Mollart introduces trepanning for economic tube production

The Mollart TPA-600 and TPA-1200 Trepanning Centre expands the range of deep hole processing solutions available from the Chessington, Surrey based company and provides a very economical process for producing tubular or cored lengths from larger material. Normally, tubes of this type would be rolled and seam welded or drilled and bored from solid creating large volumes of swarf requiring subsequent disposal. The Trepanning Centre compliments the well-proven Mollart deep hole drilling process for large bores using BTA and ejector drill heads which can produce holes up to 400 mm diameter. Said Ian Petitt, Sales Director: "The trepanning method has a major economic advantage because the core of the material is retained and can be used for further requirements of producing smaller bar or tube lengths. When high cost materials are involved the trepanning process becomes evermore viable and with difficult to machine materials, these can be unpractical to roll." The Trepanning Centre uses a hollow endmill style rotating cutter head with the larger TPA-1200 machine powered by a 45 kW motor through a three speed gearbox. The material to be processed is held stationary in a hydraulic fixed chuck and is supported using a steady on the bed. The toolhead has a relatively narrow cutter width to produce a kerf of 10 mm through a series of standard ISO insert cartridges equi-spaced on the inner and outer diameters. On a 250 mm cutter for example, up to eight cartridges would be utilised to enable a balanced cut to be performed. The cutter is fed by two, 300 litre/min capacity high flow coolant pumps to clear swarf created from the high penetration rate of feed and to prevent the material packing and eventually jamming. Filtration, chip conveyors and chillers are all included in the machine's specification. The stroke of the TPA-1200 machine is 600 mm, however, by trepanning part way, withdrawing the cutter head and rotating the part 180 degrees, the machine can be recycled to produce a total tube depth up to 1.2 m deep with a typical low level of mismatch at the centre within 0.5 mm. The cutter head is programmable between 10 and 850 revs/min. A typical time to process mild steel with a 250 mm bore by 600 mm deep would be within eight minutes. The machine uses Fanuc OiM control as standard, however, other systems can be interfaced and operational software is written by Mollart engineers. A range of material handling devices can also be provided by Mollart. Both the TPA-600 with a maximum trepanning diameter of 250 mm and TPA-1200 machines can also be used for drilling from solid using spade or U-drills.