For the Die Casting Alloys Using, You Need To Know?

die casting alloys

Die casting alloys are typically non-ferrous, and many are available with a wide range of physical and mechanical properties that cover almost every conceivable application a designer might need. Die casting molds can handle various alloy families and produce different results, but die casting is usually most effective for metals with low melting temperatures. So for die casting alloy selection, the following information will help you in 4 main areas:

  • Die casting alloy requirements
  • Common die casting alloys
  • Main characteristics
  • Die casting alloy selection and standards
  • Standard documents reference

Table of Contents

Requirements for die casting alloys

When choosing to die casting alloy material, we should fully consider its use performance, process performance, production conditions, economy, and other factors. 

Use performance:

①Mechanical properties. Tensile strength, high-temperature strength, elongation, hardness.

② Physical properties. Density, liquid-phase line temperature, solid-phase line temperature, linear expansion coefficient, body expansion rate, specific heat capacity, and thermal conductivity. 

③ Chemical properties. Heat resistance, corrosion resistance.

Process properties:

①Casting processability. Flowability, thermal crack resistance, mold adhesion.

② Cutting processability. Welding performance, plating performance, heat treatment performance.

Basic requirements for die-casting alloys:

① Good fluidity when superheat temperature is not high, easy to fill complex cavities to obtain die castings with good surface quality. 

② Small linear shrinkage and cracking tendency to avoid cracks in die castings so that die castings have high dimensional accuracy.

③ Small crystallization temperature range avoids the die castings’ excessive shrinkage.

④ Have a particularly high-temperature strength to prevent deformation or cracking when pushing out the die casting.

⑤ High strength at room temperature to meet the needs of large thin-walled complex die casting production.

⑥The physical and chemical interaction between the wall of the mold has a slight tendency to reduce the sticky mold and mutual alloying.

⑦ Having good processing properties and a certain degree of corrosion resistance.

⑧ Preparation of die-casting composite castings, the prefabricated type needs suitable preheating.
 

Commonly used die casting alloys and their main characteristics

The most commonly used die casting alloys are aluminum, zinc, magnesium, copper, lead, tin, and some metal matrix composites. Lead, tin-based low melting point alloys are suitable for die-casting complex and precision castings, but due to the low strength of lead and tin, tin is expensive and not easy to obtain.
Now the main characteristics of several commonly used die-casting alloys are introduced as follows:

Die casting aluminum alloy
The main characteristics are as follows:
1) Smaller density, high specific strength.
2) Good mechanical properties at high and room temperature, especially the impact toughness, are excellent.
3) Good electrical and thermal conductivity and good mechanical cutting properties.
4) The surface has a layer of chemically stable and densely organized aluminum oxide film, which has good corrosion resistance.
5) It has good die-casting performance, surface roughness, and slight thermal cracking.

Die casting aluminum alloy chemical composition

Mechanical properties and applications of die-cast aluminum alloys

Mechanical properties and applications of die-cast aluminum alloys

Die Casting Zinc Alloy
Die-casting zinc alloy is also a widely used die-casting alloy at present.
The main characteristics are as follows:

  • Die-casting zinc alloy has good die-casting performance, good fluidity performance, and can die-cast die castings with thin wall thickness, which makes up for the weight effect of high density. It has a small crystallization temperature range, easy to shape, not easy to stick to the mold, and easy to demold.
  • Lower pouring temperature and longer die casting mold life.
  • Smaller shrinkage rate, easy to ensure the dimensional accuracy of the die casting.
  • Higher comprehensive mechanical properties, excellent resistance to pressure and wear.
  • The surface of zinc alloy die casting can be treated with various anti-corrosion and decorative treatments, such as chemical treatment, anodic oxidation, electroplating, electrostatic spraying, vacuum chrome plating, etc.
  • Zinc alloy has no corrosive effect on the press chamber and die casting molded parts in the casting temperature range.
  • Problems: The aging phenomenon is more serious. Zinc alloy die castings cause deformation or changes in dimensional accuracy over time, significantly reducing strength and plasticity. At the same time, when the operating temperature changes, its mechanical properties also change. If the working temperature is lower than -10℃, it will sharply reduce the impact toughness, and above 100℃ will significantly reduce the strength, and the creep phenomenon will quickly occur. Therefore, zinc alloy die castings are used in a narrow range of ambient temperatures.

Chemical composition and mechanical properties of die casting zinc alloys

Chemical composition and mechanical properties of die-cast zinc alloys

Die casting copper alloys

Die casting copper alloy is mainly a die casting brass alloy. Although its melting point is higher, it still has a certain application value because of its many superior properties. The main characteristics are as follows:

①Mechanical properties and wear resistance are better than aluminum, zinc, and other die casting alloys.

