Die-cast toys use real metal in the mold rather than just plastic, which is why they tend to be much heavier than their plastic counterparts along with earning the name die-cast. While this process dates back to the beginning of the 20th century, the practice remains in use today with some toys, particularly high-end collectibles. If you collect toys, chances are own some die-cast toys already; they're frequently used in toy lines like Hot Wheels and Transformers.
Behind the Scenes
At the factory, a large container of plastic or metal is put into a hot barrel designed to melt its contents. When it's melted, a screw-type plunger starts pushing it through a nozzle against a mold, or specific shape, for a toy; think of a mold like an enclosed ice cube tray. The melted contents are injected to the side until it fills each of the cubes and sets. The mold is usually kept at a specific temperature so that the toy can harden and form only once the injection is complete.
The term "die-cast" refers to casting a mold using a mixture of metals concisely labeled "ZAMAC": zinc, aluminum, magnesium and copper. Commonly, many manufacturers inject plastic into the mold to create a lightweight toy with lower costs; replacing the plastic with molten metal instead creates a heavier and stronger figure, but drives the cost of the toy up. Depending on the figure, a manufacturer might use both materials to make a toy; for example, some Transformers toys use a plastic body, with specific parts made of die-cast metals. The most common application of die-cast is using it in the lower half of an action figure to add stability.
History of Die-Cast Figures
Many types of die-cast toys exist, though the first use of die-cast in toys dates back to the turn of the 20th century when the Dowst Brothers released basic car bodies in the United States. Companies from the early 1900s also produced toys using cast iron and similar techniques. In 1968, Mattel took the country by storm with the introduction of large scale die-cast in the Hot Wheels line, carving out the path for future companies to manufacture die-cast toys for kids and adult collectors. The trend continued throughout the years with other companies releasing die-cast toys, such as Hasbro with the Transformers brand and Trendmasters with the Voltron brand.
Current Die-Cast Use in Toys
Although older Transformers used a fair amount of die-cast metals in production, you won't typically see it used in the current day due to cost cuts in manufacturing. In a similar vein, most inexpensive toys at the store won't feature metals; even many Hot Wheels cars use a mixture of die-cast and plastic, reserving the larger amount of metal for collector lines like Pop Culture and Retro Entertainment. Other high-end collectible figures, such as the imported S.H. Figuarts toys, will have small amounts of die-cast for stable standing. While you may see toys with some die-cast use, the practice is typically saved for higher-end, more expensive toys designed for collectors instead of children.
Maintaining Die-Cast Toys
Children's die-cast toys will need little maintenance; these sturdier figures last much longer than plastic, and many die-cast toys last longer than a child's interest in them. Collectors need to pay better mind, of course. If you don't want to spend too much time dusting open figures, consider saving for a quality display case; keeping a clean, waxed die-cast toy in a display case drastically reduces how often you'll need to maintain the setup. Wiping a waxed figure with a microfiber cloth gently wipes away any dust that has accumulated -- something you'll do often if you don't keep it inside a case. Avoid washing a die-cast toy to prevent rusting.