Trushape is a gravity die casting foundry in India pouring aluminium alloys into reusable dies designed in-house, for dense, repeatable castings from 0.1 to 3 kg (0.22 to 6.6 lb), held to ISO 8062-3 DCTG 7 to 9 and heat treated, machined and tested under one roof for buyers across North America and Europe.
Gravity die casting, also called permanent mould casting (permanent mold casting in the US, Kokillenguss in German, moulage en coquille par gravité in French), is a casting process in which molten metal is poured into a reusable die and fills it under gravity alone, with no applied pressure. The die is preheated and coated, opened once the metal has solidified and used again, so every casting comes from the same cavity.
Trushape Precision Castings is an ISO 9001, ISO 14001, ISO 45001 and ISO 13485 certified gravity die casting foundry in Bhavnagar, Gujarat, India. We cast aluminium alloy parts from 0.1 to 3 kg (0.22 to 6.6 lb) in dies designed in-house, hold ISO 8062-3 DCTG 7 to 9, and heat-treat, CNC machine and test them under one roof for buyers across the United States, Canada, Mexico, the United Kingdom and the European Union.
Follow one aluminium housing, from the die that shapes it to a finished, inspected casting. The die is made once; steps two to six repeat, in the same die, for every casting it makes.
Every die is designed in-house, and made in-house or by a partner toolmaker when required. Each half is CNC machined: the cavity is cut to the part plus the shrinkage the metal loses as it cools, with the sprue, runner, riser and vents in the same face.
The die halves are heated to their working temperature, around 400 °C (about 750 °F), and sprayed with a refractory coating. The coating controls how fast heat leaves the metal, protects the die face and helps the casting release.
A core rises into the cavity to form the bore, then the moving half closes against the fixed half and the die is clamped. Passages a solid core could not be pulled out of can be formed with sand cores instead.
Molten aluminium at around 680 to 750 °C (1,256 to 1,382 °F) is poured from a ladle into the basin. It runs down the sprue and rises through the cavity from the bottom, calmly and with no applied pressure, until it fills the riser.
The die draws heat out fast, so the metal freezes into a dense, fine grain. It solidifies from the bottom towards the riser, which stays liquid longest and feeds the shrinkage of the casting below it.
The moving half opens, the core is pulled and ejector pins push the casting out of the fixed half. The die is coated again where needed, closed, and the next casting is poured into the same cavity.
The sprue, runner and riser are cut off. They are clean metal of the same alloy, so they go back to the furnace to be melted again.
Aluminium castings are solution treated, quenched and aged to the T6 temper, then faced, bored and drilled on our CNC machines and inspected to your drawing, so parts leave ready to assemble.
A gravity die is a precision tool: two halves, a core, ejector pins and the channels that feed and vent the metal. Open it, take it apart and switch on X-ray to see how the pieces work together, pick a part to find it, and drag to turn the die.
An example die for the housing in the process above. Real dies are designed in-house for each part, and some add side cores, sand cores or more ejector pins.
A gravity die works like a heat exchanger that runs in a loop. It is coated, closed, filled, drained of heat, opened and emptied, then it does it all again, which is why its castings repeat so closely. Play the cycle, jump to a stage, or switch on thermal view to watch the heat move.
With the die open, the faces are sprayed with refractory coating where it has worn. The spray also takes a little heat off the die face.
The die is preheated to around 400 °C (about 750 °F). The other temperatures are indicative for an aluminium alloy casting and are shown to explain the cycle: real temperatures and cycle times depend on the part, the alloy and the die, and are set when a new die is tried.
