Learn how to select thermal insulation for ovens, engine bays, and other high-temperature applications.
General Manager of Elasto Proxy
Thermal insulation is used in high-temperature environments such as ovens and engine compartments. Many different types of materials, including fireproof rubber, are available. Choices include ceramic fiber, fiberglass, mineral fiber, mineral wool, polyurethane, silicone, and various specialty or proprietary materials. As you can see from this list, some thermal insulation is made of polymers. Others, such as metal foils, are not.
Thermal insulation materials come in different forms, too. Choices include boards, blocks, cords, coated fabrics, flexible sheets, foams, paper, and tapes. As a custom fabricator, Elasto Proxy can source thermal protection materials in these and other form factors. We then convert stock items to create specialty thermal insulation that meets all of your application requirements.
For example, using our water jet cutting machine, Elasto Proxy can convert sheets of melamine foam into thermal insulation with specific length and width dimensions. Our skilled production personnel can also convert thin sheets of aluminum foil-faced fiberglass fabric. Sometimes, however, cutting isn’t that all you need. That’s because your application requires more than just thermal insulation.
Learn how the physical properties of rubber effect compound selection.
General Manager at Elasto Proxy
Technical buyers and part designers need to select rubber materials that meet all of their application requirements. Elastomers have inherent physical properties, but these properties can be enhanced through compounding.
During compound selection then, it’s important to understand a rubber’s physical properties and to know how each property is measured. This will help you to ask for and receive the compound that you really need. Physical properties of rubber include:
The following sections provide a high-level look at each physical property. Future articles in this series will examine each property in greater detail.
Elastomers have an inherent hardness because of their chemical structure. This hardness can be modified, and the processed hardness then measured in terms of durometer (duro) on a Shore scale. For soft to medium-hard rubber, Shore A is used. At 40 duro, solid rubber profiles have the consistency of pencil erasers. At 90 duro, they’re hard like hockey pucks. Which hardness do you need?
Tensile strength (TS) is the amount of force that’s required to pull a rubber specimen apart until it breaks. Known also as ultimate tensile strength (UTS), TS is measured in either pounds per square inch (psi) or megapascals according to ASTM D412. For technical buyers and part designers, tensile strength matters because it represents a rubber’s point of failure caused by stretching.
Tensile modulus (TM) sounds similar to tensile strength, but these two properties are not the same. TM is the force or stress that’s required to produce an elongation percentage or strain in a rubber sample. In general, harder rubber has a higher tensile modulus. Such rubber is more resilient, but also more resistant to extrusion, a process for manufacturing stock materials used in custom fabrication.
Elongation is the percentage increase (strain) in the original length of a rubber sample where a tensile force (stress) is applied. Some elastomers stretch more than others. For example, natural rubber (NR) may stretch up to 700% before reaching its ultimate elongation, the moment the NR breaks. By contrast, fluoroelastomers may rupture at 300% elongation. How much do you need your rubber parts to stretch?
Resilience or rebound refers to a rubber’s ability to regain its original shape and size after a temporary deformation, such as contact with a metal surface. Resilience is especially important in dynamic seals, components that create a barrier between moving and stationary surfaces. If your application requires weatherstripping between a door and a door frame, the compound’s resilience is important to consider.
Compression set is the amount by which an elastomer fails to return to its original thickness after a compressive load is released. When a rubber seal is compressed repeatedly over time, progressive stress relaxation occurs. In terms of the seal’s life, stress relaxation is like dying. Compression set is like death itself – the end result of a steady decline in sealing force. How long do you need your seal to last?
Tear resistance describes an elastomer’s resistance to the growth of a nick or cut when tension is applied. Also known as tear strength, this physical property is measured in either pound force per inch (lbf/in) or kilonewtons per meter (kN/m). If you need edge trim that will contact rough metal edges or sharp objects, consider tear resistance during compound selection.
Abrasion resistance describes a rubber’s resistance to being worn away from rubbing or scraping. In industrial applications, abrasion-resistant rubber is used with conveyor belts that move coal and in pumps that handle slurries. Material loss due to abrasion can be measured with various instruments according to tests such as ASTM D394.
Specific gravity is the ratio of the weight of a material to the weight of an equal volume of water at a specified temperature. For chemists, it provides a way to identify compounds. For technical buyers and part designers, it’s important to know that rubber with a low specific gravity offers more square inches per pound of stock. Rubber with a higher specific gravity provides advantages in molding consistency.
How Can We Help You?
Do you have questions about the physical properties of rubber? Contact Elasto Proxy for more information, and enjoy the short video below that accompanies this article.
Learn how to select the right rubber compounds for your seals, gaskets, and insulation.
