Page 32 - MetalForming December 2019

FABRICATION
Three Sawing Tips:
Mind the Material, Production Needs
and Blade
“If it's wrong at the saw, you spend the rest of your time
trying to fix it.”
This simple yet sage advice from Jay
Gordon, North American sales manager for saws and hand tools at The L.S. Starrett Co. (www.starrett.com), speaks to the importance of starting a tool- or part-build project correctly. That means assessing the material, your unique production requirements and the saw blade. Along with Jordan Schimel, The L.S. Starrett Co. product manager for saws and hand tools, Gor- don details these cutting tips for Met- alForming’s readers.
Material Decides the Saw
“Different materials provide differ-
ent properties,” Gordon offers. “Com- pare soft aluminum to a tool steel or high-nickel steel. Across materials, it’s soft versus hard versus tough. Cutting aluminum with a very fine-toothed blade will rip off the blade teeth, where- as the same blade cuts Inconel with no problem.”
“The reverse also holds,” he con- tinues, “as a coarser blade, say a 1.4 to 2 variable-pitch blade for example, will be fine for aluminum. (Tooth pitch is the number of teeth per inch). Cutting the same-sized piece of Inconel would ruin the blade due to lack of penetra- tion, resulting in a high chip load on the teeth. In general, the development of variable-pitch blades over the past couple of decades has expanded the
30 MetalForming/December 2019
www.metalformingmagazine.com
Article photos courtesy of The L.S. Starrett Co.
Close attention here means less angst later on as material transforms into tooling or workpieces.
BY LOUIS A. KREN, SENIOR EDITOR
work range of blades, making them more effective across material types and workpiece sizes.”
A basic rule of thumb: cut with a minimum of three teeth in the material at all times. Minding this rule helps when selecting the right blade for the piece size to be cut.
“You can get away with a few more teeth on harder material due to the lack of chip-load issues as compared to softer materials,” Gordon says.
Rake angle, which refers to the angle between the face of a tooth and a line perpendicular to the surface being cut, also depends on the material. The high- er the positive rake angle, the more aggressive the cut.
“A softer material doesn’t require a large rake angle,” explains Gordon, “whereas harder material requires the more aggressive cut offered by a higher positive rake angle to penetrate the material.”
A variety of exotic materials, includ- ing higher-strength steels and others with unique recipes, have inundated tool-build and part-production oper-