A flat, round disc of sheet metal, called a preform blank, rotates at high speeds on a spinning lathe. Rollers apply pressure to the blank, and the metal is shaped over a form called a mandrel, taking its shape.
The finished product of a spin forming process is smooth, without any chipping, wrinkling or warbling, and it can be tubular, spherical, bell-shaped or cylindrical. The process lasts less than ten minutes per piece, is cost-effective and offers a high degree of precision and accuracy. Spin forming machines can be manually operated or controlled by computer numerical control systems, which make the process fully automated.
Many kinds of metal can be shaped by spin forming, including aluminum, titanium, stainless steel and copper, which are formed into blanks by stamping, deep drawing or press forming. The blanks become products like lighting fixtures, cookware, bowls, decorative and ornamental products, nozzles, tank heads, funnels, pressure vessels and cartridges for the aerospace, food and beverage, marine, lighting, pharmaceutical, defense contracting and cookware industries. Many products have decorative detail, varying thicknesses and complex shape designs.
While standard spin forming is most often used, there are a couple of other variations that meet specific design specifications. The tube forming method manufactures metal tubes that are open on one or both ends and have uniform or varying wall thickness. When standard spinning does not meet complex design requirements, flow forming is used.
It is a more advanced spinning process that allows variation in wall thickness of its products and produces a finished shape by working from the thickness of the starting blank, which creates a thinner part than the original starting perform. Finally, during hydroforming, instead of a mandrel, the metal flows around a punch by using a high pressure hydraulic system.
All of these methods produce parts that don’t generate any wasted or scrap material and are manufactured in small to medium runs with short lead times. Since spin forming is a cold working process, the tensile strength and ductility of the metal is retained or increased after forming, meaning spun metal products fare well in a number of applications and environments.