General Manager at Elasto Proxy
Are you a technical buyer or a product designer? Have you ever heard the saying, “Be careful what you ask for because you just might get it”? If you need seals, gaskets, or insulation, it’s important to ask for more than just “black rubber”. If a supplier provides what you think that you need on the basis of color alone, your rubber parts may not support your product designs.
Yes, the color of a compound can be important. For example, if the color of a rubber gasket needs to match that of a medical assist device, you’ll want to work with a custom fabricator who can source materials from an extruder that uses pantone color matching. But even in this example, the rubber’s color probably isn’t the only consideration. Does the elastomer need to be soft and antimicrobial, too?
Industry and Application
Getting the seals, gaskets, and insulation that you really need involves answering a series of questions. You may think that all you want is “black rubber”, but a custom fabricator who takes the time to listen will analyze all of your requirements. Here at Elasto Proxy, our solutions providers understand that even if you do ask for “black rubber”, there’s probably more to your application. By asking you questions and carefully listening to your answers, we’ll help you to select the right rubber.
For starters, the industry that you serve is important. If you need a door seal for a dump truck, we’ll ask about exposure to cold temperatures and off-road conditions. If you need seat molding for buses or rail cars, we’ll ask if fireproof rubber is what you’re looking for. In the case of an oven seal, our solutions providers will find out if there’s exposure to direct flame. In the case of a hatch seal, we’ll want to know if your application involves contact with chemicals such as gasoline or diesel fuel.
Material Requirements and Compound Ratings
Industry and application are important, but there’s usually more to the story of what you need. What are your other material requirements? Do you need rubber parts that are molded or extruded? Since there are different ways to define an elastomer’s hardness, do you need a rubber seal with a specific Shore A durometer? What about ASTM call-outs? There are over 30 different categories and hundreds of individual ASTM designations, each with an alphanumeric code.
Speaking of standards, do you need to meet regulatory requirements or industry specifications? For example, buyers in the mass transit and rail industries may need to source rubber parts that meet flame, smoke, and toxicity (FST) standards such as SMP 800-C. In both the food and medical equipment industries, there are FDA standards for rubber articles. EMI / RFI shielding for military electronics might need to meet MIL-DTL-83528C requirements for elastomeric shielding gaskets
Fit and finish are important, too. What are your part’s surface finish requirements? The RMA Handbook from the Rubber Manufacturers Association (RMA) contains tolerance tables for molded and extruded rubber, and for both spliced lengths and cut lengths. Does your seal, gasket, or insulation need to meet the requirements of a specific RMA Tolerance Class? Part tolerances may vary depending upon the compound that you select.
“Be careful what you ask for because you just might get it” shouldn’t be a cause for concern when it’s time to select compounds for seals, gaskets, and insulation. Ask Elasto Proxy for what you need, and we’ll make sure that what we provide is what your application really requires. Contact us for more information, and watch this short video to learn more about compound selection.
Learn how ASTM standards help manufacturers to source rubber gaskets, and find out which ASTM specifications buyers and designers need to know.
General Manager at Elasto Proxy
Standards from organizations such as ASTM International help manufacturers to design and develop products that meet established requirements for quality, reliability, and performance. For engineers and technical buyers, these standards can inform decision-making throughout a product’s life cycle. For example, depending on your project’s specifications, you may need to select gasket materials that meet ASTM standards for rubber.
ASTM’s rubber standards are numerous, however. There are over 30 different categories and hundreds of individual designations, each with an alphanumeric code. Buyers and designers don’t need to know every detail, but it helps to know that that there are three broad categories for rubber gaskets: Composite Gaskets, Specifications for Gasket Materials, and Form-In-Place (FIP) gaskets. Let’s look at the first two categories since they apply to gaskets you’d source from a custom fabrication specialist.
Composite gaskets consist of multiple elastomeric materials and may even include metal. Although our focus is on rubber, take a look at the complete list of ASTM standards in this area.
Sealability of Gasket Materials
Sealability of Enveloped Gaskets
Nonmetallic Enveloped Gaskets for Corrosive Service
Thermal Conductivity of Gasket Materials
Metal Layer Gaskets for Transportation Applications
Sealability of Sheet, Composite, and Solid Form-in-Place Gasket Materials
Static Sealing Pressure using Pressure-Indicating Film (PIF) for Transportation
Comparison of Nonmetallic Flat Gaskets in High Pressure Saturated Steam
Some of these ASTM standards describe test methods, design practices, or material classifications. Others offer guidance for evaluating material performance, suitability for transportation applications, or material properties such as thermal conductivity. How would a buyer or designer use these standards? How does working with an experienced custom fabricator support compound selection?