Gravity die casting typically holds ISO 8062-3 grades DCTG 7 to 9, tighter than sand casting because the die repeats the same cavity every time. Slide to your nominal dimension and pick a grade to see the total tolerance it allows as-cast.
| Nominal size (mm) | Nominal size (in) | DCTG 7 | DCTG 8 | DCTG 9 |
|---|---|---|---|---|
| Up to 10 | Up to 0.39 | 0.74 | 1.0 | 1.5 |
| 10 to 16 | 0.39 to 0.63 | 0.78 | 1.1 | 1.6 |
| 16 to 25 | 0.63 to 0.98 | 0.82 | 1.2 | 1.7 |
| 25 to 40 | 0.98 to 1.57 | 0.90 | 1.3 | 1.8 |
| 40 to 63 | 1.57 to 2.48 | 1.0 | 1.4 | 2.0 |
| 63 to 100 | 2.48 to 3.94 | 1.1 | 1.6 | 2.2 |
| 100 to 160 | 3.94 to 6.30 | 1.2 | 1.8 | 2.5 |
| 160 to 250 | 6.30 to 9.84 | 1.4 | 2.0 | 2.8 |
| 250 to 400 | 9.84 to 15.75 | 1.6 | 2.2 | 3.2 |
Total casting tolerance in millimetres to ISO 8062-3. When the tolerance is symmetric, half of it applies either side of the nominal dimension, so DCTG 8 at 40 to 63 mm means ±0.7 mm (±0.028 in). Gravity die castings of 0.1 to 3 kg rarely exceed 400 mm; larger sizes are in the full table on our tolerances page. The grade for each part is agreed at drawing review, and tighter tolerances on critical features are reached by CNC machining.
Full ISO 8062-3 and VDG P690 tolerance tablesEvery route has a sweet spot. Pick a process to raise its profile in 3D and drag to turn the chart. The scores are relative and indicative; the right choice always depends on shape, size, volume, alloy and tolerance.
A reusable die, designed in-house, gives dense, fine-grained aluminium castings with a smooth surface and close tolerances, part after part. The die costs more up front and pays back with volume.
A ceramic mould around an expendable wax pattern gives the finest detail and the tightest tolerances of any casting process, near net shape, in almost any alloy, steels included.
A thin, rigid resin sand shell made on a heated metal pattern gives smoother, more accurate castings than other sand processes, with fast cycles for medium to high volumes of steel parts.
Chemically bonded sand sets at room temperature around a pattern, so tooling is simple and cheap, but every casting needs a new mould and passages need cores. We run no-bake sand from 3 to 40 kg.
A foam pattern in loose, unbonded sand forms internal passages, undercuts and curves with no cores and no parting line, so assemblies become single castings.
| Criterion | Gravity die | Investment casting | Shell molding | No-bake sand | Lost foam |
|---|---|---|---|---|---|
| Typical tolerance | ISO 8062-3 DCTG 7 to 9 | CT5 to CT7 (VDG P690) | DCTG 8 to 12 | DCTG 11 to 14 | DCTG 11 to 14 |
| Mould | Reusable die, designed in-house | Ceramic shell, one per casting | Resin sand shell, one per casting | Bonded sand, one per casting | Loose sand round a foam pattern |
| Weight at Trushape | 0.1 to 3 kg | 0.003 to 30 kg | 5 to 60 kg | 3 to 40 kg | 3.5 to 90 kg |
| Alloys | Aluminium alloys | Almost any | Carbon, low-alloy, stainless and tool steels, copper alloys | Most ferrous and non-ferrous | Almost any, except low-carbon grades |
| Surface as-cast | Smooth, from a coated die | Finest, Ra 3.2 to 6.3 µm | Smooth for a sand process | Sand texture | Coating texture, no parting line |
| Tooling | A die, the highest cost of the five, reused for the whole run | Moderate; none with 3D-printed patterns | Metal patterns, moderate cost | Low | Foam pattern tool, moderate cost |
| Best volumes | Medium to high | Prototypes to high volume | Medium to high | Low to medium | Medium to high |
Pick what your part needs most. The deck turns to the alloy we would start with, with ASTM, EN and UNS equivalents, relative ratings and the parts it usually goes into.
Need: Good castability, all-round use
Typical parts: pump housings, motor end shields, pulleys and general housings.
The all-round workhorse of gravity die: sound, light castings with good corrosion resistance, as cast or heat treated.
Need: Highest strength after T6
Typical parts: brackets, levers, and pump and valve bodies that need strength.
