The things you don’t see on the football field

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soccer stadium

There’s probably very few people in this world who haven’t spent at least a minute in the past weeks watching football championship matches, or at least catching the day’s summary on the news in the evening. A rather painful moment for me to be writing this, being German. And, to add insult to injury, my wife happens to be Mexican! Yes: ouch!

Nevertheless, it’s not the sports results I wanted to talk about here (clearly!). There are many different factors that have to come together and work properly for the championship to be a success. I bet you’re guessing this has to do with adhesives.

To begin with – the ball. Nothing would be possible without is. The ball used to be sewn by hand, joining together different elements over two layers of lining. Nowadays, it’s produced of fewer individual parts bonded by special adhesives. That makes it lighter, more aerodynamic and less permeable to water when it rains.

The gear that the players use to be both: light on their feet and protected in duels that sometimes happen on the field, must be of top quality and super reliable. Use of adhesive made it possible for the cleats to be lighter, more flexible and follow the players movement more closely, while the shin guards now adapt to the shape of the leg much better and pinch much less.

And that’s only the elements involved in the game directly. There is a number of other objects indirectly involved that benefit from the use of adhesive, like the stadium itself (flooring, walls and ceiling installations), floodlights, other lighting systems and various displays as well as the very buses on which the teams are transported from their accommodation to the stadium.

Where hybrid adhesives are your best bet

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As much interest and amazement as our videos of pulling trains or parking trucks on rigs bonded with hybrid adhesives generated, let’s be honest: how often do you need to pull a train or park a truck in that way? Not very often.

There are, however, very realistic situations in industrial manufacturing or repair, where hybrid adhesive becomes indispensable. This technology is completely innovative and we are discovering new possibilities with it almost on daily basis. I’m going to share only a few fields in which they will usually outperform any other available option.

when hybrid is your best bet

One of the most common challenges in modern manufacturing is joining of two or more materials of very different characteristics. This is usually a challenge for the traditional methods as well, not only for bonding. Different materials mean different adhesion properties, but can also mean different reactions to thermal cycling, humidity, impact stress, or any number of other factors to which the final product might be subjected.

Hybrid adhesives tackle this challenge because they adhere well to a huge multitude of substrates and withstand well the majority of mentioned factors. Bonding of dissimilar substrates is most often a requirement in the production of indoor and outdoor signage and advertising elements, bonding of equipment tags and RFID tags and in the production of special architecture, like awning arms, railings and the like.

Another common requirement in, for example, production of heavy lifting equipment, street furniture, conveyor belt frames and fitness equipment is impact strength in general. Which is also where hybrid adhesives will perform considerably better than other technologies. If you need to pair that with fast curing, chemical, heat or moisture resistance, you’ll often find a hybrid adhesive is your only choice. Some of the typical examples are vibration dampers, magnetic motors, electric scooters, vending machines, plumbing production, building construction, elevator panels etc.

Dispensing and assembly of liquid gaskets

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I wrote a lot about the liquid gaskets in the last posts and, as I’ve mentioned previously anyone who is interested in more is welcome to request the complete Gasketing design guide. Nevertheless I have to mention a few more things related to dispensing and assembly of parts when liquid gaskets are used.

When it comes to preparation of the parts, the same golden rule is valid as always with bonding – clean the parts as thoroughly as possible. Normally, pre-produced metal parts will carry instructions from the manufacturer for cleaning before putting them into further use, and they should always be followed.

RTV Elastomers will be slightly less sensitive to contaminants than anaerobics.

Single Rotary

Possibility of automation is often a critical factor when decision is being made on how to seal your flanges. With liquid gaskets the dispensing can be fully automated. Dispensing them robotically is actually the most reliable method for high volume production. Anaerobics can be screen printed as well, but this method is more suitable for medium volume productions which don’t require any flexibility in the process. I definitely recommend consulting an expert before setting anything up.

 

Gaskets: Anaerobics versus RTV Elastomers

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AN_vs_RTV gasketing

As magical a liquid as anaerobics may seem, they are not necessarily suitable for every flange type. They are most suited for sealing rigid flanges, designed to achieve optimum stiffness between two parts, minimise movement between them and transmit forces from one to another. Typical examples of such flanges can be found in vehicles, including gearbox housings, bedplate to crankcase, water pump to engine block and cam cover to cylinder head.

Anaerobic FIP (formed-in-place) sealants are ideal for rigid bolted joints because they offer metal to metal contact, ensure correct bolt tension, add structural strength, offer high pressure resistance and extensive on part life when exposed to air, making multiple application methods possible.

