Diestøping

Diestøping, commonly known as die casting, is a metal casting process in which molten metal is forced under high pressure into a steel mold called a die. The method yields parts with high dimensional accuracy, a smooth surface finish, and excellent repeatability, making it well suited for high-volume production.

The process involves two main machine types: hot-chamber and cold-chamber. In a hot-chamber machine, the injection mechanism is immersed in the molten metal, while in a cold-chamber machine the metal is ladled into a separate shot sleeve. Molten metal is injected at high velocity and pressure, rapidly filling the die before the metal solidifies. After cooling, the part is ejected, trimmed of flash, and finished as needed. Die designs include runners, gates, and vents to control flow, shrinkage, and air release.

Common die-cast metals include zinc alloys (for example Zamak), aluminium alloys (such as ADC12), and magnesium alloys (like AZ91D). These alloys are chosen for fluidity, strength-to-weight ratio, and corrosion resistance. Tooling costs are high, but unit costs decrease with volume, making die casting economical for mass production. Tolerances are typically tight for small to medium parts, with shrinkage allowances built into the design.

Advantages include high production rates, good repeatability, and low downstream finishing for many parts. Limitations involve high tooling costs, size and weight constraints, and potential porosity if gating and venting are not properly designed. Die-cast parts are widely used in automotive, electronics housings, hardware, and consumer products. Recycling of scrap metal and energy considerations are important aspects of its sustainability profile.