Molding Technology for Electrically Conductive Elastomer Gaskets

Hello, and welcome. My name is Jarrod Cohen, the marketing communications manager for Parker Chomerics. This is the Molding Technology for Electrically Conductive Elastomer Webinar. Thank you all for joining today. I see folks are still entering the room, so we are going to get started in just a few more seconds. Thank you. All right. I think folks have just started. Just wanted to touch on a couple of housekeeping details for everyone before we begin, so please be sure to set yourself on mute if you have not already.

After we run through the slides, we will have time for a live question and answer session. So if you have any questions during the presentation, please feel free to type them in that Q and A box. We'll make sure to address them at the end. And finally, not to worry if you miss any part of this presentation, the webinar will be recorded and available to view after the call. So with that, let's introduce our speakers. We have Sierra Eiden and Ben Nudelman. Sierra, are you there?

Hello and welcome, everyone. My name is Sierra Eiden. I am the aerospace and defense market specialist for Chomerics. I'm a mechanical engineer and I've been with Chomericsfor over eleven years.

Hi, everyone. My name is Ben Nudelman. I'm a global market manager for Chomerics and have been with the team for five years.

So for today's agenda, we'll first start talking about Parker Chomerics and introduce who we are. Then we'll get right into section one with Conductive Elastomer material review and just reviewing what our electrically conductive elastic materials. Then we'll talk about types of molding, whether it be over molded or vulcanized or molded placed gaskets.

Then we'll talk about why you would actually want to choose a molded part versus, say, an extruded part or another different type of conductive elastomer. We'll talk about tooling considerations. And then finally we'll get into the all important application examples and the question and answer at the end of the Webinar. So go ahead. If you have a question, please don't forget to submit it. And we will now get started.

So first, just a quick note about who we are. Parker Chomerics is a division of Parker Hannifin Corporation. We are the global leader in the development and application of EMI shielding and thermal interface materials. So our core competencies are in materials science and process technology, and at Chomerics, we really do offer a complete market driven product development cycle. So we feature integrated electronics housings, and we're proud to offer custom engineered solutions and a fully integrated global supply chain that we manage that for a lot of our customers worldwide.

Hello, everyone. Thank you. To everyone joining the webinar today. Our first section is going to go into some details in selecting the right conductive elastomer for a molded EMI seal. There'll be a lot of technical details. So please use the Q and A feature throughout the webinar to ask questions and we will get to them at the end.

That's right, Sierra. And just to confirm, this webinar is all about molded elastomers in the technology and processes involved. We have made other webinars in the past on conductive elastomer gasket design, as well as limiting corrosion with electrically conductive materials. You can find those webinars and a few other ones at Parker Chomerics or reach out to one of us for more information. Now let's jump right into the content as a review.

Electrically conductive elastomer seals consists of two components an elastomer base used to provide weather sealing and a conductive metal filler used to create an electrical seal for EMI shielding. These seals are used in a variety of sealing applications and come in an almost infinite number of design possibilities and performance options. Emi seals differ from traditional seals in that they rely on the compression of the electrically conductive particles to create the electrical path for grounding and shielding of electromagnetic interference.

The first thing you want to consider when starting your design for a molded conduct of elastomer gasket is the binder system. So we have three main elastomer binder types, which are silicone Fluorosilicone and EPDM. The binder is an important choice related to the environment in which the gasket will be exposed, as well as various fluids that it may come into contact with.

So silicones, for instance, are elastomers that have a high resistance to compression set and withstand a broad temperature range. And while silicones tend to perform well in applications that may see humidity, they do not tend to hold up as well against harsh chemical exposures to things like bleach, cleaning solvents or hydraulic fuels. Fluorosilicones are far more resistant to these types of chemicals, and they also tend to perform better than their silicone counterparts for corrosion resistance. Believe it or not, for seals that will interact with hydrocarbon fuels or CBN agents like super tropical bleach, EPDMs are the best choice. And while EPDM binders are also resistant to vapor transmission, they tend to take a greater compression set in some applications, so picking the wrong material for an application could lead to failure in your grounding, sealing and shielding.

