compression set

Compression set: permanent deformation at compression

What is the “compression set” or “permanent deformation at compression”, relaxation under stress and viscous sliding or “Creep” in relation to the elastomeric gasket or an antivibration system?

All these concepts are related but different stress/strain and compression measurements are all influenced by temperature and compound formulation.

Here is a brief overview of the compression set, stress relaxation and viscous sliding or “creep” and how each relates to commercially available gasket materials and custom-made vibration dampers and mountings.

What is “compression set”?

The compression set of rubber materials expresses how much a material does NOT regain in thickness after being compressed for a period at a specific temperature.

The sample is first compressed to a certain percentage of its thickness, possibly also subjected to heating, for a certain period of standard time.

Then freed by compression and measured and the test results (e.g., ISO 815 / ASTM D395 / UNI 4913) are expressed as a percentage of lack of initial thickness.

The temperature of the test should be similar or in relation to the conditions of use. The most common are 23°/25°C (ambient), 70°C and 100°C.

The compression set, relaxation under stress and viscous “Creep” are all affected by both temperatures and formulations. A material that has a high compression set at room temperature may have a compression set greater than 70°C.

Having a low compression set (lower percentage of crushing memory) means having greater tightness over time, for example for an O-ring or a gasket. But depending on the applications the needs change.

For static applications where the gasket will not be exposed to significant pressures, such as the gasket of a glass, a light rain compared to pressure washing is a not so critical situation.

However, once the gasket is crushed permanently, it is susceptible to leakage. Door seals for an electrical or control casing are subject to periodic compression and recompression; therefore, the rebound or compressive strength set is important.

What is relaxation under stress?

Stresses in a compressed gasket are generated in response to the clamping load. An easy way to imagine this effect is the return pressure of the gasket. Over time the polymers will relax or push less.

The extent of relaxation depends very much on the polymer and temperature. Imagine crushing a gasket in a vice. Initially it may take for example 100 kg to obtain this 50% deflection, but over time, a possible load cell can indicate 75 kg.

The amount of return pressure will decrease after a certain period. If you expose the rubber to higher temperatures, the value may be lower.

This return pressure is important during sealing because the gasket must push harder than the stresses or pressures exerted by the external environment or from the inside, for example in an electrical box or a hydraulic valve.

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What is “Creep”

Creep refers to the long-term deformation in gaskets or vibration dampers from being under a constant load.

So like imposing a weight resting on a rubber plate, and measure the thickness at constant intervals, after being loaded, for a predetermined time and temperature.

In operation, sliding or “creep” in compressed gaskets or vibration dampers is often controlled with compression limit switches or compression heights set.

In motor vibration dampers, for example, if the motor is coupled with rotation transfer systems (gearboxes, propeller axes or drive shafts), the Creep value is very important to control over time the offset of the motor with respect to external components.

The compression set is the most commonly tested property for elastomeric gaskets/rubber materials. Test data is available in most commercial product data sheets.

It is correct to deduce that the material with a good resistance to the compression set will also have good relaxation properties under stress, however, verification still requires testing.

Understanding how materials deform and bounce is critical to long-term sealing performance. Applying an incorrect gasket can lead to costly damage to equipment in operation.

Even using an anti-vibration device with an incorrectly formulated compound can be detrimental to the engine/transmission coupling system.

In gasket applications, a material with excellent characteristics is generally silicone, thanks to its temperature stability, as well as for fluoroelastomers as long as you formulate and produce the articles with the correct precautions to obtain maximum performance.

At high temperatures, an incorrectly processed fluoroelastomer would be similar to a common oil-resistant rubber. Similarly, silicone would be more sensitive to the compression set.

Even common elastomers can have good characteristics compression sets or creep, it is necessary to formulate the compounds correctly to obtain the best results.

Per ulteriori informazioni sugli elastomeri ad alte prestazioni per applicazioni di guarnizione e ammortizzazione, rivolgetevi a Cavallero Gomma o compilate il form presente sul sito.

