by Jenny Knodell, IQS editor
It seems like I never have any change in my wallet anymore. I’m too busy dumping it all into machines everywhere I go—gas stations, grocery stores and city streets are all sprinkled with quarter-eaters, and I fall victim every time. Commercial products that consume my laundry money like parking meters and gumball machines have been around for about a century, and have one thing in common besides accepting change—their metal housings and components are both manufactured by the die casting process. Die casted products are extremely strong, temperature resistant and heavy, making them the perfect candidates for public machines that accept money.
Die casting involves molten metal, and in the case of these products, iron or zinc, that is poured into a holding furnace under high pressure and injected into a mold by a steel plunger to form the metal part, which can be complex and just about any size. A mechanical claw removes the shape from the die and places it on a conveyer belt to cool. Post-forming processes are often done to increase properties and improve the finish. Die casted products are extremely strong and heavy. These features are very useful for coin-operated machines in order to prevent tampering and theft. Parking meters are often embedded in concrete, which makes thievery a difficult if not impossible process. Gumball machines, however, are often placed on the pavement or floor of a business, and therefore need extra weight to hold them in place.
Courtesy of Kinetic Die Casting, Inc.
From the outside, it looks like gumball machines are made out of plastic. Don’t be fooled—these dispensers are composed of a die casted zinc base, coin mechanism handle, chute and lid, making free gumballs a bit easier to obtain than free quarters. Parking meters are not quite as much fun as gumball machines, but are manufactured the same way. They’re found in just about every urban street around, and are composed of 3 main metal parts—the housing for the meter operating mechanism, a meter head and a vault for receiving coins. Much to the dismay of perspective quarter bandits, they are all manufactured by die casting and made of either cast iron or zamac, a zinc and aluminum alloy.
Die cast metal is strong enough to withstand a screw driver, so even if quarter dispensing machines are stolen, the change is not accessible because the vault won’t open without a key. Since parking meters and gumball machines are often located outside in all climates, the casings are galvanized via hot dipping in molten zinc for corrosion resistance caused by harsh weather conditions. They are also sometimes buffered by a rotating cloth for a shiny finish, or covered in powder paint of different colors (often red) which is baked on.