Metallic fillers give conductive elastomers of conductivity and EMI shielding properties, with each type of filler meeting different needs. For example, silver plated aluminum will provide excellent shielding effectiveness as well as high corrosion resistance on aluminum substrates or conversion coded aluminum substrates. Pure silver fillers, for example, will give excellent conductivity and present the lowest contact resistance.

There's a particle specific to Chomerics, and we developed it in the more recent years. It's our nickel-plated aluminum particle, and this will yield the highest shielding effectiveness across the frequency spectrum as well as the highest corrosion resistance over time. So in applications that will not see environmental exposure or those that do not require high levels of shielding, something like a nickel plated graphite is a very common, economical option.

It's important to note that the material properties determine the ability of a specific binder and filler combination to be processed in a certain way. Some materials can be extruded or molded into different shapes and sizes, while others can only be extruded or only molded. Still others can only be molded into just flat sheets. These are factors to consider when deciding on a material.

Yeah. And at the same time, because of the number of materials available, there may be a few different types that are ideal materials that fit into your application needs.

When designing conductive elastomers, one important factor to consider is tolerancing so in general, molded parts can hold tighter tolerances than extruded parts, which can be a huge advantage for small or intricate gaskets. However, these are still made of rubber, and they can't be held to precision tolerances like machined parts. So please pay attention to the published standards and you will have the best chance of success.

So when it comes to assembling molded parts into applications, sometimes a pressure sensitive adhesive, or PSA, is a great tool for the ease of assembly. Molded sheets and die cut parts can be provided with an electrically conductive acrylic based PSA.

Okay, so now let's jump into the different types of molding methods and the features and parts associated with each.

The first and by far the most commonly used molding technique is known as compression molding. It uses a charge or a small amount of raw material placed into a mold that is then compressed and cured into the specific shape of the mold. This process is used for many different parts, including standard gaskets and o-rings, as well as large molded sheets. Sierra, what's the next molding process?

So next up is injection molding, and this molding process injects the raw material into a set of passageways known as spruce and runners into a mold and then cures the material after it has reached the final part cavity. So because it requires material to flow, it can only be used with select conductive elastomer materials and is often used for parts like conductive grommets or to over mold parts directly onto a substrate. Injection molded parts often have additional material that must be trimmed or cut off, that is located at the gate or at the point at which the runners meet the final part cavity.

Finally, a molding process that's actually rarely used with conductive elastomers, but we wanted to touch on anyway is known as transfer molding. It can be used for parts with very complex geometries or parts that have undercuts that would be difficult to remove from the mold with other processes. This process can actually sometimes be used with co-molded parts, and we'll discuss those types of parts in a couple of minutes.

Yeah. In general, much of this information is not typically needed to design a custom conduct of a last summer, and our engineering team will decide which process is best aligned with the part based on cost effectiveness and capabilities, and our team also may suggest modifications to your part based on design for manufacturability.

Here are a few examples of standard parts that are molded. O-rings and d-rings in just about every shape and size can be molded, and we are already tooled up for thousands of industry standard parts. This includes jam, nut seals and mill spec o-rings, as well as most common connectors looking to convert from a non conductive to a conductive seal. Waveguide gaskets are also very commonly molded from conductive elastomer materials.

Connector gaskets for mounting flanges and D-sub miniature connectors are die cut from sheets of material, and while the steel rule dies for many of these common profiles are already tooled. Custom shapes are simple to design as well, and other than die cut connector gaskets, like Ben mentioned, grommets, o-rings d-rings, they all fall into this category of common molded parts. So to see a long list of already tooled up parts, please see section six of the Chomerics Elastomer Engineering Handbook.

Molded sheets are one of the most commonly molded parts because they can be cut into limitless other parts. They're often available in thicknesses as low as .010 of an inch and up to a quarter of an inch or even greater, and in terms of the XY dimension, they can be manufactured in sheets up to about 30 inches by 30 inches if needed.