② Strong corrosion resistance in the atmosphere and seawater.

③Good electrical and thermal conductivity and anti-magnetic properties. It is often used to make parts on instruments that do not allow interference by magnetic fields.

The casting temperature of die-casting copper alloy is high, the life of the die-casting mold is relatively low, and the price of raw materials is high. Therefore, the current application in the die casting industry is somewhat limited.

Chemical composition and mechanical properties of die casting copper alloys

Chemical composition and mechanical properties of die-cast copper alloys

Die casting alloy selection and standards

Die casting alloy selection good selection is one of the essential links in the design of die casting work. Different kinds of die casting alloys, their performance varies. Designers in the selection of die-casting alloy not only consider the required performance but also the process performance of die casting alloy should also give sufficient attention to meet the performance of the premise, as much as possible to use the excellent process performance of the die-casting alloy. The performance of die-casting alloy includes the use of performance and process performance of two aspects, its project and content see die casting alloy performance.

Performance Category

Item

Content

Performance in Use

Mechanical Properties

Physical Properties

Chemical properties

Tensile strength, Elongation, Hardness, Density, Melting point, Freezing point, Coefficient of linear expansion, Specific heat capacity, Thermal conductivity, Corrosion resistance

Process Performance

Casting Process Properties

Machinability

Welding properties

Heat treatment properties

Flowability, Resistance to thermal cracking, Mold adhesion

 

The factors that should consider for choosing die-casting alloy are as follows:

① The state of the force of die casting is the primary basis for choosing to die casting alloy, but not the only basis.

② die casting working environment state. Die casting working environment state as follows. a. Working temperature: high and low-temperature requirements. b. Contact medium: humid atmosphere, seawater, acid, and alkali. c. Confinement requirements: air pressure, hydraulic confinement.

③The working conditions in which the die casting is located in the whole machine or parts.

④Requirements made for the size and weight of the die casting.

⑤ Production conditions: melting equipment, die-casting machines, process devices, materials, etc.

Different kinds and grades of die-casting alloys, their various properties vary. In use, the choice of the alloy is difficult to give a specific principle. In many cases, it is determined through production, equipment conditions, practical experience, the source of the alloy, etc. The principles considered are described below when one can choose only in terms of serviceability.

① For zinc alloys, several grades do not differ much in terms of use and process. 

②There are many grades of aluminum alloys. YL102 aluminum alloy has better airtightness, poor machinability, and severe surface pattern of castings; YL104 has improved machinability. Usually, when these two grades can be used, YL102 is the primary grade, and YL303 has good corrosion and heat resistance and is suitable for a wet environment. YL108 has good die-casting, strength, and cutting performance, but the excessive zinc content reduces the corrosion resistance.

③ For magnesium alloy, by small, solidification is faster, and does not occur with the type wall adhesion, so the die-casting process is faster than aluminum alloy, and because of its high specific strength, suitable for die-casting large thin-walled parts. Magnesium aluminum zinc system casting magnesium alloy can cast the shape and cavity shape complex castings, plus magnesium alloy in gasoline, kerosene, lubricating oil is very stable, and therefore more for the aviation industry fuel system and lubrication system. Die-casting magnesium alloy can also be used as a large amount of energy absorption parts and aircraft landing wheel hub when subjected to impact loads. 

④ For copper alloy, lead brass castings in seawater and hot water flow is prone to dezincification corrosion phenomenon, so in the humid atmosphere or SO 2 atmosphere are not suitable for use. While silica brass has better resistance to thermal cracking due to small linear shrinkage and better airtightness and corrosion resistance and filling formability is also perfect, can die-cast thin-walled parts.

Die Casting Alloy Standard Reference

  • JIS B 0409 : 1980 Permissible Deviations In Dimensions Without Tolerance Indication For Die Castings
  •  JIS H 5301 : 2009 Zinc Alloys Die Castings
  • JIS H 5302 : 2006 Aluminium Alloy Die Castings
  • ASTM B 85 : 2003 Standard Specification for Aluminum Alloy Die Castings
  • DIN1725 : 1986 ALUMINIUM ALLOYS, CASTING ALLOYS; INGOTS (PIGS), LIQUID METAL; COMPOSITION; INFORMATION ON ALLOYING PROCESSES
  • NF A5-705-1984 ALUMINIUM AND ALUMINIUMALLOYS. RECTANGULARSECTIONEXTRUDEDBARS. DIMENSIONALTOLERANCESANDRECOMMENDEDDIMENSIONS. 

To do an excellent job of making die casting products, not only need suitable materials but also need the responsibility and advanced technology of die casting manufacturer. V1DIECAST team consistently adheres to the core value of achieving customers first. Help our customers do the best die casting products, so please don’t hesitate to contact us to get your project helps.

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