casting proces s is favored for its unique advantages. This article will provide a detailed analysis of the high pressure die casting proces s, including definitions, characteristics, processes, advantages and challenges, key process parameters, die casting material selection, equipment and mold selection, and process application analysis. As a comprehensive guide, everything you want to know about high pressure die casting proces s information, can be obtained in this article, an article to solve all your doubts. Below we will be divided into points to introduce:

1.Definition and characteristics of high pressure die casting proces s

(1) definition

High pressure die casting proces s is a kind of process technology through the molten metal under high pressure quickly injected into the mold cavity, and then cooled and solidified to form castings. The core of high pressure die casting proces s lies in its high pressure and high speed filling process, which makes the liquid metal can fill every corner of the mold in a very short period of time, so as to form a dense organization, the surface of the casting.

(2) Main features

1) high pressure and high speed filling

High pressure die casting proces s using high pressure (usually in 15-100MPa) will be molten metal alloy into the mold cavity.

Liquid metal to high speed (10-50 m / s, even more than 80 m / s) filling cavity, filling time is very short, about 0.01-0.2 seconds.

2) Precision molding

Capable of producing castings with high dimensional accuracy and good surface finish, which can usually be used without subsequent mechanical processing.

Complex structures such as threads can be cast, and it is suitable for casting of highly fluid metals.

3) Mass production and economic efficiency

High machine productivity, a mold with multiple cavities, easy to realize mechanization and automation, suitable for mass production.

Due to the casting size is accurate, the surface is bright and clean, reduce the processing equipment and man-hours, improve the utilization rate of metal.

2.High pressure die casting process principle and flow

(1) process principle

The basic principle of high pressure die casting proces s is the use of high pressure will be molten metal liquid quickly pressed into the mold cavity, the metal liquid in the high pressure rapid cooling and solidification, the formation of a predetermined shape. In this process, the flow and solidification of the liquid metal are strictly controlled to ensure the quality of the castings.

(2) Process Flow

1) Mold preparation:

The mold needs to be preheated to working temperature to ensure the fluidity of the liquid metal filling and the quality of the casting. The preheating temperature and time of the mold need to be optimized according to the specific alloy material and casting structure to ensure that the mold maintains a stable temperature field during the die casting process.

2) Close the mold:

Die casting machine’s moving mold and fixed mold closure, forming a complete cavity. Closing process need to ensure that the mold alignment accuracy and clamping force, in order to avoid in the high pressure filling process, such as leakage or flying edge problems.

3) Injection:

The molten metal liquid into the cylinder of the die casting machine. The injection process needs to control the temperature and flow of the metal liquid, in order to ensure that the metal liquid in the filling process has enough fluidity and temperature uniformity.

4) Pressure injection:

Through the die casting machine’s pressure injection mechanism, the metal liquid with high pressure and high speed injected into the mold cavity. Pressure injection process need to accurately control the pressure injection speed and pressure injection, in order to ensure that the metal liquid can uniformly fill every corner of the mold, to avoid underfilling or pores and other defects.

The process of molten metal gradually filling the mold cavity

5) Cooling and solidification:

Liquid metal is rapidly cooled and solidified in the mold to form castings. The cooling process needs to control the cooling speed and temperature distribution of the mold to ensure the solidification quality and internal structure of the casting.

6) Mold opening and ejection:

After the casting is completely solidified, die casting machine to open the mold, and through the ejector mechanism will casting from the mold ejector. Mold opening and ejecting process need to ensure the integrity of the casting and surface quality, to avoid damage or deformation and other problems.

7) post-treatment:

Necessary post-treatment of die castings, such as deburring, surface treatment, heat treatment, etc., in order to improve its dimensional accuracy, surface quality and mechanical properties. Post-treatment process needs to be selected and optimized according to the specific requirements of the casting, in order to ensure that the die casting can ultimately meet the requirements of use.

3.The advantages and challenges of high pressure die casting proces s

(1) the main advantage analysis

1) high dimensional accuracy:

Due to the metal liquid under high pressure to fill the mold, the casting of the dimensional accuracy is very high, can reach the micron level. Therefore, high-pressure die casting usually do not need or only need a small amount of mechanical processing can be used directly, thus significantly reducing the production cost and processing time.