We wanted to note that not only can conductive elastomers be made into sheets, but broadband radio frequency or RF absorbers can also be molded into sheets that can again be die cut. Most sheets can be cut by die cutting, automated knife cutting, water jet, or even hand-cut with a utility or X-ACTO knife for prototype needs.

And again, for more specifics on die cut gaskets, see our previous webinar on electrically conductive gasket design. Like we mentioned earlier, co-molded parts are examples of parts that can be molded using two different elastomers of the same family.

A conductive silicone molded with a non-conductive silicone can be made together into a single final part. This can be a fine option when the environment is extreme, for instance on the deck of a Navy ship or a tropical location where salt, fog, humidity and moisture can be a huge problem. By using the nonconductive seal outboard and the conductive seal inboard, it removes the electrolyte or the harsh fluids from the equation and protects that conductive gasket from exposure, thus preventing electrolytic corrosion. Reinforced molded seals are high performance gaskets often used for defense and aerospace applications where it sees very high shock and vibe. These are molded from a corrosion resistant elastomer and have a fabric reinforcement layer that is sandwiched by the elastomer.

Ben, what kind of materials have we seen used for reinforcement, besides fabrics?

That's a good question, Sierra. Most commonly, we use a Dacron material which actually increases the tear strength of the gasket and provides resistance to abrasion, which means it can keep the gasket intact and providing EMI shielding. Even when some of the outer layers of the elastomer itself have been cut. Aluminum or other metal mesh can be layered into the elastomer for things like lightning strike protections a a high current carrying material.

Chase molding is an excellent way to design a molded part that would otherwise have to be die cut and waste the entire center of the gasket, adding cost. By designing a picture frame shaped mold and then cutting away the edge flash or adding through holes, the unit cost is reduced because of minimizing raw material. The scrap factor rule of thumb is if we can save 25 square inches of material, then we'll most likely go through the process to build a Chase mold.

That's a great point, Ben, and I also want to note that this is a very application specific. You still have to account for the molded tool cost factor in the quantity of gaskets you plan on producing. A die cut out of a sheet may be great for prototypes. Or conversely, if your plan is only to make a handful of parts, the tooling charge may not equate to the cost savings of the scrap material from the center. So keep that in mind.

Flash is the residual material attached to the part at the mold lines. As a result of the tolerance of the molding, tool flash can be harmless, or it can actually prevent affected sealing. So there may be requirements to remove the flash in a process called de-flashing. Sierra, can you tell us about the types of de-flashing?

Sure, Ben. So the first of three types of de-flashing that we perform at Chomerics is cryogenic de-flashing. So this uses liquid nitrogen to freeze the parts temporarily, and break away the flash by running the frozen parts through a tumbler, for instance. This process doesn't do any damage to the parts and targets the flash because of the thin amount of material that becomes brittle and breaks off when it's frozen. But depending on your overall part size, you may or may not be able to fit them all in the tumbler. So when this is the case, the two other de-flashing methods are hand trimming and tear trimming, and hand trimming uses a blade to carefully cut the flash off, and tear trimming is exactly what it sounds like tearing off the flash by hand.

As you can imagine, hand and tear trimming require a little bit more labor. While cryogenic de-flashing is mostly an automated process, so there may be differences in cost involved.

And I wanted to add a quick note on de-flashing if possible. One thing you have to consider is if you do an over molded type design where you're molding on to a metal housing, those won't be able to go through cryogenic de-flashing, as you would be tumbling metal parts, and they could be damaged in the process.

Perfect. In this next section, we will talk about overmolded, mold in place and vulcanized covers. And I wanted to just stop here and remind everybody that we do have a question answer session at the end of this webinar. So please continue asking questions using the Q and a feature here at the bottom.

So overmolding is the process of molding a gasket directly onto a metal or composite substrate. Instead of trying to insert a gasket into a groove or using an adhesive or mechanical type fastener, the gasket is actually permanently bonded onto the cover.

