Rubber Milling

Rubber milling can recycle used tires, conveyors, and other rubber products that have outlived their usefulness. Crushed or ground rubber trash can create new products or materials, such as playground flooring, athletic tracks, and insulation.

2. Cost-effective

Instead of disposing of rubber waste in landfills or incinerators, it is more inexpensive to recycle it through milling.

Recycled rubber can be sold or used in industrial processes, removing the requirement for new raw materials and possibly reducing manufacturing costs.

3. Versatility in the Milling Process

The rubber particles produced during milling process can be used for various projects, such as making rubber goods, constructing noise barriers, and paving roads.

They can also be used with other materials like concrete or asphalt to improve specific properties.

4. Environment Benefits

Rubber milling has the potential to minimize the environmental effects of waste disposal, including greenhouse gas emissions, by reducing the amount of rubbish that is disposed of in landfills or incinerators.

5. Energy Savings

Rubber milling can reduce energy consumption by lowering the energy required to produce new rubber products.

Recycled rubber requires less energy to create than new rubber since the milling process needs less energy than producing new rubber materials.

Choosing a Rubber Milling Machine

The following are the factors to be considered when choosing a rubber milling machine:

· Safety Features

The rubber milling machine should be designed to ensure safety to avoid injuries that might be caused to operators. The milling machine must have a start and emergency stop button. Cost

· Type of Rubber

Various rubber compositions require different milling machines. When choosing the milling machine, it is important to consider the type of rubber that needs to be milled.

· Cleaning and Maintenance

It is critical to select a machine that can be easily washed and cleaned and one with easily accessible parts.

· Size of Rubber Particles

When selecting a milling machine, one should consider the size of the rubber pieces desired. Hence, choose one that can mill the rubber into the size of particles one needs.

· Capacity

The milling machine chosen should be able to produce the volume and capacity of rubber needed.

· Cost

The cost of the milling machine must be considered. Choose a relatively affordable machine that can provide value for the money in terms of its output.

· Power and Speed

For the smooth running of the rubber milling process, it is important to consider the speed and power of the machine before purchasing.

The Step-by-step Rubber Milling Process

The rubber milling process consists of four steps, which include:

1. Mastication of Rubber

Mastication and softening is the first step of the rubber milling process in batches. The process is carried out in substantially enclosed mixing machines such as Banbury mixers or rubber mills.

The enclosed mixing machine, in this case, Banbury mixer, is made of backspin paddles inside an hourglass-shaped chamber that can hold up to 1.5 tons of rubber.

While using rubber mills, enormous steel cylinders up to 3 meters long are close to one another and horizontally opposite, rotating steadily in the opposite direction and at slightly different rates.

Rubber is softened and sheared in the paddle-to-wall gap of the enclosed mixing machine and the space between the two cylinders of the roller mill.

2. Mixing Rubber

Mixing rubber is done shortly after softening the rubber, using equipment similarly used in mastication.

Reactive additives, fillers, oils, and protective chemicals are incorporated in the base elastomer by combining shearing and mixing processes.

The enclosed mixing machine may create up to a half-ton of combined materials in a few minutes.

Afterward, the compound is kept in storage until used in steel pallets that can hold up to one ton of rubber after it has been treated with sprayed soap to stop it from adhering.

1. Shaping Rubber

Shaping the rubber mixture can be done in numerous methods. Items like wire coverings, tire treads, and long and continuous tubing can be made using injection molded parts. Injection-molded parts are also employed to create some profiles that cab be lengthened later. Wide sheeting is created using multi-role calendars.

The rubber mixture is pumped into a mold chamber via channels with the desired shape in transfer and injection molds then it is pressure-cured.

2. Curing Rubber

Compacted steel molds heated to the ideal temperatures are then cured. A typical cure lasts for some minutes at 160 °C.

Thick products may need prolonged cure times at moderate temperatures because rubber slowly permeates heat.

Typically, the compound is kept in the desired shape by applying higher pressure or one amplitude.

Once the mixture is molded, it can also be cured by steam treatment in microwaves, autoclaves, a hot bath of molten metal salts, or by running through a fluidized bed. Treatment is administered at almost atmospheric pressure, in case this happens.

How Two Roll Rubber Mill Works

A two-roll rubber mill is used to transform natural rubber into different compounds. To mix the rubber and components used to make the rubber compounds, two horizontally opposed stainless steel rolls revolve in the reverse direction toward one another at various speeds.

