Introduction

Rubber is one of the most used raw materials across different industries. Both natural and synthetic rubber is used extensively to make everything starting from the tiniest of home goods to massive structures used in industries. There are different types of rubber molding used in producing rubber components, and the features of the product would depend on the manufacturing process and the type of molding chosen.

Did you know that India is the fourth largest consumer of rubber? According to sources, the per capita consumption of rubber is 1.2 kg. The Indian Rubber Industry states that rubber manufacturing companies in the country produce more than 35,000 different rubber products. All these products use one of the below molding types to be manufactured.

Here are the three most popular types of rubber molding used by industries to create rubber components and products.

Rubber Injection Molding

Rubber injection molding is probably the most straightforward and commonly used type of rubber molding chosen by manufacturers across the world. As the name specifies, this type involves injecting a rubber compound into a mold and keeping the mold under high pressure for the component to get shape.

There are four sub-components of rubber injection molding.

1. Organic rubber injection

Organic rubber injection starts with prepping the rubber component by stripping and mixing it before feeding it into the screw. As a result, there is no need to preheat the rubber and the completion type reduces too.

2. LSR injection

Liquid Silicone Rubber (LSR) injection is a type of liquid injection method used specifically for silicone rubber. Parts of liquid silicone are sent into the injection unit. This is cured and injected into the mold.

3. Thermoplastic rubber injection

Thermoplastic rubber injection is a process of using thermoplastic elastomers, also known as TPEs, to create molded components in. This type of rubber molding process needs high temperatures to work and that is one challenge in using TPEs. However, with TPEs, the manufacturer can avoid the initial tasks of mixing and vulcanizing.

4. Custom rubber injection molding

This is a completely customized process where the manufacturer decides every single aspect of injection molding, starting from the raw material used, the injection molding process, and the temperature and pressure decided based on customer requirements.

Advantages of rubber injection molding

• Lower costs – injection molding is usually cheaper to achieve, and that makes it a preferred type of rubber molding.
• Easier process – rubber injection molding is a straightforward process that does not involve many complicated steps, and this is also an advantage of using this over other types of rubber molding.
• Better precision – in case smaller and more intricate parts are to be produced, the best choice in the list of different types of rubber molding is rubber injection.

Disadvantages of rubber injection molding

• Higher setup costs – while the cost of producing rubber components is lower for rubber injection molding when it comes to the setup costs, this involves more initial expenses. The cost of the production machinery is higher too.
• Generation of waste – the process of producing rubber using this type of rubber molding generates more amounts of waste that can be avoided when other types of molding processes are used.

1. Compression Molding

Compressing molding is also one of the popular types of rubber molding used in creating rubber components across different industries. As the name suggests, this process uses compression to create the structures.

Preheated materials are poured into the mold or cavity, and the mold is then closed and compressed at a certain temperature and pressure. Usually, hydraulic pressure is used to achieve the effect.

The compression is applied for a specified period of time, and then the formed structure is removed.

A compression unit usually consists of the following parts.

1. A movable top half of the mold
2. A fixed bottom half of the mold
3. An ejector pin to remove the finished product

Advantages of compression molding

• Low initial setup cost – the initial cost of setting up is quite low, compared to other types of rubber molding.
• Works for low-volume production – the cost of production does not increase, even for low-volume outputs.
• Works best for large components – large components can be easily produced using this method.

Disadvantages of compression molding

• Low dimensional tolerance – this type of rubber molding does not work well for components that are small and intricate. Precision molding may be needed for certain components where even the smallest of shape changes may be detrimental. In that case, compression molding cannot be chosen.
• High wastage production – there is high wastage produced with the production process.
• High production time – the time taken to produce components is high, as there is a considerable waiting time after compression.

2. Transfer Molding

Transfer molding is another of the popular types of rubber molding that produces rubber components of different types. There are two major halves of the mold. The upper half has a cavity where the raw material needs to be placed.

The upper half comes with a plunger that can be used to push the raw material through a narrow cavity.

The raw material goes to the heated mold through this cavity and takes shape. Once the product cools down and is vulcanized, it can be extracted through the bottom half by removing the ejector pins.