2) good surface quality:

High pressure die casting surface finish is high, surface roughness is usually below Ra3.2, and even can reach the mirror effect. This makes the high pressure die casting in appearance and functionality have high requirements, especially in electronic products, home appliances and other high requirements for the appearance of the field.

3) organization dense:

High pressure die casting proces s, the metal liquid under high pressure rapid solidification, the formation of the organization structure dense, high strength and hardness. Therefore, high pressure die casting has high mechanical properties, can meet the high strength, high wear resistance application requirements.

4) high production efficiency:

High pressure die casting proces s has a short production cycle, usually only a few seconds to a few minutes to complete the production of a casting. In addition, high pressure die casting machine can realize automated production, significantly improve production efficiency and output.

5) complex structure parts:

High pressure die casting proces s can produce complex shape, thin wall deep cavity parts, this is other casting method is difficult to realize. For example, automobile engine block, gearbox shell and other complex parts can be molded by high pressure die casting proces s one time, reduce the assembly process, improve the overall performance of the product.

(2) the challenges faced

Although the high pressure die casting proces s has many advantages, but also faces some challenges, mainly including:

1) porosity problem:

In the high pressure die casting proces s, due to the metal liquid filling speed is extremely fast, easy to form pores inside the casting. These pores will reduce the mechanical properties of the casting, affecting its service life and safety. In order to reduce the generation of porosity, need to optimize the mold design and die casting process parameters, such as the design of the exhaust system, injection speed and pressure control.

2) Crack problem:

During high-pressure die casting, due to the fast cooling rate, the casting is easy to stress concentration within the casting, resulting in the generation of cracks. Cracks not only affect the appearance quality of the casting, but also may cause fracture and failure of the casting. In order to avoid cracks, it is necessary to control the cooling rate and mold temperature, and to carry out appropriate heat treatment.

3) mold life:

High pressure die casting process, the mold undergoes high pressure and high heat environment has a great influence on its life. Mold material selection, heat treatment process and surface treatment technology is crucial to the life and stability of the mold. In order to improve the mold life, need to use high-performance mold materials and advanced manufacturing technology, and regular maintenance and maintenance.

4) process control:

High pressure die casting proces s involves several process parameters, such as injection speed, injection pressure, mold temperature, etc. These parameters have a direct impact on the quality of castings. Therefore, the need for precise control and optimization of process parameters to ensure the quality and stability of castings. Advanced die casting machine control system and simulation analysis technology can help realize the precise control and optimization of process parameters.

4.The key process parameters of high pressure die casting proces s

(1) temperature parameter control:

1) pouring temperature:

Generally higher than the alloy liquid phase line temperature 10 ~ 20 ℃, such as aluminum alloy 620 ~ 720 ℃. Lower pouring temperature can reduce the gas involved and mold loss.

2) mold temperature:

Preheating to the appropriate temperature (such as aluminum alloy 210 ~ 300 ℃), to help avoid the metal liquid cooling, to extend the life of the mold, and improve the surface quality of the casting.

(2) Pressure parameter control:

1) mold filling pressure:

Related to the metal flow rate, affecting the casting densification. Reasonable setting of mold filling pressure can avoid porosity and inclusions.

2) Compaction pressure:

Applied after the end of filling, to ensure that the casting organization is tight. The compaction pressure should be adjusted according to the casting wall thickness and material.

(3) Speed parameter control:

1) punch speed:

Divided into slow compression injection and fast compression injection. The slow stage is used to exclude air, and the fast stage makes the metal liquid fill the cavity quickly.

2) Inner gate speed:

Affect the filling time and casting quality. It is usually adjusted between 2000 and 4000 mm/s to prevent gas wrapping and mold erosion.

(4) Time parameter control:

1) Filling time:

Should be as short as possible to avoid early solidification, but need to ensure that air and steam have enough time to escape.

2) holding time:

From the beginning of pressurization until the casting is completely solidified, need to be set according to the thickness of the casting and the material, in order to ensure the casting dimensional accuracy and internal quality.

3) Mold retention time:

Appropriately set the time to prevent casting deformation and cracking, usually according to the nature of the alloy and casting structure to determine.

