Die Casting Machine Troubleshooting: Causes & Fixes

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Problems on this page:

Gas porosity in castings Die soldering or part sticking Excessive flash at the parting line Short shot or incomplete fill Heat checking on the die Shrinkage porosity Ejector marks or bent castings Plunger tip or shot sleeve wear

Gas porosity in castings

Hits OEE: Quality

Symptoms: Voids or blisters found on machining or X-ray, leak-test failures, blistering after heat treat, scrap concentrated on specific cavities.

Air trapped by turbulent fill

Reduce gate velocity or re-time the shot so the cavity fills more smoothly; review runner and gate design.

Inadequate die venting or vacuum

Clean and enlarge vents; check the chill-vent or vacuum-valve seals and timing.

Excess die lubricant or plunger lube gassing off

Cut spray volume and extend blow-off; switch to a lower-residue lubricant and confirm the die is dry before the shot.

Low metal or die temperature

Raise holding-furnace and die temperature to spec so gas escapes before freeze-off.

Prevention: Vent and vacuum maintenance, controlled lube spray with blow-off, metal and die temperature control, shot-profile verification; log scrap by cavity to catch drift early.

Die soldering or part sticking

Hits OEE: Availability

Symptoms: Aluminium welds to the die face, parts stick and tear on ejection, rising cycle time, drag marks and pickup on the casting surface.

Insufficient or failed die-release lubricant

Restore even lube coverage on the hot spots; check spray pattern, nozzle blockage and dilution ratio.

Metal temperature too high

Lower the holding-furnace temperature toward the low end of the alloy window; verify the thermocouple.

Localised die hot spots or poor cooling

Check cooling-line flow to the affected insert; clear scaled or blocked cooling channels.

Worn or damaged die surface or coating

Inspect and re-polish or re-coat the affected area; correct low alloy iron content that promotes soldering.

Prevention: Die-temperature mapping and cooling-line checks, disciplined lube coverage, alloy chemistry control, scheduled die-surface inspection.

Excessive flash at the parting line

Hits OEE: Quality

Symptoms: Thin metal fins along the parting line or slides, heavy trim load, dimensional creep, flash breaking off into the die.

Insufficient clamp or tie-bar force

Check clamp tonnage and tie-bar strain balance; correct for projected area and intensified pressure.

Worn or damaged parting faces

Blue-check the parting line; dress or repair worn faces and slide fits.

Intensification pressure too high for the die

Trim intensification to the minimum that still fills and feeds; recheck for shrink before cutting further.

Die deflection or debris on the face

Remove flash and debris every cycle; check for die deflection and support the affected area.

Prevention: Tie-bar strain balancing, parting-face inspection, right-sized clamp for projected area, keep faces clean; trend flash by shot to catch tie-bar drift.

Short shot or incomplete fill

Hits OEE: Quality

Symptoms: Rounded or missing edges, unfilled thin sections and far cavities, non-fill at the vents, rejects rising on cold starts.

Low metal or die temperature

Raise metal and die temperature to spec; let the die reach thermal steady state before running parts.

Insufficient shot volume or biscuit too short

Increase the metal charge and set the correct biscuit thickness; check ladle accuracy.

Slow injection or low intensification pressure

Raise fast-shot velocity and intensification to fill before freeze-off; verify the accumulator pre-charge.

Blocked gates or vents

Clean sprayed-up gates and vents; confirm runner and gate cross-section against the part program.

Prevention: Thermal warm-up discipline, verified shot weight and biscuit, accumulator pre-charge checks, gate and vent cleaning; log fill rejects by cavity.

Heat checking on the die

Hits OEE: Availability

Symptoms: A fine network of cracks on the die surface shows as raised lines on the castings.

Large temperature swings each shot

Preheat the die before production and keep die temperature stable.

Too much spray cooling the surface

Spray only as much release agent as the die needs.

Die steel or heat treatment

Review the steel and heat treatment with the toolmaker.

Stress relief overdue

Stress relieve dies on the schedule the toolmaker gives.

Prevention: Die surface inspection at every die change.

Shrinkage porosity

Hits OEE: Quality

Symptoms: Irregular voids in thick sections and leaks at pressure test.

Thick sections not fed during solidification

Review the casting design and the gating.

Intensification pressure low or late

Check the third phase pressure and timing.

Hot spots in the die

Check the die cooling.

Metal temperature too high

Check the holding furnace.

Prevention: X-ray or section checks on new dies and after changes.

Ejector marks or bent castings

Hits OEE: Quality

Symptoms: Deep pin marks, bent or cracked castings at ejection.

Casting too hot at ejection

Lengthen the cooling time.

Uneven ejection

Check the pins and the ejector plate.

Casting sticking in the die

Check die release and draft.

Prevention: First-off checks after die work.

Plunger tip or shot sleeve wear

Hits OEE: Availability

Symptoms: The plunger sticks, metal flashes behind the tip, shots are inconsistent.

Tip lubrication missing

Check the plunger lubrication.

Shot sleeve worn

Measure and replace the sleeve.

Plunger tip worn

Replace the tip on a planned shot count.

Prevention: Tip and sleeve life tracked in shots.

Guidance only. Molten metal and stored hydraulic and accumulator energy are lethal: follow lockout/tagout, isolate and dissipate accumulator pressure, and verify against OEM manuals before acting.

Related equipment guides: injection moulding · hydraulic system · electric motor · PLC controls

Stop the same defect coming back

Recurring porosity, soldering and short shots usually trace to a process drift you cannot see by hand: a creeping die temperature, a slipping shot profile, a stack of unlogged micro-stops between good castings. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring defects: the six big losses · root cause analysis · FMEA · preventive vs predictive maintenance · OEE in metals & foundry