Advantages of transfer molding

• High dimensional tolerance – as long as the mold is shaped right, the final product can be designed to have high dimensional tolerance.
• Metal-rubber bonding – this technique can be used to create precise and high-quality metal rubber bonding designs.
• Easy molding process – the overall process of molding is straightforward and easy, saving time and effort.

Disadvantages of transfer molding

• High initial costs – the initial setup costs for this type of rubber molding are pretty high.
• Additional finishing processes – the final product must go through additional deflashing techniques to be completed.
• Additional prepping time – the raw material needs to be cured for a specific amount of time before it can be molded. This increases the overall cycle time of production.

3. Rubber Molding with Arvico Rubber

Arvico Rubber is your favorite rubber component manufacturer, and we specialize in using all these three types of rubber molding to create components based on your specifications.

Arvico Rubber comes with 55+ years of experience in this industry, and some of the components we specialize in are gaskets, diaphragms, seals and sleeves, expansion joints, O-Rings, and bearing bushes.

We understand how important dimensional tolerance and quality are to our clients, and that is why we always have prep meetings to understand the requirements completely before accepting projects.

Our design team can produce molds with 100% precision, and all finished products go through multiple levels of quality testing before reaching our clients.

Whatever type of rubber molding you want for your components, we get that done in the quickest possible time. Please get in touch with our expert consulting team to know how we can help improve the quality of your manufacturing process with our components.

The tensile strength of rubber is a very important factor that determines the quality of the polymer chosen. Tensile strength tests are also part of quality checks to determine whether a finished polymer product is of expected quality.

Tensile strength determines how much load rubber can handle before breaking up or getting damaged. As someone using rubber components, you should be aware of the tensile strength of rubber to ensure your machinery or part works according to specifications.

What is Tensile Strength?

By definition, it is the maximum force that a material can handle (rubber, in this case) before it breaks down. The unit of tensile strength is pounds per square inch (psi). The tensile strength can also be denoted as Mpa (Megapascals).

Different types of rubber have different kinds of tensile strengths, and manufacturers may be asked to choose the type of rubber depending on the strength they need.

Why know the Rubber Tensile Strength? 

Rubber is a flexible and moldable material. When you keep putting pressure on the material, after a point in time, the fibers of the material will break, causing damage. Knowing the tensile strength of rubber will help in knowing the exact point at which this breakdown will occur.

There are three basic types.

1. Yield strength – This is the maximum force the rubber can handle without going through permanent deformation. For instance, when a rubber band is stretched to a particular point and left free, it returns back to its original shape. That’s the yield strength.
2. Ultimate strength – This is the tensile strength of rubber very close to the breakdown point. Any force beyond this may cause breakage of the material.
3. Breakdown strength – This force will cause permanent deformation or damage to the rubber material.

How Does Tensile Impact Product Performance?

Multiple rubber components like valves, seals, and diaphragms may be used in machinery. These components play several roles, including sealing, friction reduction, leakage protection, or vibration suppression.

One inferior quality rubber seal with low strength may cause hazardous leakages and harm people and property in a matter of seconds. A low-strength valve may get damaged and break down when there is an inflow of erosive fluids, leading to productivity loss.

Let’s consider a simple rubber valve fitted in tires to control air pressure. The valve must handle the internal air pressure for it to work for long. Air valves with low strength may need to be replaced more often, bringing down the quality of the product.

Finding the Tensile Strength of Rubber

Two common test methods are used in finding the tensile strength of rubber.

1. Dumbbell cut-out method – In this method, a small piece of the sample rubber is cut into the shape of a dumbbell. The cut-out should be between the thicknesses of 1.3 mm and 3.3 mm. The sample will now be stretched until it breaks. The force applied and the elongation shape will be noted down, and the tensile strength will be calculated.
2. Ring cut-out method – This method is similar to the first method except that the sample will be in the form of thin rings. These rings would be stretched, and the force applied and elongation shape will be noted to calculate the tensile strength.

How Does the Rubber Strength Vary Between Different Types of Rubber?

The physical properties of different types of rubber change their tensile strengths too. The polymer chains and the crosslinks that make up a material decide how strong the final rubber will be.

Synthetic rubber can be created using a mix of different polymers and additives to make them exceptionally strong and of high tensile strength of rubber.

