Recently on LinkedIn, I posted a commentary from Scott Evans of Kollmorgen detailing the benefits of today’s servo-driven designs.
In response, one reader — machine design engineer and independent contractor machines Jon Holler — posted a thoughtful reminder that mechanical cams are still a viable option for a lot of designs. In fact, new software tools have made mechanical cam designs more sophisticated and competitive than ever.
Here’s what Jon had to say.
But I’ve seen little on the comparisons of mechanical cams and servomotors …
… and with new CAE software, the design of mechanical cams is faster and more advanced than ever.
That means that the playing field is now leveled a bit.
Advantages of mechanical cams abound
Synchronization is inherent to the cam profile, which is useful where several cams work in synchronicity (within multi-axis designs). There are no errors to cause interference and subsequent damage; neither is there downtime for homing routines.
Mechanical cam motion is high-tech on the engineering side (thanks to new software tools that make their design more advanced than ever) but their operation is low tech. In addition, mechanical cams are a low-maintenance option with long design life and minimal component wear.
Mechanical-cam applications in robotics
In robotics, an end effector is the device at the end of a robotic arm that interacts with workpieces or the environment in some way. Also called end of arm tooling or EOAT, the exact geometry of this device depends on the robot application. Linkages have end effectors too — and here, cams can spur the motion can come from cams.
In some setups, several end effectors come together in close proximity while the cams that drive their complex strokes run remotely. This is particularly useful where the required motor size — that sufficient to move application loads — and mechanisms to convert rotary motion to linear won’t fit into the design space.
In fact, mechanical cams excel at repeatable high-speed synchronization in close proximity to where machines interface with workpieces … which cannot always be said of servomotor systems.
Other benefits of mechanical cams include the fact that they consume low energy consumption in some applications. Plus, CAD/CAM software makes CNC programming of setups incorporating mechanical cams quite simple. In addition, the latest generation of coated cutting tools make cam fabrication fast … and hardened tool steel can now be milled for finish cuts.
Disadvantages of mechanical cams
All engineered designs have drawbacks, and mechanical cams are no exception. The biggest drawback is that there’s a lack of flexibility if product changes are expected. Mechanical cams are also incapable of infinite positions and multiple moves with a single EOAT — as what XYZ tables output when integrated into milling machines and other assembly processes.
For more information on whether mechanical cams may be a fit for your design, contact Holler Machine Design and Automation at hollerdesigns.com.