TPT January 2020

C U T T I NG T E CHNOLOG Y & S AW I NG

When to use a slide saw vs a pivot saw? By Willy Goellner, founder and chairman, AMSAW

Finite element analysis (FEA) is a technological ad- vancement in ma- chine design that allows the stiffness of a structure to be measured and adjusted. Rather than in-

YOUR floor space and layout, budget, and customer needs will determine if a carbide slide saw or carbide pivot saw is best for your machine shop operations. Carbide slide saws and carbide pivot saws are best for applications that require high speed and productivity in a restricted floor space. There are several models available including horizontal slide saws, vertical slide saws and pivot saws. Some models are less expensive because of their simple design. Heavier machines tend to perform better, but come at a higher cost. To select the best carbide saw for your application, you need to consider the features and design elements of each. If it is possible to design a machine with equal or greater rigidity at a lower initial cost, while also building in greater simplicity that lowers the maintenance effort, the cost per cut over the life of the saw can be reduced. At this point, science makes a difference.

taller and more unstable. To make it more stable requires a heavier and more massive base. The vertical orientation of the structure also makes it more difficult to assemble, which increases the machine costs. In addition, the chips are disposed in a horizontal direction, which makes them harder to contain and collect, requiring more expensive guarding than horizontal machines that eject chips directly onto the chip conveyor. Modern pivot saws are the least expensive because they use fewer and simpler parts, require less maintenance and need a smaller footprint. They also have greater stiffness, because the pivot is mounted on the lower fixture base close to the floor plate so that the ground absorbs more vibration. The slow-turning, heavy-duty, pre- loaded taper roller bearings of the pivot structure are sealed in a housing and lu- bricated for life, minimising maintenance requirements. Pivot saws can be designed with a closed-loop force arrangement, which cuts the compliance of the feed mechanism nearly in half, because the cutting action is halfway between the ball screw nut and the pivot point. These saws also take up less floor space, allowing more efficient use of the facility. You also want to consider the materials being processed aside from the saw design, and maintenance factors because exotic materials are challenging to cut. A poorly designed slide saw can fail, while a well-designed pivot saw may shine. Carefully evaluate the saw you choose, test cut, and pick a well- designed and cost-efficient model.  Advanced Machine & Engineering | AMSAW www.amsaw.com

creasing machine mass, greater rigid- ity can be designed into the saw by properly arranging ribs and supports in critical areas within the machine structure. This technique reduces machine weight without sacrificing stiffness, while simultaneously decreasing cost. Therefore, it is a key factor to combine experience with proper engineering, advanced software and test instruments. The original structure of carbide saws were slide-types. Today they are available in horizontal, inclined and vertical configurations. Pivot saws were developed later. Slide-type saws require more components than pivot saws, which can increase their overall price point. The first carbide saw was an adaptation of the slide-type high speed steel (HSS) saw. These saws slide horizontally on rigid box ways or anti- friction linear ways. Experts argue whether low-friction, lined slides moving on solid, rigid, and hardened box ways reduce vibration better than hardened linear slides rolling with hardened rollers on hardened guide-rails. Independent of the methods, all slide- type saws need at least a four- or six- point automatic lubrication system to guarantee a long, trouble-free service life of the sliding components. That means the users must factor in the following when calculating the total cost per cut: • Cost of the lube system • Lubricant costs • Higher maintenance costs • Costs to clean up the lubricant Vertical saws are used for cutting multiple tubes or billets in layers. In a sense, this model is a horizontal slide saw with the slide turned in a vertical position. Vertical slide saws are the most rigid, but also more expensive because their vertical arrangement is

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JANUARY 2020