Sand and permanent mold casting, ready for your production line.
Aluminum-silicon alloys and other nonferrous metals, with in-house patternmaking, CNC machining and dimensional inspection in the same operation: from drawing or sample to a ready-to-install part.
The most direct route from an idea to a complex metal part.
Casting means pouring molten metal into a cavity that reproduces the negative shape of the part and letting it solidify. Compared with machining from solid, casting produces internal cavities, ribs, channels and organic shapes that would be costly or impossible to machine, with far better material yield and a cost per part that drops as the run grows.
At Fundimoldes, casting isn’t an isolated process. It starts in engineering —where the parting line, cores, feeding and machining allowances are decided—, continues in our in-house pattern shop, where patterns, match plates and core boxes are built, and ends with CNC machining and dimensional validation. That short chain reduces handoffs between suppliers and keeps the technical traceability of every pour.
Our main family is aluminum-silicon alloys: silicon improves the fluidity of the molten metal and reduces the tendency to crack, making it possible to fill thin walls and demanding geometries with good dimensional stability.
Typical values for Al-Si alloys. Actual capability is validated per project based on geometry, weight, material and tolerances.
From pattern to cast part.
Aluminum casting
Green sand, gas-cured sand and permanent mold for industrial components, plates and mold parts.
02 / 04Casting patternmaking
Patterns, match plates, core boxes and auxiliary elements with shrinkage already compensated.
03 / 04Permanent molds and gravity dies
Repetitive casting with manual, semi-automatic, and automatic systems.
04 / 04Engineering and design
3D CAD, reverse engineering and production-ready technical documentation.
Sand or permanent mold: how the molding system is chosen.
The molding system defines precision, finish, mechanical properties and, above all, the economics of the project. The general rule: sand wins on flexibility and low tooling cost; permanent molds win on repeatability, finish and properties when demand is recurring.
| Criterion | Green sand | Gas-cured sand | Permanent mold |
|---|---|---|---|
| What the mold is | Silica sand with clay and controlled moisture, compacted over the pattern. Destroyed with every pour. | Sand with a gas-cured binder. A more rigid, dimensionally stable mold. | Machined metal mold, reusable for thousands of pours. |
| As-cast tolerance | ISO 8062 · DCTG 10–13 | ISO 8062 · DCTG 9–12 | ISO 8062 · DCTG 7–9 |
| Typical roughness | Ra 12,5–25 µm | Ra 6,3–12,5 µm | Ra 3,2–6,3 µm |
| Minimum wall in aluminum | ≈ 4–5 mm | ≈ 3–4 mm | ≈ 3–4 mm |
| Draft angle | 1–3° | 1–2° | 2–3° external, more on internal faces |
| Tooling investment | Low: pattern and plate | Low to medium: pattern and core boxes | High: permanent mold machined from steel or cast iron |
| Competitive volume | One-offs, spare parts and short or medium runs | Technical parts with complex cores | Repeat runs of hundreds to thousands of parts |
| Microstructure | Slow cooling, coarser grain | Similar to green sand | Fast cooling against metal: fine grain and better mechanical properties |
Tolerance grades per ISO 8062-3 for aluminum alloys; industry reference values. Functional surfaces are brought to final dimension by CNC machining.
The alloy is chosen for function, not habit.
Each alloy balances fluidity, strength, machinability, heat-treatment response and corrosion behavior differently. These are the reference families most used in gravity casting.
| Alloy | EN designation | Characteristics | Typical applications |
|---|---|---|---|
| A356 · AlSi7Mg | EN AC-42100 | Excellent castability, good ductility and corrosion resistance. Accepts T6 treatment, which markedly increases its strength. | Structural components, plates, housings, mold parts |
| A413 · AlSi12 | EN AC-44100 | Eutectic composition: the highest fluidity in the family. Very good pressure tightness; not heat-treatable. | Thin walls, sealed housings, hard-to-fill geometries |
| AlSi10Mg | EN AC-43000 | A balance of fluidity and strength; heat-treatable with good weldability. | Technical parts, brackets, machinery components |
| 319 · AlSi6Cu4 | EN AC-45000 | Copper adds high-temperature strength and good machinability, at the cost of lower corrosion resistance. | Components operating at temperature, blocks and bodies |
| Bronzes and other nonferrous alloys | Per specification | High wear and corrosion resistance. Evaluated by application and volume. | Bushings, friction parts, components exposed to moisture |
The final alloy is defined with you based on function, operating environment, subsequent machining and heat-treatment requirements.
