Novel chain designs resist elongation

Modern manufacturing has produced a whole new set of demands on industrial chain.

Modern manufacturing has produced a whole new set of demands on industrial chain.

Operating environments have to be cleaner and quieter to work in, while power transmission systems have to be smaller, but still retain the ability to transmit equal or increased levels of power as the larger systems they have replaced.

There are other considerations too: today, chain is used in a wide variety of precision indexing and conveying applications where the relationship between pairs of chain is more critical than in drive applications.

Maintaining an accurate overall length tolerance in attachment chain is essential for conveying and index drive equipment used in such applications as inserting components, product assembly lines.

integrated circuit boards and board/paper and packaging amongst many others.

However, standard chain undergoes eventual wear elongation resulting from the constant sliding friction that occurs between the bearing pin and bushings.

This causes chain pitch discrepancies, which can affect final product quality, necessitate continual chain adjustment, and make frequent replacement inevitable.

In addition to elongation that happens over time and in normal use, the problem also occurs due to: incorrect or insufficient lubricant; misalignment of the chain; incorrect chain tensioning (ie chain is too slack or too long); excess load (including shock loads); worn sprockets; corrosion caused by environmental conditions; and wear due to abrasive contaminants mixing with the lubricant.

Happily for chain users, elongation is not difficult to spot.

Slack chains are an obvious consequence of the problem, as is reduced accuracy in a process or operation.

Other warning signs are occurrences such as chains climbing and disengaging from sprockets, and excess noise during startup.

In among all the factors that cause elongation, the two most common are probably inadequate lubrication, and mechanical wear caused by debris retained in external lubricant.

Both are major contributors to reduced chain life, and hence, higher product replacement and maintenance costs.

Tsubaki has developed a means of overcoming these problems with its nonlube Lambda chain.

Often, the qualities of nonlube chain are associated with clean industries such as food, electronics, pharmaceuticals and the like, but Lambda is increasingly being used with success in much more arduous applications such as sawmills.

Along with the capability of reduced downtime, longer life and the elimination of further lubrication, the Lambda design offers users another key benefit.

The design features specially coated bearing pins and extra durable rollers.

These rollers facilitate super smooth engagement on the sprocket for longer periods of time, resulting in reduced wear.

In addition, and critically for eliminating elongation, as the rollers are dry to the touch the chain does not pick up surface debris; it therefore goes some way to help avoid the wear problems that finally result in elongation.

Lambda has exhibited its resistance to elongation in all types of industries, from confectionary to plating.

In all these applications it has been employed to overcome the high maintenance costs resulting either from downtime due to regular chain re-tensioning, or the costs of replacement chains and lubricant.

Another innovative developed by Tsubaki to overcome the problem of chain elongation, especially where high precision indexing or positioning is required, is Bearing Bush Chain.

In tests conducted using standard RFN Double Pitch Bearing Bush chain to a length of 2m, consistent stopping accuracies of +/-0.5mm have been produced.

In other applications HG series chains, with ground attachments, have been reported as attaining accuracies of +/-0.2mm.

However, as an indication for more typical applications, a 10m conveyor line will have a stopping accuracy of +/-2mm.

The key to the high precision of Bearing Bush chain is its innovative design.

Uniquely designed needle bearings eliminate almost all pin-bushing wear by converting sliding friction into rolling friction.

The rollers in the needle bearings separate the pin and bushing surfaces that rub against each other in standard chain, causing wear.

They roll easily along both surfaces drastically reducing friction and eliminating wear.

In addition, the space between the bushings and rollers is half that of standard chain and therefore provides especially accurate chain sprocket adjustment.

An additional feature of the Bearing Bush design is that the pin bushing area is filled with a specially formulated grease and then sealed to keep lubrication in and contaminants out.

This is also the case with stainless steel versions of the chain.

The resultant benefit is that, in all cases, the chain articulates extremely smoothly and can be used without any additional maintenance.

Bearing Bush chain offers the user the benefits of zero wear elongation across all its configurations: double-pitch, double-pitch stainless and conveyor configurations.

The reliability of these chains is underpinned by plastic bearing seals and oil seals that prevent dust from ever entering the bearing/bushing interface.

In addition, specially designed grease seals are inserted between the pins and bushings, when the chain is used in moderately wet conditions, such as shower testers, and where dripping water is present.

Tsubaki's problem solving chains, not only for addressing the problem of elongation, but also those of corrosion, lubrication and extending chain life, along with a chain length tolerance matching centre for attachment chains are available direct from the company and locally from UK national distribution partners.

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