Every tool and die making, precision machining, aerospace, and injection molding shop has at least one metal cutting saw that uses special band saw blades. This is because almost all components start out as part of a bar stock that must be cut to proceed to the next step. This procedure is more important than is often believed. Because it is such a common and inaccurate operation, it is taken for granted. Many machining hours could be saved by using a more precise sawing operation, simply because there is less material to mill and square.
The typical scissor type machine is difficult to align on the line to cut and therefore most tool manufacturers act conservatively and keep more than enough stock. After all, it’s much easier to take it off than to put it back on! Band saws that use parallel posts to guide the blade have the advantage of facilitating accurate alignment of the saw on the workpiece. It is possible to cut very close to the final dimension, while still producing a straight cut.
Precise cuts save a lot of time in machining to square the component. This precision also makes material removal cutting much faster. This, in turn, saves carbide cutters or interchangeable inserts used. It follows that the high-speed spindle experiences a lighter workload, which extends its useful life.
Another savings is in the number of parts that can be cut from a single bar of tool steel. Some tool shops use carbide-tipped chop saws for this initial operation. This is very efficient, as long as the volume is fairly low. Many mold making shops don’t use as many core and cavity blocks, and this is a very good way to cut the material.
Larger shops benefit from a more automated cutting operation, with bar stock being automatically fed, cutting machining and on and off. Steel suppliers use them for the high volume of steel blocks they ship to their customers.
The vertical band saw is also widely used in precision workshops. Not too many years ago, almost all through cavities in mold bases were drilled at all four corners of the cavity and then cut with a band saw to remove most of the steel. The pockets were then milled on a hand machine, such as a Bridgeport.
Fortunately, those days are long gone and these same cavities are now wire EDMed or cut on a CNC milling machine. There are many horizontal, universal and vertical CNC machines capable of cutting cavities in mold bases.