Dry lubrication systems are one of those alternatives. They can replace conventional “wet” lubrication systems, which consume large amounts of water and energy and may contribute to unsanitary plant conditions. In wet systems, the lubricating agent is a solution composed of water and a water-soluble lubricant. The solution is sprayed onto conveyor chains and chain guides.
In contrast, dry lube systems dispense a dry film solution formulated without water-soluble components. One such dry lubricant, for example, contains PTFE as a solid lubricant, as well as mineral oils and additives. This lubricant adheres well to conveyor surfaces and exhibits superior anti-wear characteristics.
When applied to conveyor chain surfaces and chain guides, dry lubricants leave behind a lubricating film that greatly reduces the coefficient of friction between the sliding surfaces. This protects the sliding parts of conveyors and minimizes conveyor wear when loaded. No water is required for lubrication, and concerns over handling and reprocessing wastewater are eliminated.
Controlling Lubricant Delivery
Typically, dry lubrication systems feature an integrated control unit that enables users to program the system’s lubrication parameters and to monitor system operation. Lubrication lines connect the central unit to a series of positive displacement metering devices capable of dispensing lubricant volumes down to 1/3 of a drop. The devices can be located at various lubrication points along conveyors. Some systems can lubricate as many as 200 different points.
During operation, the metering devices deliver small, precise volumes of lubricant to lubrication plates located under the conveyor chain. As the conveyor runs, the chain’s surface slides over the lubrication plates, coating the chain with dry film lubricant. Dry lubricant is also supplied via a secondary line to the conveyor’s chain guides.
Improving the Plant Environment
To improve sustainability and create a safer, more sanitary workplace, a major manufacturer recently converted to dry lubrication on multiple beverage bottling lines. Previously the conveyor lines were spray-lubricated with a mixture of water and soluble lubricant. But this method resulted in excessive water usage and related problems such as slippery floors, increased humidity and the potential for organic growth.
Initially the manufacturer installed a dry lubrication system on one beverage bottling line. The system featured a central control unit equipped with a built-in lubricant reservoir and a pneumatically driven pump. When this trial proved successful, the company installed dry lubrication on three additional conveyor lines.
There were immediate improvements in sustainability and efficiency. Reductions in water usage on the four lines totaled 350,000 liters per month. Lubricant use and cleaning expenses were also cut, and the change contributed to a more hygienic plant environment.
Cutting Lubricant Costs, Waste
The lubrication of rolling bearings on material handling lines also has implications for sustainability. Manual relubrication is imprecise and often results in overuse of grease or oil, worsening disposal problems and increasing lubrication costs. Overlubrication also causes a bearing condition called churning, which impairs operating efficiency, wastes energy and eventually leads to premature bearing failure.
Automatic lubricators offer a potential solution. They attach directly to bearing arrangements and provide a steady, regulated flow of lubricant, eliminating the need for manual relubing. Single-point lubricators can hold up to 250 milliliters of lubricant and operate for a full year without requiring a refill. They are especially suitable for mounting in hard-to-access or high-temperature areas.
A corrugated-packaging company had success with an automatic lubricator program. The company installed single-point lubricators on 100 bearings located on its conveyor lines. Previously, there had been numerous problems due to improper lubrication practices, including overgreasing.
The self-contained, single-point lubricators each contain a gas cell or electric motor which, when activated, drives a piston, dispensing grease at a predetermined rate. An accompanying software program calculates the correct lube interval and grease amount for the application, enhancing lubrication accuracy.
According to the company, the lubricator program helped it realize significant savings, including those associated with greater conveyor uptime, reduced grease and bearing-related costs. There were also reductions in scrap materials associated with fewer bearing failures. The company quickly recouped its original investment, achieving an ROI of 205%.
Rolling bearing selection in material-handling applications also impacts energy use and sustainability. In recent years new performance classes of bearings with more advanced materials, optimized internal geometries and higher load-carrying capacities have been introduced. In addition to extending bearing life, these advances make bearing downsizing feasible, replacing standard-size bearings with smaller bearings having the same load-carrying capacity. The result can be significant reductions in energy consumption.
In some material handling applications, advanced bearings can be fitted with efficient contact seals and lubricated for life with biodegradable grease. This eliminates relubrication and lube disposal issues and enhances overall sustainability.
Brian Richards is Technical Sales Support Manager--Lubrication, SKF USA Inc. He can be contacted at [email protected]; phone: 757-927-0823.