When it comes to over molding, there are several terms used industry wide. The term over molding covers the whole category of molding. A conductive elastomer directly onto a suitable substrate.

Whereas vulcanized covers are typically precision molded aluminum covers for military applications due to the technical requirements, coatings, markings, cost, and sometimes the production rates involved.

With a mold in place or liquid injection molding, the process involves any suitable substrate and is often used with commercial applications. So one factor to consider is that the plastic or composite substrate must be able to withstand the high heat elastomer molding process for a certain duration of time. So molding onto thin walled areas can cause warping of the housing during the mold in place process. So moral of the story, make sure you pick your plastic substrate wisely, and we would be happy to provide you with design support on that if you have any questions.

And one last point on over molded covers is that the substrates need to be free of dust, particulates and greases and really should be cleaned prior to the elastomer molding to make sure that the elastomers molded effectively onto the park for long term durability.

Great. Okay. Now before we talk about tooling and application examples, we just wanted to briefly go back over the overall pros and cons of a molded part.

Specifically, we wanted to talk through exactly where you would benefit from molded parts in some situations where you may want to steer clear.

The biggest advantage of molded parts are the no seam construction and form stability. So while an extrusion is spliced together, a molded part has no seam because it's formed as a single complete part and form stability means that the shape it was molded into is the shape it will stay in. This is a big help during installation of molded gaskets in serpentine type shapes, for instance.

Other advantages include a lot of design flexibility and some mechanical advantages, such as tighter tolerances, like we mentioned before.

We will admit, though, that molded parts are not perfect and do have some drawbacks. So the cons of molded parts include a higher upfront tooling cost and a slightly longer lead time required for the design.

Most of the disadvantages of molded parts can actually be addressed, though. Mold flash, for example, can be dealt with. And while the upfront cost may be greater, high volume production can lead to lower unit costs and lower overall project costs.

The profiles you see here are pretty much the standard cross sections for molded parts and the pros and cons of each. So, strip profiles have the same properties as a die cut gasket from a molded sheet and have the advantage of flexible mounting methods using either a pressure sensitive adhesive or some type of bolt hole.

Solid-O is by far the most common profile and is best for environmental ceiling, but does require a group. Solid D profiles have benefits of both solid-O profiles and flat gaskets, but should be mounted well so as not to roll over on themselves.

Solid profiles tend to have excellent environmental ceiling capabilities but are limited in their compression range compared to their hollow profiles. These hollow profiles can only be extruded, which is a consideration when planning for applications and some of the other features of molded versus extruded parts.

While the maximum deflection percentage of conductive elastomers is 25% of the outside diameter or height for solid profiles, hollow profiles can withstand deflection levels up to 100% of the inside opening.

All right, so this is our last section before our application case studies, and this is on tooling considerations. While most of the details around tooling are taken care of by our engineering team and doesn't require much customer input, we also want to give you some background on the factors that impact tooling. There are a lot of factors that go into tooling design, both for standard compression mold and four types of molding, like over, molded or vulcanized covers. The part size and shape will impact the cavitation or the spacing of the part in the mold, and the elastomer and substrate materials will also have a factor on tooling because of the material properties, like shrink rate.

Standard molds for radially symmetrical parts such as O-rings or D-rings will typically have a twelve inch by twelve inch steel mold with a nine inch by nine inch usable area. Within this usable area, the parts will be placed in the square grid pattern of 9, 16, 25 or even more parts if they're really that small.

And an important reminder, designing and machining a mold takes time, and so you need to factor in that to your project timeline.

Okay, now for the finale, we have some examples of where molded gaskets were the best choice for the customer applications.

So this first application we want to talk about is a medical device handset. We had a customer with a very complex Serpentine groove pattern, and they were hand installing this extruded cord into a groove, which you can imagine took a very long time. So the reason they chose the hollow O-ring cord was because it could friction fit into the groove and not pop out. However, it got to the point where the assembly process became a significant bottleneck, so we worked with them to design a mold in place solution that would mold the gasket directly onto their plastic housing. Amortized out over time and due to the high production volumes. The cost of additional tooling was well worth the investment for their time savings, so the new design also made the solution more robust and more reliable, while maintaining the same low closure force that they had originally needed.

