A simple guide to lubrication free chain
04 July 2016
David Compton of Renold Chain discusses the latest developments in lubrication free chain technology and the increasing range of industrial applications that now benefit from this innovation.
With a long history in a myriad of industries, precision roller chain remains the technology of choice in a wide range of applications. A deceptively simple mechanical system, quality precision roller chain combines high efficiency and dependable durability to provide a long lasting, cost effective solution for mechanical power transmission. A correctly specified chain benefiting from appropriate lubrication, either manually or via an automatic system, will almost certainly deliver the best all round performance and longest working life possible.
There are however a range of applications where the provision of adequate lubrication may be difficult or undesirable. Access to the chain for maintenance may be difficult or the nature of the lubricant itself may be problematic due to the risk of contamination. In these circumstances, OEMs and end users are discovering that a lubrication free chain is likely to be the best solution. But what do manufacturers mean by lubrication-free, and what are the latest options available to engineers that address the diverse requirements of industrial applications and operating conditions?
The most significant element of chain wear occurs at the load bearing surfaces in-between the pin and bush components during normal operation. This wear causes elongation of the chain and is accelerated if loads are high/highly dynamic or where lubrication is inadequate. Compensation for this elongation can be achieved using chain tensioners or regular adjustments during routine maintenance. Eventually wear reaches a point where adjustment is no longer satisfactory and the chain needs to be replaced. The more basic the design and manufacture of the chain and the poorer the lubrication regime, the more rapid the wear and required maintenance.
The most common type of lubrication free chain, which is suited to the widest range of applications, is of carbon alloy steel construction with an oil impregnated sintered bush. Careful design ensures that lubricant is released from the bush onto the bearing surfaces during operation and remains inside the chain. A good quality lubrication free chain is interchangeable with the same size of standard chain and can generally be selected as a replacement option without the need to change the existing sprockets. Chains of this type commonly require little or no maintenance during their normal service life.
Selection of these precision roller chains offers a range of benefits; the obviation of additional lubrication reduces maintenance burden and eliminates the risk of oil contaminating the end product or other parts of the process. In addition to reducing maintenance costs, it removes the need for drip guards, contributes to a clean environment and eliminates potentially costly automatic lubrication systems. Where lubrication is eliminated, the ongoing cost savings can be significant - particularly in food industry applications where a costlier food grade lubricant would otherwise be required.
Renold first introduced lubrication free chains during the 1950s in response to specific customer requests. In the intervening half century the technology has undergone a constant process of refining and optimisation. The latest generation of lubrication free precision roller chain, known as Syno, is the most advanced development so far and benefits hugely from advances in materials technology, surface treatment know-how and manufacturing processes. In addition to chain characteristics and properties, attention has been paid to the development and selection of high-tech lubricants which provide the exact properties required to maximise the benefits of advanced chain design.
The Renold Syno range comprises of three lubrication free solutions designed specifically to meet the requirements of particular applications. Typical applications include food manufacture, car assembly plants, steel mills, textiles, electronics, saw mills, paper manufacture and many more.
Syno NP deploys a custom developed nickel plating process which provides excellent anti-corrosion properties and incorporates a food grade lubricant within the sintered bush. To further enhance performance & durability, an innovative food industry approved treatment process is applied to its roller surfaces. It is dimensionally interchangeable with standard chain and, with ISO standard pin diameters, it can be supplied with standard attachments on the outer links.
Syno PC, poly-steel chain, is designed with polymer inner links and with high grade stainless steel pins and outer plates. The elimination of metal from the bush and roller components means that no lubrication is required. As a result, it enables a wider range of lower power applications to benefit from a lubrication free chain solution and can even be run under water if required. It is lightweight, corrosion resistant and is able to accept standard attachments on the outer plates.
For heavier duty applications, Syno PB polymer bush chain provides greater wear and fatigue resistance. Renold’s polymer sleeve – constructed from a specially developed material – is located between the pin and the bush, eliminating metal-on-metal contact in this critical area of the chain. With a corrosion resistant surface treatment available, this precision roller chain brings lubrication free operation to a much wider range of arduous applications.
Continuing developments in modern lubrication free precision roller chain make it a realistic option as an upgrade from standard chain in an ever expanding list of applications. A range of technologies are now available that allow the reduction or elimination of lubrication along with protection against corrosion.
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