steel

In printing, steel means the mechanical components that form the body and skeleton of a printing press, the rollers that transfer ink, and the plates that hold type or images. Steel is chosen for these parts because it withstands repeated impact, maintains precise dimensions under stress, and resists wear from constant friction with paper, ink, and other steel surfaces.

The most critical steel in a press is the forme bed, the flat steel surface onto which type or printing plates are locked before the press cycles. This must be perfectly flat and rigid because any deviation translates directly into uneven impression and poor print quality. Impression cylinders are also steel, typically hardened steel rolling over the forme bed or the paper, applying the pressure needed to transfer ink. Steel rollers that distribute ink across the forme are called composition rollers when they have a rubber or synthetic coating, but their cores are always steel.

Steel components must be hardened to specific Rockwell scales depending on their function. A roller that contacts paper directly may be hardened to C45-C55; a bearing surface or guide rod might be C20-C35. Too soft and it deforms under the press's load; too hard and it becomes brittle and cracks. Precision ground steel shafts, cams, and linkages control the timing and motion of the press. Any scoring, rust, or pitting on these surfaces degrades performance immediately.

Maintenance and storage of steel components in printing is straightforward but essential. Steel parts must be kept dry because rust eats into precision surfaces and cannot be merely cleaned away without loss of dimension. Acid from old ink and paper moisture are the main culprits. Hardened steel that has cracked or shattered cannot be welded back into service safely, so replacement is the only option.

The term steel in trade conversation usually refers to the structural and wearing parts collectively, as opposed to the rubber, wood, and fasteners that surround them. A printer might say the press is built on good steel, meaning the frame and cylinders are substantial and well-made. Poor steel quality, corrosion, or wear is often the root cause when a press stops holding register or produces ghosting and streaking that cleaning cannot fix.