The Metal Cut Off Saw And Band Saw Blades For Tool And Die Making
By Randy Hough
Every tool and die, precision machining, aerospace and injection mold making shop has at least on metal cut of saw that uses special band saw blades. This is because almost all components start out as part of a bar stock that must be sawed off in order to proceed to the next step. This procedure is more important than often realized. Because it is such a common and inexact operation, it is taken for granted. Many hours of machining could be saved by using a more precise sawing operation, simply because there is less stock to mill and square up.
The typical scissor type machine is difficult to line up over the line to cut and thus most toolmakers act conservatively and leave more than enough stock. After all, it is much easier to take it off than put it back on! Band saws that use parallel posts to guide the blade have the advantage of facilitating accurate alignment of the saw over the workpiece. It is possible to cut very close to the finished dimension, while producing a straight cut.
Accurate cuts save a lot of time is the machining to square up the component. This accuracy also makes the stock removal cutting much quicker. This in turn saves the carbide cutters or indexable inserts used. It follows that the high speed spindle experiences a lighter work load, which prolongs its service life.
Another savings is in the number of pieces that can be cut from a single bar of tool steel Metal, such as PX-5, NAK-80, D-2 and Beryllium Copper are rather expensive and any material saved is money saved. Some tool shops use carbide tipped cut off saws for this initial operation. This is very efficient, as long as the volume is rather low. Many mold making shops do not use that many core and cavity blocks, and this is a very good way to cut off the stock.
Larger shops benefit from a more automated cut off operation, with automatically fed bar stock, cut off machining, and on-off switching. Steel suppliers use these for their high volume of steel blocks sent to their customers.
The vertical band saw also is used a great deal in precision machine shops. Not so many years ago, almost all through pockets in mold bases were drilled in the four corners of the pocket, then band sawed to remove the bulk of the steel. Then the pockets were milled in a manual machine, such as a Bridgeport.
Thankfully, those days are long gone and now these same pockets are Wire EDM'd or cut on a CNC milling machine. There are many horizontal, universal and vertical CNC machines capable of cutting pockets in the mold bases.
Randy Hough writes about carbide cutting tools.
"You know Dad, I've been thinkin', one is a lot more than zero!" my son, Thomas, age 5.