The Fabricator - November 2013

4. How much unplanned downtime do we have?

Various factors can cause unplanned downtime, and many have to do with improper band saw settings or using the incorrect blade for the job.

Consider a pinching situation when cutting a large I or H beam. Internal stresses in the work build as the blade cuts through. Once those stresses release, the cut portion of the workpiece may physically move, begin to close in behind the cut path left by the blade, and grab the back of the blade, causing it to stall.

;e same thing happens when, say, cutting a
branch on a tree with a hand saw. At a certain point,
When band sawing metal, a wider kerf can help
eliminate the problem. Specialty blades designed
for structural beams and similar materials pro-
duce an extra-heavy kerf, minimizing the chance of
pinching during an operation.

Back to the tree example, there’s another rea-
son that the hand saw becomes pinched. ;e cut
surface the hand saw produces usually isn’t the
smoothest. When a tree pinches the saw, it tends to
get stuck in place against the rough ridges of your
cut in progress. If the surfaces were smoother, the
tree branch wouldn’t become stuck so easily.

Similarly, when you are band sawing metal, a smooth cut surface allows the backing steel of the blade to slide more freely, so you avoid getting stuck by pinching. Modern blade technology, including the tapered back, makes this smooth surface possible (see Figure 3).

Blade changeover also adds to your downtime. To reduce the changeover frequency, you may find that it is cost-e;ective to pay the extra money to purchase a high-end blade. Also, before you purchase your next band saw machine, consider that blade length also a;ects changeover frequency. A band saw runs in a loop, and the shorter that loop

Modern Machine Tool has been building cutoff lathe machines for almost a century. Our lathes have evolved over the years into a completely automatic operation—from feeding to cutting to finishing. Our compact cast iron slide unit offers rigidity with the speed and serviceability of linear technology. The precision ground, ball-screw driven slides with high torque digital drives provide easy set up and increased tool life. An optional two axis servo slide is available for simple turning, boring and drilling operations. These systems can handle material . 25” to 8”. Call us today and find out how speed and precision have become one.

FEATURES:
• Two Axis Slide
• High Torque Digital Drive
• Menu Prompted Touch Screen
• Digital Read Out or Servo Positioned
• Heavy Duty Stock Stops
THE HOT RODS OF CUTOFF LATHES