History and Types
– Annular cutter patented in 1973
– High-speed steel type patented in 1983
– Tungsten carbide tipped type patented in 1985
– Two main types: High-speed steel (HSS) and Tungsten carbide tipped (TCT)
Qualities and Benefits
– Annular cutters are 3 to 4 times faster than conventional drill bits
– No pre-drilling or step-drilling required
– Can be used at higher cutting speed and feed rate
– More efficient and less wear compared to other drills
– Best used with drill press or magnetic drilling machine
– Requires less thrust and energy to drill through material
– Internal lubrication provided through a hole with pilot pin
– Faster and more efficient for deep-hole drilling
Usage and Sizes
– Used with light-duty drilling machines or portable magnetic base drilling machines
– Low RPM requirement (minimum 50 RPM)
– Available in various sizes from 12mm to 200mm and larger
– Common cutting depths of 30mm, 55mm, 75mm, and 110mm
– Can be sourced in different cutting depths depending on requirement
Re-sharpening and Cost
– HSS annular cutter can be easily re-sharpened on a grinding machine
– Can be reused until desired cutting length is available
– HSS core drills are cheaper than TCT core drills for smaller diameters up to 40mm
– TCT core drills are cheaper than HSS for diameters above 41mm
– The cost per hole made with a core drill is less compared to twist drills
– A single core drill can make 5 to 10 times more holes than a twist drill
– The initial cost of a core drill is higher than a twist drill
Special Applications
– Annular cutters can make holes in pipes and tubes without dimpling and deburring
– Annular cutters should be used with a magnetic base drilling machine and a tube/pipe clamping device
– HSS annular cutters are commonly used for drilling tubes and pipes
– Rail annular cutters are designed for drilling railway tracks
– Rail annular cutters are available in HSS and TCT types, with TCT cutters being more popular
– TCT cutters are preferred for their ability to cut harder materials
– Rail annular cutters are manufactured with special grades for railway track drilling operations
– Comparison between HSS and TCT core drills
– Re-sharpening of TCT core drills is more difficult due to the geometry needed for carbide
– Improper grinding of carbide can lead to breakage Source: https://en.wikipedia.org/wiki/Annular_cutter
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An annular cutter (also called a core drill, core cutter, broach cutter, trepanning drill, hole saw, or cup-type cutter) is a form of core drill used to create holes in metal. An annular cutter, named after the annulus shape, cuts only a groove at the periphery of the hole and leaves a solid core or slug at the center.
An annular cutter is a more expensive and efficient alternative to spiral drill bits and standard hole saws. An annular cutter is similar to a hole saw but differs in geometry and material. The two most common types are high-speed steel (HSS) and tungsten carbide tipped (TCT).
Like a hole saw, but unlike a spiral drill bit, an annular cutter cuts only the periphery of a hole, leaving a circular "slug" at the center.[citation needed]
Annular cutters are best used with a drill press or magnetic drilling machine, both for their stability against high torque forces created by such a drill bit and lower RPMs compared to other types of drills.
