Portable drilling of holes for construction and steel fabrication applications can be slow, inefficient, and inaccurate. Annular cutters offer an alternative to twist drills and conventional cutters for operations requiring holes in steel while providing cleaner cuts, easy slug ejection, and long tool life.
Using a twist drill is the conventional method of creating holes in metal. Twist drills have only two cutting edges, which require more time and power and cause increased wear because the complete area of the hole is removed and turned into chips. The twist drill has a center point, which is not really a point but the intersecting line where the two cutting edge angles meet at the web of the drill. This is called the “dead zone” of a twist drill because at this point the slower surface speed reduces cutting efficiency and requires that increased feed pressure be applied in order for the cutting edges to bite into the material.
An annular cutter is a hollow tool that provides multiple cutting edges. Annular cutters drill a burr-free hole by cutting material around the periphery of the hole and ejecting the center as a solid usable slug. It’s an efficient way to create holes ½” to 4” diameter and up to 3” deep. Final holes are smooth and no reaming, predrilling or step drilling is required. The wall thickness of the cutter is only ¼” thick so that no matter what size hole you are cutting, you are only removing a small amount of material around the edge of the hole.
Annular cutters are manufactured in several different configurations including carbide-tipped annular cutters and carbide tipped stacked annulars for maximum cutting performance. Tests on 25mm construction steel with a Champion AC35 drill press show a result of over 2-1/2 times as many holes drilled compared to a high-speed steel annular cutter. Other types available are high-speed steel annular cutters as well as other materials & coatings such as titanium nitride coated, and cobalt stack cut.
Twist drilling requires a machine with more horsepower because a large amount of force is needed to “push” the material from directly under the tip of the bit outward, where the two cutting edges can bite and convert the solid material into chips. Annular cutters can cut at higher feed rates with lower horsepower consumption and run on smaller, lightweight, but powerful portable magnetic drill presses and drill up to 4 times faster. These machines may be used in any position – vertical, horizontal, or overhead.
Finally cleanup and recycling for environmental purposes are easy as scrap from annular cutters consists of a minimal amount of swarf and a solid slug.
The carbide & high speed steel annular cutters discussed above can be found on our website.