By: Willy Goellner, Chairman & Founder—Advanced Machine & Engineering/AMSAW

Carbide saws using coated carbide- or coated cermet-tipped blades are designed to cut extremely hard or special alloy materials. The effectiveness of the blade also depends on how well the saw is built. Vibration analysis for your carbide sawing machine is important for monitoring your blade health and the quality of the cut.

The relatively brittle carbide or cermet tips require very rigid and backlash-free machines that operate with low vibration. Vibration analysis prevents cracking of the carbide tips and helps maintain a steady chip load on each tooth of the saw blade.

The spindle drive gears also require low backlash supported by preloaded, heavy-duty bearings to minimize vibration. The same is true with the feed mechanism of the slide or pivot version.

Vibration Analysis for Slide Versus Pivot Saws

There are two common types of saws, differentiating in the way the blade is fed into the workpiece: slide-type and pivot-type saws.

Slide-type machines are more common. The head slide for these types of machines is arranged in a horizontal, angular, or vertical position.

The preloaded slide glides on box ways or preloaded linear ways. Designers still debate whether box ways using low friction lining and hydraulically preloaded gibs have a better dampening effect than linear ways with hardened ways, roller housings, and rollers.  

Slide type saws feature  an open-loop force arrangement (Figure 1) and must be designed with more stiffness compared to the close-loop pivot saws. reference: Sawing Academy “picking the right carbide saw”).

 Pivot-type saws are simpler with fewer components. When they are properly designed with oversized taper roller bearings, they become very rigid. Preloading the pivot bearings to the limits creates a slower rotation of the pivot, which helps decrease the vibration of the machine.  

Built for extreme stiffness, a pivot mechanism for the spindle gear box is  nested in a rigid base close to the floor. It is fed by a heavy-duty ball screw attached to an upper sub-assembly, such as the fixture frame.

The spindle center is located between the pivot center and the feed mechanism. The feed and gravity force of the head pull the ball screw under tension. This eliminates the need for a preloaded ball nut and provides a steady feed for interrupted cutting, enhanced longevity, and efficiency.

This arrangement provides a closed-loop force distribution because closed-loops are stiffer than open loops. It also reduces the compliance of the feed mechanism due to the ratio of ball screw and spindle center in relation to the pivot center in half, and contains the cutting forces within the closed loop (Figure 2).

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