pressure casting (high pressure die casting, die-casting)

defined:

pressure casting method is higher than the atmospheric pressure the pressure, so that the molten metal at high speed filling die-casting mold cavity under pressure, within a short time to get the casting of high precision and excellent surface for mass production casting method.
High pressure and high-speed filling die-casting mold cavity die-casting of the two main characteristics. It is commonly used in the injection pressure from thousands to tens of kPa, and even up to 2 × 105kPa. The filling speed is about 15 50m / s, sometimes even up to 100m / s or more. Filling time, generally in the 0.01 ~ 0.2s within the quench solidification under high pressure to the actual occurrence of the crystalline particles of very small (about 0.013mm).

pressure casting technology can be divided into two types:

1. (1) hot chamber method (hot-chamber -)

2. (2) cold chamber method (cold-chamber -)

different from the above two kinds of methods is to set the location of metal melting pot. In the hot chamber method, the metal melting pot set the machine, the jet tube is often immersed in the molten metal, the pressure of molten metal into the mold to the casting work. Such a casting technology, the supply of melt easily, work efficiency, but the product size is not too much. In the cold chamber method has a separate furnace, the molten metal by hand tools or mechanical arm pouring jet barrel, and then molten metal is pressed into the mold. Pressure die for permanent mold can be used repeatedly, so the production rate is very high. Smooth surface of the mold of improving the aesthetic appearance of the casting, and reduce the preparatory work of the plating or other polishing operations.

die casting advantages and disadvantages:

die casting advantage of

1. （1）Product quality and good

Light, pass the good thermal properties, high dimensional accuracy of castings, generally the equivalent of six to seven, or even up to 4; surface finish (powder); high strength and hardness, strength is generally higher than sand casting to improve 25 to 30% , but the elongation is reduced by about 70%; size and stability, interchangeability; can be die-casting thin-walled castings of complex. For example, the minimum wall thickness of zinc alloy die castings up 0.5mm; aluminum alloy castings of up to 1mm;

2. （2）The high of production efficiency

Machine with high productivity, such as horizontal cold air die casting machine die-casting 600 to 700 times an average of eight hours, a small hot chamber die casting machine every eight hours on average die casting from 3000 to 6000; long life and die-casting mold, a pair of die-casting mold, die casting aluminum alloy life of up to 100,000 die times; easy mechanization and automation.

3. （3）The excellent of economic results

Die-casting can get a smooth surface and accurate size of the casting surface roughness unfeigned degree is often up to 12S. Machining in general no longer be directly used, or very small processing volume, mass production can save the cost of materials, processing and assembly fees, lower production costs; casting will be easy to price; can cast package of parts of other materials, access to the die-casting alloy No physical characteristics actually. Not only save the assembly man-hours to save metal, In addition, recyclable good characteristics, is an excellent environmentally friendly metal material.

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die casting shortcomings

Die-casting has many advantages, but there are some shortcomings to be resolved. Such as:

1. （1） when the die-casting due to the high speed of the liquid metal filling cavity, the flow pattern of instability, it is usually die-casting method, the casting is easy to produce pores, can not be heat-treated;
2. （2） concave complex castings, die-casting production is more difficult;
3. （3） the melting point alloys (eg copper), low die-casting mold life;
4. （4） should not be a small batch production, mainly due to high die-casting mold manufacturing costs, die casting machine, high production efficiency, small batch production uneconomic.
5. （5） The tightness of the castings, the molten high-speed filling the die-casting mold, will produce the phenomenon of turbulence, the local formation of pores or shrinkage holes affect the casting of the resistance to air tightness.

casting range of applications and development trends

The die-casting is one of the most advanced metal forming method is a little chip and chipless effective ways.die casting size and weight, depending on the power of the die casting machine. Increasing the power of the die casting machine, casting shape size from a few millimeters to 2m; weight from a few grams to several Ten kilograms. Abroad can be die-casting diameter 2m, weight 50kg of aluminum castings. Die Casting also is no longer confined to the automotive industry and instrument industry, and gradually expand to other various industrial sectors, such as communication equipment, agricultural machinery, optical equipment, machine tool industry, electronic industry, defense industry, medical equipment, watches, cameras and household hardware dozens of industries. A vacuum die casting, die-casting technology, the new process of the oxygenase die casting, fine speed density die-casting, as well as soluble core applications.

