By Stanislav Venclik
Engineering Manager at Wheelabrator
When I was little, one morning every fortnight started earlier than usual – I had to get up quickly and wait in line for “ABC”, the most famous Czech magazine for “young engineers and biologists”. Sometimes I was lucky and got my hands on a copy, sometimes it was sold out by the time I got there – even though I was on the pre-order list!
One of the reasons copies of ABC were so precious to me were the paper cut-out models inside them – sometimes castles and famous buildings (which I found a bit boring), sometimes tanks, artillery, and space shuttles (which were all right), sometimes trucks and cars (which I found very interesting). But the best cut-outs were definitely the models of GP motorcycles and Formula 1 cars.
Depending on the type of model, some of the cut-outs didn’t even make it out of the magazine, some were done just when I had free time. But with the coveted GP motorcycles and Formula 1 cars, I could not wait a single second, and the completed model was soon ready to take its best place in my little showcase – usually very late in the evening of the day I bought the magazine.
Over time, I perfected the art of building the models, finding new ways of doing things and improving the designs, making them perfect. Years pass, the models are first covered with layers of dust, then the showcase disappears. What remains is this determination to perfect. It’s a trait I’ve seen in all my colleagues and I bet most engineers have a similar story to tell.
Perfecting the blast wheel – one prototype at a time
I was reminded of my early quest for perfection during the development of our new COMET HD blast wheel – especially when we went about fine-tuning the latest prototype.
Like all those years ago, I’m being impatient again, hurrying across to Pre-Assembly to see how the 3D models we did in the design department work in reality. I start to “play” with the blast wheel, dismantling and assembling it again and again. The guys in Pre-Assembly must think I’m mad, so frequent are my little visits, trying this and that, asking them to tweak here and there.
If that’s mad, then at least I’m not alone. When the global development team met at our test centre in Schaffhausen the other week (to welcome the latest prototype, take lots of pictures of it and then test it to destruction), I noticed I wasn’t the only one eager to get my hands on our latest iteration of COMET HD.
There’s a certain magic in making – and it was palpable across the team. We design these pieces of steel, work out how everything should fit together, send drawings off – and what comes back is something we came up with. In our heads, as engineers.
And as engineers, we start to play. Like when we tested if we can dismantle the front wall of the blast wheel as we’d imagined it.
No more welding over holes – but will it work?
We all know all too well what the situation at the customer would be: A front liner is not replaced in time, so abrasive starts to attack the welded housing made of mild steel, and it’s only a matter of time until there’s a hole in the front wall and abrasive is flying everywhere.
We also know what the customers usually do on this occasion. They take a piece of steel or an old blade and weld it over the hole. Job done! Or rather not. After a short time the hole is there again and layer after layer is welded over the returning weak spot.
For COMET HD, we had come up with a solution for this recurring problem. From the very beginning our intention was to have the front wall screwed on, rather than welded – making it easily replaceable. Some people were sceptical about this, including one customer I explained this feature to at GIFA.
Which is why we were so keen to test it out. On this new prototype it’s surprisingly easy to replace the front wall – even for us! Remove lid and front liner, loosen six screws, remove the front wall, put the new one in place and tighten the six screws, slide in front liner and fix the lid. Done in under 10 minutes!
Hang on, you say, slide the front liner in? How on earth would that work? How do you hold it in place? No screws? – No screws. Just another piece of the COMET HD jigsaw.
During the design of an early prototype we had the excellent (and seemingly simple) idea of using springs to hold the liner in place. What followed was a long and complicated process to find the best way of doing this, and define the right spring shape and force. And we’re still working on optimizing the spring force.
But it works! After removing the lid with integrated top liner you simply grab the front liner and pull it out. If it’s locked with abrasive (or if you’re simply too lazy to pull it out) you can use a puller to do the job for you.
And when assembling the front liner, you slide it in and push it into position. And you don’t have to worry, whether you’ve pushed it far enough or not. The special hinged lid works as a lever when closing it, forcing the front liner into the proper end position. Fool-proof.
The side liners of the blast wheel don’t have the usual fixings either, i.e. they’re not cast, threaded inserters or welded nuts. They are clamped in place and the thread is outside of the blast wheel to reduce any possible damage from abrasive.
To make the life of maintenance staff easier, we’ve included pins to support the side liners in their proper position. When assembling the side liners you place them in their proper positions, as defined by the pins, and then just tighten the clamps. When dismantling, you simply release the clamps and the side liner is still sitting on the pins, rather than falling down.
This just as one little example of how much there is always left to discover when drawings become prototypes, when cut-outs come to life. There were many moments like this during the development of COMET HD, where we were amazed at how everything fell into place.
All the features of the new blast wheel were born out of this spirit of impatience, discovery and perfectionism – the special shape of impeller, control cage, blades, and housing, the new safety mechanism on the lid, the Precision Lok.
And all these tweaks and improvements add up to the best wheel we’ve ever made. We can’t wait to see it go live on customer machines. That’s when the real magic happens.
Back to where the magic started – what’s your version of the ABC magazine? Let me know in the comments!
Explore the new COMET HD Wheel here.