The view from of Tower Hill from our office.
I once attended a lecture given by a gnarled old university professor on the subject of the environment and he started by stating, “Pollution is created each time money changes hands” so I suppose by definition that makes the bankers the biggest polluters on the planet! There is just so much hype and nonsense written these days about saving the planet. The fact is that the planet will still be here when we have exhausted all its resources and polluted the environment completely, it’s simply the reality that man seems incapable of comprehending.
The fact is that all you moulders out there will ultimately be sitting around on an acidic cloud, chatting away about the good old days and how you had wished that the rotational moulding industry could have been less energy intensive and wasteful. Lets face it, we belong to an industry which is up just behind the bankers. Our raw material is created from cracking crude oil, our energy input just heats the birds, we waste even more energy to cool the product and then we load it to transport and ship mostly air.
A good day at the factory is a bad day for us all.
Hypocrites…I here you say! We accept that in our everyday operations we at Rota Design use our share of these precious resources and it is true that we design products for the industry which require polymer and energy input. The answer is that we all need to do our bit to minimise the impact of our operations and to be conscious of the effects of our actions upon the environment. To emphasise this point we only have to look at the beauty all around us as we look out of our office.
We should also look to the past for answers to today’s problems. David always looks to the Victorian engineers for solutions to situations we face every day; the solution is usually there if only you know where to look!
The offices of Rota Design look down upon a valley where the traditional industry was textiles. Many mills grew in the industrial revolution of the nineteenth century from the manufacture of cotton and woollen cloth and its supply to Europe and beyond.
The Rochdale canal through Mytholmroyd
The canal, opened in 1801, superseded the pack horse routes over the Pennines and allowed cloth to be transported to the major ports for export to the US. At one time some enterprising local sold cloth to make officers uniforms for both sides of the US civil war!
Later, in the 1840’s, the railway came. The engineer for the line was one George Stephenson of the “Rocket” family fame and the improvement in communication coupled with the speed and ease of transportation of products and mobility of people served to enhance the industry. The mills were originally powered by water. What could be greener!
With the advent of steam power, mechanical power was added to assist but not to replace. Only a few dark, satanic mills were built locally powered solely by steam. The problem is as it is today; local supplies were being exhausted and the cost of shipping raw materials to the factories increased exponentially.
Owners of the mills were forced to look at efficiency, they had to innovate, obtain alternative supplies of raw materials and to look to technological advances to keep them in business. There are certainly many relevant parallels to be drawn today from these observations.
The father of the steam engine, James Watt, whilst watching a kettle boil realised the potential of steam to drive machinery, but soon understood that its the efficient conversion and use of energy that is the cleaver bit!
We recommend building efficiency into designs, i.e. efficiency in terms of optimisation of design and material usage. If we use less material, it follows that it takes less energy to melt the polymer and less energy to cool the polymer and the tool.
The Victorian engineers learned that when you construct anything you induce forces within the structure which convert into stresses of one sort or another. Concentrated stress can be dealt with by the localised addition of reinforcement or by the specification of higher performance materials. The problem in general terms with rotationally moulded products is that we have only one material to play within the design. (I accept we now have multi-wall and foamed products, etc. as options here.)
The options in simplistic terms as a designer are limited to varying the geometry of the product, varying the polymer grade or, varying the wall thickness or, add structural members to withstand the forces being applied.
So we have to design the geometric features of the product in such a way so as to avoid high stress concentrations and to endeavour to distribute the stress evenly throughout the product. This is where finite element analysis (FEA or FEM ) is the best available tool to us to replicate these conditions and to use the results to optimise the grade of polymer and its shot weight to meet the challenge.
An example of a complex steeel fabricated tool.
Alternatively you could go to manufacture of the tool and test product in the physical world to International Standards, but this approach is somewhat expensive and as the per case studies in previous articles in this series, provides no guarantee of success. The issue, as in the case of an underground tank or chamber undergoing physical testing, is how do you identify where the higher stress levels are located?
Polymer products in certain circumstances fail even when the stress level is below yield. So now you’ve paid out significant costs for design of the tank, bought the tool, paid for the manufacture of a “typical” product and subjected it to testing at an accredited test facility to Internal Standards, and you still do not know the areas of maximum stress or the values of stress at any given point.
Given that the short term factor of safety is the polymer yield stress divided by the maximum stress level you don’t even have the ability to define a short term factor of safety to assist you in making a judgement if the product is fit for purpose or not! Great!
