Metal core drilling redefined

The metal core drilling machines RB 35 SP and RB 50 SP from Hockenheim-based tool manufacturer Alfra are fitted with a powerful neodymium permanent magnet with pre-stressing, whereby considerable magnetic forces can be achieved even with small mass application. With an innovative and patented concept for magnet alignment, the machines can be used even on thin-walled materials from a thickness of 3 millimetres. Conventional metal core drilling machines fitted with an electromagnet can be used only from a material thickness of approx. 6 to 8 millimetres.

SP line opens up new application scenarios

“As our new metal core drilling machines can already be operated safely and comfortably on thin-walled materials, we are opening up completely new application areas to our customers,” Alfra director Markus Döring explains. According to information from the expert, both models can be used to work even on thin lining sheets, such as are usual in façade, container and ship construction as well as many other application areas.

Records in industrial safety and ergonomics

Models RB 35 SP and RB 50 SP cover a drilling range up to 35 mm or 50 mm – with a cut depth of 50 mm, which can be achieved with both devices. An adjustable lifting range is also included on board in both drilling units. The tool for adjusting and fixing is located in the new grip plate in a clever and user-friendly way.

The two drilling systems also achieve records in industrial safety and ergonomics. The ergonomic activation of the magnets with a handy strap positioned on the side, close to the body of the magnet, has also been completely redesigned. The new design also sets new standards for weight; 9.9 kilograms (RB 35 SP) and 11.5 kilograms (RB 50 SP) are below the values at which machines with similar performance weigh in. This is made possible by the permanent magnets used.

“Metal workers often need a third hand if they have to use the metal core drilling machine in a fixed position overhead or vertically. Our magnet is slightly pre-stressed and holds the deadweight of the device by means of the magnetic field reduced to a sensible level. Completely relaxed, the user can move the machine into the drilling position and get started. This is another invaluable advantage,” Markus Döring knows, “as it is simply impossible with conventional systems.” With the new operating concept of the permanent magnet, the metal core drilling machines can also be positioned between the flanges of a steel beam with no problem.

Permanent magnet technology pays

Unlike conventional systems, the permanent magnets moreover stand out for their lasting stability and long durability. In Markus Dörings experience with everyday use, this pays: “In practice, the drilling systems often remain on the material with the magnet activated whilst the user pauses or is distracted by secondary activities. As a result of the constant power consumption, a conventional electromagnet heats up over the course of the time when it is switched on, which substantially reduces not only its performance but also its service life.” This is not so with the new neodymium magnets of RB 35 SP and RB 50 SP. By virtue of their innovative concept, they require little maintenance and stand out for their long durability.

Convincing overall concept

With the activation of the magnet using the ergonomic hand lever, the electrical circuit for the magnet is no longer required. Only a large and clearly visible membrane keyboard perfectly protected from external influences remains for activation of the motor. The 5-metre-long connecting cable demonstrates that Alfra really has thought of all the details. An LED light, which is optimally positioned on the housing in the field of vision, indicates readiness for operation by means of a green light. In addition, an integrated sensor measures the magnetic field and displays it by the status of the LED: if the material is too thin then the LED lights up in red; if there is sufficient material then the LED indicates this with a green light. The machine cannot be started in red status.                                                                                                                                                           

…And that is still not enough

The product developers at Alfra have thought even of small details and fitted both metal core drilling machines with a temperature sensor for the motor and with a wear sensor for the carbon brushes of the drive. This eliminates overheating of the machines and the wear level monitoring shows at an early stage when the machine requires maintenance, which generally means that expensive repairs can be avoided. Moreover, the metal core drilling machines have integrated internal cooling.

The magnetic holding surface of the permanent magnet is also permanently durable due to its TiN coating and the surfaces are optimally protected, which makes adherent metal shavings easy to remove. The ALFRA Rotabest RB 35 SP and RB 50 SP are supplied in highly robust, oil repellent, double-skinned plastic cases.

Safety First

In operation and on the construction site, safety and accident prevention must be considered at all times. Alfra sets new standards here with the new metal core drilling machines. Even in the case of a power cut, the devices remain stuck to the workpiece. A look at the repair departments of many manufacturers reveals that “crashes” occur regularly there – even if the user is obliged additionally to secure machines in a fixed position with a belt.