When it comes to flexible flanges, however, your best choice are RTV (Room Temperature Vulcanising) elastomers. They are best suited to seal i.e. gearbox covers, timing chain covers, stamped sheet steel parts, thin-walled metal castings and oil pans. Normally, flexible flanges don’t support the function of the parts, so micro-movement can be tolerated and optimum clamp load distribution is not crucial.

You’ll usually find flexible flanges covering openings in housings, sealing liquids inside components or protecting them from external contamination, covering moving parts for safety etc.

While anaerobics remain liquid on parts for as long as they are exposed to oxygen, RTV elastomers will cure into rubbery solids by reacting with the moisture from the environment. So there is a considerable difference in on part life between the two, which is important to take into consideration when suitability of the manufacturing process is being decided.

In both cases – rigid and flexible flanges – there are certain design recommendations to be followed to make the flange best suited for either anaerobic or RTV elastomer FIP gasket. Details can be found in the Gasketing design guide which I am happy to share on request.

To all the hardworking engineers out there!

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Christmas

It’s that time of the year once again! Time to take a well deserved break, slow down and take it easy. I know there’s one wish that applies to you all: may all the machines you tend to all year through, lovingly repay you for all the care you give them by running smoothly and without any need for interventions during the upcoming festive days!

Merry Christmas and all the best to you all for the coming new year!

 

Formed in Place

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To recap from the previous article, FIP (Formed-In-Place) gaskets are applied as a bead or a screen print of a liquid material, just before the two mating flanges are assembled. As the flange surfaces come together, the sealant is smeared between them and forced into surface imperfections, providing total contact and forming into a durable seal.

FIP

Unlike conventional gaskets, cured FIPGs adhere to every part of the joint and therefore don’t require extreme compresive loading to form a seal. With FIPG you can also forget about gasket relaxation and need for re-torquing. The metal to metal contact that FIPGs secure enables more accurate maintaining of tolerances while any scratches or damages to either of the surfaces can be sealed by the liquid material. Most of the FIP sealants have really good resistance to solvents and other industrial chemicals and unlike solid gaskets can be applied to vertical surfaces without any need for additional adhesive to hold them in place till assembly.

In terms of curing chemistry, there are two most frequently used types of FIP sealants:

  • Anaerobic (curing between metal surfaces in the absence of oxygen)
  • Room Temperature Vulcanising (RTV) elastomers

Anaerobic sealants are best suited for sealing of very rigid flanges such as gearbox housings, bedplates to crankcases, water pumps to engine blocks, and cam covers to cylinder heads.

They ensure minimum movement between parts, optimum stiffness between the two surfaces and transmit forces from one part to the other.

RTV elastomers cure to rubbery solids by reacting with the moisture in the environment. They are best suited for flexible flanges, like gearbox covers, timing chain covers, stamped sheet steel parts, thin walled metal castings and oil pans. Normally, they do not support the function of the component so micromovements can be tolerated.

Some of the additional benefits that RTV Elastomers offer are: high gap filling, sealing of T-joints, creating seals on non-machined flanges as well as between metal and plastic or two plastic components.

For more details, please request your copy of the Gasketing design guide.

Rigidity, positioning and surface smoothness

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Rigidity_positioning and surface smoothnessž

A flange rigidity critically influences the required minimum surface pressure at mid-point between two bolts of a flanged joint. It also very much influences the type of a gasket suitable for the said joint. Where adequate bending rigidity is maintained, soft gasket materials and non-curing liquid gaskets can be used.

When deciding which of the gasketing options is suitable for your design, apart from flange rigidity, you must also look into the required / possible bolt spacing and positioning and the resulting stress distribution. Each of these factors are inevitably influencing each other and your selection of gasket material.

With conventional gaskets, surface finish or surface texture is an additional crucial factor, since the initial compressive load required to deform the gasket into the flange surface irregularities increases with rougher surface finish. Although it’s not to be completely neglected, the surface finish becomes much less important when using a liquid gasket material. For details you can consult the Gasketing design guide which I’m happy to share on request.

When talking about liquid gasket materials, there are several types depending on application method, curing method and timing or technology.

  • FIP (Formed-In-Place) Gaskets are formed by the application of a bead or by screen printing of sealant, which is then assembled in the uncured state.
  • CIP (Cured-In-Place) Gaskets are formed by the application of a bead of elastomer to one flange that is cured before the flanges are assembled. The gasket is then compressed by the mating flange to form the seal.
  • IIP (Injected-In-Place) Gaskets are liquid gaskets that are injected, after the assembly of the joint, into a groove between the two flange faces and then cured.
  • MIP (Moulded-In-Place) Gaskets are moulded directly onto one of the mating parts, usually into a groove.

I’ll go into the details of each and their advantages and recommended application areas in the next article.