ball

In metalworking, to ball means to heat scrap metal or small pieces in a furnace until they soften, then compress or roll them into solid spheres. These balls become feedstock for rolling mills, wire drawing, or further refining. The process consolidates small fragments and loose material into a uniform, handleable form that moves predictably through subsequent machinery.

The furnace temperature depends on the metal. Steel balling typically occurs at 1100 to 1300 degrees Celsius, hot enough for plastic deformation but below full melting. Aluminum and copper require lower temperatures. Once heated and plastic, the metal is pressed between rollers or in dies until it forms a roughly spherical mass. The size varies by mill and metal type, but balls commonly range from 25 to 100 millimeters in diameter.

Balling serves a practical purpose in scrap recovery and yield management. Rather than feeding uneven chunks into a rolling mill (which can jam, wear rolls unevenly, or create inferior product), operators consolidate the material first. This is especially common when rerolling turnings, clippings, or off-spec material that would otherwise waste furnace capacity.

Variants and challenges

Some mills use rotating drums or tumblers to round the heated metal, while others rely on compression in specially shaped cavities. Balled material must cool uniformly to avoid cracking; rapid cooling or uneven temperature gradients can cause surface checks or brittleness. The balls must also reach sufficient density to prevent porosity defects downstream.

The term appears mainly in older mill records and small-scale reroll operations. Modern large mills often bypass balling by feeding scrap into electric arc furnaces or induction units, where melting and casting replace the intermediate ball-forming step. However, it remains standard practice in some ferrous and non-ferrous shops where cost or equipment constraints favor solid feedstock over melt-and-cast cycles.