The Rota Wheel prescribes our methodology for design.
Optimisation of polymer will provide you with the best return on your investment since savings in polymer, energy, productivity and transport costs go straight to your bottom line.
The Rota Wheel best describes the process from concept through analysis and design verification – that’s right we produce a report at the end of the design and analysis process and are confident enough to stake our name and reputation on it.
About 25% of our project work over the last year has been associated with design optimisation and improvement. Some clients have benefited from reduced shot weights varying from 8 up to 24% in one case.
Typically following our analysis we recommend minor geometric changes or polymer amendments and the output is quantifiable in terms of material costs and product performance. On some occasions the conclusion is to start again as we demonstrate the product design and function is fundamentally flawed.
Inside the Leonardo moulding machine.
The design of larger products should be revisited periodically to assess if technological developments such as new polymer grades and process enhancements could be utilised cost effectively – remember every time money changes hands it causes pollution.
We recently read an article where rotational moulding had been achieved using solar power. Whilst the use of this technology is interesting the question is can it be adapted universally and in what timescale. If not, then move on. Late in 2011 the UK government reduced the price it would pay for energy generated by wind power and fed back into national grid by 55% – effectively a change in policy which makes the payback period for the introduction of such innovation nonsensical.
We welcome the control of energy that Leonardo brings to the industry and we applaud the attempts to retain the heat energy that Rotoline provides, but its just not enough is it? I don’t believe anyone has advertised the total savings of polymer and energy from these innovations, but we know from studies undertaken recently that these are insignificant in comparison to the savings possible through optimisation of the product that we can and has achieved.
The left hand tank has a constant wall thickness and the righthand tank shows a variable wall thickness saving polymer and energy and processing time.
One idea which could be developed for the industry is the heat capture systems being developed and implemented in F1 cars. The heat generated as the vehicle brakes is conserved and released upon demand to provide an additional short term energy release to provide a serge of power. As the technology evolves these innovations become available and cost effective for other applications. Getting the product specification right is an important factor in the process and in our experience requires someone with sufficient knowledge and experience of the industry sector to ask the right questions. As engineers, we work in a systematic manner and at times we inadvertently annoy and frustrate our clients with the level of detail we delve into.
On the other hand, we recently had a situation where a client thanked us for preventing a disaster where the specification was inconsistent with local requirements, and if we had not acted in this manner, would have resulted in the client producing a product which could not sold or installed in their home country.
Returning for a moment to local history. The area where our office is situated is known a Cragg Vale. There are many remote farmhouses and the 1760’s it was estimated that as many of 70 to 80 locals became “coiners”. The process involved taking Coins of the Realm and scraping gold shavings from the outside diameter of the coins. The edge of the coins were then reworked and the scrapings melted down to make new coins, which were stamped and edged. The coins found their way back into circulation via the local merchants and ale houses.
The practice began to destabilise the economy with the result that an exciseman was sent from London to investigate. The main protagonists made the mistake of shooting the exciseman through the head and some were eventually “Hanged By the Neck Until Ye Be Dead” at York for their troubles.
These men were just recycling gold and probably caused a minimal amount of pollution compared to the return; always assuming that you ignore the fact that they forfeited their lives. Maybe the rotational moulding industry could learn from the coiners and invest in optimisation of their “gold” polymer. They won’t be hanged for the offence and the green credentials the company obtains as a result of the initiative could be shouted about whilst they count the gold which has landed on the bottom line.
One final thought we had, is that you could add small amounts of uranium to the polymer and use this to mould road traffic bollards. The bollards would glow in the dark and save on the cost of lighting energy. Could this be justified on the basis that the number of people killed by radiation is infinitesimal when compared to the number involved in road traffic accidents?
In summary, we at Rota Design are arguing that the technology our industry labels “State-o-the-Art” is actually doing very little in reality to take the industry from the dark satanic age through the revolution into a more sustainable world. The industry is simply unsustainable in its present form and as pressure grows the concrete and GRP brigades will continue to home in on this fact. The level of failures of rotationally moulded tanks and chambers, which we know to occur on a worldwide basis, is also doing untold harm to the industry’s reputation and potentially eroding our future.
We must work together to overcome these issues and the most effective action we can take is to stop the failures now and begin the process of reduction in energy and polymer consumption. We have demonstrated on many occasions that this can be achieved cost effectively and we trust that our series of articles on the subject of “Prevention of Failures” has sparked further discussion on the subject. I hope we have convinced you to act – please feel free to contact us for more information.