Selection of die-casting machine

1、 Selection steps of die-casting machine

1) Check the technical parameters and processability of the die-casting machine according to the technical requirements, service conditions and die-casting process specifications of the castings, and preliminarily select the appropriate model.

2) According to the technical parameters and process requirements of the preliminarily conceived die casting mold (die), the die casting process parameters and the overall dimensions of the die casting mold (die) are calculated, and the appropriate model is selected.

3) Evaluate the working performance and economic effect of the die-casting machine, including the yield, qualification rate, productivity, stability, reliability and safety of operation.

2、 Selection method of die-casting machine

1) In actual production, the selection of die-casting machine mainly depends on the type of die-casting alloy, the outline size and weight of the casting to determine the use of hot chamber or cold chamber die-casting machine. Hot chamber die-casting machines are usually used for zinc alloy castings and small magnesium alloy castings. For aluminum alloy, copper alloy castings and large magnesium alloy castings, cold chamber die-casting machines are mainly used. The vertical cold chamber die-casting machine is suitable for castings with central radial and cylindrical shapes and the conditions for opening a central runner.

2) The model and specification of the die-casting machine are selected according to the material, contour dimension, average wall thickness and net weight of the die-casting. The actual process parameters such as the size of locking force, the amount of each pouring, the filling degree of the injection chamber can be calculated as the basis for selecting the model.

3) The size of the die-casting mould (die) shall match the corresponding size of the mould (die) installed on the die-casting machine. Its main dimensions are the thickness of the die-casting mould (die) and the distance between the parting surfaces of the mould (die). The basic parameters of the die-casting machine must be met:

① The thickness H of the die casting mould (mold) shall not be less than the minimum (mold) thickness given in the machine manual, nor greater than the maximum (mold) thickness given. The H setting shall meet the following conditions

Hmin+10mm ≤ H set ≤ Hmax - 10mm

Where H is set - thickness of the designed mold (die) (mm);

Hmin - minimum thickness of the mold (die) given by the die casting, namely "die thickness" (mm);

Hmax - maximum thickness of the mold (die) given by the die-casting machine, namely "die thickness" (mm).

② After the die-casting machine opens the mold (mold), the distance between the parting surfaces of the die-casting machine (mold) should be greater than or equal to the minimum distance from which the casting can be taken out.

L ≥ L

As shown in Figure 1, the minimum distance for the die casting mold (mold) pushed by the push rod to take out the casting.

L ≥ L core+L piece+K

Where, K is generally 10mm.

3、 Example of selection method of die-casting machine

Example A box casting is known, as shown in Figure 2. The following model selection analysis is based on the technical parameters of the horizontal cold chamber die-casting machine model produced by Lijin Machinery Factory Co., Ltd.

Basic condition Material is aluminum alloy; Overall dimensions (length × wide × Height) is 280mm × 180mm × 80mm； The average wall thickness is 3 mm; Net weight of casting is 1240g

1. Calculation of projected area casting

A1=280mm × 180mm=50400mm2 

Gating system A2=(0.15 ～ 0.30), 0.21 for A2

Then A2=0.21 × 50400mm2=10584mm2 

Residual material (material cake) A3=π d2/4, and the diameter d of the pressure chamber is φ 70mm (i.e. punch diameter φ 70), then A3=3847mm2

Spill discharge system A4=(0.1 ～ 0.2), if 0.12 is selected for A1

A4=A1*0.12=6048mm2 

Total projected area:

A=A1+A2+A3+A4=50400mm2+10584mm2+3847mm2+6048mm2=70879mm2 

2. Calculate expansion force and locking force, and preliminarily select the type

(1) If the casting has only general requirements and belongs to common parts, the specific pressure of pressurization pbz=40N/mm2 (MPa) and expansion F=40N/mm2 shall be selected × 70879mm2=2835160N, F lock=F expansion/K, K=0.85, F lock=2835160N/0

85=3335482N=3335.482kn 

The locking force of 4000kn can be selected, and the force machine of DCC400 can be selected.

2 mm2 (MPa) F expansion=70N/mm2 × 70879mm2 

=4961530N, F lock=F expansion/K, K=0.85 F lock

=4961530N/0.85=5837094N=5837.094 kn 

The model with 6300kn locking force can be selected, and the DCC630 model is selected as the force machine.

3. Calculate the weight of molten alloy

Net weight of casting G1=1240g; Check the table to find out the liquid density of aluminum alloy ρ= 2.5g/cm3。 The average depth (thickness) of runner system G2 is 7mm (0.7cm)

G2=V2  ρ= A2 × zero point seven × 2.5=186g 

Residual material (cake) G3 is set with a thickness of 30mm (3cm) G3=V3

ρ= A3 × three × 2.5=288.5g 

The overflow channel depth of overflow system G4 is 6mm (0.6cm)

G4=V4  ρ= A4 × zero point six × 2.5=90.8g Total weight of molten metal poured

G=G1+G2+G3+G4 =1.81kg 

4. Check the filling degree of the pressure chamber

(1) When DCC400 is selected, the punch diameter φ 70 pouring volume is 3.6kg filling degree φ= 1.81/2.6 × 100%=50.3%, the filling degree is usually 40%~75%, and DCC400 selected above meets the requirements.

(2) When DCC630 is selected, the punch diameter φ The pouring amount of 70 is 4.3kg filling degree φ= 1.81/4.3 × 100%=42.1% DCC630 also meets the requirements.

5. The relationship between the die casting mould (die) and the size of the machine mold is found out. In DCC400 and DCC630 models, check the technical parameters such as the die thickness, die thickness, the travel of the movable seat plate, and the internal dimensions between the pull rods. Check whether the corresponding dimensions of the designed die casting mould (die) meet the requirements.

6. Check the injection energy. Analyze the maximum metal static pressure and flow P-Q2 relationship diagram of the injection system, and check whether the injection performance of the selected die casting machine can meet the required energy requirements. After checking the machine parameters, the die-casting machine model can be determined theoretically.

4、 Statistics on the actual selection of die-casting machines in Japan Statistics on the actual selection of die-casting machines (Japan)

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