For a machine to work efficiently, there are hundreds, sometimes even thousands, of moving parts that must work together in perfect harmony. Bearings are a vital part of this equation, and are used in almost every machine.
In the packaging industry, it is especially important that the bearings not only meet a superior standard of cleanliness, but also perform a high number of cycles without failure or mechanical issues.
These days, engineers are relying on plastic bearings more and more to get the job done. Plastic bearings are cost-effective replacements for most ball bearings, and since they are self-lubricating and operate oil-free, plastic bearings will not contaminate the food or drink being handled by the machine.
Rink GmbH & Co. KG, an expert in automated packaging machinery used for capping, de-crowning, and emptying bottle sets, uses iglide plain bearings and DryLin linear plain bearings and guide systems from igus because they are able to operate for several million cycles without any maintenance.
To date, Rink has nearly 1,000 machines in use worldwide. One popular model is specifically used to recycle returnable bottles and can process up to 60,000 bottles per hour. The machine enables the user to decide whether the bottles are placed in boxes or individually uncorked or unscrewed. The machine is also now equipped with an all-new, patented feature: a neck-sleeve remover that automatically detaches any remaining parts of the bottle's screw-top closure.
Rink chose to use plastic bearings because they meet the demands of its machines' sophisticated and intelligent motion control system. The bearings are able to handle tens of thousands of bottles per hour and have achieved more millions cycles without being replaced. Plastic bearings also meet the hygiene requirements of the beverage industry. Since they do not require lubrication, they will not attract dirt or dust into the system, which also prevents the bearings from seizing.Plastic bearings meet high demands
Another design challenge was finding the right linear plain bearing for the machine's valve system. Once a bottle is uncorked, the valve seals the bottle so its contents can no longer come in contact with the outside environment.
Rink design manager Olaf Staave chose DryLin R linear plain bearings for very specific reasons: "The linear bearing used in the valves had to be free of lubricant and also [deliver] a long life with very high clock rates. It had to be easy to clean, resistant to corrosion, and resistant to the aggressive cleaning agents that are used for hygiene reasons," he said.
DryLin R linear bearings consist of a stainless-steel housing with a replaceable, self-lubricating plastic liner made of iglide J material. The plastic liner is ideal for packaging applications since it is highly wear-resistant, delivers a low coefficient of friction in dry operation, and possesses superior chemical resistance. Even after millions of cycles, the plastic bearings have almost no wear.
"We now have a lot of experience with igus bearings," said Staave. "The materials are resistant to cleaning agents and [perform even in] wet applications. The [liners] have lasted four million cycles before being replaced."