Common problems and solutions for silicone casting

Silicone casting is a common prototype process, currently mainly used for making prototype models with material requirements, small-scale model production, and small-scale production. The application industries include intelligent hardware, modified car parts, toys, communication equipment, plastic shells, medical equipment shells, robot shells, etc. The advantages of silicone based prototype models are: silicone has a low viscosity, is easy to operate, does not deform or shrink, is easy to remove, the surface of the mold is smooth, and the simulation effect is good.

Common problems for silicone casting as follows:

1、 Dimensional deviation and product deformation
Causes and solutions: It is closely related to the temperature control of molds, especially in the production process of molds. Other reasons such as the scaling ratio of the prototype and the shrinkage of the material should also be well controlled. Products with a length exceeding 1.5 meters need to be made using reinforced molds

2、 The products produced cannot be assembled
Cause and solution: The drawings of product engineers are set according to the injection molding process of the mold, often without considering the difference between the replication process and the injection molding process. Due to the vacuum adsorption molding process, the precision of the product can be controlled within ± 0.1mm. For assembly products with higher precision requirements or requirements for hand feel tightness, small batch production engineers need to adjust the replica prototype and add post-processing assistance to meet the assembly requirements

3、 Finished products become brittle and crack
Causes and solutions: The main cause is the use of domestically produced inferior materials and defects in the replication process. The solution is to ensure that the material procurement channel is guaranteed. If there are no problems with the materials, improvements can be made in the process, paying attention to controlling the oven temperature and heating time, cooling time, cooling method, etc.

4、 Bubbles and hollows
Causes and solutions: The formation of bubbles in replica products is related to the reaction between silicone mold materials and curing agents. When vacuuming, it is important to control the time. If the time is too long or too short, bubbles may easily form. Additionally, it is related to the product structure and the location of the feed inlet. The formation of bubbles on the surface of a product can greatly affect its appearance and material durability, so strict adherence to the manufacturing process is necessary to effectively avoid them

5、 Product details are missing
Causes and solutions: In the production process of some slender products, it is easy to lose details. The main reason is that the silicone mold is not baked properly and is prone to deformation, resulting in loss of details. In addition, during the process of making molds, the damage to the prototype of the product directly leads to the loss of details in the replicated product. In addition to improving the process as a solution, it is necessary to carefully inspect every step of prototype polishing, mold making, and finished mold making.

6、 Surface roughness and unevenness
Causes and solutions: The quality of replica products is closely related to the prototype. To improve the surface quality of the finished product, it is necessary to first improve the manufacturing process and surface effect of the prototype, which can be produced through CNC. In addition, the use of domestically produced inferior silicone gel can also lead to rough and uneven surface of the mold. The solution is to use imported silicone molds for production, select the most suitable process to make the prototype, and ensure the hardness, surface, and compatibility between materials.

7、 Fading after coloring and orange peel on the surface
Causes and solutions: The discoloration problem is related to the smoothness of the product surface, the selection of primer and topcoat, and is a problem involving multiple reasons. The main solution is to choose a primer that is compatible with the material, such as a two-component primer combined with automotive specific paint. Good paint can not only improve the surface effect of the product, but also increase its resistance to aging and corrosion.

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