Chain reactions

Written by: Matt Bailey | Published:

Power transmission chain may be a mature technology, but suppliers are still developing new solutions. Matt Bailey reports.

While energy chain is an essential engineering product, it has long been mistakenly seen as a commodity. However, companies in the industry are continuing to develop and refine designs. One of the key factors behind this refinement is the environment. Derek Mack of Tsubaki says: "We are always upgrading and bringing new products to market that fit in with our green ethos," he claims, "while many of our competitors are consolidating and going down the low cost route."

How this green ethos manifests itself in the product line is in innovations like 'lube-groove' technology. Mack explains how it works. "The bearing area of the chain has a pin, bush and roller. On Tsubaki medium-sized chain, the bush has lubrication grooves along the internal diameter. They retain lubricant between the bearing areas so that the pin which sits inside the bush is constantly being lubricated, reducing metal-on-metal contact and hence chain wear. This significantly lengthens the lifetime of the chain."

While it would be difficult to produce actual application-based figures on chain life extension and energy consumption, Mack says the benefits are considerable. "It is difficult to measure energy consumption and all chains produce more or less the same energy consumption anyway. I couldn't claim that our chain consumes less energy than our competitors - although we do make special, premium, top-end chains with bearing rollers fitted which are particularly good in this area – but on the standard range, the environmentally friendliness comes from the chain's long life. We make it once, we transport it once, it is fitted once and then recycled once, thus reducing raw materials and associated energy. Similar chains from other suppliers may last three, five or even seven times less. The total lifetime cost of ownership is reduced."

As in other areas of engineering, the steady development of materials is having an impact on chain. "The introduction of plastics has already happened and our R&D department is looking at special alloys and materials for the future," confirms Mack. "We have a big commitment to R&D. Plastics is an interesting area for chain manufacture and we have stainless steel and engineering plastic lubrication-free PC chain, while our R&D team continues to look at other materials. Our Lambda steel chain is also lubrication-free, utilising a special oil impregnated sintered bush in combination with a special coated bearing pin to reduce friction between critical components and increase the life of the chain without any additional lubrication."

While the latest iteration of Lambda lubrication-free chain is due to be released next year, Tsubaki has other irons in the fire. "We have a new corrosion resistant chain, NEP (new environmental plating) which has two coatings to prevent corrosion. Where some corrosion-resistant chain designs cause problems as their coatings wear off, NEP is RoHS complaint and its coatings are not harmful."

Another key innovator in this area is Igus, which has for some time pioneered the use of plastic energy chains. It has recently developed a new, lighter version of its popular E4.1 range. The E4.1 light is of low weight, which makes it particularly well-suited to highly dynamic applications and means that it offers even more filling space for cables and hoses, as well as a new mechanism for quickly opening crossbars on both sides of the chain simultaneously.

The E4.1 extends the modular energy chain range, which already comprises of more than 70,000 parts for almost every energy chain solution. The specially-designed outer links set the pretension (or camber), allowing assembly without pretension to be carried out for cramped conditions or for vertically hanging energy chains.

For designs with a change of direction of rotation, such as in zigzag applications, the direction of bending radius can be varied through the rotatable inner link. The tongue and groove design, which interlocks the chain links, ensures good torsion resistance and high stability, particularly for side mounted applications.

For applications requiring high filling weights and long self-supporting distances, the double stop system with large stop-dog surfaces helps ensure optimum load distribution. Both the brake and stop-dog systems create a noise-reducing effect that results in a particularly smooth running chain. While also offering a range of advanced power transmission chains – including lube-free – Renold Chain has taken a very proactive approach to spreading best practice and encouraging preventative maintenance as a means of lengthening chain life.

The company's David Turner says Renold Chain sees a requirement to educate and inform its customers as well as selling them product. "We have always wanted to be perceived as the custodian of best practice. If there is a particular reason why chain has worn out we want customers to be aware of it so they can understand how to make their chain last longer."

Organisations may find that they are repeatedly replacing a product that has the same wear pattern or failure process and, "there may be something symptomatic about this," suggests Turner, "it may not be just wear and tear". As a prime example of this approach the company has recently tackled the problems with a transmission chain jumping or climbing its sprockets.

"A common cause of this is excessively worn sprockets, or worn chain, or both," says Turner. "Worn sprockets will also cause chain to wear rapidly, so it's important to replace it and check the condition of the sprockets before fitting new chain. Look at the faces of the sprocket's teeth. Any wear will be seen as a polished worn strip, about the pitch circle diameter on each of the teeth."

According to Turner: "It's worth pointing out that low cost, poor quality sprockets on most industrial applications are a false economy," he says. "A good quality sprocket should last through the life of several chains before anything like the amount of wear shown here will have occurred. If there is an imperfection or if the sprockets aren't aligned properly it will create lots of vibration and noise and use more energy and if you can save, say, one percent on your energy bill at today's prices that can have a significant impact."

Power transmission chain has been around for a while and perhaps familiarity can breed contempt or at least indifference. "Many people see it as just oily metal," says Turner. "But there's more to it than that. We also manufacture electronic products for predictive maintenance. Smartlink monitors the load on the chain, feeding back strain information – and exactly which part of the cycle this strain occurs in – remotely using GPRS.

The ability to predict chain wear or elongation is also important. We have a product called Wear Monitor in the pipeline which uses sensors positioned next to the chain to assess it as it goes past and tell you whether it is extending and give you a prediction of when it will reach two or three percent elongation and need changing, so you can plan maintenance."

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