Resources: igus Inc., www.igus.com
To that end, engineers are increasingly turning to plastic bearings for packaging tasks ranging from cartoning and filling, to palletizing, labeling, and inspection. Plastic bearings are inherently corrosion resistant and maintenance-free, making them cost-effective replacements for most ball bearings. They are also self-lubricating and operate oil-free — a major advantage because lubricants can contaminate food and attract dust and dirt, which can eventually cause bearings to seize.
For instance, a pasta manufacturer recently replaced V-grooved, track-guided rollers on its cartoning machines with plastic plain bearings from igus Inc., East Providence, R. I. The machines, which operate 24/7, use a shuttle bucket to carry and unload 1-lb portions of pasta. The bucket travels 18 in., 240 times a minute, to keep up with the machine’s load station.
Despite the rapid cycling and extreme acceleration, the iglide J plastic bearings last more than three times longer than the previous roller bearings and have reduced annual repair costs by $7,800. And the lube-free bearings cannot contaminate the pasta or packaging.
Replacement, if necessary, takes less than 2 hr — in contrast to the full day of downtime it takes to rebuild just one set of rollers. And, as an added benefit, the company reports vibration issues have been eliminated and the machines run much quieter.
In another case, an OEM turned to plastic bearings for equipment that packages flour, sugar, and various types of pet food. The machines operate around the clock and are expected to last 20 to 30 years. To meet the demanding durability requirements, the company’s engineers specified igus DryLin R linear bearings on guide rods in the machine’s trimming and pressing stations.
The linear bearings’ aluminum adapter fits over a plastic liner. The beefed-up construction lets them carry up to thirty 50-lb bags/min on each machine, 43,200 times per day.
The dry-running bearings are unaffected by flour or sugar dust that gets stirred up during packaging. The bearings will not contaminate the food or get clogged with flour and sugar, unlike bearings that require constant lubrication.
The machines also use a new type of hybrid linear bearing on the machine’s bag magazines, which hold packages open as they are filled. The DryLin WJRM combines a rolling-and-sliding carriage that cuts friction and significantly reduces the necessary drive force, compared with standard bearings. Like its other igus counterparts, the hybrid bearing is also dry running and does not require lubricants. And it reportedly installs easily, thanks to a low profile and its ability to fit into tight spaces.