The second grade, i.e., the Alloy Grade for plate over 1/4" thick, is recommended for longer life when shearing the hi-
tensile steels or for high production shearing. This recommendation applies only to plate over 1/4" thick; however, they are
much more resistant to abrasion and indentation than the first grade and retain their hardness regardless of the number of
times they are sharpened. As a general rule, their life is 3 to 4 times and the cost about 25% more than the Standard
Grade 1. Common trade names for these blades are Electric Induction, Tufcut, E. I.S., Duro-Chrome, Century, Asko and
No. 2 grade.
The third grade, i.e., the Alloy Grade for plate under 1/4", is recommended for long life when shearing the hi-tensile
steels or when the shear is used on a continuous basis. They should not be used for plate over 1/4" thick as they are
liable to chip or crack. Like the second grade, the third grade retains hardness throughout its thickness. As a general rule,
they have a life of approximately 7 times that of the first grade and cost slightly over 50% more. The common trade
names for this grade are High Chrome, High Carbon, Multi-Cut, leencut, Battle Axe, Peerless, Squarkeen and No. 3
grade.
It is essential, when the above selection has been made, that the blades are used properly. For clean cuts and long
life, they should be adjusted for shearing various gauges of material and the edges should be turned when dull. When
shearing thin sheets, dull blades show up as 'a burred edge on the sheared piece. On heavier sheets and plates, dull
blades may cause the turning of metal between the blades, resulting in an extremely large burr. Dull blades increase the
shearing resistance and therefore may overload the shear, cause it to stall, or even result in blade breakage. Improper
grinding may also cause the blades to break; therefore, it is essential to have experienced grinders resharpen the blades.
They should be kept clean from dirt, metal chips, etc. A lubricant is used by some to increase blade life, and there are
many makes of satisfactory lubricants available. Those lubricants used on punches and dies are generally satisfactory.
Blades should never be adjusted out of parallel excepting when required to counteract deflection, i. e., "center bow. "
Special blades are obtainable for special applications such as hot- shearing, magnesium shearing and other special
The trade names mentioned apply mainly to the Midwest. There are many Eastern and Western as well as Foreign
makes of blades that we have no knowledge of; therefore, we cannot classify them into the three grades. Figure 17 shows
dimensions of the blades used on Lodge & Shipley shears.
Figure 17. Blade Dimensions for Shears
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