The steps from ballscrew, to flatbed linear, to tubular linear electric motors each represent improved performance in a few key areas.
An important change from ballscrew to linear motion is going from indirect to direct drive, with no need for gearboxes or belts to create movement. Going from rotary direct motion also means big potential increases in speed and acceleration. Although ballscrews still have their advantages, there are trade-offs when selecting any type of actuation based on the application, there are some clear areas of superiority when comparing linear versus rotary motion, and manufacturers offer drop-in replacements as a response to this.
One of the standout advantages is dynamism, with much better acceleration and velocity possibilities. With ANCA Motion’s LinX M-Series, a velocity of 10m per second can be achieved, along with a maximum acceleration over 30G. Continuous force range is between 90N and 160N.
Another advantage of tubular over flatbed actuation is longer machine life due to there being no contact between moving parts; electromagnetic forces generate the motion, rather than contact between a nut and screw. Going from flatbed to tubular actuation also means greatly improved thermal stability, and therefore less expansion, meaning components and the system will perform with better accuracy.
Heng Luo, Product Manager at ANCA Motion, explains the advantages of the M-Series: “Because the motor is floating in the machine structure, that enables us to put a water-cooling jacket around the motor and completely take the heat out of the motor. That’s a vast advantage from a thermal perspective compared to a flatbed.”
Options such as the M-Series are growing in popularity in food and beverage, pharmaceutical and other applications where hygiene is important. The absence of direct contact between parts and the elimination of any need for rail tracks means no need for lubricants, which can risk contamination. Flatbed motors can be challenging to seal and protect, and tubular motors provide a superior level of protection from material ingress, as well as increased safety levels for the operator. M-Series magnets are also sealed in a stainless steel tube, with an IP 67 rating achieved.
A further area of advantage is the smoothness of tubular motors versus flatbed-style motors. Windings are in an epoxy, with no iron core in the motors’ magnetic circuit. This means no downforces and much less cogging. The M-Series also offers high levels of positional accuracy, with a resolution of 10 micrometres, as well as an integrated position sensor.