Zinc is the reason for the high-temperature brittleness, and JIS provisions required in 1.0%, and foreign regulations to add the amount required to allow less than 3%. When the addition is kept below 1.0%, die casting, less likely to cracking phenomenon.

the physical properties of cast aluminum alloy

following composition table for the use of generic specifications of the aluminum alloy suitable for die casting.

general use material ADC12 market share above 70%, and most meet the conditions of the aluminum alloy of the die-casting.

project	general die casting aluminum alloy
specifications-JIS	ADC1	ADC3	ADC5	ADC6	ADC10	ADC12
specification-ASTM	A413	A360	518	514	A380	A383
tensile strength (kg/mm2)	29.5	32.2	31.5	29	33	33.
yield strength (kg/mm2)	13.3	16.8	19.6	15.5	16.2	16.6
elongation rate ( %)	3.5	3.5	5	7.5	3.5	2.5
shear strength (kg/mm2)	17.5	18.2	20.3	18	19	20.3
fatigue strength (kg/mm2)	13.3	12.6	14	13.5	14	14
specific gravity (density) (G/cm3)	2.66	2.68	2.53	2.68	2.76	2.7
melting point (℃ ;)	580	600	620	630	590	580
thermal conductivity (cgs )	0.29	0.27	0.23		0.23	0.23
Brinell hardness (10/500)	80	75	80	50	80	85
electrical conductivity (copper)	31	29	24		23	23

Note: This table is to compare the specimen based on experiments.

project	zinc alloy
specifications-JIS	ZDC1	ZDC2
tensile strength (kg/mm2)	33	29
elongation ( %)	7	10
red. Click value (kg/mm2)	16	14
specific gravity (density) (G/cm3)	6.7	6.6
melting point (℃ )	386.1	386.6
Brinell hardness (10/500)	91	82

Note: This table is to compare the specimen based on experiments.

Remarks: the ADC12 theoretical maximum tensile strength 33kg/mm2, but because of the die-casting there will be volume gas, the actual strength

insufficient 33kg/mm2.

2 6061 T6 yield strength 28kg / mm2 , the maximum tensile 31.5kg/mm2.

3 A356 T6 The maximum tensile strength 28kg/mm2.

die-casting aluminum alloy the characteristics and reference use cases

Specifications		aluminum features	reference use cases
JIS	ASTM
ADC 1	A 413.0	corrosion resistance, die-casting, low pressure resistance.	vehicle body frame, front wheel, automatic bread lined.
ADC 3	A 360.0	impact value and pressure resistance, corrosion resistance, poor casting pressure.	car flywheel cover, motorcycle crankcase, automotive flywheels, ship machinery.
ADC 5	518.0	corrosion resistance, good high impact value of the elongation, the cast is bad.	agricultural machinery, shipbuilding, machinery, tackle, wrenches, reel.
ADC 6	514.0	good corrosion resistance, castability a little better than the ADC 5.	brake handle, ship machinery, axle box, water pump, heat sink.
ADC10	A 380.0	mechanical properties, machinability and good castability.	3C products, car carburetor, CNC parts, cylinder heads, motorcycle shock absorber, engine crankcase, side cover, cylinder block, agricultural gearbox, crankcase cover, VCR, Block, photographic body, the body of power tools, motor rotor, car rack, and head and body, tackle body, the hinge device, gas regulator, cover up and down, dispenser parts.
ADC12	A383.0	mechanical properties, machinability and good castability.