This type of application is not unique to medical devices. We had a very similar application where the assembly process of installing an O-ring into a vertically oriented group was causing significant headaches. Vulcanizing a gasket onto an aluminum cover reduced the overall manufacturing costs, removed the mess caused by using adhesives to try and keep a gasket in place, and simplify the supply chain for the full build.

Nearly a decade ago, QSFP style connectors became very popular for high speed input output interconnects. There were already some solutions for grounding these connectors, but environmentally sealing them was an added challenge. The connectors themselves were small, but the real estate to place a gasket was even smaller. The solution was to use an economical nickel plated graphite elastomer that was molded directly onto the aluminum connector body. The overmolded part held a very tight tolerance and was designed to reduce any pinching of the gasket at the corners to make sure there was a consistent environmental seal.

So this next application is for a conductive o-ring that was used on an exhaust recirculation sensor mounted in the exhaust stream of a diesel engine. Originally, the customer had used a traditional standard non electrically conductive O-ring needed to swap it out for a conductive O-ring due to the failure in their EMI testing. Because of the need for a tight seal, no amount of flash would be tolerated along the outside sealing edge. So because of this, we switched to an injection molded fluorosilicone conductive O-ring that would stand the exhaust the high temperatures, and we were able to locate the gate onto the inside surface and that was hand trimmed. So this process worked very well for both the initial prototype phase as well as the high volume production because they were able to eliminate that flash on their critical sealing surface.

A relatively recent application that we had seen is the design of VR headsets. These headsets had several small components and needed shielding at the USB charging connector, the lid to frame interface, and at the microphone. So because of the small form factor, we needed tight tolerances and went with a gasket that used a very small conductive particle. In this case, CHO-SEAL 1270, which is made from a silver plated copper flake in a silicone binder, was the perfect material.

And lastly, a door gasket on a military vehicle. So the original design called for a very large hollow extrusion, but it kept being damaged. When the gasket was stepped on, the soldier would get into the vehicle and the gasket would catch on his boot, so the team even had to have a roll of extra material in the back of the truck to replace the seal. But this rework cost was adding up pretty quickly. So the other concern was that the door was constantly being opened and closed slammed shut. So we ended up designing a molded gasket that was reinforced with a Dacron ripstop fabric. The fabric prevented the gasket from punctures and tears that would cause it to fail. The solution met the shielding, environmental, and durability requirements while saving costs and time on the rework process.

Thank you all for joining us today. And we'll now be answering some of the questions you all submitted. As a reminder, the Q and A feature will remain open. So please continue asking questions as we answer some of the ones that have already come in.

All right. Thank you all, so before we begin, I'd like to introduce Harish Rutti. He's a regional sales manager, and he'll be joining Ben and Sierra for our question and answer. Harish, are you there?

Hello, everybody.

All right, guys, so let's get into some questions. I see there's a few coming in. One question I have from Chuck Cunningham. Are the substrates and their manufacturing done within Parker Chomerics or contracted outside?

So the machined metal substrates, we do buy those from outside machine vendors. We also have our own machine shop within Chomerics . We do our own manufacturing of plastic molded housing. We do have our own plastic molding facility, and then we do mill and plate our own particles. So we do that part of it as well. So we do machine substrates, the plastic molding substrates, and we do that all within Parker Hannifin at the Chomerics division. And that is the following question in regards to tooling, are they built in house or contracted out? Depending. We do also work with outside vendors just depending on volume, complexity, and customer preference.

And then the third follow on question from Chuck, "who owns the tooling?" So typically, Parker Hannifin owns the tooling. However, there are some instances where the government owns the tooling, so it just depends on that requirement and the negotiations at the time of quote.