Eight stages, one operation.
The quality of a casting is decided long before the metal is poured. This is how a project moves through the plant.
Design review
Wall thicknesses, section changes, radii, parting line and surfaces to be machined.
Gating system
Sprue, runners, gates and risers to fill without turbulence and feed the zones that solidify last.
Patternmaking
Pattern, match plate and core boxes with shrinkage and machining allowances already built in.
Molding and cores
Preparation of the sand mold or permanent mold and placement of cores, inserts or cooling coils.
Melting and melt treatment
Temperature control, degassing and melt cleaning to reduce porosity and inclusions.
Gating and solidification
Controlled filling and directional cooling from thin sections toward the feeders.
Demolding and cleaning
Sand removal, cutting off the gating and feeding system, and surface preparation.
Machining and validation
CNC on functional surfaces, visual inspection, dimensional inspection and 3D scanning against CAD.
Six design decisions that make a casting cheaper and better.
Most defects and cost overruns originate in the drawing. Reviewing these points before requesting a quote shortens lead times and improves the result.
Uniform wall thickness
Isolated masses solidify last and cause shrinkage cavities. Keep walls uniform and make gradual transitions between sections.
Generous radii
Sharp internal corners concentrate stress and create hot spots. An internal radius on the order of the wall thickness is a good starting point.
Draft angles
1° to 3° on vertical walls lets the pattern be drawn without damaging the mold. In permanent molds, internal faces need more draft.
Defined machining allowances
Every surface to be machined needs a material allowance agreed in engineering and clear datums for fixturing the part.
Parting line and cores
Every core adds cost and a source of variation. Simplifying internal cavities or aligning them with the parting line reduces both.
Inserts and cooling coils
Tubes or metal components can be embedded during pouring. They need supports in the mold and a design that ensures bonding without melting the insert.
Casting defects have known causes and are controlled through the process.
A sound casting doesn’t depend on luck at the pour. These are the most common defects in aluminum and how they’re prevented.
| Defect | What causes it | How it’s controlled |
|---|---|---|
| Gas porosity | Molten aluminum absorbs hydrogen from moisture and releases it on solidifying, forming rounded pores. | Melt degassing, dry and preheated tools and ladles, sand with controlled moisture. |
| Shrinkage cavities | Zones that solidify last with no metal available to compensate for shrinkage. | Properly sized risers, chills and a design aimed at directional solidification. |
| Oxide inclusions | Oxide films and dross carried in by turbulent filling. | Gating systems that slow the metal, ceramic filters and melt cleaning. |
| Cold shut or misrun | Metal fronts that lose temperature before they meet. | Proper pouring temperature, well-placed gates and respect for minimum wall thickness. |
| Hot tears | Shrinkage restrained by the mold during the solidification range. | Adequate radii, collapsible cores and alloy selection. |
| Sand defects | Low permeability or uneven mold compaction. | Sand control, mold venting and coatings. |
Standard acceptance criteria: visual inspection, dimensional inspection and 3D scanning according to scope. Additional testing such as dye penetrant, radiography or leak testing is quoted separately.
Where our castings end up.
What we’re asked most about casting.
When is a permanent mold better than sand?
When demand is recurring and the volume allows the tooling to be amortized. As a reference, a permanent mold starts to pay off in runs of hundreds or thousands of parts; for single units, spare parts or small batches, sand is usually cheaper and faster to set up.
Can you cast from an existing or damaged part?
Yes. The part is captured through 3D scanning or reverse engineering, the CAD model is rebuilt to compensate for wear and shrinkage, and the patterns are made from it.
What tolerances can I expect on a cast part?
The as-cast part is governed by casting tolerance grades that depend on the process and size. Surfaces that require fitting, sealing or mounting are CNC machined to final dimension.
Why does porosity appear in an aluminum part?
Because of hydrogen dissolved in the molten metal or unfed shrinkage. The first is controlled with degassing and moisture control; the second with feeding design and uniform wall thicknesses.
Can the parts be heat treated?
When the alloy allows it, such as A356 or AlSi10Mg. The required treatment is defined in the technical proposal along with the acceptance criteria.
What information do I need for a quote?
A drawing or 3D model (or a physical sample), material, quantity, functional surfaces, tolerances and operating conditions. With photos and approximate dimensions we can give you initial guidance.