The fact that initial lowest cost for a component or system often proves to be the most expensive in the longer term has prompted all sectors of industry to consider the merits of whole life costing. But the issue raises something of a dichotomy, with the OEM on one side, and the user on the other. The OEM’s objective is usually to achieve the lowest installed cost for equipment, while the user wants maximum reliability and long operating life.
The OEM is all too aware that quoting a high price can cost him a job; yet as experience shows, things tend to go wrong sooner rather than later with equipment that is built down to a cost.
Unfortunately, despite the many lessons, the cost-down philosophy still appears to permeate levels of industrial supply, from bearings, to hydraulic and pneumatic components, drives, gearboxes and chain. What this means for the eventual end user of these products – a manufacturer or food processor or materials handling company with deadlines to meet – is a potential time bomb in the production or materials handling system. With downtime a key production indicator, this is clearly not acceptable.
Increasingly, companies are waking up to the fact that in order to achieve increased throughput and realise the full potential of their existing assets, they must achieve improved production efficiencies. Achieving these efficiencies means minimum downtime, and this requires a whole new approach. Namely, to adopt components and equipment that might cost a bit more initially, but are fitter for purpose in the longer term.
One area that illustrates this philosophy is conveyor chain. In the warehousing and logistics sector the predominant type of chain employed is BS specification chain. This often has a low up-front cost, so hardly anyone questions that it might not provide the best solution for all applications. Especially so with alternatives costing perhaps three times more, despite the fact that these alternatives can easily pay for themselves many times by providing up to 20 or even 30 times longer operating life.
Issues with low cost warehousing chain become manifest when problems of chain elongation or even breakages occur. This is often an indication that the chain supplier/manufacturer was not exactly in full control of key manufacturing procedures such as heat treatment and quality control. The benefits of these become much clearer when the chain is actually in use and exposed to all the vagaries of the materials handling environment.
With conveying applications using lengths of chain in pairs or multiple strands, length tolerance is really important and no more so than when trying to maintain an accurate overall length tolerance in attachment chains, many of which are employed in warehousing and logistics operations. Utilising lower cost chain that has not been manufactured to the highest standards can hasten the onset of wear elongation as a result of constant sliding friction between bearing pin and bushings. This causes chain pitch discrepancies, which have to be compensated for with frequent adjustment, leading ultimately to premature replacement.
In amongst all the factors that cause elongation, two of the 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 to higher product replacement and maintenance costs.
Tsubaki has developed a means of overcoming these problems with its non-lube Lambda chain, which has proved to reduce downtime and provide longer service life in many applications. Lambda features specially coated bearing pins and extra durable rollers, the latter providing super-smooth engagement with the sprocket, resulting in reduced wear. In addition - and critically for eliminating elongation - the rollers are dry to the touch, so the chain does not pick up surface debris.
Lambda’s benefits have also been proven in a real time life test, where competing chain products were fitted to five identical tracks and then replaced each time they failed with the performance history logged. Although the Tsubaki lube-free Lambda variant was several times that of the cheapest chain used on the test, this was completely offset by the reduced maintenance, downtime and replacement costs associated with the Lambda installation.
These results suggest strongly that the whole life cost approach delivers lower costs for the warehouse operator in the longer term. However, in some applications the case for higher up-front cost will always be difficult to argue. Tsubaki has addressed this with its new BS RF series flat side-plate chain, which provides users with improved performance and wear life, and delivers overall cost savings based on the whole life cost approach. Every facet of this chain, including material selection, manufacturing technique and heat treatment, has been optimised to ensure reliable operation and long life.
Robert Young is with Tsubaki