The next question we have comes in from Adam. He says, "how do you protect molded parts during manufacturing, transportation, et cetera, so the gasket isn't damaged before reaching its final application?"

So we've been molding parts for decades and have kind of gotten to the point where we've optimized the process of both the manufacturer as well as packaging and transport of the gaskets themselves. So during the manufacturing, we make sure to use proper manufacturing methods as well as mold releases if required for some of these parts during transportation, typically, the gaskets are bulk package, but for custom or unique parts, those gaskets can be packaged in a way so as to make sure not to damage them during transportation. In general, most of the time the gaskets because of the flexibility of the material. Because it's a rubber substrate there typically isn't a whole lot of damage, especially for smaller bulk packaged parts.

A question here from Steven. Very specific material related. "What's the difference between CHO-SEAL 1298 and 1287?" Both are silver plated aluminum in the fluorosilicone resin. The CHO-SEAL 1298 has a passivated silver aluminum particle which provides an improved corrosion resistance over the 1287 for aluminum flanges.

Okay, so a question came in from Adam. "What is the best conductive PSA or pressure sensitive adhesive that you have available for strip gaskets?"

So we have a silver plated copper in acrylic adhesive. That's our standard. However, I have seen other customers use some of our CHO-BOND conductive adhesives. We do make a full line of conductive adhesives, which we also did a webinar on if you guys are interested. We typically don't recommend that as it could cause a galvanic couple between the two different materials. But typically we use our CL- 130, which is a silver plated copper in acrylic.

The next question we have comes in from Cameron. "Can the customer swap materials on the same mold? I know they have different shrink rates, but can it be done if needed?"

So that's actually a good question. With several of our materials, they actually have a very similar shrink rate. So once the mold is designed, there are some materials that can be interchanged without having to go through an additional tooling process or an additional molding process. Again, a lot of that comes down to our engineering and manufacturing team. And in general, materials can be swapped out if program requirements require things like additional resistance to harsh environments. But there are several materials that do have similar manufacturability and can be replaced without having to go through additional tooling.

A question here from Sanjeev, "why friction fit can't be considered with molded parts?" sierra, can I pass that on to you?

Of course, yeah. So the reason why molded parts cannot be friction fit is because you depend on the hollow profile to be friction fit. Whereas we can mold hollow shapes, they're typically not small enough to be fit into a groove like the molded hollows are going to be a little bit bigger, probably Dacron reinforced. So really, because molded parts are typically not hollow and hollow is friction fit. Basically, those are together. So hopefully that makes sense.

To add a little bit of context to that. Typically, when designing a group for things like a hollow gasket, if a hollow gasket has, for example, an outside diameter about 0.080 of an inch, the groove will actually be under sized to something like 0.079 or .078 inch in order to get that friction fit. And then the gasket actually ends up deflecting in on itself, filling in that open space with a solid gasket, such as a hollow D profile, you aren't able to do that because of the area that the gasket falls into.

So that again, that's just another reason. That because molded parts can only be made in solid profiles, they can unfortunately not be made into friction fit gaskets.

The next question we have comes in from Cameron as well. "Are there size limitations on molded gaskets?" In general, there are some size limitations. We typically max out our molding, our mold tools at around 36 x 36 inches. Sometimes we have the capabilities to go a little bit beyond that. That being said, there are creative solutions for moving very large parts, oftentimes moving them in pieces or in a pattern that is better able to fill in that 36 inch x 36 inch mold area that can then be used to create a much larger molded part.

So there are some limitations, and I think it really comes down to application specifics. So reach out to one of us or to your sales engineer, and we can certainly talk through that application.

Yeah and I'd like to add to that, Ben. So whereas Chomerics division is one of 150 divisions of Parker Hannifin, yes. Chomerics may have size limitations due to the size of tooling and what daylight we have to work with on the molding press. However, Parker Hannifin Engineering Materials Group mold the seals that go on the International Space Station, the mating gaskets. So we have sister capabilities with our sister divisions to mold very large parts. So please reach out if you have any specific requirements.

