June 25, 2016 / best practices, blade failure, blade life, blade selection, Cost Management, LIT, ROI
In band sawing, forges and other industrial metal-cutting companies typically rely on two types of blades—bi-metal and carbide-tipped blades. Both blade technologies offer more performance and life expectancy than carbon steel blades, and choosing between the two types used to be fairly straightforward. However, advancements in both technologies have made it a little more difficult for companies to make the best blade choice for their operations.
While sawing is just a small part of the forging process, achieving operational excellence requires managers to optimize all aspects of the forging operation. To help forges make the best decision about the “right” blade type for their band-sawing operations, below is a brief overview on both blade types from the white paper, Selecting the Right Cutting Tools for the Job.
Bi-metal blades are a common choice for most metal-cutting applications, especially since they are more affordable than carbide-tipped blades. In bi-metal blade construction, high-speed steel edge material is welded to fatigue resistant spring steel backing, providing a good combination of cutting performance and fatigue life.
Generally speaking, bi-metal blades are sub-divided into the following two categories:
- General-purpose blades are often used for easier-to-cut metals such as aluminum and non-ferrous metals, carbon steels, structural steels, and some alloy steels. These blades are also good for switching between different metal types and sizes, as well as from solids to structural pieces. However, some industry experts warn to be judicious when switching between different metal types, sizes and shapes, as subjecting blades to different types of cutting can shorten blade life.
- Production-sawing blades tend to be more versatile and are able to cut everything from the easiest-to-cut materials to difficult-to-cut nickel-based alloys. These blades are also ideal for cutting structural pieces and bundles, and they typically offer a long blade life and fast, straight cutting.
Like bi-metal blades, carbide-tipped blades are made of at least two different types of material. In most cases, carbide tips are welded to a high-strength alloy back, providing a longer lasting, smoother cutting blade.
Although carbide-tipped blades are typically more expensive than bi-metal blades, shops may elect to trade up to a carbide-tipped blade for three key reasons:
- longer life
- faster cutting
- better finish
The various choices of carbide-tipped blades will cover the machinability spectrum, but they are most often used for hard-to-cut materials like super alloys. High-performance carbide-tipped blades work especially well with hard tool steel that needs to be cut fast. Some high-performance carbide-tipped blades—especially coated versions—can offer extreme cutting rates, while others can perform exceptionally well when cutting super alloys.
Weighing the Options
As explained in the white paper, Top 5 Operating Challenges for Forges that Cut and Process Metal, having the right blade for the job optimizes cut times, cut quality, and blade life, especially when cutting tougher metals like stainless steel and super alloys. This is particularly important in forged materials, which require aggressive blades with varied tooth geometries that can get underneath any scale buildup.
Of course, there will always be instances when the “right” blade choice won’t be clear cut and will require managers to strategically choose between a “good,” “better” and “best” option. For example, bi-metal band saw blades have been traditionally used for easier-to-cut metals such as aluminum and non-ferrous metals, carbon and structural steels, and some alloy steels. However, as featured here in Modern Metals, LENOX offers a carbide-tipped band saw blade that has been designed specifically to cut aluminum and non-ferrous alloys. The new blade has a range of features that are optimized for aluminum cutting applications, including a specialized grade of carbide on the tip, a multi-chip tooth pattern, and a high rake angle.
Another example is noted in an article from Canadian Industrial Machinery. According to the article, bi-metal blades can be used to cut super alloys; however, as the article explains, cutting speeds will need to be slower and blades will wear out faster than when using carbide blades. “An experienced operator can adjust parameters to cut the occasional super alloy with a bimetal blade, but carbide is the choice to cost-effectively cut large quantities of hard materials,” the article states. “Blade choice comes down to a cost-per-cut situation and what fits with a shop’s operation.”
Making the Right Choice
Indeed, blade selection needs to take into account the total operational costs of running the blade, including maintenance costs and equipment requirements. Case in point: While carbide-tipped blades are more advanced in the right application, they do not perform well with a lot of vibration. Therefore, they can only be used with certain saws. Metal-cutting operations using carbide-tipped blades need to make sure they are using a saw that can run the blade speeds that are required.
In the end, the “right” blade choice requires forges to weigh the following:
- upfront costs against overall operating and maintenance costs
- long-term productivity of a machine and its intended use
- equipment and blade life, as well as cost per cut
By understanding some of the basic features of each blade type and then strategically assessing operational needs and goals, managers can make informed purchasing decisions that will factor into the bottom line and, ultimately, contribute to the shop’s overall success.