The BTA tooling and process operation is coordinated through the Chessington, Surrey-based, and newly formed BTA application centre team, drawing in Mollart’s machine tool design and development plus the coolant and filtration and build facility in Resolven, South Wales.
The HD1-BTA-3M is a modular constructed BTA machining system able to produce precision drilled holes up to 150mm diameter from solid in packaged lengths of 3m over a wide range of materials including exotic steels. These drilling depth-based bed lengths can be extended to 6m, 9m and 12m capacities. Also within the specification is the capability to counterbore existing bored holes to 200mm diameter over the full depth capacity of each 3m length module.
BTA or STS (single tube drilling system) demands higher power than conventional drilling or gundrilling for deep hole applications and uses a highly rigid drill head system that is secured to a support and feed tube with either brazed carbide or indexable inserts. Filtered coolant is pumped in high volume under pressure to the cutting edge of the tool between the outside of the tube, the cutting head and the newly created bore of the workpiece.
The highly stable and rigid cutting tool system uses the coolant flow to effectively flush chips back through the drill head, tube and machine spindle for collection. As a result, penetration rates are high and several times faster than more conventional drill types with good geometry and surface finish being maintained.
The first Mollart HD1-BTA-3M machine is being installed at the Chessington headquarters to expand its subcontract drilling capability. Involving Botek engineers – a leader in deep hole drilling systems and tooling – to work with the Mollart team, will further expand its capability to produce larger deep holes in a wide range of materials including Inconel and Super Duplex stainless steel.
Indeed, the capacity of the new drilling platform module will be capable of accepting billets of material up to 400mm diameter by 3,000mm long and weighing up to three tonnes. These are typically required by sectors such as oil and gas and subsea, which are already regular sources of business for Mollart.
Such is the match of BTA tooling to the processing capability of the HD1-BTA-3M machine, that to maximise rigidity and stability, a heavy cast frame carries twin rack-and-pinion drives. These can be extended when additional modules are linked together to satisfy increased demands for depth of hole.
The precision racks have servo backlash elimination and a four-speed automatic selection gearbox that develops a massive thrust of 70Nm at just 50rpm. Power to the drilling head is 37kW and the workhead can also be counter-rotated between 50 and 2,500rpm.
The new generation machine is able to perform push-boring and pull-boring tasks for hole enlargement applications as well as skive burnishing to create higher orders of size and surface finish.
Once the machine is in production within Mollart’s BTA Application Centre, it will not only be used as a prototype process development platform for machine tool sales but also, to support Botek’s BTA supplied tooling customer tooling trials.
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