Wednesday, October 3, 2012

Explore the Guided Motion Possibilities of Linear Bearings with Applications Engineer Dan Fletcher, Coffee Chat Part I of III

PRECISION AND SPEED These two factors are critical when spec'ing what linear guide system works best for your application. Many other variables must be considered as well, such as environment type, duty cycle, length, temperature and payload weight. To help explain how to choose the right guide wheel system for you, we turned to one of our applications engineers, Dan Fletcher.

What makes the DualVee® wheel stand out from other linear motion technologies? 
Dan: In each of the three major linear motion technologies (profile rails, round rails, and guide wheels), ball bearings recirculate. In profile and round rails, however, the bearings ride on the guide rail and are exposed to any of the contaminants that may settle on the rail. The bearings in a 90° double-vee guide wheel are self-contained and isolated from the environment, so there is no contact between the bearings and the rail.

Why is the actual shape and form of the wheel important?
Dan: Most contaminants that settle on vee guide rails are swept away when the wheel passes over the rail. When the wheel spins at a constant speed, the diameter at the inner vee travels at a slower rate than the diameter at the outer vee, causing a velocity gradient that pushes the debris outward.

How did DualVee Motion Technology come about?
Dan: The double-vee design was originally developed in 1967 as a replacement for flat rollers on machinery at a fertilizer packaging plant, where debris from the processing operations continuously clogged the bearings, causing equipment to shut down. The 90° double-vee approach, with its inherent wiping action, proved ideal.

What are some other advantages of choosing a DualVee-based linear motion system? 
Dan: Those self-contained ball circuits have other, lesser-known advantages, too. The containment can cut noise levels by up to 20 percent in some applications compared to alternative re-circulating technologies. The DualVee runs smoothly for several reasons. For one, it has a constant radius ball bearing path. Its carbon, stainless steel and composite components also contribute to its effortless movement.

What about noise? 
Dan: The steel versions are slightly louder, but permit fast acceleration, up to 5 gs, and speeds up to 5.5 m/s. For quieter motion, and a more economical option, the polymer versions works well in chemical-exposed settings and lighter-load applications.

[ Read about DualVee's tolerances and lubrication requirements in Part II—tomorrow! ]