Silicone rubber products production process

All silica gel products must be made before the production of silica gel mold, through the mold to develop new products.

(1) The mold meets the requirements

1. When the wear resistant blank is plastic deformed in the mold cavity, it flows and slides along the surface of the mold cavity, so that there is fierce friction between the surface of the mold cavity and the blank, which is easy to lead to the failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the die. Hardness is the main factor affecting wear resistance. In general, the higher the hardness of the mold parts, the smaller the wear amount, the better the wear resistance. In addition, the wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material.

2. Most of the conditions of strong and ductile molds are very bad, and some often bear large impact loads, which lead to brittle fracture. In order to prevent the sudden brittle break of the mold parts, the mold should have high strength and toughness. The toughness of the die mainly depends on the carbon content, grain size and microstructure of the material.

3, fatigue fracture performance in the process of mold, under the long-term action of cyclic stress, often lead to fatigue fracture. The fracture forms include multi-impact fatigue fracture with small energy, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture.The fatigue fracture properties of the die mainly depend on its strength, toughness, hardness, and the content of inclusions in the material.

4. High temperature performance when the temperature of the mold is high, the hardness and strength will decrease, leading to early wear or plastic deformation of the mold and failure. Therefore, the die material should have high tempering stability to ensure that the die has high hardness and strength at temperature.

5. Cold and hot fatigue resistance Some molds are in a state of repeated heating and cooling in the process, which causes surface cracking and peeling, increases friction force, hinders plastic deformation, reduces dimensional accuracy, and leads to mold failure. Hot and cold fatigue is one of the main forms of hot working die failure, so this kind of die should have high resistance to cold and hot fatigue.

6, corrosion resistance Some molds such as plastic molds, due to the presence of chlorine, fluorine and other elements in the plastic, after heat decomposition precipitation HCI, HF and other strong erosive gases, erosion of the mold cavity surface, increase the surface roughness, aggravate wear failure.

(2) The mold meets the requirements of process performance

The manufacture of molds generally has to go through several processes, such as forging, cutting and heat treatment. In order to ensure the manufacturing quality of the die and reduce the production cost, the material should have good malleability, machinability, hardenability, hardenability and grindability; It should also have small oxidation, decarbonization sensitivity and quenching deformation cracking tendency.

1. Malleability has low resistance to hot forging deformation, good plasticity, wide forging temperature range, low tendency of forging crack cold cracking and mesh carbide precipitation.

2, process spheroidization annealing temperature range is wide, annealing hardness is low and the fluctuation range is small, the spheroidization rate is high.

3, cutting machinability cutting parameters, low tool loss, low machining surface roughness.

4. Oxidation and decarbonization sensitivity when heated at high temperature, oxidation resistance is good, decarbonization speed is slow, it is not sensitive to the heating medium, and the pitting tendency is small.

5. It has uniform and high surface hardness after quenching.

6, hardenability quenching can obtain a deeper hardening layer, the use of moderate quenching medium can be hardened.

7, quenching deformation cracking tendency conventional quenching volume change is small, shape warping, distortion is slight, abnormal deformation tendency is low. The sensitivity of conventional quenching cracking is low and insensitive to quenching temperature and workpiece shape.

8. Grinding ability

(3) The mold meets the economic requirements

When selecting material for mold, we must consider the principle of economy and reduce manufacturing cost as much as possible. Therefore, under the premise of satisfying the performance, the first choice of lower, can use carbon steel without alloy steel, can use domestic materials without imported materials. In addition, the production and supply of the market should also be considered when selecting materials, and the selected steel types should be as few as possible and concentrated.