Voice coil motors (VCMs) are a mechanical marvel, seamlessly merging actuators and sensors into a single powerhouse. These devices deliver blistering speed, pinpoint precision, and unwavering long-term performance. They've earned their stripes in tasks requiring surgical precision, such as product testing, autofocus systems, and even the delicate mechanics of hard disk drives. (Fun fact: The term "voice coil" originates from one of its initial applications, in which it was used to provide the mechanical movement in loudspeakers.) Beyond this, they've found homes in a vast array of industrial and scientific applications, from sorting and testing to precise alignment tasks. Similarly, you can find VCM’s in our test fixtures and custom equipment, and industrial automation solutions.
Today, we’ll share how we have leveraged the precision and speed of VCM’s in SMAC’s family of cutting-edge linear actuators, specifically the LPL and LDL models. While other servos are locked into position or velocity, SMAC’s voice coil motors offer the added flexibility of constant force output, finely adjustable to ~10 grams. They're fully programmable right out of the box, enabling users to streamline their work and validate accuracy simultaneously. SMAC actuators offer complete control in three distinct modes --Force, Velocity, and Position.
• Force Mode operates without feedback from the encoder. Although the actual position is monitored, it doesn't influence the output.
• Velocity Mode allows the actuating rod to glide with specified velocity, acceleration, force, and direction. It can rev up to an impressive 20Hz. This can be used in SMAC’s patented 'Soft-Land' procedure which allows the actuator to both measure and manipulate very delicate and high value components with ease (more on this below).
• Position Mode guides the actuating rod to a multitude of positions along the stroke. Here, you can tinker with acceleration, velocity, and force settings to execute absolute, relative, or "learned position" maneuvers with precision. When we say precision, we mean it; standard positional accuracy stands at 5 microns. You can also upgrade to a 1um, 0.5um, 0.1um or jaw-dropping 50 nanometer resolution encoder. This level of accuracy applies to both linear and rotational positioning.
SMAC's patented 'Soft-Land' procedure allows the actuator to both measure and manipulate very delicate and high value components with ease.
- Fully programmable in Position, Acceleration, Velocity and Force
- Sub- micron resolution (5 µm to 100nm)
- Low moving mass = high acceleration
- Direct drive = no backlash, excellent repeatability
- Force control = Soft - Land capability
- >250 million cycles MTBF = Long operating life
- < 55dB = Officially ‘Silent’ in operation
You can seamlessly switch between these modes during a single stroke. For instance, start in Position mode and smoothly transition to Force mode as your application demands.
Controller Options and Communication
SMAC offers actuators with built-in controller/drives for single-axis applications. Alternatively, you can opt for external controllers, ideal for both single and 2-axis actuators (linear/rotary, X/Y, and grippers). These controllers empower you to program position, velocity, and force modes with ease.
Standard SMAC actuators come equipped with four 5-24V digital I/O, an analog input, analog output, serial communication for seamless data exchange, and options for EthernetIP and EtherCAT communications. Connectivity simplifies integration into your mechanical systems. The VCM includes an encoder and other hardware, eliminating the need for arduous programming. Say goodbye to the days of configuring air lines, fittings, flow controls, analog signals for PLCs, and end-of-arm tooling. SMAC actuators seamlessly integrate with your PLC.
We recently configured the SMAC LDL40C in a low-profile bag dispenser fixture for our client Oranje.
The standout feature was its remarkable ability to maintain a constant force with utmost precision. Whether it was handling delicate tasks or exerting force consistently, the VCM proved its reliability time and again.
Additionally, the VCM exhibited an impressive speed that surpassed my expectations, making it a standout choice for applications requiring rapid and accurate movements.
While we were pleased with our experience, here are a few notes to consider before buying a SMAC voice coil motor:
- Size and Shape: These devices aren't the tiniest on the block, and their unique shape might not suit all applications. However, SMAC has responded by introducing the LDR8, their slimmest model to date. For fresh projects, it's a breeze, but if you're planning an equipment upgrade, expect to invest a bit more effort.
- Interface: The G-code interface isn't the most intuitive for all integrators like us. We needed more time budgeted to learn the G-code interface. Thankfully, SMAC was responsive and provided great support.
- Cost: For simple linear motion applications that don't require speed, positional, or force feedback the VCM can be higher cost with starting models at $300. That being said, they do provide longevity. Cheaper pneumatic cylinders are budget-friendly up front but have a shorter lifespan of ~10 million cycles than SMAC actuators with controllers which boast a staggering lifespan of 100 to 300 million cycles.
Noteworthy is SMAC's recommendation to opt for an actuator capable of two to three times the force required in your application. This would allow the maximum force needed to be a continuous value for safety. If your application requires precise force accuracy, it is critical that the coil temperature doesn't increase.
That being said, our sole regret in utilizing the SMAC VCMs is that we weren't aware of their capabilities for our projects sooner. We have already begun integrating them into fixtures similar to our custom carton erector. These exceptional components have proven instrumental in reducing noise levels, significantly accelerating cycle times, and enhancing overall turnaround times for our clients. Our engineering team highly recommends the SMAC actuators for their precision, speed, and exceptional control.