The following are the tensile strengths of different types of rubber, as marked by Arvico Rubber experts.

As you can see, PTFE rubber (Polytetrafluoroethylene rubber) is the strongest in terms of tensile value. Natural rubber also has a good tensile strength of 22. Materials like silicone, Viton, and nitrile fall under the bottom three in terms of tensile strength.

How to Change the Strength of Rubber?

Naturally, different types of rubber come with different tensile strengths. However, you can change the tensile strength of a particular polymer by mixing in different fillers with different chemical properties to the polymer while producing it.

Do remember that the tensile strength change with different scenarios. While in normal state, natural rubber has a higher tensile strength than silicone rubber, when these materials are heated, the tensile strength gap reduces between these two types of polymers.

How to Test the Tensile Strength of an Existing Rubber Component?

Let’s say you ordered a million pieces of rubber valves, and the rubber component manufacturer gave you some samples to check out.

It is important for your team to find the tensile strength of rubber used in making the component before giving the go-ahead for the rest of the component manufacturing.

The easiest way to do this is to use either the dumbbell cut-out test or the ring cut-out test. A small part of the component can be cut or molded into either of these shapes, and the tensile test can be conducted.

If possible, ask the manufacturer for a raw piece of the polymer to conduct the test, which may give more accurate results. It is always recommended to get the tensile test done and not depend on the values that the manufacturer mention, especially when the order is large.

Takeaways

Knowing the strength of the rubber used in creating your components will help you use the component in an effective manner. While higher tensile strength is usually considered beneficial, you need to remember that polymers with high tensile strength may have other limitations, like a high oxidation rate or being erosion-prone.

We at Arvico Rubber start all client discussions with a clear mention of all essential features of the polymer of choice, including its tensile strength. We can also help clients choose the right polymer from the different types of rubber materials that we offer, depending on their component usage and specifications.

If you would like to know more about tensile strength of rubber and other component offerings and our success stories, please get in touch with us at info@arvicorubber.com. You can also check our expansive product portfolio online and place orders for custom-engineering products of different specifications.

Many industries prefer vulcanised rubber over traditionally processed rubber because the former is stronger, more durable, and can handle extreme temperatures much better. Vulcanisation is a relatively new process and has existed for only a few centuries.

This blog will take you through the basics of vulcanised rubber, its history, uses, types, and other useful information that will help.

What is vulcanised rubber?

Vulcanisation is a process of hardening rubber. There are two kinds of rubbers commonly used – natural and synthetic. About 70% of all rubbers used these days are synthetic. These rubbers are created using various techniques and with different additives in rubber industries, depending on what features the final product needs to have.

In their initial stages, synthetic and natural rubbers can be very sticky and with low tensile strength and may not be useful at extreme temperatures or pressures. That’s why such rubbers go through vulcanisation to improve their beneficial properties and make them durable. 

A brief history of vulcanised rubber

During the 1800s, the number of vehicles produced started slowly increasing all over the world. In really hot countries, there was one problem, though. The rubber in the tires got heated up on the road and would stick to the road and burst off after a while.

Rubber manufacturers were trying all kinds of ways to improve the life of tires, and this is when Charles Goodyear, a chemist, tried adding different chemicals to rubber and heating it to see if the physical properties changed.

It tool him a while to realize that the heating process was making beneficial changes and not the chemicals added. Over time, he created a process of adding sulfur and heating rubber to make it durable and hard.

This process was patented and was called vulcanisation. Vulcanised rubber handled high temperatures easily and was flexible, hard, and extremely durable. Right now, all rubber tires are vulcanised to improve their shelf life.

Where are vulcanised rubber used?

There are so many uses of vulcanised rubber in industries and everyday life. Some of the popular uses are mentioned below.

Did you know that about one billion tires are produced worldwide every year? Vulcanised rubber is in great demand throughout the year and will continue to be used for various purposes over the years.

Do also read our blog on rubber deterioration to understand how to prevent the failure of rubber parts.

Stages of vulcanisation

There are three basic stages in creating vulcanised rubber.

1. Induction stage
2. Curing stage
3. Optimum stage

Induction stage – This is the first stage of creating vulcanised rubber. Here, the right rubber material is chosen, and in many cases, it is shaped before it gets heated. This is because once the rubber heats and hardens, it may be impossible to shape. This stage is also called the scorching stage. The heating happens gradually, and the cross-linking begins.

