Electric Actuation - Accuracy and Rigidity

Accuracy and rigidity of actuators are crucial for metal machining

Published On: 9 November 2021
Electric Actuation - Accuracy and Rigidity

When assembling prefabricated metal components and frames, exacting accuracy is consistently needed to ensure a productive work rate and to avoid rejects. To achieve this, drills, routers and cutters have to provide a controlled action that ensures precision and avoids deflection during high speed operation. This relies on the rigidity and precision provided by the actuators, and a multi-axis linear system can help OEMs design more productive, high performance machines.

Gerard Bush of INMOCO explains the key considerations in actuator selection for metal machining.

When metal framework is assembled onsite, such as aluminium frames for doors and windows in construction projects, it’s vital that the prefabricated pieces are delivered with holes drilled and pieces cut with precision. These projects demand speed of installation and if the framework includes inaccuracies or defects, this means time onsite to rectify the issue or the introduction of waste through rejects.

As a result, a key requirement for metal working machines from routers to drills is precise control and stability in the automation process to enable accurate positioning throughout the machine’s operation. Without consistent accuracy, this results in poor fit and finish of the completed framework that can impact the quality of construction and efficiency of build.

A major cause of inaccuracy in metal machining is deflection. A common problem when machining with high speed drills and routers on aluminium framing, as the material moves through the machine, the cutting axis can bite, bend or wobble. Crucial to avoid deflection, it’s imperative that the machine’s actuators securely hold the drill or withstand the force of the press to prevent misplaced drilling or cutting.

The more exacting the specification or intricate the operation, the more crucial this becomes. If the actuator system can’t provide rigidity to sustain secure retention amid high paced machining, the pace of manufacture has to slow accordingly, impacting productivity. Alternatively, the machine risks inaccuracies and defects, affecting product quality and introducing waste.

To combat deflection, ideally the actuator requires a single body frame with a thick aluminium base, factors that contribute to high rigidity. Smooth action and control of the rail stage will also optimise control, and actuators specific to the task, such as Tolomatic’s TRS, provide high positional screw accuracy with the roller nut model providing ± 0.0102mm/300mm.

Combined with a controller and its software program, a multi-axis approach to metal machining of prefabricated framework can increase productivity by speeding up production. On such an approach, material can be automatically moved into position. A three-axis linear actuator system operating across X, Y and Z planes of movement can drill and route the top, bottom and front sections. High-speed tool sets can be mounted on multi-axis actuator system and cut holes and shapes according to the controller and software with a 90-degree upcut saw cutting the product to the required size. Introducing Tolomatic’s TRS actuators can achieve a three-axis configuration, mounted carrier-to-carrier with no additional mounting plates required.

The generation of swarf and fine particles is an inevitable by-product of metal machining applications. To avoid this material entering and fouling the actuators and impacting their service life, adequate sealing is required. A retained exterior dust band will keep contaminants from entering the actuator interior, protecting components to provide reduced maintenance and increased uptime. In addition, positive pressure with air lines and filters will ensure that contaminants do not enter the interior of the actuator. Ideally, the body of the actuator should be constructed from fatigue and corrosion resistant stainless steel. The wiper and seal on the actuator’s rail stage surface should also be integrated into the carrier design to provide consistently smooth and controlled operation.

OEMs might have their own choice of motor to power the actuator and INMOCO’s engineers can also advise on the optimum combination according to the application’s requirements. Tolomatic’s TRS can be delivered with mounting hardware specific to the required motor with in-line or reverse parallel mounting. In combination with the actuation system, INMOCO can also specify control hardware and assist in the selection and development of motion programming to optimise throughput and control accuracy for the desired application.

Removing deflection combined with high positional accuracy will ensure precision cutting and drilling across metal machining applications. Adequate sealing and protection of the actuator system will not only ensure smooth, service free operation, it will also reduce the total cost of ownership and enhance the lifetime of the machine.


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