Antifriction linear bearing systems are crucial to the production output, accuracy, and repeatability of today’s modern CNC routers and water-jet cutters. The woodworking industry relies on these machines to rapidly mass produce products ranging from door panels to structural framing for cabinets. A prominent byproduct within the industry is sawdust.
Sawdust build-up can cause premature failure in rolling-elements within linear bearing systems. It finds its way through their best sealing systems and quickly clogs the ball tracks of conventional linear ball bearings. When the ball tracks jam, they start spalling (grooving) the shafts that the bearings run along, causing a faster ingress of sawdust through the shaft groves and eventually resulting in the complete failure of the system.
Generally, sawdust and other common environmental factors pose several problems in rolling element bearings. Contaminants and debris can become stuck in the bearing cage and cause the system to seize up and fail. Vibration causes the bearings to shift off their track or become dislodged. Both outcomes lead to catastrophic failure and unplanned downtime, creating lost profits and increased production time for the manufacturer.
In this industry example, a manufacturer was using a commercial wood sander on large furniture. The wood sander station sits on a 180 lb steel base and uses high-speed oscillating motion (1735 RPM) for short, 4 mm strokes. The oscillating mechanism is operated by two cam assemblies running with a roller bearing in between.
The sander suffered from two major bearing issues. First, the short, reciprocating motion is under constant use by two labor shifts for a total of sixteen hours a day for six days a week, until it eventually breaks down. This constant use meant the sanding table would only successfully function for about one week before failing. This would lead to a costly cycle of replacing damaged parts and awaiting the next shut down.
Second, for the old roller bearings to function properly, precise alignment was crucial. The slightest misalignment resulted in grinding between the cam and roller bearing. High friction and heavy shock loads caused fretting on the system. In fact, shop employees commented that contact between the roller bearing and the cam system would create so much friction and heat that the roller bearing would glow red. Even when lubrication was applied, misalignment and high temperatures (110°F) as well as grinding would persist, and the system was unable to last a full week.
In response, PBC Linear engineers were brought in to examine the internal components. After their analysis was complete, they recommended completely swapping out the failing rolling element bearings with customized Simplicity® plain bearings.
The advantages of Simplicity plain bearings include:
For this particular application, PBC Linear designed an optimized bearing assembly that would rock along with the motion of the cam system—completely eliminating misalignment issues. We used an internal, periodic lubrication system to facilitate smooth oscillating motion. This extended the life of the system from one week to over a year of smooth, non-stop and maintenance-free performance.
The manufacturer noted significant cost savings as a result of life improvement. Weekly replacement parts for the previous internal design had amounted to $300 per week. Our new bearings netted the company $15,000 in annual cost savings! Overall, the manufacturer was pleased with the new Simplicity bearing assembly for its enhanced system integration, quieter operation, and cost savings.
Simplicity linear motion technology from PBC Linear is designed to last. This is in part due to its patented FrelonGold® liner, but also its lack of moving parts. The liner helps to greatly increase load and speed capacities, tolerate a variety of different environments, and avoid catastrophic failure. Extreme heat and cold, contamination, debris, submersion, and shock vibration do NOT affect the performance of the bearings. The patented, self-lubricating design also requires virtually no need for further lubrication. For the woodworking industry, the liner helps the bearings to harmlessly absorb wood shaving debris and continue optimal function even in high vibration areas such as water-jet cutting or sawing.
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