His majesty – the Shaft

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Shaft group

One might argue there is nothing terribly exciting about a plain, smooth, cylindrical piece of metal that any shaft fundamentaly is. But most of them are incorporated into crucial systems of equipment of extremely high financial value and crucial significance for the plant functionality.

Taking proactive approach to maintenance of shaft mounted assemblies can help prevent most common failures, allow for recycling of parts to avoid scrap and even restore shafts to as good as new condition.

Corrosion, wear and errosion are the most well known enemies of shafts. Depending on the type and degree of wear, though, you can use one of the following methods:

  • Sleeving – to instantly restore worn or damaged shaft
  • Bonding – to fill the gap with repair adhesives while maintaining the load bearing capacity
  • Rebuilding – for badly worn shafts where metal-filled compounds need to be used

Sleeving presumes the use of a material similar to the one the original shaft is made of. This material can be fixed to the damaged part of the shaft using products like Loctite 603 or 648. Same products, with the addition of Loctite 660, can also be used for bonding or you might need to select a product from the epoxy range, such as Loctite EA 9466, depending on the depth of the wear or damage. For rebuilding of the badly worn shafts, the right choice are definitely the epoxies, such as Loctite EA 3478 which contains metal particles, making it even stronger and more durable.

There are also the usual, typical maintenance products to choose from, like threadlockers, anti-seize products or cleaners. Find out more.

Industrial centrifuge – no lunch break allowed!

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centrifuge

Decanter centrifuges are typically used in a wide variety of industries, like oil and fats processing, starch technology, food and beverages manufacturing, pharmaceutical and enviromental industry and many more. One of the most common uses is actually dewatering of industrial and municipal waste sludges. Which means the centirfuges are pretty much running 24 hours a day, 7 days a week. Which in turn means that any failures must be dealt with in a speedy and efficient manner.

There are several factors that can jeopardise your centrifuge. The bowl outside surface, lower housing, conveyor hub, flights and feed zone are exposed to errosion and chemical attacks. Damages caused in this way can be tackled by using ceramic coatings and putties from Loctite range of products. Many of them are resistant to chemicals, wear and sometimes even elevated temperatures so they will not only repair already existing damages, but also protect the surfaces from future attacks.

Main and headwall bearings can fail due to insufficient lubrication or a combination of imballance, high speed and load. This can be avoided using Loctite retaining compounds.

Locking of the infeed pipe and feed device screwes is something that should go without saying, as is the sealing of bowl flanges to prevent any leakages.

Check here for details of the products. Please be aware that some of the products may have been renamed or rebranded so best to consult an expert locally here as well.

Industrial gearbox and what you can do for it

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gearbox

I’ve been writing quite a bit about industrial pumps, but pumps certainly aren’t the only devices extensively used in various industries. Gearboxes don’t fall far behind on that list either. And they come in as versatile applications as one can imagine: from the use on pencil sharpeners and 3D printers, through elevators, gates and conveyor belts, to heavy duty applications like those in mining and quarrying and moving heavy loads.

Much like with any piece of industrial machinery that’s expected to run efficiently and without interruptions for as long a lifespan as possible, there’s a number of things that can go wrong in its duration, and many factors that can impact the efficiency and longevity of any given gearbox.

However, there are many predictable failures and mishaps that can be prevented by taking steps already at the gearbox assembly or before putting it in service. Bearing spinout and fretting can be prevented by using the retaining compound Loctite 641. You can prevent leakages between oil seal and housing by securing your bolts with threadlockers (Loctite 243 or 248 are recommended). Loctite 577 or 572 will seal and lock your threaded fittings, while Loctite 518 will take care of sealing your rigid flanges. And that’s just naming a few, all before any issues have occured. There are many more pure repair options, too, like repairing cracks or porosities on the housing, removing and converting rust, as well as lubricating and seizure preventing solutions. Find out more.

Managing expectations

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When adhesives are used for repairs, it’s extremely important to know what you can expect from the part repaired in such a way. Lack of trust in adhesives is often a consequence of wrong expectations.

