Epidor SRT uses state-of-the-art technology for the machining of parts from elastomer dollas, sheets or “raw” raw material.
The basic polymer of an elastomeric compound is rubber, produced from natural or synthetically manufactured latex. Currently, more than 32 synthetic elastomers or rubbers are known. The initial step is the design of the elastomer formulation to which we demand certain properties such as hardness, color, degree of chemical resistance or remaining deformation, among others.
If required by the formulation, both rollers can be heated to the desired temperature.and maintain a temperature set point. After a certain time has elapsed, theThe mixing operation is completed and the desired formulation is obtained. This formulation, which does not yet have the elasticity of an elastomer, it is called a “raw” mixture.
The crude mixture is stored at controlled temperature until consumption. It can be reserved as a block or extruded as an o-ring or tape.
Thus, for large quantities and relatively small sizes, injection molding is preferably used. For small quantities and yet small sizes, injection molding is compression molding is chosen.
Profile extrusion, profile cutting and subsequent bonding by vulcanization or gluing.
The elastomer pellets are fed into an electrically heated extruder that melts and compacts the elastomer along the screw to be ejected through a nozzle or die. The diameters of the nozzles are variable as well as their geometries.
Machining By machining a bar or tube from the material of interest with a lathe or CNC. The bar is clamped to a chuck while a tool removes material until the desired part is obtained. It is an interesting option when small quantities are desired, since there is no mold cost in this case.
Cut There are several technologies, each with its own advantages (knife, waterjet, laser, die, guillotine), which use as raw material semi-finished products in the form of raw material sheets already vulcanized, or profiles in the case of the guillotine.
Rotomolding This sometimes artisanal technique, in which the mold is immersed in a bath of liquid raw material. The shapes obtained can only be symmetrical, and it is particularly used in the manufacture of bellows in small series.
The final hardness of the formulation is variable and is adjusted depending on thes reaction conditions. After the curing reaction, a morethat is now elastic and responds to the elastomer formulation.
In the case of molding, vulcanization is part of the process and takes place in the same act of molding.
In extrusion, on the other hand, the vulcanization is a post-treatment of the vulcanization process itself. extrusion. It can be carried out in some type of tunnel immediately downstream of the extruder or in autoclaves with the previously extruded material.
In the case of cutting and machining, already vulcanized semi-finished products are used.
Depending on the geometry of the finished product, its material and tolerances, we will use different deburring systems, such as manual, cryogenic or mechanical deburring.
Subsequently, a number of additional processes can be applied, depending on the application, such as parts cleaning or surface treatment (see our blog post: O-rings: high-performance surface finishes)
The basic polymer of an elastomeric compound is rubber, produced from natural or synthetically manufactured latex. Currently, more than 32 synthetic elastomers or rubbers are known. The initial step is the design of the elastomer formulation to which we demand certain properties such as hardness, color, degree of chemical resistance or remaining deformation, among others.
Index
First stage: Preparation of the formulation
At this stage, various additives are combined with the base polymer (NBR, EPDM, FPM...) to design a mixture called “formulation”, with specific and concrete properties. Any variation of additives will influence the final characteristics of the formulation and may improve a certain property to the detriment of another. Thus, for example, a certain NBR formulation cannot be expected to maintain its high chemical resistance to lubricants and, at the same time, improve its behavior at low temperature. An elastomer formulation contains, among other additives, the following:- Vulcanization accelerators.
- Pigments.
- Stabilizers against aging caused by sunlight, ozone, weathering...
- Plasticizers that improve flexibility and reduce brittleness.
- Flame-retardant, flame-retardant, antistatic agents...
- Filler fillers that only increase the density of the formulation.
If required by the formulation, both rollers can be heated to the desired temperature.and maintain a temperature set point. After a certain time has elapsed, theThe mixing operation is completed and the desired formulation is obtained. This formulation, which does not yet have the elasticity of an elastomer, it is called a “raw” mixture.
The crude mixture is stored at controlled temperature until consumption. It can be reserved as a block or extruded as an o-ring or tape.
Second stage: Processing of the part
Injection or compression molding For both techniques, the process is essentially the same. The elastomer is placed in a hot mold and pressed. It is then cooled and the “molded” part is removed.Thus, for large quantities and relatively small sizes, injection molding is preferably used. For small quantities and yet small sizes, injection molding is compression molding is chosen.
Profile extrusion, profile cutting and subsequent bonding by vulcanization or gluing.
The elastomer pellets are fed into an electrically heated extruder that melts and compacts the elastomer along the screw to be ejected through a nozzle or die. The diameters of the nozzles are variable as well as their geometries.
Machining By machining a bar or tube from the material of interest with a lathe or CNC. The bar is clamped to a chuck while a tool removes material until the desired part is obtained. It is an interesting option when small quantities are desired, since there is no mold cost in this case.
Cut There are several technologies, each with its own advantages (knife, waterjet, laser, die, guillotine), which use as raw material semi-finished products in the form of raw material sheets already vulcanized, or profiles in the case of the guillotine.
Rotomolding This sometimes artisanal technique, in which the mold is immersed in a bath of liquid raw material. The shapes obtained can only be symmetrical, and it is particularly used in the manufacture of bellows in small series.
Third stage: Vulcanization and post-curing
For the raw mixture to be elastic, a chemical reaction called “vulcanization”, “curing” or “cross-linking” must take place under certain conditions of pressure and temperature. This is an irreversible chemical process. For this, a reaction catalyst is added to the mixture, which can be an organic peroxide, metal oxides or a sulfur-releasing compound whose vulcanization is known as “sulfur curing”. Bridges are created between the long polymeric chains, and the rubber then becomess elastic and resistant, returning to its original shape after deformation. Al Since this is a slow reaction, the process can be continued in autoclaves, and the following are used accelerators in mixtures to improve manufacturing yields.The final hardness of the formulation is variable and is adjusted depending on thes reaction conditions. After the curing reaction, a morethat is now elastic and responds to the elastomer formulation.
In the case of molding, vulcanization is part of the process and takes place in the same act of molding.
In extrusion, on the other hand, the vulcanization is a post-treatment of the vulcanization process itself. extrusion. It can be carried out in some type of tunnel immediately downstream of the extruder or in autoclaves with the previously extruded material.
In the case of cutting and machining, already vulcanized semi-finished products are used.
Fourth stage: Surface finishing
Certain manufacturing systems, such as molding, which is the most commonly used, can generate certain burrs or material remains in the parts in areas of mold joints, core insertion in complex molds or remains of injection ducts.Depending on the geometry of the finished product, its material and tolerances, we will use different deburring systems, such as manual, cryogenic or mechanical deburring.
Subsequently, a number of additional processes can be applied, depending on the application, such as parts cleaning or surface treatment (see our blog post: O-rings: high-performance surface finishes)