Two hollow rollers rotate in opposite directions and are the major functioning components. On the operator side, the component is called the front roller.

It can roll forward and backward manually or electrically to change the roll frequency and conform to the operation’s needs.

The two rollers are normally the same size and rotate at various speeds. The crude glue or glue material is subjected to strong shear to achieve the mixing goal, and the distance between the two rollers is drawn while the roller rotates.

Types of Rubbers for the Milling Process

The rubbers used in the milling process are as follows:

· Natural Rubber

It’s the most typical kind of rubber utilized in rubber milling. Natural rubber offers a well-rounded collection of qualities obtained by lapping rubber trees.

It is water-proof, has a significant usage ratio, high strength, and resilience.

· Neoprene Rubber

For applications like friction belts and engine fluid tubing, neoprene rubber is well known for maintaining its mechanical qualities throughout a wide temperature range.

It is both very chemically stable and corrosion-resistant.

· Butyl Rubber

Because of its versatility and gas impermeability, butyl rubber is well-known. Because of the rarity of this composition in rubber products, it is frequently employed in creating seals, liners, and inner tubes.

· Styrene Butadiene Rubber

It is a synthetic rubber that excels at abrasion resistance. Its toughness, water swell resistance, and set compression suit tough applications.

· Nitrile Rubber

Nitrile rubber is a higher-quality rubber with excellent mechanical integrity and compression set. It can be used in sealing components since it resists chemical deterioration when exposed to machine fluids like gas and oils.

Safety Precautions when Milling Rubber

Safety measures to be followed when milling rubber involves a wide range of activities, including what to avoid and what to do before and during milling rubber.

Before using a milling machine, be sure you comprehend the manual and have received the appropriate training.
Put on the proper safety glasses. Wear additional personal safety gear as required, such as hearing protection and footwear.
Keep tools, materials, and scraps off the work surface.
When the machine is running, please do not leave it unattended.
Keep grease and oil off the area around the milling machine.
Wearing loose clothing, jewelry, watches, or gloves is prohibited. Constrict and tie back long hair.
Stop the machine immediately and notify the supervisor if there are any problems.
Use lifting equipment to transport heavy work from or to milling machines as necessary.
Ensure that the operator can easily access every machine’s start/stop button and that the emergency stop button is on every piece of equipment.

Grinding of Cryogenic Rubber vs. Milling of Cryogenic Rubber

Both cryogenic rubber grinding and cryogenic rubber milling subject the rubber to cryogenic temperatures to reduce its particle size.
Cryogenic rubber grinding is commonly preferred to cryogenic rubber milling because it does not result in the melting of the rubber particles.
Cryogenic rubber milling generates larger rubber particles than cryogenic rubber grinding, which generates smaller rubber particles.
In cryogenic rubber milling, less heat is produced, resulting in no rubber melting, as opposed to cryogenic rubber grinding, which produces more friction and heat, causing rubber particles to melt and clip together.

Limitations of Milling Rubber

The following are the limitations of milling rubber:

1. Contamination Risks

Substances such as metal grit or dirt can contaminate the rubber during milling, changing its original properties for various industrial applications.

2. Dust Generation

Rubber milling produces dust, which can be hazardous to the environment and workers if not handled properly.

3. Sensitivity to Temperature

Rubber is sensitive to temperature; the heat produced during the rubber milling process might interfere with its good original characteristics, thereby making it inefficient for its intended purpose.

4. Equipment Limitations

The final product, in terms of the shape and size of the rubber to be milled, can be greatly affected by the type of milling equipment chosen by the manufacturer.

5. Limited Applications

Because the rubber milling process produces tiny and standard rubber particles, it cannot be used in other applications that require large particles.

Applications of the Rubber Milling Process

The following are the uses of the rubber milling process:

Sports and Recreation – Sports grounds built with recycled rubber from milling include playgrounds, running tracks, and artificial grass.

Consumer Products – Recycled rubber made by milling is used in making carpet padding, floor mats, and soundproofing.

Construction – Rubber milling processes make recycled rubber in construction materials like asphalt, cement, or rubberized coatings.

Transportation – Recycled rubber scraps produced during milling are used to construct roads, bridges, and railroad ties.