Casing

• The most noticeable part of the microwave is its outer casing. While some microwaves have a plastic outer casing, many use sturdy metals, such as stainless steel. This helps the microwave blend well with other kitchen appliances while also giving the unit a protective casing that resists stains or impact. Stainless steel, like all solid metal, does not allow microwaves to pass through but instead reflects them back. The casing, however, has little or no contact with microwaves and, instead of serving as a layer of protection between the user and the microwaves, serves as a barrier between the outside world and the working parts of the machine.
  
  

Cook Chamber

• Although placing metal in the microwave is dangerous to the machine and the user, most cooking chambers feature metal walls. The metal used is often stainless steel and while it may cause problems if left unvarnished, manufacturers line the metal walls with a plastic enamel paint. While thin, this layer is protective enough that the metal outer wall is not disturbed during the cooking process. These metal walls prevent the microwaves from passing into the machine.
  
  

Magnetron

• The magnetron is the part of the microwave that generates its heating capability. This magnetron consists primarily of a cathode cylinder, an antenna, a filament, heater and a magnet. The magnet is made from an iron alloy that is permanently magnetized. When the magnetron generates microwaves, they are diffused using a fan that is also made from metal such as steel.
  
  

Nuts and Bolts

• Of course, none of the parts of the microwave would stay together without the help of several nuts, bolts and screws fastening each piece to the other. These pieces are made from galvanized or stainless steel and, when in the cooking chamber, are sprayed with the same plastic enamel as the microwave inner walls.
  
  

Wiring

• Wiring delivers power to the microwave magnetron assembly and to the display pad. This wiring is insulated copper wiring, just like the type commonly found in home appliances ranging from refrigerators to vacuum cleaners. The copper wiring is shielded and insulated by a plastic coating.