Injection parameters during die casting includes injection speed, injection pressure, pressure range,holding time and so on.

In the high-pressure die casting (HPDC) process, injection parameters are key factors in determining casting quality, density, and dimensional accuracy. A reasonable combination of injection parameters is essential for achieving high-quality die-cast parts. Different alloys, wall thicknesses, and geometric complexity can lead to fine-tuning of specific values. We recommend to conduct orthogonal experiments or numerical simulations before actual production.

Injection parameters during die casting are not fixed values. They change with part wall thickness, projected area, and alloy type. Thin-wall parts need high speed. Thick-wall parts need lower speed to avoid turbulence. Aluminum and zinc have different injection pressure needs. This article also covers how parameters interact and gives a systematic approach to parameter adjustment.

In the article, we will introduce injection parameters during die casting from five aspects. Firstly, setting injection speed parametes. And then, setting injection pressure and intensification parameters. Next is pressure range, setting time parameters. Finally, case study of HAICHEN’s technology of injection parameters during die casting.

Setting Injection Speed Parameters

Injection speed has two stages: slow shot speed and fast shot speed. Each stage affects casting quality differently.

• Slow shot speed
• Fast shot speed
• Speed switch point
• Speed effect on defects

Slow shot speed

The slow shot stage is the low-speed movement from the start position past the shot sleeve inlet. Its job is to push the metal smoothly and let air escape through vents. Injection parameters during die casting typically set slow shot speed at 0.1-0.3m/s. Too fast causes air entrapment. Too slow extends cycle time.

Fast shot speed

The fast shot stage is the high-speed movement filling the mold cavity. Its job is to fill the cavity completely before metal solidifies. Thin-wall parts (wall thickness <2mm) need 3-5m/s. Thick-wall parts can use 1-2m/s. Injection parameters during die casting must consider alloy fluidity.

Speed switch point

The position where the machine switches from slow to fast shot is very important. Switching too early pulls in air. Switching too late lets metal cool and solidify. The switch point is usually set when the metal front reaches the gate. HAICHEN machines can set the switch position precisely, error under 1mm.

Speed effect on defects

Too high fast shot speed creates turbulence, pulling air into the metal and causing porosity. Too low fast shot speed causes cold shuts and short shots. Optimizing Injection parameters during die casting requires finding the right balance.

Setting Injection Pressure and Intensification Parameters

Injection pressure decides how well the metal fills the cavity. Intensification pressure feeds the casting to eliminate shrinkage.

• Injection specific pressure
• Intensification pressure
• Pressure switch timing
• Pressure and clamping force

Injection specific pressure

This is the pressure the plunger applies to the molten metal per unit area. For aluminum, use 40-80MPa. For zinc, use 20-40MPa. For magnesium, use 30-50MPa. Injection parameters during die casting take higher values for thin walls, lower for thick walls.

Intensification pressure

Intensification applies extra pressure after cavity filling to compensate for shrinkage during solidification. Intensification pressure is usually 1.5-2 times injection pressure. Injection parameters during die casting need pressure build-up time within 10-30ms, or feeding effect drops.

Pressure switch timing

Intensification must start just as the cavity fills. Starting too early causes metal splash. Starting too late makes feeding useless. HAICHEN machines use real-time closed-loop control to detect fill end from the injection curve and trigger intensification precisely.

Pressure and clamping force

Injection pressure and part projected area together decide the mold separating force. Clamping force must exceed separating force, or flash will occur. When calculating Injection parameters during die casting, check that machine clamping force is enough.

Pressure range

• High-Pressure Die Casting (HPDC)
• Low-Pressure Die Casting (LPDC)
• Conventional (Medium-Pressure) Range

Pressure is another key parameter in the die casting process. The appropriate pressure range should be determined based on the shape, wall thickness and material properties of the casting.

• For simple shapes and thin-walled castings, lower pressures can meet the requirements.
• For complex shapes and thick-walled castings, higher pressures are required.
• In addition, the magnitude and duration of pressure also need optimize based on the material and mold structure.

High-Pressure Die Casting (HPDC)

In high-pressure die casting machine, the pressure range range

• Conventional injection pressures range from 10 to 200 MPa (approximately 1,500 to 29,000 psi).
• Some large or thick-walled parts (such as transmission housings and battery trays) can reach 250 MPa (approximately 36,000 psi).
• Typical industrial practice uses pressures between 100 and 200 MPa (approximately 14,500 to 29,000 psi).

Low-Pressure Die Casting (LPDC)

• Injection pressures are only 0.01 to 0.1 MPa (approximately 0.15 to 1.5 psi), primarily used for slow, top-fill processes.

Conventional (Medium-Pressure) Range

• Most technical literature cites a standard injection pressure range of 1,000 to 20,000 psi (approximately 6.9 to 138 MPa) for die casting machines.
• For aluminum and magnesium alloys, the typical range is 3,000 to 10,000 psi (approximately 14,500 to 29,000 psi). 20-69 MPa)
• Zinc alloys and copper-based alloys can have higher injection pressures, 6,000-15,000 psi (approximately 41-103 MPa).

Setting Time Parameters

Time parameters include fill time, holding time, and cooling time. They directly affect cycle time and casting quality.

• Fill time
• Holding time
• Cooling time
• Optimizing time parameters

Fill time

Fill time is the duration from when metal first enters the cavity until the cavity is full. Injection parameters during die casting for aluminum thin-wall parts need fill time within 10-50ms. Too short creates turbulence. Too long lets metal solidify early.

Holding time

Holding time is how long intensification pressure stays on, to feed during solidification. Injection parameters during die casting typically set holding time at 1-3 seconds. Thicker walls need longer holding time. Too short holding causes shrinkage. Too long extends cycle time.

Cooling time

Cooling time is the period after holding when the casting stays in the mold until it reaches ejection strength. Injection parameters during die casting decide cooling time by part wall thickness and mold cooling efficiency, usually 1-2 seconds per mm of wall thickness.

Optimizing time parameters

Shorter fill time improves surface finish but increases porosity risk. Shorter holding and cooling times improve efficiency but may cause shrinkage and distortion. Optimizing Injection parameters during die casting requires balancing quality and efficiency.

HAICHEN’s technology of injection parameters during die casting

HAICHEN machines give users the tools to set and maintain perfect parameters.

• Solve porosity in an automotive bracket
• HAICHEN advantage of control injection parameters during die casting

Solve porosity in an automotive bracket

One of our Haichen customers had porosity issues in aluminum engine brackets. The parts failed pressure tests. HAICHEN engineers found their old machine could not hold a stable intensification pressure. On their new HAICHEN machine, we set a precise, multi-stage injection profile with a longer intensification phase. This allowed the molten aluminum to solidify under constant high pressure. The porosity was eliminated, and part strength met all standards.

HAICHEN advantage of control injection parameters during die casting

HAICHEN die casting machines use closed-loop servo systems and high-quality hydraulics. This means when you set a parameter, the machine repeats it exactly for every single shot. This stability is what turns good settings into perfect, consistent parts. It reduces scrap and gives our clients confidence in their process.

Haichen die casting machine

Haichen is one Chinese die casting machine manufacturer for more than 10years. At the same time, we produce both high pressure cold chamber die casting machine and hot chamber die casting machine. They have durable and highly precise features.

Haichen also produce die casting machine auxiliary equipment. Such as conveyor, vacuum machine, mold temperature controller, industrial robot, sprayer and so on.

We supply cold chamber and hot chamber die casting machine spare parts.

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