The two roll rubber mill is a machine used to process natural rubber into various compounds. Two horizontally opposed stainless steel rolls rotate in opposite directions towards each other at different speeds to mix the rubber and ingredients used to create the rubber compounds.
Natural rubber, which is harvested from a rubber tree, hevea brasiliensis is the base for many rubber compounds made using a two roll rubber mill. Rubber trees are tapped to remove the latex that is stored in their trunks. This material can then be mixed with additional ingredients to create rubber. Other natural sources of rubber are obtained from the Sapotaceae and Palaquium trees native to the Malay peninsula, as well as the Mimusops globoosa tree native to Panama. [1] Synthetic rubbers have also been created and are also used to create rubber compounds. [2]
In the 1830s, Edwin Chaffee developed a technology similar to the two roll rubber mills that are used in rubber production. His machine included multiple rollers that were used to flatten rubber into thin sheets. Chaffee then created the two roll rubber mill which shears and mixes the rubber by having two rolls rotate in opposite directions, at different speeds. The two roll rubber mill is used in almost every rubber production facility today. Many other inventors created rubber mills with varying degrees of similarity to Chaffee's initial designs. [3] George Watkinson patented a three roll design in 1894 while Harold Denmire patented a four roll design in 1932. [4] [5]
To produce the rubber used in tires, hoses, shoes and many other applications, the rubber first has to be created using a two roll rubber mill. A rubber mill consists of two horizontally opposed stainless steel rolls that rotate in opposite directions, at different speeds. The rolls rotate towards each other, one faster than the other. The distance between the two rolls can also be adjusted by the operator. The opposing rotation directions and different speeds produces a combined shear and compression force on the material being mixed on the mill. With open roll rubber mills, the operator may also be in charge of adding ingredients to the rubber while it is being mixed on the mill. Because chemical reactions are occurring during the process of mixing a rubber compound, the compound often heats up. To help keep the rubber compound cool, often one of the rolls is hollow and can be hooked up to a cooling water line which then allows cool water to flow through the roll, cooling the metal roll and therefore the rubber. [2] [6]
While the process of operating a rubber mill sounds simple enough, it is very dangerous and many precautions are added to ensure the safety of the operator. Operators and safety personnel must go through extensive training in order to be certified to operate a rubber mill. Because the two rolls of the mill are rolling inwards, it is easy for an individual's hand to get sucked into the mill. This not only crushes the hand, but if the individual quickly removes their hand, it can result in degloving. Safety features include emergency stop bars located 40” vertically above the rolls, which can be pulled at any time to stop the rolling of the mill. Pressure sensitive body bars are also located at knee height so that the machine can be stopped by the operator tapping the bar with their knee. Protective equipment such as safety glasses are also worn. There is also normally a safety operator, in addition to the main operator that is also trained to use the rubber mill and is trained on what to do in the case of an emergency situation. [7]
Rubber compounding means incorporating rubber ingredients into a rubber mixture so it is evenly dispersed, then the rubber mixture is called a rubber compound. The mill aids in two main steps of rubber processing - mastication and mixing. Mastication is when the raw polymer is sheared and the broken down to create an easier flow. This allows for better incorporation of materials, which leads to the mixing component, when the other materials for a compound are added. [6]
To create a rubber compound on a mill, first a raw polymer, or base polymer, is needed. The polymer can be a number of things, including natural rubber, such as of SMR CV, SMR 20, SMR L or a variety of synthetic rubbers such as nitrile (NBR), ethylene propylene diene monomer (EPDM), butyl, polycholorprene (CR), Polyisoprene (IR) and others.
The raw rubber after being masticated, in which normally for natural rubber, other ingredients needed to be compounded into the raw polymer either on a mixing Banbury Kneader or other rubber mixing machine then pass to two roll mill for dispersion and sheeting out for rubber compound that is suitable for molding dimension. Rubbing compounding also can be mixed on two roll mill by sequentially adding the ingredient and fold, cut and roll the rubber to mix. This process create rubber that can be used to create products.
Ingredients added to make a rubber compound include oils, fillers and accelerator, which usually includes sulfur or peroxide, and may also include a metal oxide either as activator such as zinc oxide, in some cases as filler and also as activator. After mixing, a compound is removed from the mill in a large sheet, and then molded into its desired product. [2]
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation.
Vulcanization is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides.
Flexography is a form of printing process which utilizes a flexible relief plate. It is essentially a modern version of letterpress, evolved with high speed rotary functionality, which can be used for printing on almost any type of substrate, including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging.
Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. Its texture is reminiscent of rubber because of the physical-chemical properties of its polymer, plasticizer, and resin components, which contribute to its elastic-plastic, sticky, chewy characteristics.
A paper machine is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.
