Give sawing its due: General Industry Coverage

An old toolmaker once told me that the lathe is the foundation of a machine shop. He said operating a shop without a lathe would be impossible because it was used for more jobs than any other machine. I was very green at the time, so I took his words as the truth. But after many years of machining, including starting three machine shops from scratch, I have discovered he may have been exaggerating a little. If I could go back and have the conversation again, I would argue that sawing operations are the foundation of a machine shop.

Most workpieces come from shapes like angle iron or larger bulk materials, such as round bar, flat bar, sheet and plate, and sawing is by far the most efficient method for separating workpieces from bulk materials.

Some may argue that shearing is better than sawing because it is faster. However, plate shears are good only for shearing flat materials. Angle iron, channel and round bar can be sheared with machines like ironworkers and bar shears, but these machines cut a limited number of shapes and sizes. Tubes also may be sheared but strictly with specialized machines that can be justified by very large production quantities.

Vertical bandsaws are ideal for rough-cutting features before going to a mill. CNC vertical bandsaws called plate saws are common at steel warehouses. Image courtesy of C. Tate

Shearing always causes some amount of edge deformation. As the diameter or thickness of a material increases, so does the amount of deformation. Edge deformation can result in extra machining, increased handwork or a poor fit during fabrication.

Benefits of Sawing

A saw can cut many sizes of bar and is limited only by the size of stock that will fit physically into a machine. Saws also are capable of cutting an infinite number of shapes as long as a piece may be clamped. In addition, saws can be tooled up to cut odd shapes, whereas ironworkers and shears are dedicated to specific shapes. Saws do not cause edge deformation, and a good saw delivers very clean cuts and square ends. Shearing machines are definitely faster, but a saw is more flexible and provides a better cut.