A higher-purity relative of LM25 that heat treats to T6 for the best strength and ductility.
Need: Thin, pressure-tight walls
Typical parts: electrical enclosures, covers, lighting housings, LED heat sinks and marine parts.
A eutectic alloy with excellent fluidity for thin, pressure-tight walls.
Need: Bright, corrosion-resistant finish
Typical parts: architectural hardware, marine fittings and instrument housings.
A bright finish and corrosion resistance with no need for heat treatment.
A starting point for engineers comparing cast grades across North American and European specifications. Final selection always follows your drawing, service conditions and governing standard.
| Alloy family | Common grades | Equivalents | Why it is chosen | Typical parts |
|---|---|---|---|---|
| Aluminium-silicon-magnesium | LM25 | EN AC-42000, BS 1490 | Sound, all-round castings, as cast or T6 | Pump housings, motor end shields, pulleys |
| Aluminium-silicon-magnesium | A356 | EN AC-42100, ASTM B108, UNS A13560 | The highest strength after T6 | Brackets, levers, pump and valve bodies |
| Aluminium-silicon | LM6 | EN AC-44100 type, BS 1490 | Fluidity for thin, pressure-tight walls | Enclosures, covers, LED heat sinks |
| Aluminium-magnesium | 535.0 | ASTM B26, UNS A05350 | Bright finish and corrosion resistance as cast | Architectural and marine hardware |
Equivalents are the closest common matches, shown for comparison. We cast to the ASTM, EN, BS or customer specification on your drawing and verify the chemistry of every heat by spectrometer. Steels and nickel alloys are cast by our investment, shell, no-bake and lost foam processes.
See all 50+ alloy gradesMost moulds are made for one casting and broken to free it. A gravity die is made once and filled again and again. Same cavity, same coating, same cycle, so every casting comes out like the last, from 0.1 to 3 kg, in aluminium alloys.
A die repeats the shape; testing proves the metal. We check what matters on site: the chemistry of every heat, the properties after heat treatment, the soundness of critical sections and every critical dimension against your drawing.
Every heat checked on Spectromaxx and Bruker spectrometers against your aluminium grade.
Test bars pulled to prove tensile strength, proof stress and elongation to your material specification.
Hardness checked after heat treatment, to the scale your drawing names.
Internal soundness of critical sections, to the acceptance level you specify.
Surface-breaking cracks and porosity on aluminium castings.
Leak tightness of pump and valve bodies, housings and fittings where your plan requires it.
Dimensional reports on bores, faces, profiles and datums against your drawing.
Electrical conductivity of aluminium castings, where the part needs it.
One record from melt to dispatch, ready for your incoming inspection and your customers' audits. Material certificates are issued to EN 10204 3.1 as standard, and to 3.2 when your order calls for independent inspection.
Good castings start on the drawing board. These are the guidelines our engineers use when they review a new gravity die part. Hover or tap a card to turn it over.
Parting line. Where the die splits sets the draft directions, where flash forms and where machining stock goes. Agree it at design review, before the die is cut.
Draft. A permanent die cannot be broken away, so walls need draft to release. Faces that shrink onto a core or pin need more draft than outside walls.
Walls. The die chills metal fast. Even walls fill and freeze evenly; blend thick to thin gradually and let heavy sections feed from a riser.
Corners. Fillets help the metal flow, cut stress in the casting and in the die, and make the die last longer.
Cores. Holes that a core can be pulled straight out of are cast in. Curved internal passages need sand cores, so we look at them together at design review.
Undercuts. The die opens in straight lines. An undercut needs a side core or a sand core, which adds cost, so move or machine it where you can.
Tolerances. Gravity die holds ISO 8062-3 DCTG 7 to 9. Features across the parting line or formed by moving cores vary most, so mark datums and we machine the few that need more.
Volume. A die pays back over medium to high volumes. For prototypes and small batches, investment casting or rapid manufacturing with printed patterns needs no die at all.
We work to the aluminium alloy, tolerance and inspection standards common on North American and European drawings, and to your own specification and inspection plan.
