Specific lengths of billet and finished steel specified by product standards. The production and use departments of steel products can save metal effectively, organize production easily, make full use of equipment capacity, simplify packaging and facilitate transportation. Different countries have special regulations on steel length. The method of steel sizing varies with the scale of production, the degree of mechanization and automation, and the variety of steel products.

　　Commonly used method of sizing:

　　(1) Length is set by a ruler. The ruler is located behind the shearing machine or sawing machine and is used with it. There are two main types of sizing machine: door type and cantilever type. Portal sizing machine is a device which installs multiple sizing baffles on the portal frame. When in use, different sizes of baffles are lifted and lowered by pneumatic or electric according to the length of sizes. It covers a large area and is inconvenient for loading and unloading. Cantilever ruler is driven by motor with long lead screw. When the screw rotates, it drives the ruler block to move horizontally. Location is more accurate. The simplest length fixing device is to suspend two or three cutter baffles on the polishing rod and manually pull the landing baffle. The fixed length machine is often used in old-fashioned boarding and reinforcing bar factories with small production scale. When cutting a long steel with multiple saws at the same time, the length can be adjusted by changing the distance between the saws.

　　(2) Fixed length with flying shears. In the finishing production line of continuous rolling mill and strip mill, the fixed length of steel is regulated by the special mechanism of flying shear itself installed on the production line. The automatic regulation of fixed length can be realized in different ways: electrical logic circuit and photoelectric components; variable speed crankshaft and gear mechanism; crank pendulum and mechanical eccentric or hydraulic eccentric mechanism, etc.

　　In addition, advanced cursor projection device or roller for measuring the length of steel plate are used to determine the length of steel plate in the production of thick plate.

　　(3) Non-rulers are required for fixed-size products. Fixed-rulers and non-rulers in profiles are supplied in accordance with the provisions of the national standards. No ruler is supplied according to customer's requirement. If the length of reinforcing bar is 9 meters, while the buyer only needs 6 meters, the supplier can only supply 6 meters, that is, no ruler. Its essence is that the length is different, but the standard used is different.