Tooling specialist Horn has announced an expansion of its product portfolio to include tools tipped with cubic boron nitride (CBN) for machining difficult materials such as superalloys and hardened steels.
The ultra-hard material is capable of smooth machining even during interrupted cutting when hard turning and grooving. By extending its existing standard ranges of Supermini 105, Mini 11P, 229 and 315 systems, Horn is able to deliver the CBN tools quickly from stock.
The Supermini system is available in left and right hand versions with different corner radii. The CBN-tipped variants are for internal machining from a diameter of 2mm and different lengths of solid carbide body are available. Tools in the Mini family can be used from an internal diameter of 6.8mm and are also available in left and right hand versions.
The single-edged tool type 315 is for external grooving from a width of 0.5mm. In the cutting insert system 229, the previous CBN substrate CB 50 is replaced by the higher performance substrate CB 35. Inserts are available with two different corner radii and cutting widths from 3mm to 6mm.
CBN is the second-hardest material after diamond. Tools made from CBN wear much more slowly than other cutting materials when used appropriately. It is consequently possible to achieve higher dimensional and profile accuracy, even when machining hard materials such as steel up to 70 HRC.
There are no different grades of CBN. Differentiation between tools is down to the CBN volume fraction, the fillers, grain size and the ceramic/metallic binder phase (cobalt/nickel). This results in different CBN substrates. Hard machining is usually carried out without coolant, as these cutting materials have high heat resistance and the elevated temperature within the chip formation zone has a positive effect.
Whereas carbide suffers a significant loss of hardness at around 800°C, the hardness of CBN remains almost unchanged at temperatures up to 1,200°C. Another significant advantage is good chemical resistance, even at these high temperatures.
In addition, following the launch of its polycrystalline diamond (PCD) tipped parting-off tools, Horn has introduced new step drills having cutting edges tipped with PCD for drilling, boring and countersinking non-ferrous metals, such as in the production of aluminium wheels.
The tool system allows greater drilling precision and produces better surface quality due to the sharp cutting edges. The tools permit high cutting parameters during machining, which makes it possible to reduce the processing time and hence the cost per component in series production.
Horn only offers the PCD-tipped step drill as a special tool. The PCD tip is available on tools of 4mm diameter and above. All variants have an internal coolant supply. The carbide monobloc shanks, which are available in all common DIN diameters from 6mm to 25mm, ensure good vibration damping during machining. The monobloc shank is available in a steel variant from a diameter of 32mm.
PCD is a synthetically produced, extremely hard, intergrown mass of diamond particles with random orientation in a metal matrix. It is produced by sintering together selected diamond particles at high pressure and temperature. Economical machining of steel is rarely possible due to the affinity of iron for carbon in the diamond. As the temperature increases, the carbon from the diamond diffuses into the steel, severely limiting tool life.
Horn Cutting Tools