Sandgjutning

sandgjutning is a traditional metal casting process that uses a sand mold to transfer a pattern into a furnace or furnace-like environment. The sand, typically a mixture of silica, clay, and water, is poured around a pattern creating a negative cavity. Molten metal is then poured into this cavity, taking the shape of the pattern. Once the metal cools and solidifies, the sand is removed, revealing the final casting.

The technique has roots in ancient civilizations, with evidence of sand casting found in Roman, East Asian, and sub-Saharan African cultures. Modern sandcasting evolved during the Industrial Revolution, where improvements in sand binders, retorts, and pouring equipment increased efficiency and quality. Today, sandgjutning is employed across industries for its versatility in producing complex shapes and its cost effectiveness for moderate production runs.

Key materials include casting sand (silicon dioxide rich sand), binders such as bentonite clay or synthetic polymers to add cohesion, and pattern materials ranging from wood and metal to high‑temperature composites. The mold is usually vented through small channels to release gases, preventing defects.

Advantages of sandgjutning include the ability to cast large or irregular components, minimal need for expensive die tooling, and the potential for rapid prototyping. However, it typically results in a lower surface finish and dimensional accuracy compared to investment casting or machining. The process also generates waste that must be managed; however, sand can often be reclaimed and reused after cleanup.

Modern adaptations, such as computer‑controlled molding and vapor‑phase binders, have improved repeatability and efficiency. Sandgjutning remains a foundational skill in foundry training and continues to be critical for manufacturing a wide range of metal parts.