Curing stage – In this stage, the rubber gets heated to up to 400 degrees Fahrenheit. At this temperature, permanent cross-links are formed, and the vulcanised rubber slowly forms.

Optimum stage – In the optimum stage, the heating process is finished, and the rubber is let to get back to its new, finished state. Beyond the optimum stage, if the rubber remains hot and keeps changing properties, it is called the over-curing stage. 

The number of crosslinks formed depends on how long the rubber was cured, the curing material used, the time given for the rubber to reach the optimum stage, and the natural properties of the type of rubber used.

The science behind vulcanised rubber

Natual rubber and SBR rubber vulcanisation

The science behind sulfur vulcanisation is based on cross-linking action. Sulfur vulcanisation is popularly applied to natural rubber and styrene-butadiene rubber (SBR). These types of rubber are first heated, and sulfur is added to them.

When the rubber is heated, some of the C-H bonds in the material are replaced by sulfur atom chains. This is called crosslinking. The more crosslinking that happens, the more changes the rubber material goes through.

Sulfur cross-linking gives the material strength, durability, and heat resistance.

Polychloroprene vulcanisation

Neoprene or polychloroprene is a type of rubber that also has several beneficial properties and hence is often vulcanised. The vulcanised rubber, in this case, comes with both the natural benefits of neoprene rubber and the strength of the vulcanisation process.

In this process, neoprene rubber is heated along with metal oxides like Zinc oxide, Magnesium oxide, and lead oxide.

What are the other additives added to vulcanised rubber?

Apart from the curing materials like sulfur or metal oxides, the following are other additives added to vulcanised rubber.

1. Accelerators that quicken the vulcanisation properties like guanidines, xanthates, thiazoles, thiurams, and dithiocarbamates
2. Anti-oxidants like phenolics, amines, and phosphites
3. Coagulants like calcium chlorides and acetic acids
4. Softeners, if needed
5. Dyes or color pigments
6. Surfactants
7. Anti-foaming agents

Benefits of vulcanised rubber

The following are some of the benefits of vulcanised rubber.

1. High resistance to temperature changes
2.  Is not affected by heat
3. Very durable and long-lasting
4. Returns to original shape quickly
5. Good insulator
6. Resistant to oxidation and UV damage
7. Resistant to abrasion

Conclusion

Vulcanised rubber is one of the most versatile materials ever found, and there have been so many industries benefit from it. vulcanization makes rubber stronger, more flexible, and extremely heat resistant.

Just like any other product, the way vulcanised rubber is made reflects in its rubber quality. So make sure you pick the right manufacturer.

If you think your rubber components don’t last as long and as well as they used to, then maybe vulcanised components are what you need.

Arvico Rubber can help you choose the suitable rubber material to create components in, so their physical features can handle the internal and external factors they come in contact with. With an in-house designing team and a state-of-art manufacturing facility, we ensure the components we manufacture are precise and 100% adherent to expectations.

Rubber extrusion is the process of turning rubber into a product with a specific and intended shape and size. Depending on the end shape, different rubber extrusion profiles can be available. Arvico Rubber has many standard extrusion profiles for commonly used products and also has an in-house team to customize the profiles based on exact customer requirements.

This blog will take you through different kinds of rubber extrusion profiles, their production process, use, and benefits.

How Does Rubber Extrusion Work?

Extrusion is the process of forming a shape by pushing a material through a predesigned mold. Rubber extrusion profiles have an easy and straight forward working mechanism.

The rubber manufacturer has an extruder machine, and the specific profile-shaped die or mold is fitted in. A rubber compound is now chosen. The compound is the base material in which the profile needs to be made in.

You can create rubber extrusion profiles in any of the following rubber compounds, including the ones below.

1. Silicone
2. EDPM
3. Neoprene
4. Nitrile rubber
5. Viton
6. Butyl

Silicone extrusion profiles are very popular among our clients because of the various beneficial physical properties of silicone rubber. Silicone profiles come with the following features.

One of the main parts of an extruder that leads to 100% of design specifications being met is the die or mold. This can be made of steel or other durable materials. When the die is designed to match client requirements 100%, the end product will have the right design too.

