Metal coil winding and metal coil unwinding equipment is used to process continuous lengths of metal sheet, wire or foil in converting, coating, sheeting, and manufacturing applications. Metal coil winders and metal coil unwinders are used to produce solenoid bobbins, solenoid potted coils, transformer coils, choke coils, inductor coals, and generator coils. Metal coil unwinders are also used with a variety of products, and may be incorporated into a coil coating line that includes a web unwind or feed section. Metal coil winding and unwinding equipment features single-spindle and multiple-spindle designs, and is available in benchtop and stand-alone models. There are many types of metal coil winding and metal coil unwinding equipment. Choices include programmable coil winders, mechanical coil winders, and hydraulic traverse coil winders. Specifications vary by product type. Programmable coil winders have parameters such as tooling and wire sizes, winding speeds, and maximum coil traverse. Specifications for mechanical coil winders include maximum opening between the headstock and tailstock, winding wire gauges, wire coil sizes, and features such as safety guards and acceleration controls. Hydraulic traverse wire winders enable operators to change wire sizes without resetting the machine. They use hydraulic valves for control over the coil traverse. Speed, coil diameter, and wire gauges are important specifications to consider when selecting all types of metal coil winding and unwinding equipment. Metal coil winding and metal coil unwinding equipment includes coil cradles, centering reels, and pallet decoilers or pan reelers. A coil cradle holds a metal coil by its outside diameter (OD), cradling it on powered rollers called nest rolls. A centering reeler holds the metal coil by its inside diameter (ID) over a mandrel with an expanding arbor assembly. Pallet decoilers or pan reelers load an entire pallet of pancake or oscillated wound coil and are used primarily in narrow strip applications. Specialized and proprietary metal coil winding and unwinding equipment is also available. Suppliers of metal coil winding and metal coil unwinding equipment may designate winding machinery and unwinding machinery for specific applications. Examples include fan winding machines, armature winding machines, CNC winding machines, and transformer winding machines. Metal coil winding and unwinding equipment also includes automatic multi-axis winding machines, stator winding machines, servo motor coil winding machines, and watch coil winding machines.