1. What is the reason for the poor tensile force of mold silica gel?

Mold silica gel has the characteristics of high temperature resistance, good tension, many mold turnover times and high repeated use times, which is loved by silica gel products factory! However, some manufacturers add a lot of silicone oil to the silica gel in order to make the silica gel easier to operate! As we all know, silicone oil can destroy the molecular weight of silica gel, reduce the viscosity of silica gel, make silica gel softer and easier to operate, and finally lead to poor tension in the production of silica gel mold! Less mold turning times! What are the influencing factors for the small number of silica gel mold turnover? Cotelli of Shenzhen silica gel products factory analyzes as follows: in fact, we have already mentioned the first point above. Due to the excessive addition of silicone oil, the second point is due to the use of silica gel molds with low hardness for building products. Because the silica gel is too soft, the performance is not strong and insufficient, resulting in the reduction of tensile and tear strength, and the produced molds are easy to deform, To reduce the number of mold turning! There are also some small products with complex patterns. Because the silica gel is too hard for a long time, it will be very brittle! It is easy to break. Opening the mold with a silica gel mold with high hardness will also reduce the turnover times of the silica gel mold! As for solving the problem of less mold turning times of silica gel, we only need to focus on the concept of using silica gel with appropriate hardness to make molds!

2. Solution of silica gel thickening?

Generally speaking, it's OK to put the liquid silica gel for half a year. If it exceeds one year, the viscosity of the silica gel will thicken with the increase of time. The expired liquid silica gel will solidify into a mass with almost no fluidity, which will make us very difficult. The fluidity of expired liquid silica gel will be very poor and almost form a mass, which will cause difficulty in mixing AB glue and non leveling during glue filling. If adding a large amount of silicone oil will reduce the tear resistance and toughness of silica gel after curing, how to increase the fluidity of liquid silica gel without affecting the performance of silica gel?

There is an expansion bolt on the market. You can buy one with suitable length according to the amount of your silicone, as shown in the figure below. After we buy it, we break the front opening of the expansion bolt jacket into a cross shape with pliers, then tighten the nut, tighten it, and a simple mixing head is ready. Next, clamp the mixing head on the electric drill and start crazy mixing. The stirred silica gel recovers its fluidity again. The liquid silica gel that has just been stirred will be a little hot due to friction and molecular movement, and there are many bubbles. It is unwise to use it immediately. First, it is easy to bubble. Second, it is easy to bubble because it has heat, which will accelerate the reaction speed. Let it cool for a while

3. The silicone of liquid mold is partially cured and partially uncured

When making silica gel mold with liquid silica gel, sometimes after waiting for 48 hours, we find that the mold silica gel is still not cured, or only partially cured and partially non cured. What is the reason for the non curing?

Reason 1: too much curing agent or too little curing agent will affect the curing of silica gel.

A: add the curing agent according to the specified proportion, and see whether the manual is volume proportion or weight proportion.

Reason 2: different types of curing agents cannot be mixed, and the addition mold adhesive will not react when it comes into contact with the tin component in the condensed silica gel.

Answer: use the curing agent of corresponding model. Operating tools are also classified and not mixed. If it is the operation of addition molding silica gel, do not come into contact with condensed products.

Cause 3: silica gel and curing agent are not stirred evenly.

Answer: silica gel and curing agent should be fully stirred evenly during operation, and pay attention to the on the bottom of the container.

Cause 4: incomplete curing (not fully dried) only occurs on the contact surface of the master mold, and other parts are cured intact.

A: make a layer of isolation film on the surface of the master mold to prevent the components in the master mold that are not conducive to silica gel curing from contacting the silica gel of the mold.

Cause 5: too low temperature can also cause non curing. When the operating temperature is lower than 0 ℃, silica gel will not react with curing agent.

A: when the temperature is 20-30 ℃, it is the most ideal mold silica gel curing temperature.

4. How to solve the deformation of mold silica gel and the causes of mold rubber deformation

1) The lining shell of mold glue is not accurate enough.

2) The mold silica gel was not fully cured before it was put into use. Although the mold can be taken out within a few hours after pouring the mold, it usually takes more than a week for the mold glue to fully cure. If time permits, experienced people usually take out the mold and start using the mold after pouring the mold for a month.