Fact is, a repaired part cannot be expected to last forever, performing in the same way it always has. You must ask yourself why it failed in the first place. Was it put under forces too high to withstand? Did a high stress impact damage it?

You’ve all heard the saying that a chain is only as strong as its weakest link – it’s the same with any part: it will break on its weakest spot. Very likely, the design at the breaking point was less than perfect and presented a failure risk from the beginning. Once you’re forced to repair, you might want to consider slight changes in the design of the part. Perhaps you’re able to enlarge the area you want to bond, add some additional or reinforcing material. Only bonding the part back together without taking any additional actions to improve it will quickly result in a new failure, once put under the same forces that made it fail before. Even when the adhesive itself is strong enough, it doesn’t help with the material of the repaired part being too weak.

You have to be especially aware when you’re repairing high strength materials like metal. Adhesives are in their chemical basis plastic materials. Which makes them about ten times weaker than metals. So adapting the design of the part becomes crucial here as well.

And finally, it is possible that you’ve adapted the design and the adhesive is in principle strong enough, but the repair still doesn’t work. Well, then the reason for the failure may be in the one thing I keep hammering in most of my articles: surface preparation. Cleaning, cleaning and more cleaning. Roughening the surface can also help, when possible, because it basically enlarges the adhering surface area on micro level. And again – if you feel insecure about what to do, never hesitate to contact an expert.

If you absolutely must weld

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Ceramic Shield

I may be an enthusiast for bonding and adhesives, but even I do realise that sometimes nothing replaces welding. I also know, as well as any welder out there, that spatter left behind isn’t exactly welcome and nobody likes removing it. It adheres to your shroud and contact tips, your work parts, it can even interfere with the quality of your weld seam.

There are different protective coatings that can be used to minimise this. Normally, they require frequent re-touching to work, which means you’ve got to stop your welding, put down your welding gear and dedicate time to reapplying the protective coating.

Unless you use Loctite SF 7900 Ceramic Shield. Believe it or not, once applied this product will protect your shroud, contact tips, work parts and surrounding surfaces for the duration of an entire shift: 8 hours. It can also be used on laser and plasma cutting nozzles or jigs, fixtures and fittings. You can find more information here or watch the video.

Making the correct choice

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Selecting the right tool for a job can make the world of difference in how smoothly you’ll be able to work and how good will the outcome actually be. Same is valid for selecting the best possible adhesive, if bonding is a part of what you’re producing or processing.

The possibilities are many more than one might think, and making a mistake is easier than getting it right. So, start from the essentials. What is your application like? Which materials are you bonding? Is there a gap to fill? Does the part need to withstand high temperatures? Or do extreme loads exist? Will it be exposed to aggressive environments or impacted by the weather and outdoor elements? Is the speed of curing of the adhesive important for your process? Or do you favour flexibility of the bond line?

Even after you answer all these questions, you might want to prioritise all your answers, because very likely, more than one of these factors are going to be important at the same time.

If the speed matters most, then cyanoacrylate technology is your best bet. CA is the base chemistry of what the non-engineers would call super-glue or instant adhesive. However, if flexibility of the bond line is also high on your priority list, you may want to reconsider.

In case you require a seal as well as a bond, you may want to look into anaerobic adhesives or silane-modified polymers.

Silicones are among the more flexible adhesives and secure excellent gasketing performance as well.

For high gap filling requirements, you’re most likely to find your solution among epoxies.

If your application combines many of the above requirements, but none of them go to the extremes, hybrid technology could be your solution. Hybrids combine properties of CAs and either epoxies or MMAs, which gives them the versatility that isn’t found in any other adhesive.

I’ve only touched the very few chemistries and there main properties, but you can explore more here. As always, for your final decision, I strongly recommend contacting an adhesive expert.

Truck challenge

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truck for blog

Perhaps you’ll say that once we pulled 208 tons with the help of Loctite HY 4070, it can’t get much more impressive than that. 7,5 tons truck doesn’t sound like much of a challenge, does it? But this time it was shear strength of the adhesive we’ve put to the test. Have a look!