Revolutionary new mixed-matrix materials, such as composites and powdered metals, challenge cutting tool OEMs to deliver products that excel under extreme cutting conditions. To make components from such unique materials, shops must carefully choose their cutting tools and workholding to get the best results.
As opposed to solid materials that are composed of a single substance, mixed-matrix materials have multiple components, such as glass-reinforced plastic or blends of powdered metals, that make cutting more complex. Pockets of different materials within the mix sometimes create inconsistent cutting conditions, and also tend to be highly abrasive, which can decrease tool life and surface finish quality.
Though challenging to machine, these materials provide a host of benefits to manufacturers, especially those in the energy, automotive and aerospace industries. For them, benefits include wear, heat and impact resistance and reduced part weight.
One example is frac plugs, which are used in oil and gas exploration to contain the blast after a well is drilled. The components are made from a special glass-reinforced plastic that is especially beneficial in this application because it is both hard enough to exert sufficient pressure on a pipe to stay in place during extraction, yet soft enough to prevent damage.
One of the biggest challenges associated with mixed-matrix materials is their constantly changing “recipes.” Each change to the mix alters the way the material cuts, which impacts cutting tool performance and longevity.
To overcome such challenges, cutting tool OEMs, like Seco Tools, conduct extensive research on materials to deliver appropriate application recommendations and develop new products that keep pace with evolving customer demands. The company studies interactions between cutting tools and component materials and the impact of machining operations on tool life as well as customize tools for specific applications.
When it comes to a material’s effects on cutting tools, chemical reactions between the component material and the metal in the cutting tool can also cause the tool to prematurely degrade. For instance, a component made of a material with high ferrite content will attack the boron in cubic boron nitride (CBN) indexable inserts, so an insert produced from materials that will chemically interact less with the component are needed.
Likewise, mixed-matrix materials affect chip control differently. Depending on the mix, powdered metals may break up easier when cut, so chips are easier to control. However, high-density powdered metals create chips that are more difficult to control.
To achieve the overall lowest cost per part on mixed-matrix components, shops want a good balance between tool life and productivity. This goal greatly impacts machining processes and cutting tool selection. Higher feed rates deliver more productivity but decrease tool life, while slower machining lends itself to long tool life but limits productivity.
Several other factors influence cutting tool selection. These include continuous cut conditions versus those with interrupted cuts, as well as the stability of the machine tool and workholding being used. Workholding for mixed-matrix materials needs to be rigid enough to hold the component in place under strong cutting forces but without damaging the part.
Such special materials frequently require cutting tools that are equally as specialized. In these cases, cutting tool OEMs develop custom tooling that exceeds the capabilities of off-the-shelf options. For frac plugs, for example, Seco created super-positive polycrystalline diamond (PCD) inserts specifically to machine the proprietary glass-reinforced plastic.
To choose the best cutting tools for mixed-matrix materials, cutting tool OEMs, such as Seco, look at specific material composition to determine how these factors will affect the cutting tool. Because of the many variations possible, these new materials require a range of different approaches. However, each new mixed-matrix application teaches cutting tool suppliers how to make their customers’ jobs easier.