3) The soft silica gel mold is not put into the hard lining shell immediately after each use of the mold.

4) The die is subjected to deformation pressure for a long time in the process of use.

5) The quality of the used mold silicone is too poor, or the shrinkage rate is too high or there are too many fillers (reducing the cost of mold glue). The shrinkage rate of high-grade mold glue is 0.1%, that of ordinary mold glue is about 3%, and the shrinkage rate of poor mold glue is higher.

5. How to prolong the service life of mold silica gel

When using silica gel mold, manufacturers are generally concerned about the turnover times of silica gel mold. In the process of production and use, how to use silica gel mold to make silica gel mold more durable and longer service life?

1) When making silica gel mold, the silica gel mold shall be completely vulcanized before use. The silicone mold can be vulcanized for about 12 hours at room temperature, or for about 4 hours at about 60 ℃.

2) When the mold is used frequently, the rest time of the mold shall be increased appropriately.

3) Use the resin with good quality and choose the resin with less heat.

4) A proper amount of accelerator and catalyst shall be added to the resin and mixed evenly.

5) Do not stack the mold together when placing it. Stacking is easy to cause bending and warping of silica gel mold.

6) If the silica gel mold is not used for a long time, it should be placed in a cool place after pouring and stored away from light.

7) After the silica gel mold is used, it shall be cleaned with mild soapy water.

6. Selection of mold silica gel and mold line

First, it is convenient to take the mold

Second, the mold line should be selected so as not to affect the overall effect of the product

Third, it does not affect the product quality. For example, the mold line position of waterscape series products is too high, and there are too many materials to seal the mold line, so the product cracking is easy to occur; Fourth, reduce the process operation procedures, such as half opening the mold.

7. Why does the mold silica gel have less mold turnover times?

① Too much silicone oil is added in the process of making the mold. Silicone oil destroys the molecular weight of silica gel, so the mold will be turned over less times and not durable.

② If you make small products with complex patterns and use silica gel with high hardness to open the mold, there will be less mold turnover times, because the time when the silica gel is hard will be very brittle and easy to break. On the contrary, if you make large products and use silica gel with small hardness to make molds, the result will also be unsatisfactory. Because the silica gel is too soft, its tensile and tear strength will be reduced, and the mold will be deformed, so the number of mold turnover will be reduced. The quality of mold glue itself is very good. There is no difference between good and bad silica gel, only suitable and unsuitable. If we use silica gel suitable for the hardness of the product to make the mold, this situation will not occur.

8. Why does the mold glue burn?

Because unsaturated resin and resin products will generate a lot of heat when they react with resin after adding peroxide curing agent. Generally, the curing time of resin is

3 minutes, so demould as soon as possible after 3 minutes to prevent the silica gel mold from burning.

9. Pouring of mold glue, manufacturing method of split mold and external mold:

Slice mold or slice mold operation method: the vacuum pumped silica gel shall be constructed by brushing or pouring. If you are making a piece mold or a piece mold, you have to apply a layer of release agent or isolation agent on the product or model you want to copy before brushing, and then apply silica gel on the product (Note: be sure to brush evenly). After waiting for 30 minutes, stick a layer of gauze or glass fiber cloth on the surface to increase the strength, and then apply the second layer of silica gel. After the silica gel is dry, Then make the external mold, which can use gypsum or resin and other materials.

Operation method of pouring mold or pouring mold: pouring mold or pouring mold is used for relatively smooth or simple products, that is, surround the product or model you want to copy with rubber plate or glass plate, and pour the vacuumized silica gel directly onto the product. After the silica gel is dried and formed, take out the product and the mold will be formed (Note: the pouring mold is generally made of silica gel with relatively soft hardness, so that demoulding is easier and the products in the silica gel mold will not be damaged). The above is the whole process of using and operating the silica gel mold.

Production of external mold: generally, the method and material used is to surround the mold with rubber plate or wood board. Once the mold cabinet is filled with gypsum, the other way is to use resin brushing. After brushing a layer of resin, paste a layer of glass fiber cloth, then brush and paste again, and repeat two or three layers to complete the external mold of the mold.