Design of vending machines

The basic design of a vending machine starts with the cabinet, which is the steel shell that holds all the internal components and determines the overall size and shape of the machine. Inside the cabinet is a steel lining called the tank. The tank and cabinet are tightly integrated, with enough space in the middle for a polyurethane foam insulation layer. Combined, the tank and foam insulation help keep the internal temperature stable and protect the product from extreme temperatures outside the cabinet. Although all products and distribution mechanisms are contained in a cabinet, they are actually installed in a can in the strictest sense of the word.

The exterior of the cabinet is coated with acrylic powder paint and baked. The powder coating enables the machine to withstand extreme temperatures, salt or sand, customer abuse, and other conditions that require high surface durability.

Canned feeder stacks or feeder trays are installed inside the machine for storage and distribution of products. Each tray is equipped with a large rotating steel wire spiral to accommodate the product. Feeder trays can slide in and out of the machine for easy maintenance and re-storage of merchandise. The feeder stack and tray also contain motor controls that physically propel products forward until they are released from the stack and fall into the access area. When a customer selects a product, a rotor turns and propels the individual products, dropping one can or bottle at a time. In the same way, the spiral on the snack food tray rotates and pushes the products forward until they fall off the tray.

Some vending machines, especially cold drink vendors, have two doors. Both have vending machine buttons and inner doors that seal the inside of the machine and provide additional insulation. The outer doors contain electronic controls that enable customers to purchase and receive goods. The outer doors also include signage and illustrations, generally silkscreen printed on panels that fit into the front panels. Front panel lighting is generally installed behind the panel. Exterior doors include heavy duty winches, locks and hinges to deter theft and vandalism.

Electronic components, such as coin and bill validators, test coins and scan dollar bills that have been inserted to ensure the cash is a real and appropriate amount. A panel of control buttons allows customers to make choices. These buttons are connected to the motor control of the cash delivery machine and tray to activate the rotor that releases the product into the bin. The machine holds a set number of coins and releases the correct change after the customer makes a choice. Newer machines are also likely to include validators that accept debit and credit cards, LCD panels that display price details and machine status information, and voice chips that provide transaction details to customers by voice.

Design changes occur most often in the mechanisms that handle and distribute the large number of different types of bottles, cans, boxes, bags and other packaging on the market. When 20-ounce (592 ml) plastic soda bottles were first introduced to vending machines, they tended to get stuck in the machine. Designers had to redesign how the bottles were stored in the machine and delivered to customers. The constant changes in product packaging ensure that designers must always look for practical and more efficient ways to sell their products.