Gomma-naturale

Natural rubber: how it is produced and main uses

The main characteristics of natural rubber

Natural rubber is a widely present product in our everyday life. Yet, still today there are many doubts about it: how is it produced and what are its potential? In this regard, the first thing to know is that we have a material produced thanks to the latex of the rubber tree, whose scientific name is Hevea brasiliensis. As the name also implies, we are talking about a type of trees that originally grew only in certain areas of Brazil.

Although it is a plant that prefers the natural habitat of the central Amazon, nowadays various crops with the rubber tree can be found practically all over Southeast Asia. The latter is an area where the climate is particularly favorable for the growth of this plant and which currently covers almost all of the world’s needs.

Natural rubber accounts for approximately 40% of the total amount of rubber used and present in the world. However, synthetic rubber made in suitable industrial complexes is often preferred, since it has lower production costs and a more controllable constancy of characteristics. At the same time, synthetic rubber has properties that natural rubber does not have.

The manufacturing process

As for the rubber processing process, it is useful to know that the latex is collected from the tree thanks to an incision on the bark of the vegetable. The liquid comes out of the tree and begins to drip, thus being collected in special containers. Once the collection has been carried out, the buckets with the latex are taken to collection tanks. Thanks to the reaction due to exposure with acidic reagents, the white liquid coagulates, like milk with rennet.

Once coagulated, the natural rubber is pressed into sheets and transported to special factories where the process of compaction into bales is carried out. Only subsequently, at destination and depending on the needs, the material is specially processed to obtain belts, tires, gaskets, insulating materials and many other products.

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Some curiosities about rubber

In large part, rubber is used to make tires for aircraft, trucks and cars. To produce just one small tire, latex from over four rubber trees is needed (unfortunately) and harvesting, as well as being manual, is long and linked to natural cycles. It is interesting to consider that natural rubber could be produced even in the absence of these trees and using some shrubs and plants but with extremely limited productivity. Some modern studies also by large multinationals foresee the cultivation of these species even at latitudes like ours, with promising results in terms of latex quality, but far from the quantities of sub-tropical regions.


The current plantations of Hevea are very extensive, but they are slowly changing and in some cases getting sick and by their nature they need a lot of attention and it is advisable to plant the trees not very close to each other. In fact, it seems that, if they are too close to a distance, they quickly become more vulnerable to diseases and especially to the attack of an aggressive fungus. The parasitic fungus damages the structure of natural rubber trees and compromises their proper development.

This is also one of the reasons why production in Brazil is struggling to restart as it should. Fortunately, in Asia this fungus is almost completely absent and very strictly controlled, which is why there are no major problems with the growth and use of rubber trees. Even some ornamental plants that we keep at home, such as the “Ficus Elastica” with large and rounded leaves, produce a latex very similar to that of Hevea and in some cases it is also used.

Natural rubber or artificial rubber?

Natural rubber is widely used in the production of food products. It is also used for many other applications, as we said before. However, many times it is preferred to use synthetic rubbers, which have many properties that the natural one cannot guarantee. Artificial materials are great for manufacturing most everyday products.

Many types of synthetic rubbers are used instead of natural rubber for the production of industrial items such as gaskets, sleeves, grommets that will have to resist oil, sea water, intense cold such as ozone or very high temperatures, up to at 250 ° C and above. Operating in this sector, we can say with certainty that in many of these cases the synthetic ones are much more suitable than the natural solution. They guarantee those properties that are needed to make work what they were designed and applied for. Do not hesitate to contact us for more information.

