New Bearings Reduce Maintenance Costs for Sapphire

The economics of maintaining the tyre shredding machines operated by Sapphire Energy Recovery have reportedly been transformed by the employment of an adapter-mounted ball bearing system provided by East Midlands company Bearing Transmission & Pneumatics (BTP). Switching to a BTP supplied Dodge Grip Tight bearing, which features a flinger seal and a built-in mechanism for removing the bearing from the shaft, is said to have completely resolved a recurrent – and expensive – repair problem.

The high-throughput shredding machines operated by Sapphire in four UK locations convert end-of-life car and van tyres into rubber chips that are then used as an alternative to coal in cement manufacture. After shredding, the tyre chips are graded for size by a classifier with 36 sets of bearings. Due to contact with fine metal wires contained within the tyres and the water used for cooling during the process, damage was occurring to the classifier shafts’ set-screw style bearings. As a result they had a typical working life of less than six months. Changing the classifier bearings could then take anything up to two hours per bearing, depending on the problems encountered and the skill of the operators. The presence of corrosion sometimes meant that the bearings needed to be loosened by heat, for example, and in some cases the whole shaft needed to be replaced.

As Sapphire’s processing centres often operate around the clock, addressing the planned and emergency maintenance requirements of these machines became a priority for Sapphire’s reliability manager Andy Booth, and he called in Dodge distributor BTP to discuss the problem. BTP suggested that Sapphire try a type of ball bearing from the Baldor range called the Dodge Grip Tight. The bearings were a little more expensive more than the set screw type that Sapphire had been using, but demonstrations – and examples of field experience in the most hostile conditions – convinced Andy Booth that the easy-off mechanism would make changeovers a predictable operation. Furthermore, the Grip Tight ‘s built-in flinger seal is protecting the bearings in the hostile environment to such as en extent that they are typically lasting twice as long as the previous set screw types. Now, following the use of Grip Tight over a period of some 24 months, and a number of maintenance changeovers, Booth knows that the Grip Tight justifies its reputation: changeovers are predictable and take only a maximum of 15 minutes, including the time required to remove and refit machine casings. Moreover, there has been no shaft damage to date.

“The aggressive nature of tyre shredding meant that repairing these machines was taking up far too much of our time, and reducing our productivity”, says Booth. “Grip Tight bearings have given us back predictability of maintenance, with the welcome bonus of much longer life, protecting some of our company’s most crucial assets. Our operational team now has the time to be more proactive, focusing its major efforts on preventive maintenance rather than breakdown maintenance.”

“Our work means that we tend to see a lot of bearing failures, and we’ve come to regard the Dodge Grip Tight as a genuine problem solver”, says BTP’s Edward Fielding. “Although the major requirement was to simplify changeover, this bearing also manages to survive much longer in very hostile operating conditions.”