5.High pressure die casting proces s commonly used materials selection

(1) commonly used die casting alloy

High pressure die casting proces s commonly used alloys including aluminum alloy, zinc alloy and magnesium alloy. These alloys have good mobility and formability, can fill the complex mold cavity under the condition of high pressure and high speed.

Aluminum alloy because of its good strength and corrosion resistance, in the automotive and aerospace industry in a wide range of applications; zinc alloy because of its low cost and easy to process, commonly used in electronic products and small structural parts; magnesium alloy with its lightweight and high-strength characteristics in portable electronic equipment and high-performance automotive components are widely used.

(2) material performance requirements

Die casting material selection need to take into account its fluidity, mechanical strength, heat resistance and corrosion resistance and other performance requirements. Good fluidity to ensure that the material can fill every detail of the mold, and high mechanical strength is to ensure that the casting in the use of the process can withstand a variety of loads and the environment of the necessary conditions. In addition, the thermal stability and corrosion resistance of the material is also an important factor to consider when choosing die casting materials, especially in high temperature or corrosive environment castings.

6.High pressure die casting process equipment and molds

(1) the classification and selection of die casting machine

High pressure die casting machine is mainly divided into two categories of cold chamber die casting machine and hot chamber die casting machine. Cold chamber die casting machine is suitable for larger castings and high temperature alloys, such as aluminum alloy and magnesium alloy; And hot chamber die casting machine is commonly used in zinc alloy and other low melting point alloy production.

Choosing the right die casting machine is crucial to ensure production efficiency and casting quality. In addition, the choice of die-casting machine also need to take into account the production batch, casting size and shape and other factors.

(2) mold design and manufacture

Die casting mold design and manufacture is the key link in the high pressure die casting proces s. Mold design needs to accurately calculate the size of the cavity and the layout of the cooling system, in order to ensure the quality of castings and production efficiency. The choice of mold material is also very important, need to have high hardness, wear resistance and thermal fatigue resistance. Mold manufacturing process including mold design, mold processing, mold assembly and mold debugging steps, each step need to strictly control the quality, in order to ensure the service life of the mold and production stability.

7.High pressure die casting proces s application areas

(1) automobile industry:

Automobile industry is one of the most widely used high pressure die casting proces s. With the energy saving and emission reduction and lightweight trend continues to promote, die casting aluminum alloy in the automotive parts manufacturing application is increasing. Typical products include engine block, transmission housing, brake head, chassis and suspension system. These parts are produced through high-pressure die-casting process, with high dimensional accuracy, high strength and light weight, can significantly improve the overall performance of the car.

(2) Communication industry:

With the popularization of 5G communication technology, smart phones, tablet PCs and communication base stations and other equipment demand surge. Die casting process plays an important role in the manufacture of shells, frames and internal structural parts of these products. The high precision and excellent sealing and heat dissipation properties of die castings ensure the stable operation and aesthetics of communication equipment.

(3) home appliance industry:

In the field of home appliances, high pressure die casting proces s is widely used in the production of air conditioner shell, refrigerator handle, washing machine drum and other key components. The high strength and precise size of die castings not only enhance the durability and appearance quality of home appliances, but also effectively improve production efficiency and reduce costs.

(4) electronics industry:

High pressure die casting process in the electronics industry is mainly used for the production of a variety of shells, frames and structural parts, such as computer chassis, server shells, LED lamps and lanterns. Die casting excellent conductivity and high precision, to meet the special needs of electronic products for heat dissipation and electromagnetic shielding.

(5) medical equipment industry:

Because of the high precision and good corrosion resistance of die casting, so in the field of medical equipment has also been widely used. For example, high pressure die casting proces s can be used to produce surgical instrument frames, medical equipment shell and other high-demanding parts, to ensure product safety and reliability.

(6) aerospace industry:

In the aerospace field, high pressure die casting proces s is used to manufacture aluminum alloy and magnesium alloy parts and components with high strength and lightweight characteristics, such as aircraft engine parts, landing gear and so on. The high performance requirements of these parts make the die casting process indispensable in the aerospace manufacturing industry.

8.Summary

Through the introduction of the above information, you can completely know the high pressure die casting proces s with its excellent performance and wide range of applications, has become an indispensable part of modern metal processing. Through continuous technological innovation and optimization, high pressure die casting proces s will continue to provide high quality, reliable metal parts for various industries.