Let’s consider a few some examples. Do you need to source an elastomer with heat transfer properties? Then you may need a gasket material that meets the thermal conductivity requirements of ASTM F433-02(2014)e1. Does your application require minimum liquid leakage under load for a time period of 5 to 30 minutes? Then you may need a gasket material that’s been tested against ASTM F37-06(2013).
Specifications for Gasket Materials
ASTM’s rubber standards also include this gasket-related specification.
Preformed Open-Cell Sponge Rubber Pail and Drum Gaskets
This spec is very specific, of course, but it’s an important one to understand if you need to source open-cell sponge rubber for use in new or reconditioned pails or drums. ASTM F37-06(2013) divides materials into Class A (non-oil resistant) and Class B (oil resistant). In turn, each class contains Grade 1, Grade 2, and Grade 3 designations. Other material specifications also use classes and grades, so all buyers and designers can learn some important lessons about material selection from this ASTM standard.
If your project requires a gasketing material that meets Class B, Grade 1 specifications, then choosing a Class A, Grade 2 elastomer won’t do. Different types of rubber have different material properties, and a rubber that lacks oil resistance is the wrong choice for a gasket that gets splashed with machine oil. But why choose an expensive fluorocarbon or fluorosilicone if a cost-effective neoprene or nitrile will meet your oil-resistance requirements? Sometimes, selecting the right material means striking a balance.
How Can We Help You?
Choosing a custom fabricator who listens to your requirements and understands ASTM specifications can strengthen your supply chain. For over 25 years, Elasto Proxy has been helping partners in a variety of industries solve sealing and insulation challenges. How can we help you? From seal design to compound selection to custom fabrication and delivery, Elasto Proxy is ready to become part of your team.
Contact us to learn more about Elasto Proxy, or watch this short video about ASTM standards for rubber gaskets.
Learn how coated fabrics are made, how Elasto Proxy uses them, and what ice cream can teach us about specialty materials for sealing and insulation.
President of Elasto Proxy
What’s the best way to enjoy an ice cream sundae? Do you add chocolate syrup, or caramel instead? Smuckers, a well-known maker of ice cream toppings, suggests adding their Magic Shell product in any flavor. These sugary syrups are applied as a liquid and solidify into a hard shell. Industrial sealing and insulation doesn’t have much in common with dessert, but picture your ice cream with a distinctive coating. If you do, you’ll understand a bit about coated fabrics.
Industrial Fabrics and Ice Cream Sundaes
Coated fabrics consist of woven or non-woven cloth with a coating or resin that’s either applied to the surface, or saturated into the bulk of the material to impart a desired property. Typically, these fabrics are made of synthetic or elastomeric materials. Just as you can choose vanilla, chocolate, or strawberry ice cream for your sundae, you can select nylon, polyolefin, or polyester materials for your industrial fabric (just to name a few).
Then there’s the topping or coating. How does it work? A polymer or elastomer, usually in a viscous or syrup-like form, is applied to the fabric and then cured to produce a harder or tougher material. Just as you might choose caramel or chocolate syrup for your ice cream topping, you can choose fabric coatings such as polyvinyl chloride (PVC) or urethane. Alone, vanilla ice cream is tasty but plain. With a caramel topping, the taste seems sweeter. It’s similar to how coatings enhance the properties of fabric.
Depending on the coating that you choose, a liquid plastic or liquid rubber may impart resistance to water, chemicals, or ultraviolet (UV) light. Coatings can also help to retard the spread of flames, and provide cut or puncture resistance. Coated fabrics even enhance the performance of other materials that are used for thermal insulation, acoustic insulation, vibration dampening, or abrasion resistance. There’s nothing wrong with plain vanilla ice cream, but an order that calls for a sundae requires more.
Ice Cream Cakes and Composite Materials
At Elasto Proxy, we use coated fabrics to build sandwich-like structures that provide sealing and insulation solutions. In Composite Materials: Lunch Is Served, we considered how specialty seals and custom insulation can be built in layers made of foams, barrier materials, and adhesives. Depending on your application, the use of a coated fabric may be required. Instead of a peanut-butter and jelly sandwich on wheat bread, your composite may be more like an ice cream cake.
Think of it this way. The layer cake (the foam) is topped with an ice cream (fabric) that’s been covered in a caramel shell (the coating). So what happens when it’s your job to prepare such as dessert, but you’re not a cook? Elasto Proxy can recommend the right materials based on your application requirements. Our technical team can also design your coated fabric into a sandwich-like structure, and our skilled production personnel can prepare your solution with precision.
Are you looking for composite materials that can provide superior sealing and insulation? Are you wondering how coated fabrics can strengthen your insulation or seal designs? For over 25 years, Elasto Proxy has worked closely with partners in a variety of industries. Watch the short video below to learn more about how we use coated fabrics, and then contact us when you’re ready to strengthen your supply chain. How can we help you?