High-Strength Steel

Hub Industrial Supply Tests The Best Blades For The Job



Over the last decade, auto makers around the globe have been increasing the use of ultra-high-strength steels (boron steel or manganese-boron alloy steel) in critical safety areas on car frames. These new alloys are an extremely difficult cutting challenge for auto recyclers and emergency responders extracting victims from vehicle accidents.

Have we begun to create metal alloys so hard that they can’t be cut? Has cutting technology been keeping up with these advances?

The short answer is the traditional reciprocating saw is still the best tool to use for most vehicle dismantling operations. Recip blades and saws are constantly undergoing subtle design improvements, but we have yet to see the breakthrough that will make these new alloys as easy to cut as traditional metals.

It’s never been more important for saw handlers to understand and employ good sawing technique. _ e new materials are much less frustrating if you are armed with the best information.

In a series of in-house tests, we determined that in order to effectively cut ultra-high-strength steels with a reciprocating saw, both the blade specification and the saw speed (measured in strokes per minute or SPM) are equally important. Effective speed control is critical to cutting ultra-high-strength steels quickly and has the additional benefit of maximizing blade life. The results of our findings are as follows:

  • A metal cutting blade such as our HUB Premium one-inch 14TPI blades perform best when cutting ultra-high-strength steel
  • “Demolition” blades, with wider kerfs and larger teeth, did not perform nearly as well against the hardest alloys
  • Fastest cutting occurs at slower blade speed; optimal machine speed is 1250 - 1500 strokes per minute using a lower speed control setting
  • Orbital motion improves blade performance (contrary to most metal cutting applications)
  • Corded power reciprocating blade machines are necessary for optimum blade performance

The tests were performed on a B-Pillar and A-Pillar made of Boron Steel from a Mercedes-Benz R-Class.

We conducted hand testing using a corded reciprocating machine to determine the optimal TPI by testing 14, 18, 10/14 one-inch bimetal blades as well as a few others. Test results showed cutting performance in this material measured by length of the cut width after 60 seconds of cutting time. This test demonstrated that our HUB Premium one-inch blade with 14 TPI with its profile designed for heavy metal cutting applications performed best on the boron steel. Other blade specifications were tested including various profiles and TPls (including 18, 10/14 TPI and specialty grit blades) but, these variants did not cut as quickly or last as long as the 14 TPI blades.

Next, we confirmed that speed at which the blade ran (measured in strokes per minute, or SPM) had an impact on boron steel cutting performance. A hand test was conducted using an electric powered reciprocating saw cutting the A-pillar of a Mercedes-Benz using a 14 TPI bimetal blade. This test measured how long it takes to make one complete cut in the material with a failure mode of two minutes. This test concluded that in order to effectively make a cut in boron steel, the SPM setting of the machine is critical. Speed settings of 1250 - 1500 showed the best results. If the speed of the saw is set too high (>1500SPM), then excessive heat is generated, causing the blade to fail prematurely.

 

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