batter

Battering is the action of striking metal repeatedly with a hammer or pneumatic tool to deform it plastically. The hammer strikes compress the material vertically while forcing it to flow outward horizontally, increasing the surface area and reducing thickness. This is distinct from peening, which hardens a surface through cold work, or from drawing, which lengthens stock. Battering produces visible surface deformation and is often used to shape edges, flatten rolled sections, or work metal into specific profiles.

In hand forging, a smith bats stock on the anvil face with a ball peen or cross peen hammer, rotating the work between strikes to spread it evenly. In machine work, a power hammer or drop hammer does the same action at higher frequency and force. The metal must be at the right temperature, typically between 1100 and 1200 degrees Celsius for steel, or it will either resist deformation too much or begin to crack from rapid cooling at the struck surfaces.

Common faults and variations

Uneven battering creates a warped or dished surface because material flows away from repeated strikes faster than from areas struck less often. Battering too cold causes surface checking, shallow cracks radiating from hammer blows. Battering too hot can produce grain growth and brittleness. Some shops distinguish between light battering (a few rapid strikes to adjust dimensions slightly) and heavy battering (sustained work to radically compress and spread the stock), though the mechanics are identical.

The term appears in descriptions of forged gate hinges, decorative ironwork, and historical armor, where visible hammer marks show that hand battering shaped the piece. In modern industrial work, the term is less common than forging or upsetting, but battering remains the accurate name for the manual or semi-manual version of the process. It is also used in tinsmithing and sheet metal work, where controlled battering with a ball peen hammer shapes edges and raises relief.