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EPDM rubber and neoprene: technical characteristics, temperatures and properties

EPDM rubber and neoprene: technical characteristics, temperatures and properties

The world of synthetic rubber offers us numerous materials, which boast different characteristics. EPDM rubber and neoprene, which is actually the trademark of the DUPONT company of the “POLYCLOROPRENE” polymer, are part of these elements and present themselves as excellent solutions for different uses. (The name “NEOPRENE has become so common that even among technicians, to” save time “we talk about neoprene and not polychloroprene)
The first rubber is made up of ethylene and propylene copolymers, and a diene monomer, the components of the material that also give life to the acronym EPDM. It is a product that has the very interesting characteristic of resisting aging in an excellent way from atmospheric agents. What therefore makes it the material of choice, for example, for the production of car door seals.
EPDM rubber is very different from neoprene. The latter is also an elastomer, which however is produced thanks to the polymerization reaction of 2-chlorine 1.3-butadiene. It has a very particular composition and smell, which has come into common use for years: it is in fact one of the bases for the production of “Bostik” type glues. Let’s go into detail and see what there is to know about these two types of tires.

Two versatile, functional and highly appreciated materials

Those who know EPDM rubber know perfectly well that this material boasts excellent resistance to atmospheric agents and heat, usually ensuring a working temperature from -50 ° C to + 150 ° C. It is also very resistant to steam, action and contact with ozone and atmospheric agents. It also offers interesting electrical insulation properties and a fair resistance to alkaline substances, diluted acids and polar solvents. On the contrary, it is very sensitive to oils and fats and in general to all apolar and waxy substances.


This rubber also ensures excellent mechanical and dielectric properties, good resistance to abrasion, permanent deformation and UV radiation. Neoprene, on the other hand, is, depending on the formulation, flexible and resistant and is excellent for applications with sea water and exposed to atmospheric agents in general. It offers good thermal insulation and excellently resists numerous chemical agents and petroleum derivatives. This elastomer ensures a working temperature from -20 ° C to + 110 ° C. Its most famous application, in the form of foam material, thanks to its resistance to sea water, is for the production of diving suits.

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How are these synthetic rubbers used?

Due to their characteristics, EPDM rubber and neoprene are used for the production of numerous products. The first is mainly used as an insulating material. It is excellent, for example, for joining electrical cables and for creating layers of insulation and waterproofing on roofs. It is also used for the production of geo membranes and thermoplastic and mechanical products.

This material can be combined with other substances, in particular with polyurethane binders, and be used in the building sector, especially for the creation of non-slip surfaces.

Neoprene is often used in the chemical and automotive industries. It is also used in the marine industry and for the production of protective coatings and clothing. It is a material with very low breathability, a property that makes it a protagonist in the production of diving suits.

Industrial gaskets in EPDM rubber and neoprene

In addition to the aforementioned uses, it is important to consider that both materials lend themselves well to the realization of a wide range of industrial applications. Therefore, they allow you to produce excellent technical articles, some simpler and others more elaborate. In particular, EPDM rubber and neoprene are used for the production of industrial gaskets. This is because they are very elastic, flexible and resistant to high and low temperatures. They are very versatile and withstand wear and the action of many chemical agents well.


We at Cavallero Gomma are specialized in the production of industrial items and we know very well EPDM rubber and neoprene. Therefore, we put ourselves at your disposal and at the service of your company, proposing the creation of customized, functional, reliable and long-lasting products. You tell us your idea and your goals, and we show you the best solutions. Do not hesitate to contact us for more information.

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History of rubber: from its origins to today

Let’s go back in time with the history of rubber

Knowing the history of rubber is interesting, precisely because it is a very present element in our daily life. We take this material almost for granted, but the truth is that we are faced with the fruit of so much research and numerous technological discoveries. Have you ever wondered what its origin and history are up to the present day?


The history of natural rubber begins at the time of the Conquistadores. These well-known historical figures noticed the indigenous use of rubber to waterproof various artifacts. But from the end of 1500 to the end of 1700 this material, also due to its scarce availability, was not used. What else should you know on the subject?

Many important discoveries

The history of rubber continued to move forward slowly and became known in Anglo-Saxon countries for its first use, as it was ideal for “erasing” if rubbed, hence the name “RUBBER” from the root “to Rub” which means to rub.