Trushape holds ISO 9001, ISO 14001, ISO 45001 and ISO 13485. We do not hold IATF 16949 or ASME approvals, so automotive, pressure-equipment and code parts are cast to your drawing, specification and inspection plan, and product approvals stay with you. We support them with samples, test data and full records. We also do not run high-pressure die casting: every part on this page is poured by gravity. PED certification is in process.
Download our certificatesAn export-focused foundry with a dedicated export desk, already shipping castings to Germany, the UK, Belgium, Denmark, Spain and Italy. Pick a region to trace the lane from Bhavnagar.
Motor, pump, lighting and machinery makers across Illinois, Ohio and the Great Lakes.
Vehicle, electrical and HVAC equipment makers around Toronto and Montreal.
Nearshore appliance, HVAC and vehicle assemblers in Nuevo León and the Bajío that need machined castings on schedule.
Engineering, pump and electrical equipment makers around Birmingham and Manchester.
Drive, motor and machinery suppliers in Baden-Württemberg and Franconia.
Lighting, electronics, pump and valve makers in the Netherlands, Belgium and France.
Electrical machine makers in Sweden, and valve and fitting makers in Lombardy.
Series parts travel by sea freight in export packing, and urgent samples by air. Delivery terms and documentation are agreed with our export desk for each order, and every shipment carries English certificates and reports.
Drag the ring or let it turn. Each part family is a classic gravity die shape, with the aluminium alloys we typically use for castings from 0.1 to 3 kg (0.22 to 6.6 lb).
AlloysLM25, A356
IndustryPumps and water
Bores and faces machined in-house.
AlloysLM25, A356 T6
IndustryFlow control
Pressure tested on request.
AlloysLM25, LM6
IndustryElectrical machines
Bearing seats machined to drawing.
AlloysLM6
IndustryElectrical
Thin, pressure-tight walls.
AlloysLM6
IndustryLighting and LED
Fins cast in one piece.
AlloysLM6
IndustryLighting
A smooth surface, ready to finish.
AlloysLM25
IndustryPower transmission
Grooves and bores machined in-house.
AlloysA356 T6
IndustryVehicles and machinery
Light and strong after T6.
AlloysLM6, 535.0
IndustryMarine
Alloys chosen for seawater.
Alloys535.0
IndustryArchitectural hardware
A bright finish for handles and fittings.
Buyers in North America and Europe move gravity die work to us for the same six reasons.
Casting, heat treatment, CNC machining, finishing and testing in one 100,000 sq ft facility, which cuts lead times by 30 to 40%.
IntegratedGravity die, investment casting, shell molding, no-bake sand, lost foam and rapid manufacturing under one roof, so every part gets the route that suits its shape, size and volume.
6 processesLM25, A356, LM6 and 535.0, melted under control, verified by spectrometer every heat and heat treated to T6 in-house where the grade calls for it.
Al alloysISO 8062-3 DCTG 7 to 9 as-cast from a die that repeats, critical features machined, and every critical dimension verified on a Zeiss CMM.
DCTG 7 to 9ISO 9001, 14001, 45001 and 13485 systems, in-house NDT and an EN 10204 3.1 certificate with every batch.
Audit readyA dedicated export desk, English documentation and export packing for sea or air freight, plus a proven China-plus-one option.
NA and EuropeFrom carved stone moulds to dies designed by simulation, the idea is the same: a mould you can pour again.
Smiths carved reusable moulds in stone to cast tools, coins and ornaments again and again: the first permanent moulds.
As aluminium became affordable, foundries turned to reusable dies, for more consistent castings with smoother surfaces than sand could give.
Demand for light aircraft parts in the First World War, then for pistons and cylinder heads, made gravity die casting an industrial process.
Automated and tilt-pour machines raised output, alloys such as A356 and LM25 were refined for permanent moulds, and ISO 8062 gave casting tolerances a common language.
Casting simulation and CNC-machined dies made new dies faster to prove, and automated inspection made every casting easier to check.
Trushape casts aluminium gravity die parts from 0.1 to 3 kg in dies designed in-house, then heat-treats, machines and inspects them under one roof.