A calender is a series of hard pressure rollers used to finish or smooth a sheet of material such as paper, textiles, rubber, or plastics. Calender rolls are also used to form some types of plastic films and to apply coatings. Some calender rolls are heated or cooled as needed. Calenders are sometimes misspelled calendars.
Continuous production is a flow production method used to manufacture, produce, or process materials without interruption. Continuous production is called a continuous process or a continuous flow process because the materials, either dry bulk or fluids that are being processed are continuously in motion, undergoing chemical reactions or subject to mechanical or heat treatment. Continuous processing is contrasted with batch production.
Polybutadiene [butadiene rubber BR] is a synthetic rubber. Polybutadiene rubber is a polymer formed from the polymerization of the monomer 1,3-butadiene. Polybutadiene has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production. Another 25% is used as an additive to improve the toughness of plastics such as polystyrene and acrylonitrile butadiene styrene (ABS). Polybutadiene rubber accounted for about a quarter of total global consumption of synthetic rubbers in 2012. It is also used to manufacture golf balls, various elastic objects and to coat or encapsulate electronic assemblies, offering high electrical resistivity.
Rotational molding involves a heated mold which is filled with a charge or shot weight of material. It is then slowly rotated, causing the softened material to disperse and stick to the walls of the mold forming a hollow part. In order to form an even thickness throughout the part, the mold rotates at all times during the heating phase, and then continues to rotate during the cooling phase to avoid sagging or deformation. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.
Nitrile rubber, also known as nitrile butadiene rubber, NBR, Buna-N, and acrylonitrile butadiene rubber, is a synthetic rubber derived from acrylonitrile (ACN) and butadiene. Trade names include Perbunan, Nipol, Krynac and Europrene. This rubber is unusual in being resistant to oil, fuel, and other chemicals.
Foam rubber refers to rubber that has been manufactured with a foaming agent to create an air-filled matrix structure. Commercial foam rubbers are generally made of synthetic rubber, natural latex or polyurethane. Latex foam rubber, used in mattresses, is well known for its endurance. Polyurethane is a thermosetting polymer that comes from combination of Methyl di-isocyanate and polyethylene and some other chemical additives.
In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness, to make the thickness uniform, and/or to impart a desired mechanical property. The concept is similar to the rolling of dough. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is known as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is known as cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process, and cold rolling processes the most tonnage out of all cold working processes. Roll stands holding pairs of rolls are grouped together into rolling mills that can quickly process metal, typically steel, into products such as structural steel, bar stock, and rails. Most steel mills have rolling mill divisions that convert the semi-finished casting products into finished products.
Pneumatic tires are manufactured according to relatively standardized processes and machinery, in around 455 tire factories in the world. With over 1 billion tires manufactured worldwide annually, the tire industry is a major consumer of natural rubber. Tire factories start with bulk raw materials such as synthetic rubber, carbon black, and chemicals and produce numerous specialized components that are assembled and cured.
Foam latex or latex foam rubber is a lightweight form of latex containing bubbles known as cells, created from liquid latex. The foam is generally created though the Dunlop or Talalay process in which a liquid latex is foamed and then cured in a mold to extract the foam.
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
Pelletizing is the process of compressing or molding a material into the shape of a pellet. A wide range of different materials are pelletized including chemicals, iron ore, animal compound feed, plastics, waste materials, and more. The process is considered an excellent option for the storage and transport of said materials. The technology is widely used in the powder metallurgy engineering and medicine industries.
Rubber Technology is the subject dealing with the transformation of rubbers or elastomers into useful products, such as automobile tires, rubber mats and, exercise rubber stretching bands. The materials includes latex, natural rubber, synthetic rubber and other polymeric materials, such as thermoplastic elastomers. Rubber processed through such methods are components of a wide range of items.
A three roll mill or triple roll mill is a machine that uses shear force created by three horizontally positioned rolls rotating in opposite directions and different speeds relative to each other, in order to mix, refine, disperse, or homogenize viscous materials fed into it.
Thomas Hancock, elder brother of inventor Walter Hancock, was an English self-taught manufacturing engineer who founded the British rubber industry. He invented the masticator, a machine that shredded rubber scraps and which allowed rubber to be recycled after being formed into blocks or sheets. A blue plaque commemoration is placed on No. 4 High Street in Marlborough, Wiltshire in his honour.
A rotary union is a union that allows for rotation of the united parts. It is thus a device that provides a seal between a stationary supply passage and a rotating part to permit the flow of a fluid into and/or out of the rotating part. Fluids typically used with rotary joints and rotating unions include various heat transfer media and fluid power media such as steam, water, thermal oil, hydraulic fluid, and coolants. A rotary union is sometimes referred to as a rotating union, rotary valve, swivel union,rotorseal, rotary couplings, rotary joint, rotating joints, hydraulic coupling, pneumatic rotary union, through bore rotary union, air rotary union, electrical rotary union, or vacuum rotary union
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