Silica gel mold production process and common problems

Table of Contents

Production process

The choice of the form of mold opening and the choice of mold line is very important, one is to take the mold convenient, and two is the injection mold line should be selected in not to affect the overall effect of the product.

Three is not to affect the quality of the product, such as the water view series of products of the mold line position is too high, the sealing line raw material is much, the product cracking is easy to appear; Four is to reduce the flow operation procedures, such as opening half the mold.

To prevent the silica gel materials from flowing around, the mold is fixed in a regular range with wood or wood. When the mold is opened, the first part is separated by wood and mud. There is no gap between the mud and the mold, and the surface of the mud is smooth and smooth.

After the above work is ready, then the plaster mold or mold is coated with petroleum jelly or spray release agent, smooth products are required to use a clean pure cotton cloth dipped in petroleum jelly evenly coated on the mold, keep 30 minutes to make the mold fully absorb petroleum jelly.

Then wipe the surface of the mold with clean pure cotton cloth, the surface is required to be bright. And the texture of the product as long as evenly coated with petroleum jelly can be adjusted according to the formula of silica gel.

When solid silica gel is deployed, it should be stirred in an irregular direction, so that the curing agent and silica gel are fully mixed, and the air is mixed into the glue as far as possible. It is best to pump a vacuum when the smooth product is coated with the first layer of glue, and the vacuum degree is required to keep for 7-8 seconds when 0.1Mpa.

Silica gel should be time after the mold. Pour the glue at the highest part of the mold in the way of drip, so that it flows naturally. Where the flow is not in place, use the oil painting brush in place.

If it is a mold, the silicone will not only fill the whole product but also brush evenly on the mud. Each product brush at least three layers of silica gel each layer of silica gel thickness is 1mm, in the process of brushing silica gel, each layer is required to brush another layer after curing, in the third layer of the brush add a layer of gauze on the second layer to increase the strength of silica gel.

According to the requirements of different sizes of the product, the thickness of the silicone part of the whole mold is controlled in 3-4mm, and the width is not greater than 60mm of the product width. The silica gel starts to set for 20 minutes.

1. The mother mold wash dry, smooth treatment (can play a layer of release wax or brush once release agent);

2. Put 500-1000 grams of mold silicone rubber (mold silicone, mold glue, silicone rubber, silicone) into a plastic basin for use;

3. After weighing the hardener according to the weight ratio (generally 1.5-2.5%), add it into the container for mixing and stir well;

4. According to the situation (especially the first layer) add a certain amount of silica gel thinner. Until well mixed, usually 3-5 minutes.

5. After mold silicone rubber (mold silicone, mold glue, silicone rubber, silicone) is mixed with hardener, the reaction will be carried out at room temperature, and the low molecular alcohol will be released.

To make the alcohol molecules out of the colloid, the foam should be drained under negative pressure for 1-3 minutes. Equipment can also be avoided (mainly depending on the operator’s experience).

6. Multi-layer coating dies, should follow the inner, middle and outer curing at the same time as appropriate.

When the dosage of the curing agent is relatively small, the reaction time is longer, the reaction is sufficient, and the colloid is good, so the dosage of the curing agent is best less inside and more outside. When brushing the first layer (inner layer) dry after brushing the second layer.

Operation time is 30-50 minutes, and mold removal time is 10-15 hours. The curing time is 24 hours. After brushing the first and second layers, it is best to add the mold cloth, which can greatly improve the service life of the mold (but do not use glass fiber cloth, otherwise it is easy to cause stratification and scrap the whole mold).

7. Three-dimensional perfusion mold, generally with 10-15 hours of curing is better.

8. After the soft mold is made, a plaster or fiberglass coat should be made to support the silicone soft mold.


1. Select the position that is easy to work on after grouting; Choose the mold itself easy to remove the mold position;

2. The dosage of hardener must not be blindly increased to catch up with the production schedule, otherwise the service life of silica gel mold will be greatly reduced.

Common problems encountered in the application of mold silica gel

Why does the mold silica gel appear fewer times of mold turning?

In the process of making the mold, too much silicone oil is added, and the silicone oil destroys the molecular weight of the silicone, so the mold will appear fewer times of turning the mold and not be durable.

If you make small silica gel products with more complex patterns and use silica gel with high hardness to open the mold, there will be fewer times of turning the mold, because the silica gel will be very brittle and easy to break.

On the contrary, if you build products and use silica gel with a small hardness to make molds, the results will also be unsatisfactory. Because the silica gel is too soft, its tension and tearing strength will be reduced, and the resulting mold will be deformed, so the number of mold turning will be reduced.

Mold glue itself is of good quality, there is no good or bad silicone, only suitable and not suitable. We should use silica gel suitable for the hardness of the product to make the mold so that this situation will not occur.

Why does the silica gel of the mold burn the mold?

Because unsaturated resin and resin products with a peroxide curing agent, the resin reaction will produce a lot of heat, the general curing time of resin is 3 minutes, so after 3 minutes release as soon as possible, to prevent the silica gel mold will not produce the phenomenon of burning.

Why does the mold silica gel appear in the surface dry phenomenon?

Mold silica gel is a condensation type silica gel, it is by absorbing the moisture in the air and curing, silica gel in the process of making, the water is dried, and there is no appropriate amount of water, this phenomenon will occur.

Solution: This phenomenon does not belong to the product quality problem, but because there is no control of water, to improve the storage period of silica gel, the shelf life for a long time will appear some phenomenon, as long as the use of silica gel, adds 0.05% water, stirring evenly can solve some problems.

Why will the silica gel of the mold appear as the phenomenon of tension difference?

Because the customer in the process of making the mold, to reduce the viscosity of silica gel, the silica gel easy to operate, and large amounts of added silicone oil in the silica gel, will make silicone is very soft, not resistant, pull, tear strength is reduced, the phenomenon of tension variation, resulting in the mold is not durable, service life is short, the phenomenon such as fewer rolling over.

Why does the mold appear oil rising?

Mold liquid silicone gel itself is not oil, the emergence of oil is because of the operation process to add compound silicone oil (silicon oil and white mineral oil complex) because white mineral oil is a petrochemical product, not silicon oil.

Why does the mold have acid and alkali resistance and aging resistance?

In the process of making silicone molds, we suggest that customers had better not add any silicone oil. If necessary, the amount of silicone oil added should not exceed 5% ~ 10% at most.

Because the addition of too much silicone oil will destroy the molecular weight of silica gel, the mold will be resistant to acid and alkali and aging.

Why will the surface of the mold made of silica gel have marks, stripes, not smoothness, and other phenomena?

This occurs when the silicone rubber products or model to be copied has not been polished or polished. The model or product itself is not smooth or perfect, so if the product or model to be copied is not polished or polished, the silicon mold made of good silica gel will not be beautiful and smooth enough. There is also a situation where when playing release agent, no uniform brushing will cause the mold to be not smooth.

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