A production line can only move as fast as the parts used to support it. Whether it is a conveyor system, a belt, or a sorting bin, using the right actuators, linear guide rails, and bearings will result in a more efficient manufacturing process. A recent case study out of Johannesburg, South Africa, highlights the need to implement proper support bearings for production. The company chose to change bearing materials after a recent shutdown to improve production and maintenance.
Arthur Dowson Ltd. is a laminating and coating factory that creates products such as dam linings, billboards, butchery aprons, upholstery materials, placemats, tents, tarpaulins, and jumping castle fabrics. The production process starts with the fabric roll shaft, with the raw material around it resting upon the support bearings. Once it receives the coatings on the one side, the material is rolled onto another fabric roll shaft supported at the other end of the production line, which is also supported by bearings.
The Arthur Dowson company laminates and fabricates different cloth materials, including upholstery materials, placemats, tents, and tarpaulins, using large fabrication rollers.
After that, 1000 meters of the roll is typically transported back to the start of the production line, so that the reverse of the material can also be coated. The process is then repeated, and the roll of fabric gains in weight and volume as it receives additional coatings. The fabric rolls can weigh up to two tons after coating, with some clients requiring more coatings that result in an even greater fabric weight.
By switching bearing materials, the engineers were able to improve their production line and lower maintenance costs.
The previous production used Teflon and nylon support bearings for their fabric roll shaft. Upon deciding to re-establish the factory, after a temporary closure and re-location of equipment to elsewhere, a decision was made to change to more advanced version of the polymer bearings that boasts a lower coefficient of friction and requires less lubrication. Both the previous nylon and newer polymer bearings are manufactured by Vesconite. The polymer bearings are part of Vesconite’s Hilube product line.
According to Vesconite bearings mechanical engineer Juan van Wyk, the decision to use the current plain support bearing design was motivated by the fact that in the previous design, the roller bearings had to be removed with the fabric shaft. The new design—a block shape with an open end that allows the fabric shaft to be lowered onto it and then move on it—is simpler and easier to operate. The new polymer bearings also offer the advantage of allowing for easy cleaning, since the polymers are resistant to many acids and alkalis, including acetone, paraffin, and turpentine according to van Wyk.
Vesconite Hilube is designed for particularly difficult operating environments. The bearing is recommended for moist and underwater applications, including those for the pump and marine industries.
The polymer bearings’ friction coefficient (0.10) is approximately half that of nylon. This allows for a higher PV factor (load × speed). Adding external lubrication or water to the equation will lower friction even further, and the resultant PV factor. It also has a much higher load capacity compared to nylon, rubber, and elastomer bearings. Unlike nylon, the polymer maintains its strength under wet conditions and shows very little creep under heavy load. It has proven to be particularly superior in higher load applications.
Arthur Dowson maintenance manager Roy Rodgers reports that the material coating company lubricated the previous support bearings to reduce wear, and is likely to continue the practice with the new polymer support bearings. According to Rodgers, wear becomes particularly important on the support bearings at the end of the production line, since the coupling of the drive-end attachment and material shaft have a small range for engagement. The new polymer bearings will be increase the life of each of the fabrication line and minimize maintenance.