Okay. Another question here from Adam. "For custom molded gasket shapes that are cut from sheets, is it possible to add conductive PSA to the gasket surfaces that were cut out instead of the back of the sheet? What impact would that have on cost and manufacturability?" Hey, Ben, do you think you could take care of that one for me?

I can. So in general, on a molded sheet that is been die cut, the pressure sensitive adhesive is typically applied to one of either the top or bottom of the flat surfaces. I can't say we've had many applications where it's been applied to the cut surface or effectively the thick thickness of the gasket itself, but I think we've seen a lot of creative and custom solutions, so that may be something to explore individually.

As for the second part of the question, about what impact would that have on cost of manufacturability? Typically, the addition of a PSA will add a little bit of cost, but in terms of the assembly time and ease of manufacturer, it often ends up being a significant cost savings for the labor involved and oftentimes the headache that comes with assembling these gaskets into a final application.

Yeah. And just to piggyback on that, I do have a customer that has a very complex molded shape. We actually hand cut PSA strips and add them after the fact. So really, it's just hand labor and time that you're adding after the fact.

So I had one more from Adam. "Can you speak more about the maintenance or repair required for molded parts? Do these parts need to be sent back to Parker?" So if you have a simple molded o-ring and you tear that o-ring or you damage it or you over compress it, it just needs to be thrown away. There's no way to repair that. If you have an over molded cover, for instance, we vulcanized some material onto your metal housing that actually can be if somehow you chip or d-ring or repair that would need to be sent back to Parker to be reworked. We would probably just use a lot of elbow grease to get that gasket off of there and then clean the surface and just remold it back on. I have seen in a pinch, customers use some of our conductive adhesives to kind of patch those areas. Not recommended, but then again, it's all application specific. And if it works for you, it works for you. But yeah, typically if you break those, you just got to dump them in the trash and start over.

The next question we have is from Chris, "can hollow extrusions be spliced to form an o-ring? What are the inner diameter and cross section diameter design guidelines for splicing solid or hollow, if applicable, extruded sections into a ring?"

So, Chris, that's a good question. In general, yes. Extruded gaskets are very oftentimes spliced into a solid o-ring and that's kind of the alternate process to creating an o-ring that isn't molded like we discussed here. So basically, with an extruded gasket, it is created in a long strip of material that can then be cut down to size and spliced using a proprietary splicing compound. When it comes to the design constraints, sometimes gaskets can be made in hollow profiles as small as 0.050 of an inch with an outside diameter and inside diameter about 0.020 of an inch. Solid profiles and extrusions we've seen made as small as about 0.030 of an inch OD and sometimes even smaller with the ability to hold pretty tight tolerances. So, yes, there are certainly different possibilities and options for manufacturing gaskets that aren't molded. Instead, are extruded and sliced.

Just question from Charles Cunningham, "is the finished product tested for conductivity as part of the release or C of C criteria?" Sierra, another one for you, I guess.

Yeah. So we actually test our material at the batch level, so when we put the particles into the raw batches, we test those for various different criteria conductivity anything that would be listed as a material property on our data sheet.

So we do not test the finished molded gasket we test at the batch level before they're molded. So I had a question come in the chat box. Is it possible to mold from Luis, "is it possible to mold grommets using compression molding, or they only impossible with injection molding?

So there's many ways to mold. And actually, this was another question that came in yesterday, so I'll piggyback on that. So transfer molding typically is used for parts with undercuts or distinct features that may not be able to be done during compression molding, injection molding is also a great way to mold grommets, but we can do most molding, but that's something like I mentioned before, that our engineers will look at the part and they'll basically design that tool around your features on your part. So, yes, there's many ways to mold a grommet.

The next question we have is "what is the typical life cycle of a tool, and who pays for replacements?" So in general, depending on the type of the part and how many parts are being manufactured, the tooling tends to last for a majority, if not the entire life of a part, whether it's made only over the course of a few months or whether it's made over the course of several years. The tools are manufactured for long term durability and make sure that the parts don't and make sure that the tools last the entire life of the program. In general, all when there is tool management or replacement or fixing of the tools required, a lot of the times that will be done in house and covered by commerce.

