When producing silicone products, the hardness is often adjusted according to the customer's demand for product hardness, especially when producing silicone keys, in order to adjust the load of the keys, some adjustments are often made to the hardness of the rubber material. The most commonly used rubber hardness in silicone product manufacturers is usually 30 degrees, 50 degrees and 70 degrees. Although there are only these three hardness rubber materials, any one between 30 degrees and 70 degrees can be prepared. hardness.
For example, if you need to produce a silicone product that requires 6kg of rubber with a hardness of 55 degrees, you can use 4.5kg of 50-degree rubber and 1.5kg of 70-degree rubber to prepare it, and you can also use 2.25kg of 30-degree rubber. The rubber material is prepared by adding 3.75kg of 70-degree rubber material. If you are good at mathematics, you only need to formulate an equation to calculate the proportion of rubber compound. If you are not good at mathematics, you can use the following formula to calculate easily.
1. (High hardness degree - target hardness degree) ÷ (high hardness degree - low hardness degree) × required weight = weight of low hardness rubber compound
2. Required weight - weight of low hardness rubber material = weight required for high hardness rubber material
In order to facilitate understanding and memory, I express all the above formulas in words, where "high hardness" refers to the hardness value with relatively high hardness in the two rubber materials, and "low hardness" refers to the hardness value with lower hardness , For example, adjust the hardness with 50-degree and 70-degree rubber materials, then the hardness value of the 70-degree rubber material is "high hardness degree", and the hardness value of the 50-degree rubber material is "low hardness degree". A very simple and easy-to-remember formula that can be applied directly without error.
Seeing this, I believe you have already understood how to calculate the hardness adjustment, but as mentioned earlier, you can prepare a 55-degree rubber by mixing 50-degree rubber + 70-degree rubber or 30-degree rubber + 70-degree rubber. In the actual production, which two kinds of rubber materials with hardness values should be used for deployment?
The answer is: it is best to use the two rubber materials with the closest hardness difference to adjust the hardness. Unless you have to, Tang Zhongliang does not recommend using 70% + 30% rubber materials to adjust the hardness, because the two rubber materials are mixed together. Smelting is not only extremely sticky to the roller during rubber mixing, but also very sticky to the mold during hydraulic molding, which will cause certain difficulty in demoulding, especially the silicone parts and silicone buttons with more complicated structures. As for why, Tang Zhongliang does not understand. Very thorough.
To be honest, in the early days of Tang Zhongliang’s blog, he thought about writing the formula and calculation method for the hardness of silicone products, but then he thought about it, this is actually very simple, and it can be easily calculated by just listing an equation, so I put this The idea was dismissed. Until yesterday, when I was helping a client modify a drawing file, I encountered such a problem: Knowing the side length of a quadrilateral, find the length of the diagonal. My mind short-circuited for a moment. It seemed that I had learned it in elementary school, but I couldn’t remember it after thinking about it for a few minutes. I understand one thing, proficiency lies in application, and the knowledge learned will really be forgotten if it is not used for a long time. Therefore, I decided to write the formula and calculation method for the hardness adjustment of silicone products, but what I wrote was the formula I learned in the first Dongguan silicone factory where I worked, which seems to be much simpler than the equation.