Aluminum Circles for Spinning: Which Alloy, Temper and Blank Size to Order

Anyone who spins cookware, lamp shades or reflectors knows the part is decided before the lathe starts: in the circle that arrives at the shop. A circle in the wrong temper cracks halfway through, one that is too small never reaches full height, and one with coarse grain leaves an orange-peel surface. This guide covers which aluminum circle to order for spinning, how to size it, and what to check when a part goes wrong.

Spinning, shear spinning and the names buyers use

Metal spinning is called rechazado in Mexico, entallado in Spain and repoussage in French. In every case a flat circle turns on a lathe together with a form, the mandrel, and a tool pushes the metal until it takes the mandrel's shape. Two variants change the circle you should order (Tapase et al., International Journal of Engineering Development and Research, 2014):

• Conventional spinning: wall thickness barely changes; the circle is laid down over the mandrel. This is how cookware, bells and reflectors are made.
• Shear spinning: the tool thins the wall on purpose. It is common for cones.

What aluminum circle should I order for spinning?

Order the circle in the O temper, fully annealed. It is the softest condition and stretches the most before it breaks; an H temper, strain-hardened, reaches the lathe with part of its formability already used up. Among alloys, the order of ease for spinning is 1100, then 3003, then 5052 (Fletter, metal spinning tutorial, Stanford University, 1995).

Temper also sets how far you can stretch in one pass. In conventional spinning, the circle can be up to 1.75 times the mandrel diameter if the aluminum is annealed, against 1.67 if it is hard (International Journal of Machine Tools and Manufacture, 2015). For spinning, temper matters as much as alloy: a hard circle reaches the lathe with less stretch left. What each temper means is in the guide to aluminum temper designations.

How to size the blank

In conventional spinning the thickness barely changes, so the blank is sized by matching areas: the area of the circle equals the area of the finished part (Tapase et al., 2014). For a cylindrical cup of diameter d and height h:

D = √(d² + 4 × d × h)

For a hemisphere of diameter d, the circle is d × √2. Add the trim allowance your shop cuts off the rim.

Shear spinning follows a different rule, the sine law: final thickness = circle thickness × sine of the cone half-angle (Tapase et al., 2014). That is why, for cones, the circle thickness is worked back from the wall you need. A single pass can reach about 80% reduction (Ri et al., review of metal spinning, 2020).

Why spun parts crack, wrinkle or show orange peel

• Cracks in the wall: the metal work-hardened beyond what it can take. It happens with H tempers or when a part goes through several passes without an intermediate anneal. 1100 anneals at 644 to 770 °F, 340 to 410 °C (Total Materia, accessed October 16, 2026).
• Flange wrinkles: the rim of the circle compresses faster than the tool supports it. Wrinkling and cracking are the two limits that define how far a part can be spun (Ri et al., 2020).
• Orange peel: a rough surface from coarse grain. In aluminum tests, grains of 37 to 102 microns deformed evenly while grains of 270 to 444 microns concentrated the strain (Cai et al., Materials, 2022).
• Pitting and spin lines: a circle scratched before spinning, or spinning too fast (Gotham Lighting, technical bulletin on reflectors, 2003). The circle should arrive clean and protected.

Before blaming the spinner, check the mill certificate: alloy, temper and mechanical properties.

Should I spin or deep draw?

Source: Tanfield, guide for design engineers, February 16, 2026; The Library of Manufacturing, accessed October 16, 2026.

If you make cookware, you can combine both: deep draw the high-volume part and spin the special sizes or prototypes. Circles for deep drawing are chosen on different criteria, covered in which aluminum alloy to use for deep drawing cookware.

What to send for a quote

• Alloy and temper, for example 1100-O.
• Diameter and thickness, with the tolerance your process needs.
• Quantity in pieces or in pounds or metric tons.
• End use: food contact, coating or anodizing.

Almexa blanks its circles at its plant in Cuautitlán Izcalli, Mexico, from its own coil: diameters from 5.51 to 48 in (140 to 1,219 mm) and thicknesses from 0.022 to 0.157 in (0.56 to 4.0 mm), with the 5000 series up to 36 in (914 mm), in alloys 1050, 1100, 3003, 3004, 3104, 3105, 5005, 5052 and 5754. For spinning we recommend 1050 or 1100 in the O temper; the circles are annealed after cutting and every lot ships with a certificate of chemical analysis and mechanical properties. See sizes on aluminum circles or send your spec for a quote from the mill.