Okay. Another question again, related to tooling probably, "how does the use of solvent and mold release impact volume reactivity testing?" Maybe one for you, Sierra?

Sure. So solvents, mold release, how does that affect volume resistivity? I think actually, Ben, you might be better at answering this question. But one thing is, when you use solvents on conductive elastomers, depending on what it is like we talked about, with fluid resistance, you can actually swell the gasket and damage the gasket. So we do have ways of using the right solvents. But yeah, maybe, Ben, you can take this one. Yeah, of course.

So when it comes to solvents and mold releases, typically, again, this comes down to us establishing a pretty optimized manufacturing process. So like we've talked about, we've been molding custom and standard gaskets for decades. And I've gotten to the point where we're able to manufacture these parts by using mold release and additives that aren't going to damage the base material, whether it's a silicone Fluorosilicone or an EPDM. And so, really, again, it comes down to we use materials that aren't going to change the physical, thermal, electrical, any of the regulatory properties of the base material when we manufacture it and when it's being shipped.

So, yeah, long story short, there really isn't any negative impact of the manufacturing process on the base materials. And like Sierra mentioned earlier, the properties really come from the base material itself in its raw form, as opposed to no matter what size or shape is manufactured in. Just about all gaskets made out of our CHO-SEAL 1298, for example, are going to have the same electrical and physical properties as expected as we advertise.

Okay. I have one from Steve. "How does compression set impact resistance across an interface?"

So these are silicone floor silicone or EPDM binder filled with tiny little metal particles. So we have a specific compression range to deflect the gasket to get the proper sealing and shielding. So when you over compress a gasket, you can actually crush the little particles. It may take a compression set, it possibly won't bounce back, and then you wouldn't be getting your ceiling or your shielding that you've stepped in and designed in. Conversely, if you under compress a gasket, you're not compressing the little tiny particles and you're not getting the electricity flowing through. So it's really important to make sure that you dial in your compression set per hour published standards and again, best chance of success.

I'm just adding to that a little bit. One of the things we recommend and we go through with our design process is something like known as a stress relaxation process. So when the gasket is first installed, we recommend compressing it and then coming back to it an hour, 2 hours later, and recompressing or retightening the screws or bolts that are holding that gasket in place just so as to make sure you have effective contact between the particles within the gasket and the two bathing surfaces.

And then one of the last questions we have is, "what is the Ul rating for these conductive elastomers?"

In general, several many of our materials have been tested for UL rating and other regulatory properties. They are rated to UL 94 V-0. Of the ones that are tested, that's just something to take a look at when it comes to which material is right for your design. Some of our conductive customers just simply haven't gone through that testing process, but we do have several that should be able to meet those requirements, as well as other electrical, thermal, or physical properties.

We have a question quick one for Adam because he asked to follow on, "how long does rework take?"

More than a couple of days and less than standard lead time, but up to standard lead time, just depending on the complexity.

And then one from Andrew, "how can you ensure the silver plated aluminum particles flow through the part evenly?"

So Andrew, we actually developed CHO-SEAL 1215 back in the '60s. We basically design and develop these materials. We have a lot of different processes. We would invite you to come to our facility and check out our milling and plating process. But it's a tried and true process that we've been doing for 60 years. So we got it nailed down. Also proprietary, I'm sure, methods that we can't talk about.

And with that, we've actually gotten to the end of our questions. So thank you all very much for joining us for this webinar. I did want to add a little bit of a plug for some of the future webinars we have coming up.

As we mentioned in some of the applications here, molded parts are pretty commonly used in connectors, and our next webinar is going to be specifically designed and specifically geared around the connectors and cable space so understanding some of the requirements for high speed connectors, military connectors as well as cable grounding and shielding. So look for that probably around the beginning of June.

Thanks, everybody.

Thank you. Thank you. Bye.