Metal spinning (manual spinning), is a useful ‘cold forming’ process, carried out by a machine operator, on a lathe. CNC machinery is used for the spinning process (power spinning), when high volumes of production are required. Metal Spinning is a process whereby a sheet metal circle is rotated on a lathe, pressure is then applied, forming it into a symmetrical form, such as a cone, bell or dish shape (see example opposite)
The first stage is to make a mandrel (also known as a spinning mould or buck), on a lathe, around which the sheet metal (called a blank) is formed. The mandrel is often turned on a lathe from hard wood. It is held in a ‘chuck’. Wax is applied to the mandrel, to ensure that the finished metal can be removed easily. For large scale automated spinning on CNC machines, the mandrel is manufactured to high accuracy from steel.
Annealing / softening of the metal is recommended, as it enables easier forming of the sheet metal. If the metal hardens during spinning, it can be annealed again. Softer, ductile, malleable metals, are suitable for spinning.
Read more: WHAT IS MANUAL METAL SPINNING?