After several discoveries, the first factory of this material was opened. This happened in 1803 in Paris. A further step forward was subsequently taken by the Scottish Charles Macintosh who, a few years after the opening of the facility, discovered that benzene could prove to be an excellent solvent for rubber.


Its use was in fact delayed by the problem of being able to dissolve and use it more easily. In any case, even after melting it remained sticky and for this reason it was interposed between two layers of fabric.


Some time later, Thomas Hancock started making raincoats and later began using this natural product for making gloves, socks and other clothing. From that moment on, the history of rubber saw numerous evolutions and this material began to be used for many different uses.


A very important stage in its diffusion is with Charles Goodyear. This man invented about the vulcanization process in 1839, through the use of sulfur. He discovered that thanks to it, the rubber lost its stickiness and did not undergo mutations as the external temperatures changed. It also had a different mechanical stability.

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The use of rubber, from the past to the present day

After the discovery of vulcanization, rubber became the protagonist of an unstoppable development process in many different production sectors. For example, in 1955 in the UK, it was mixed with bitumen for the first time. This compound was used to cover the roads and make them more easily passable. Also in the 1950s, the history of rubber tells us that new uses for this material began to be studied, especially in the construction sector.


As an example of the resistance of natural rubber, a few years ago in London a bridge over the Thames built in the late 1800s was dismantled, which had natural rubber supports. These supports were analyzed and it was discovered that only the layer immediately on the surface was altered (after over a century) while almost all of the piece was still intact and fully functional.

For many years, in order to optimize metropolitan railway networks all over the world, rubber has been used for the production of cushioning pads.

Not just natural rubber

Today, the history of rubber continues to be written in step with a very flourishing industry and always at the center of great news and discoveries. Thanks to modern technology, currently different compounds can be created, useful for producing synthetic rubbers of various kinds.


With these materials it is possible to obtain very resistant, long-lasting and functional products, able to satisfy any need in different areas. Synthetic rubber is used to produce products for daily use and in the construction field. It is also very useful for the transport sector and the automotive industry.


There have been many attempts to replace them, even with very modern thermoplastic materials, which have excellent properties and are elastic. But unfortunately with the temperature and the friction the thermoplastics degrade quickly and lose their characteristics and all that remains is to use the “old rubber”.


To date, the history of rubber even crosses with biotechnology and the aerospace industry. This material is an integral part of the daily activities of many companies and industries. At Cavallero Gomma, for example, we use it to produce high quality industrial items. Discover our solutions as soon as possible!

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Types of tires: properties and differences


Many types of tires, for all tastes and needs

There are different types of tires and each of them boasts distinct properties and characteristics. These differences mean that one product is good for one use and another is better suited for other purposes.


The first distinction to be made in this case is the following: to date there are two main types of rubbers available, natural and synthetic ones. The latter are then divided into groups which include materials with similar characteristics, in particular in terms of chemical composition. Let’s go into detail and find out what you should know about the best known and used solutions in the different sectors for the production of various items.

Natural rubbers

As anticipated, between the two main types of tires currently available to industries, we find the natural one. It is a completely vegetable product, which is obtained mainly from the latex of the Hevea brasiliensis tree. This latex is treated and undergoes numerous processes, until it becomes the rubber we know.
This material is very performing from a mechanical point of view. However, it also appears as a very fragile product when in contact with some chemical elements and when exposed to too high temperatures. It is also heavily affected by thermal excursions, which greatly affect the seal of natural rubber. Precisely for these reasons, other types of tires have been developed, able to guarantee what this product cannot offer.

The types of synthetic rubber

When we talk about synthetic rubbers we refer to products that obviously have been created through the combination of different materials and substances. The base from which we start is that of hydrocarbon, which is produced through the processing of an artificial latex. Subsequently, thanks to the addition of other elements, many types of tires can be made. Each of them is created through a different mix of components and materials. Therefore, they are different products with different properties.


