Vulcanization

Vibriso   Vulcanization is a complex of reactions between rubber and sulfur that is still not well understood today. These reactions involve the interconnection of molecules with a long amount of displacement energy and the formation of a lattice to obtain a non-displacement structure. As a result of this reaction, mutual bonding occurs between the rubber molecule chains. In this way, the chains are prevented from sliding on each other under the applied external force and the desired elastic property is given to the material. If the amount of sulfur added to the mixture is low (0.5%-5%), soft rubber is obtained, and if it is high (25%-35%), hard rubber or ebonite is obtained. Today's modern vulcanization processes are carried out at temperatures of 120-180°C and various additives are added to improve the physical and chemical properties of the rubber as well as the properties of the vulcanization process.

Organic accelerators reduce the vulcanization time significantly compared to inorganic accelerators (lead oxide, magnesium, calcium). In addition to shortening the vulcanization time, organic accelerators allow vulcanization at lower temperatures and reduce the amount of sulfur required in the vulcanization process. In later years, ultra-accelerators were used to achieve vulcanization at lower temperatures. In addition, organic accelerators increase the durability of the rubber and improve its physical properties, especially its tensile strength. In addition to all these, the cost reduction of organic accelerators has increased the use of rubber in industry. Therefore, the availability of organic accelerators has an important place in the rubber industry. Another important additive in the rubber industry is antioxidants. Although the durability of rubber materials is enhanced by organic accelerators, antioxidants are of greater importance in improving the durability of rubber.

The third important additive in the rubber industry is carbon black. Although carbon black has been used as a colorant for many years, it was first found in 1914 to improve the mechanical properties of the material and, in particular, to increase the wear and tear resistance of parts subjected to high friction. The use of carbon black additives in automobile wheels, where the use of rubber is the highest, has increased the mechanical properties of the material as well as the life of the wheel. After a brief introduction to rubber and vulcanization, the process for the references of interest in this paper flows as follows. The compound produced in the rubber compound house is combined with metal by vulcanization process. During this joining and dough production, defects occur as a result of internal stresses and chemical reactions due to the structure of the rubber itself.

These errors are due to different variables and prevent the system from producing parts at the desired level. These variables generally depend on variables such as temperature, dough hardness, pressure, baking time, machine type, etc. In this paper, statistical methods are used to determine how variables affect the process. As rubber materials exhibit visco-elastic behavior, their mechanical properties are more affected by loading rate and temperature compared to other engineering materials. The determination of creep and stress relaxation properties, where the time factor is taken into account, comes to the fore. On the effects of carbon black concentration and aging process applied for different temperatures and times on the tensile strength, elongation, hardness values and tear strength of rubber, various studies have been carried out. During vulcanization, rubber is treated with accelerators that reduce the time and sulfur required for vulcanization, antioxidants that delay aging, fillers that increase mechanical strength and/or provide economy, as well as softeners and lubricants. It has been observed that the sulfur content should not be taken as the only variable during vulcanization, but cooking systems should be selected by evaluating the amount of cooking agent together. For the part that has flexing problems in the enterprise, experimental design is applied. The dough of the material of the selected part is subjected to pre-forming within the company. And in this way, our dough is ready for production.



VULCANIZATION ANALYSIS  

Most of the vibration dampers (shock mounts) produced by our company consist of metal components that are processed together with rubber. The metal parts to be vulcanized are obtained from suppliers. These metals are first subjected to tolerance measurements using certain methods in the incoming quality control (IQC), after which it is decided whether the parts will go into production. Accepted metals, surface preparation processes of metals are carried out with our supplier and adhesive addition is carried out within our company.

Metals with completed surface treatment and adhesive addition are kept in the production raw material warehouse for production approval after visual inspection and adhesive thickness measurements are made. Rubber production is carried out in the dough pre-forming section in the plant, the necessary specification controls are made for each different dough, and the dough coming out of the rubber raw material warehouse is first processed in the rubber laboratory after the necessary tests and conformity tests are carried out, and the approved dough is processed in this section and made ready for the vulcanization process.

After the vulcanization process, products that have completed the reaction within at least 24 hours are sent to the quality control test laboratory for control.

During vulcanization production, if the parts that have been tested and dimensionally controlled are within sufficient specification values, it is decided to continue production. If the part's stretch,