Manufacturing process

Casting

Casting forms metal parts by pouring or injecting molten alloy into a mold, which suits complex shapes, internal passages and parts that would be wasteful to machine from solid.

Process overview

Casting enables metal parts to be produced by forming molten material within a mold or die. Depending on geometry, material, quantity and performance requirements, manufacturing routes can include sand casting, investment casting, die casting and other specialized methods. Projects may require control of alloy grade, dimensional tolerances, machining allowances, heat treatment, surface quality and inspection.

The main casting routes differ in mold type and economics. Sand casting uses expendable sand molds made from a pattern and handles large parts and low volumes with modest tooling cost. Investment (lost-wax) casting reproduces fine detail and thin sections in steels and superalloys. High-pressure die casting injects aluminium, zinc or magnesium into steel dies at high speed and suits high-volume, thin-walled parts. Gravity and low-pressure die casting, centrifugal casting and lost-foam casting fill niches in between.

Most castings are not finished parts: functional faces, bores and threads are usually machined afterwards, so the drawing should show machining allowances and datums. Casting integrity depends on gating, feeding and solidification. Porosity, shrinkage and inclusions are controlled through method design and process control and, where the application requires it, verified by non-destructive testing.

Pattern and die costs, minimum quantities and lead time to first samples differ considerably between routes, so the right method depends on part size, alloy, quantity and required integrity.

Typical capabilities & what manufacturers can produce

What manufacturers can produce

  • Pump, valve and compressor housings
  • Gearbox and machine housings, bases and brackets
  • Thin-walled aluminium die-cast covers and housings
  • Investment-cast impellers, levers and small complex parts
  • Heavy sand castings such as frames and machine beds
  • Cast and machined, ready-to-assemble components

Capabilities under this process

Suitable materials

Materials commonly used with this process — an editorial reference, not a statement about facilities in the Metraxio network. Suitability always depends on the part and its application.

  • Cast Iron

    Grey and ductile iron for housings, bases and pump bodies.

  • Aluminum

    Sand, gravity and die casting for lightweight housings.

  • Stainless Steel

    Investment and sand castings for valves and food equipment.

  • Carbon Steel

    Steel castings for heavy equipment and valve bodies.

  • Bronze

    Bearings, bushings and marine parts.

  • Brass

    Valve bodies and fittings.

  • Zinc

    Small, detailed die-cast parts.

  • Magnesium

    Very light die-cast housings.

  • Nickel Alloys

    Investment castings for high-temperature or corrosive service.

Relevant industries

Industries whose Metraxio industry guides list Casting as a common process, with the typical use in each.

What buyers should specify

The details that make Casting quotes comparable and let facilities be assessed on the right criteria.

Casting and machining drawings
Separate or combined, showing machining allowances, datums and draft.
Alloy and standard
For example EN-GJS-400-15 ductile iron, EN-GJL-250 grey iron, AlSi9Cu3 or cast stainless 1.4408.
Casting method
Sand, investment or die casting if already decided — or left open for the foundry to propose.
Part weight and annual volume
The two main inputs for method selection and pattern or die investment.
Pattern or die
Existing tooling or new tooling, and who owns it.
Integrity requirements
Porosity limits, NDT (RT, PT, MT), pressure testing and mechanical test bars.
Heat treatment and surface
For example T6 for aluminium, annealing, shot blasting or priming.
Documents
Material certificates (EN 10204 3.1), first article and dimensional reports.

On Metraxio these details become a structured manufacturing requirement. Processes, capabilities, materials, certifications and part size are checked against facility profiles; tolerances, finishes and inspection details travel with your drawings and are reviewed during quoting rather than used as automatic filters.

Frequently asked questions

Sand casting or investment casting?

Sand casting suits larger parts and lower tooling budgets. Investment casting offers better surface finish, finer detail and tighter as-cast tolerances on smaller parts, at a higher cost per kilogram. Size, alloy, detail and volume decide.

Do I need a new pattern or die?

If no suitable tooling exists, yes. Costs vary by method: die-casting dies are the most expensive but give the lowest piece price at volume, while sand-casting patterns are comparatively inexpensive.

How are internal casting defects checked?

Depending on the application, foundries use radiography, dye penetrant, magnetic particle or pressure testing. The method and acceptance level should be defined in the requirement.

Casting by country

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