Pioneers in Machining Technology
When the Japanese tooling manufacturer, BIG Daishowa, first introduced its purpose-designed C-Cutters for high precision plunge-chamfering of holes, it used a standard chamfer angle of 45 degrees. Now the company has introduced two additional fixed-angle cutters for chamfering at 30 and 60 degrees respectively, as well as a universal type on which the angle can be set anywhere between five and 85 degrees.
Available in the UK through NCMT, the range comprises two 30-degree tools for chamfering holes from 16 to 85 mm diameter and three 60-degree tools for 14 to 65 mm diameter holes. The original 45-degree C-Cutters can machine holes up to 100 mm diameter. The wide, overlapping chamfering ranges save on the number of toolholders needed, minimising unproductive tool change times and the number of pots occupied in the tool magazine.
Adjustable nozzles direct coolant efficiently to the point of cutting to allow high feeds and speeds. The two sharp cutting edges of each parallelogram-shaped carbide insert, which is securely clamped by a double screw system, enable a high quality surface finish to be achieved on the chamfer, despite cutting speeds up to 240 mm/min and feed rates up to 0.6 mm/rev. This is in contrast to some tools on the market that use standard inserts, which tend to chatter when chamfering due to compromised rake and clearance angles.
The Universal C-Cutter employs a novel cartridge system for adjusting the insert angle quickly using a hex key and a direct circular scale. The shallowest chamfer angle of five degrees requires a minimum hole diameter of 5.5 mm, while for the steepest 85-degree chamfer, smallest hole diameter is 38.8 mm.