FEATURE BELTS, PULLEYS & CHAINS SPECIFYING THE PERFECT CHAIN
SOLUTION FOR HARSH ENVIRONMENTS Designing machinery that will be used in harsh environments requires special
considerations, with each component robust enough to withstand the prevailing conditions. Greg Sharp, country manager for chain specialist, Tsubaki, looks at the specification process for industrial chain in demanding applications
I
ndustrial chain has always been something of a favourite with engineers when it comes to
designing drive systems for plant and machinery. It allows simple designs to be realised, is easy to install, reliable, and maintenance is relatively straightforward. As such, chain is particularly popular for harsh environment installations, with chain manufacturers developing ranges specifically for such applications. In harsh environment projects there is a
temptation to assume that any chain will need frequent replacement, so a cheap one will reduce overall costs. However, a specialised chain that costs somewhat more but lasts considerably longer often works out more economically in the long run if specified correctly. So, for end-users looking to reduce their Total Cost of Ownership, it’s important to ask the question: How can I specify the best chain for the job?
SPECIFYING THE CHAIN When Tsubaki is asked to participate in the design of equipment for harsh environments our first step is not to reach for the catalogue of standard chains, but to start a rigorous process of understanding the environment and the duty cycle expected of the chain. This is because the phrase ‘harsh environment’ can cover a multitude of situations, including the degree of harshness, the constancy or frequency of the demanding conditions, unusual events that may arise, and the possibility of failsafe options. We need to understand the environment
maintaining chain flexibility and lubrication. Once the application is fully understood,
the chain engineers will consider the pros and cons of standard chain versus a bespoke solution for that particular job. Tsubaki has a number of products for harsh environments and it is possible that one of these will be ideal. However, is it critically important that we give full consideration to the benefits of a bespoke solution and weigh them against a standard product.
WORKING ENVIRONMENTS There are countless examples of industrial applications with harsh environments, but let’s take waste-to-energy as an example. This is a sector that is growing rapidly around the world and Tsubaki has worked with many plants, most often supplying chains for the ash conveyors. Typically these need a high load capacity and
Image Source: iStock - zlikovec
Tsubaki heavy duty chain
Standard products were considered, but A bespoke chain
was designed to meet the demands of ash conveyors in a waste- to-energy incinerator
none fully met all the criteria for long life and reliability. A bespoke chain, by contrast, could be designed to address all the requirements particular to the plant and meet specified performance parameters. In this case Tsubaki recommended the bespoke solution because it guarantees performance with very low chance of premature failure, thus ensuring the best possible TCO. As the waste-to-energy plant runs almost constantly, the avoidance of expensive, unexpected downtime was a particular concern that had to be addressed. Tsubaki developed a bespoke chain
– not only as it will be most of the time, but also at its worst. Depending on the application, the challenges may include elevated temperatures, extreme weather, dirt and corrosive atmospheres. Similarly, we assess the possibilities of conditions such as shock loading, freezing, lubrication failure and build-up of contaminants. Location may also be a consideration if it will affect access for maintenance. Once we have completed initial assessments
we begin detailed discussions with the OEMs who will build the machinery and – very importantly – the plant engineers who will operate it. The objective is to identify performance parameters required of the chain. The designers tend to focus on dynamic needs such as speed and load; while the operator on issues that affect reliability and longevity, like
50 OCTOBER 2019 | DESIGN SOLUTIONS
with increased clearance between round parts to prevent sticking rollers and maintain articulation; zinc coating on the plates and rollers; plus a special anti-corrosion coating on the pins and bushes. Heavy duty links increased the breaking load to cope with the inevitable shock loads.
run at modest speeds. One of the main challenges is ash and slurry working their way into the moving parts of the chain and reducing flexibility. They also have to withstand very high temperatures, a corrosive atmosphere and shock loads. In a recent project, a new waste-to-energy
incinerator serving the densely populated south east of England came online and was immediately busy with an almost unbroken string of refuse trucks. However, it soon became apparent that the chain on the ash conveyors needed frequent replacement, so the operators called in Tsubaki. Our engineers made several visits to make sure we fully understood the situation, then began looking at possible solutions.
After the new chain was installed Tsubaki continued to make regular monitoring visits and help with further developments. For Tsubaki, harsh environment engineering
is never only about providing a better chain solution – the pre- and post-sales support is a vital part of the job. Investing time at the start of the project allows the opportunity to fully understand the situation. Then, post-installation support ensures the project is brought to the best possible conclusion – complete with the development of an optimised maintenance and replacement regime, and Tsubaki always holding available stock of the bespoke chain.
Tsubaki
tsubaki.eu
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