These synthetic materials are very resistant. They do not undergo variations in the face of changes in temperature and offer an elasticity that allows them to be used successfully in many sectors of industry. The types of synthetic rubbers are divided into five different product groups, classified by a different letter: M, O, Q, R and U. Group O, for example, contains synthetic latex and oxygen. The tires that fall into the U group are instead made with a mix of synthetic latex, nitrogen, carbon and oxygen.

Types of tires: which is the best?

If you are wondering which type of rubber is better than the others, you will hardly find a single answer. In fact, there are no more performing types of tires: simply, each one is more suitable for a different use. For example, natural rubber is used for the creation of mechanically performing products and for food products and in contact with the skin. Synthetic ones, on the other hand, are exploited for the production of most of the products of daily and industrial use, in the presence of conditions that make natural rubber unusable or inadvisable.


Silicone rubbers, of synthetic origin, are used for the creation of VERY heat-resistant items, such as gaskets for ovens or in machinery with hot working for glass, for example, or for kitchen tools.
Many types of synthetic rubbers are used for the production of industrial items such as gaskets, sleeves, bellows, rings and suction cups. You will find some examples of these uses directly on our website. Do not hesitate to contact us for more information.

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The properties of oil-resistant black NBR rubber

The main characteristics of oil-resistant black NBR rubber

The oil-resistant black NBR rubber is one of the most used solutions on an industrial level. Therefore, it is a highly sought after and appreciated product. This happens because it is a material that does what it promises, proving to be a great help for those who work in certain contexts, productive and otherwise. To know its properties, it is useful to start from the assumption that currently there are two types of rubbers on the market: there are natural ones and also synthetic ones.

The natural ones are made by coagulating the latex obtained from the Hevea brasiliensis plant and other tropical plant species. After careful processing, we arrive at the production of a material with excellent mechanical characteristics. On the other hand, however, it is not very resistant to atmospheric agents, various chemicals, high temperatures and has poor resistance to oils. After contact and / or immersion, the oil penetrates into the polymer matrix and partly dissolves it, partly swells it. The object therefore loses its characteristics.

To make up for these shortcomings, synthetic rubbers have been developed and NBR rubber is one of them. Also known as nitrile rubber, it is resistant to oils and fuels and has good mechanical properties.

Synthetic rubbers and their characteristics

Synthetic rubbers can therefore withstand atmospheric agents, high temperatures and numerous chemical compounds. To produce them, we start with the processing of simple hydrocarbons and the polymerization of some artificial latexes. After the execution of specific production processes, different types of rubbers are obtained, such as the oil-resistant black NBR rubber. These materials have many properties in common, such as those listed above, but also different mechanical and chemical characteristics.

Synthetic rubbers have been divided into five groups called M, O, Q, R and U, which differ from each other based on the composition of the polymers present in the rubber itself. NBR rubber is part of the R group, which includes products composed of polymers containing unsaturated carbon. Generally, this material ensures a maximum operating temperature of 100 ° C, while the minimum is -20 ° C. It boasts good machinability in terms of milling, cutting and drilling.


As anticipated, the oil-resistant black NBR rubber is resistant to oils, animal fats and minerals. For all these reasons, it is suitable for industrial use, especially in contexts where various types of oils and fats are used.


What else is there to know about oil-resistant black NBR rubber?


It is important to consider that this type of rubber is mainly used indoors or in any case protected from UV rays. It is usually sold in sheets and packaged in sectionable rolls. Thanks to its particular characteristics, the oil-resistant NBR rubber is used for the production of industrial gaskets. It presents itself as the ideal solution for numerous production contexts and is the right supplement for those who want to optimize the performance of their plants and machinery.

Precisely for these reasons, we at Cavallero Gomma know it well and use it for many of our creations. Among the numerous processes carried out within our facility, we perform the shearing of the rubber through the use of traditional or latest generation tools. Our experience and our equipment allow us every time to offer an extremely functional and excellently finished product.


Do not hesitate to ask us for more information on oil-resistant black NBR rubber and our production of industrial rubber items. We will offer you customized solutions tailored to your production activity.