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.

Pineapples, oceans & refrigerated containers

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Shipping containers

At first you might be wondering what these three things have in common, but the answer is rather obvious. Pineapples will only grow successfully in certain geographical areas. For the rest of us, living in less exotic parts of the world, they become accessible because they are shipped around the world on great big ships, crossing the oceans. All the while, pineapples (and other tropical fruits, naturally) are stored in refrigerated containers. To make sure the produce stays fresh all the way to its final destination, the containers must be sealed really well. Which is where the Teroson branded sealant, Teroson MS 930 comes in.

One of the things that can change the properties of the seal and eventually cause failure of the product used is UV radiation. And there’s plenty of that on ships crossing oceans for weeks at a time. That’s why it’s extremely important that the sealant used is resistant enough to UV radiation to keep its full properties for the duration of the trip. Otherwise the beloved tropical delicacies might reach us looking rather less than appetising.

How can a little piece of rubber save the day

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As the info in the sidebar says, I’m Sebastian Horstmann. Ever since I was given a project involving adhesives during my university studies, I became fascinated by adhesives and the power of joining two substrates by what is basically a combination of physical and chemical reaction. I know – does it get more nerdy than that? Well, nerdy or not, one thing led to another and starting from that project, through my PHD thesis, adhesives in engineering became my career choice.

Strangely enough, as much as the modern engineering has developed and changed since its early days, some methods remain very traditional. Bonding as a joining method appears to still be a kind of a novelty, which really shouldn’t be the case. Human kind has used adhesive since ages. Well known is bonding of arrows for hunting back in Stone Age Times as an example. And there are many more. On the other hand, it isn’t really surprising, given the fact how little young engineers find out about bonding through regular educational channels. Over the years of supporting engineers in a number of different industries, I encountered some of the same questions numerous times which made me want to share the solutions (which are sometimes surprisingly simple) in this online format.

Testimony to the simplicity of some of the solutions are o-rings. They are basically simple, modest rubber profiles. But, if one of these plain little things fails, it can cause a lot of trouble. O-rings are very commonly used rubber seals that appear on pumps, valves, hydraulic cylinders… Malfunctioning of o-ring seals can cause leakage of fluids which were supposed to stay within closed systems. That may mean shutting down of production processes, but also present health and safety hazard, depending on the type of liquid that’s leaking out. Standard o-rings come in predefined sizes, which means that you need to keep stock of different sizes for maintenance of your machinery. However, using Loctite 406 instant adhesive and round rubber profiles, you can at any time create any size of an o-ring you require. Simple. Nothing to it. And yet, when it solves a leakage and prevents a major repair on a Friday afternoon, comes as a lifesaver, at least as far as your weekend is concerned. You can check out how to work with it in this short video:

Loctite o-ring application video

Loctite  406

Loctite 406 Bonding of a rubber o-ring

In my next posts I’ll talk about similar simple solutions to engineering problems. Solutions that are so simple they should be obvious, like securing your threaded fastners to prevent vibration loosening, sealing your threaded joints and much more. Also, I’m happy to answer any questions or exchange comments with you, so go ahead and talk to me through the comments section. Your thoughts will be appreciated.