Not many rubber manufacturing companies have the capacity to create complex rubber extrusion profiles because their die-manufacturing capacities are limited. Arvico Rubber is different, though! We understand how vital precision is in creating these rubber extrusion profiles; that is why our design team is one of the best in the country.

Every customized extrusion profile will go through multiple levels of sample testing and quality testing before full-fledged manufacturing starts. As a result, you don’t have to worry about the parts not meeting your exact needs.

All products that we manufacture go through the below range of extensive quality testing before they are sent to the customers.

What are the Advantages of Rubber Extrusion, Rubber Extruded Products and Rubber Extrusion Profiles ?

The following are some of the advantages of rubber extrusion profiles and products made using rubber extrusion.

1. An economical way to produce rubber components.
2. Wastage is minimal in this production process.
3. It is easy to customize any type of profile by just making the appropriate die cast.
4. It is possible to automate production and create multiple pieces of rubber extrusion profiles one after the other.
5. Depending on the type of rubber used, these profiles can be resistant to aging and other external factors and be flexible and robust.
6. Rubber extrusion profiles can be created to exactly match sizing and dimension requirements. You don’t have to worry about ill fits.

What are the Common Profiles of Rubber Extruded Products?

There can be so many profiles of rubber extrusion profiles that can be created. The sky is the limit when it comes to design choices. However, the following are some of the common profiles you can see being offered by rubber manufacturers.

1. Round profiles
2. Semi-round profiles
3. Square profiles
4. Rectangle profiles
5. U channel profiles
6. D, E, J, L, P, or T-shaped profiles

Extruded Rubber Seals

When we talk about extruded products, one category that we cannot miss is extruded rubber seals. Rubber seals play an essential role in almost all industries. This humble item can save expensive equipment, quicken certain manufacturing steps, and sometimes even save the plant and people in it from hazardous leakages.

As the name specifies, seals seal surfaces so that there is no leakage in the rubber expansion joints. Seals can prevent solid, liquid, and gaseous leakages effectively. Depending on what kind of product flows through pipes, the right kind of rubber seals must be chosen.

Arvico Rubber’s rubber seals are commonly used in our butterfly valves, and these offer perfect sealing in three areas – pipe sealing, flanges, and operating shafts. 

Get in touch with our experts about your exact requirements and they will be able to suggest the type of rubber material to be chosen for making the seals.

Rubber Extrusion Profile Applications

Rubber extrusion profiles can be used for so many applications, including the following.

1. Door seals
2. Window seals
3. Angle grips
4. Silicone extrusion profile tubes
5. Rubber buffers
6. Edge protectors
7. Rubber seals
8. Expansion seals
9. Sponge cords
10. Cable protectors

How to Choose the Right Rubber Extrusion Profiles

Let’s say you have a requirement to create seals for one of your parts. The first thing for you to do is talk to a rubber component manufacturer like Arvico Rubber to understand what kind of seals may suit your need.

Our team will get all the basic information right from you before we work internally on the recommendations. The details required may include what kind of part requires the seals, if the seal would come in contact with materials that flow through the parts, what size the part and the sealing joint would be, and what external factors would affect the seal during functioning.

Based on all this, our team would come up with recommendations. You may be advised to pick up silicone extrusion profiles if we think the seal needs to be resistant to oxidation, UV rays, temperature changes, acids, and sunlight, apart from being flexible but lightweight.

We may advise you to pick up nitrile extrusion seals if they come in contact with oils or gasoline. Our recommendation would also be based on other factors like budget too.

Our plant has the ability to produce 100% precise rubber extrusion profiles in whatever shape you require. We make sure even the most complex of designs are done with expertise, and all products are quality checked in multiple stages before they reach you.

Conclusion

Rubber extrusion profiles have made the production of precise and quality rubber components easy, hassle-free, and affordable too. The fact that this rubber extrusion process does not lead to excessive wastage is something environmentally-conscious manufacturers love about it.

Arvico Rubber is your perfect partner for producing rubber seals, valves, gaskets, diaphragms, expansion joints, O-rings, and extruded rubber profiles and cords with any specifications you need. We also manufacture other kinds of rubber components needed across various industries.