Plastic Bearings Picked over Bronze

Over the last century, farming has undergone a significant transformation. The days of manual and "animal-powered" farming have been replaced with mechanization. Major advances in technology and agricultural equipment have helped farming become a more efficient and less labor-intensive practice. Today, farmers rely heavily on planting, row-making and cultivating machines.

Harriston Industries is a manufacturer of farming equipment specifically for the potato sector of the farming industry. Farmers depend on Harriston's products to plant, cultivate, maintain and pick their crops. One machine offered by Harriston is "The Pick Planter," which uses individual row units with walking gauge wheels to provide a consistent planting depth. The planter's large pick wheels and a low drop point also ensure better seed placement.

For optimal performance, the row units or "pick arms" of the machine must rotate through an arc of 15 percent at a rate of 12 -20 cycles per minute. Oil-impregnated bronze bearings with graphite plugs were used to facilitate this movement until they began causing severe problems. On the West Coast, the bronze bearings were experiencing high wear and premature failure due to the very abrasive conditions caused by high levels of volcanic ash in the soil. On the East Coast, the high salt content in the air caused corrosion and seizure.

By replacing all 144 bronze bearings with high-performance plastic bearings, Harriston was able to increase the pick arms' life span by 500–600 percent. In applications where water, dirt or caustic chemicals are present, plastic bearings are ideal. While metal and bronze will rust, corrode and fail in these environmental conditions, plastic bearings operate unaffected. The planter uses iglide® J plastic plain bearings from igus®, which are lightweight and corrosion-resistant.

iglide J bearings are also self-lubricating. Each bearing contains solid lubricants embedded in millions of tiny chambers of fiber-reinforced material. During operation, the bearing transfers lubricant onto the shaft to help lower the coefficient of friction.

By making the switch to plastic bearings, Harriston's planters have longer service life, increased reliability and enhanced technical performance. Maintenance costs were also significantly reduced because iglide J lasts for years, whereas bronze bearings were being replaced two to three times each season.

"By replacing the bronze with iglide J plastic bearings, we increased the life span of the planter by 500 to 600 percent and eliminated the seizing and corrosion issues," says Dave Paschke, an R&D specialist at Harriston Industries. "Plus, the plastic bearings cost 70 to 80 percent less than bronze bearings and are more reliable. After years of use, I haven't found a bearing that is even comparable to iglide J."