High-pressure die casting machine

01

Set fill time and gate velocity for the casting

Majernikova and co-authors (MM Science Journal, December 2024) review gating design for high-pressure die casting. They state that too short a fill time leaves gases in the cavity and raises porosity, while too long a fill time lets the flow front cool so streams fail to join. Czech standard CSN 22 8601 recommends fill times by predominant wall thickness, for example 0.01–0.03 s below 1.5 mm, 0.04–0.09 s below 2.5 mm and 0.08–0.30 s below 6.3 mm. [1]

They give NADCA's fill-time relation t = K × (T_G − T_LIK + S × Z) / (T_LIK − T_D) × h_CH, with K = 0.0346 s/mm for H13 or H21 die steel with aluminium, permissible solidification S of 20–50% for 2–3 mm aluminium walls, and Z = 4.8 °C/% for hypoeutectic AlSi alloys such as 380. Recommended gate velocities are 20–60 m/s for aluminium (15–30 m/s with vacuum), 40–90 m/s for magnesium and 20–30 m/s for zinc; machines can reach 100 m/s, but moulds begin to degrade at about 40 m/s. [1]

Editorial calculation: with assumed gate temperature 650 °C, liquidus 595 °C, die 230 °C, S = 30% and a 2.5 mm wall, t = 0.0346 × (650 − 595 + 30 × 4.8) ÷ (595 − 230) × 2.5 ≈ 0.047 s, inside the CSN range. Filling 300 cm³ of casting and overflows in 0.047 s at 40 m/s needs a gate area of about 300 ÷ (40 × 0.047) ≈ 159 mm². Ask the machine supplier to confirm its shot end reaches the needed flow and pressure. [1]

Give the supplier the alloy, casting drawing with projected area and wall thickness, shot weight with runners and overflows, target fill time and gate velocity, required intensification pressure, die size and height, cycle time, extraction, spraying and trimming automation, vacuum assistance, and safety and power requirements.

02

Size the clamping force against the separating force

The clamping unit must hold the die closed against the separating force, the cavity pressure acting on the projected area of the casting plus runners and overflows in the parting plane. The same paper describes the injection as pressing liquid metal into the cavity at high speed and pressure through a complex motion system, naming porosity as the main defect. [1]

Editorial calculation: at an assumed intensification pressure of 60 MPa on a projected area of 500 cm² (0.05 m²), the separating force is 60 × 10⁶ × 0.05 = 3,000 kN; with an assumed 20% margin the machine needs about 3,600 kN of locking force. Use the cavity pressure your casting quality needs and the full projected area, then ask suppliers for the locking force, tie-bar spacing and die height that fit your die.

Editorial note: the supplier listed below makes cold-chamber machines; ask for the shot-end performance diagram (pressure against flow) of the offered size so the fill time and gate area above can be checked against it.

03

Check the casting area each plunger diameter allows

HMT Machine Tools' specification page for its H 250D horizontal cold-chamber machine shows how one clamp size serves different castings by changing the plunger. It lists 250 tonnes of locking force, an adjustable injection force of 38 tonnes with intensifier, 500 × 550 mm between tie bars, die height 225–750 mm and a 350 mm injection plunger stroke, with the 60 mm plunger as the standard shot sleeve. [4]

Editorial calculation: 38 tonnes on the 60 mm plunger (28.3 cm²) gives 38,000 ÷ 28.3 ≈ 1,343 kg/cm², matching the listed 1,345 kg/cm², and 250 tonnes ÷ 1,345 kg/cm² ≈ 186 cm², matching the 185 cm² casting area. In SI units 1,345 kg/cm² is about 132 MPa and 250 tonnes about 2,450 kN. [4]

The same page lists a free cycle time of 5.5 s, a 22.4 kW motor, a 550 litre oil tank, a machine weight of 10 tonnes and a machine area of 5.9 × 1.6 m. Ask for these values for the size you are offered so the foundation, power supply and cell layout can be planned. [4]

04

Read the machine data sheet: locking force, shot end and casting area

IDRA's XPRESS cold-chamber catalogue tabulates, for each size, clamping force, stroke, die height, platen and tie-bar dimensions, ejection force, injection force and stroke, plunger diameters, shot weight, intensified casting pressure by plunger, the casting area that pressure allows and a maximum casting area at 400 bar, with a working pressure of 160 bar. [2]

Shibaura Machine's DC-J series lists, for the DC250J, 2,500 kN die locking force, 580 × 580 mm tie-bar spacing, 300–600 mm die height and 360 mm die stroke, with injection speed of 0.1–7.0 m/s (SC), 0.05–8.0 m/s (MS) and 0.05–13.0 m/s (MH) depending on the shot-end variant. [3]

Editorial calculation: 3,000 kN ÷ 400 bar (40 MPa) = 0.075 m² = 750 cm², matching IDRA's maximum casting area; 419 kN on a 70 mm plunger (3,848 mm²) gives about 1,089 bar and on a 50 mm plunger (1,963 mm²) about 2,134 bar, matching the 1,050–2,100 bar range, so a smaller plunger raises metal pressure and lowers shot weight. For the 500 cm² example above at 600 bar, the 300 S covers 3,000 kN ÷ 60 MPa = 500 cm² with no margin, so the 3,600 kN with margin points to the 4,360 kN size. [2]

Ask for the full data sheet and shot-end performance (P–Q) diagram for the offered plunger, plus injection speed range with and without metal, and check casting area at your intensification pressure.

05

Cold-chamber high-pressure die casting machines from the listed supplier

Listings include cold-chamber high-pressure die casting machines.

06

Shot end, shot sleeve and plunger, clamping unit, die, hydraulic unit and cell automation

The shot sleeve and plunger are the part to choose per casting: on HMT's H 250D the same 250-tonne clamp covers 82 cm² of casting area with a 40 mm plunger and 373 cm² with an 85 mm one. [4]

07

Clamping force, casting pressure, injection speed, shot weight, platen and die height for a machine quotation

Clamping force follows from cavity pressure and projected area, and the published machines span 2,500 to 7,500 kN; the fill time and gate velocity worked out above decide which shot end and plunger the offer needs. [2] [3] [1]

08

Send the casting, shot and cell data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Casting: [alloy; projected area; wall thickness; weight]
Shot: [fill time; gate velocity; intensification]
Die: [size; height; vacuum]
Clamp: [locking force; tie-bar spacing]
Cell: [ladling; spraying; extraction; trimming]
Output: [cycle time; annual volume]

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