Gravity die casting, also called permanent mould casting (permanent mold casting in the US), pours molten metal into a reusable die, which it fills under gravity alone, with no applied pressure. The die is preheated and coated, opened once the metal has solidified and used again for the next casting. In German it is Kokillenguss and in French moulage en coquille par gravité.
The two halves of the die are preheated to around 400 °C (about 750 °F) and sprayed with a refractory coating. Cores are set, the die is clamped shut and molten aluminium is poured in from a ladle. The metal solidifies quickly against the die face, the die opens, ejector pins push the casting out, and the sprue and riser are cut off before heat treatment and machining.
It makes dense, repeatable aluminium parts in medium to high volumes, such as pump housings, valve bodies, motor end shields, electrical enclosures, lighting housings, LED heat sinks, brackets and pulleys. At Trushape it covers castings from 0.1 to 3 kg (0.22 to 6.6 lb) for pump, valve, electrical, lighting, vehicle, marine and hardware makers.
Gravity die casting typically holds ISO 8062-3 grades DCTG 7 to 9, depending on size, geometry and alloy. For a 40 to 63 mm (1.57 to 2.48 in) dimension that is a total tolerance of 1.0 to 2.0 mm (0.039 to 0.079 in), or ±0.5 to ±1.0 mm. The die repeats the same size casting after casting, and critical features are machined on our CNC machines.
Our gravity die line casts parts from 0.1 to 3 kg (0.22 to 6.6 lb). Heavier parts move to shell molding, up to 60 kg, or lost foam, up to 90 kg, and the smallest, most intricate parts to investment casting from 0.003 kg, so one supplier covers every size.
At Trushape, gravity die casting is for aluminium alloys: LM25 and A356 for sound, strong castings that heat treat to T6, LM6 for thin, pressure-tight walls and 535.0 for a bright, corrosion-resistant finish as cast. The chemistry of every heat is checked by spectrometer. Steels and nickel alloys are cast by our investment, shell, no-bake and lost foam processes.
Both pour metal by gravity, but sand casting makes a new mould for every casting, while gravity die casting reuses the same die. The die gives a smoother surface, closer tolerances (DCTG 7 to 9, against DCTG 11 to 14 for our sand processes) and a finer grain from faster cooling. Sand costs less to tool, so it suits low volumes and larger parts.
Both cast into a reusable die. In gravity die casting the metal flows in under its own weight, which gives sound castings that can be heat treated. High-pressure die casting injects metal at high speed and pressure for thinner walls and faster cycles, but trapped gas usually rules out heat treatment. Trushape pours by gravity only and does not offer high-pressure die casting.
Gravity die casting reuses the same die, so it suits medium to high volumes of aluminium parts from 0.1 to 3 kg at DCTG 7 to 9. Investment casting makes a new ceramic mould around a wax pattern for every casting, for finer detail, CT5 to CT7 tolerances, steels and superalloys, and parts from 0.003 to 30 kg.
Die life depends on the alloy, the shape of the part and how well the die is maintained, re-coated and stored between runs, so we do not quote a fixed number of castings. Our dies are designed in-house and made in-house, or by a partner toolmaker when required. A die costs more than a sand pattern and pays back over medium to high volumes; for prototypes and small batches we suggest investment casting or rapid manufacturing instead.
Reusable moulds are ancient: early smiths carved moulds in stone to cast tools again and again. Reusable dies for aluminium came into use in the early 1900s, and demand for light aircraft parts in the First World War, then for pistons and cylinder heads in the 1920s and 1930s, made gravity die casting an industrial process.
Yes. Trushape exports castings to Germany, the UK, Belgium, Denmark, Spain and Italy and serves buyers across North America and Europe, including the United States, Canada and Mexico. Parts ship by sea or air freight with English documentation and EN 10204 3.1 certificates, and delivery terms are agreed per order.
One die, poured again and again, so every casting matches the last. Trushape casts, heat-treats, machines and verifies aluminium gravity die parts under one roof for manufacturers across North America and Europe.