Silicone mold production technology. Silicone mold manufacturing technology: features, additives. Profit calculation and payback

In construction, molds are often used to produce various products and products. The most basic of them are polyurethane and silicone. It is possible to pour not only gypsum and concrete into them, they are also used to make unnatural stone. All this can be made by hand. Even if it seems that you need to own some kind of knowledge, this is a misconception. This article will tell you in detail how to make a polyurethane mold, a mold for pouring from plaster, silicone, a mold for pouring gypsum, concrete. She will also teach you how to craft a matrix for the production of molds from silicone or polyurethane with your own hands. The most basic thing is to figure out how to build, according to the rules, a practical template for a matrix that is suitable for materials such as polyurethane, formoplast and silicone.

An unnatural stone, at the present time, is a good, profitable business. To open your own business, with the prospect of further growth, does not require a lot of cash investments. An unnatural stone can be easily made using all technologies with your own hands. But, for a start, it is important to have a room with a suitable temperature so that work can be carried out year-round.

The production of non-natural stone requires good, high-quality shapes, which cannot be obtained without a matrix. The manufacture of a matrix sample must be approached very responsibly, because the strength of the final product depends on it.

Some consider it impossible to make an artificial decorative stone at home. But, thanks to striving and desire, everything becomes possible. The materials are best of good quality and combined with some additives. For example, the setting time of silicone and its fluidity can be adjusted using catalysts.

It is quite achievable to release a matrix for the production of silicone and polyurethane molds with your own hands, with the help of which the casting process itself will be possible. To make a matrix, you need to purchase or find a sample by which it will be possible to copy or produce forms identical to the presented model.

If it comes to an unnatural stone, then in the given circumstances the specimen must be of perfect geometric shape, without gaps and possible deformed corners. Most often, for the production of molds from polyurethane, to create an unnatural stone or a sample for the production of molds for a stone, a variety of raw materials are used. For example, gypsum, drywall, or styrofoam. Sometimes they come to the method of copying from an unnatural or gypsum stone, but a sample from a natural stone is considered an ideal option.

For this, a natural stone is taken, cut into thin plates (about 1 cm) and glued with glue. The stone must acquire a geometry that is impeccable in all respects. If there are uneven sides or protrusions, then a grinder and a machine will come to the rescue, which will align or remove all unnecessary parts. The finished stone with removed irregularities is ready for gluing.

Stage 2. Production of a matrix for creating molds from polyurethane or silicone, formoplast, liquid plastic

The created model must be glued to some base in order to make a matrix from it. An excellent option would be to use chipboard as a stand. The finished model must be glued to the chipboard using silicone sealant. But this can be done exclusively on the glossy side of the stand.

For gluing, a silicone sealant is taken and applied to reverse side the prepared model. All edges and corners are well traversed. When turning the stone over, press it firmly against the chipboard tray. Next, with a spatula, carefully go over the joints, making sure that all air bubbles disappear. Excess air is useless when filling with polyurethane or silicone. After covering, the workpiece should be left to dry completely. After that, it was time to build the matrix boards. The height of the walls must be higher than the height of the glued stone. The material for this can be plastic, steel or duralumin corners. At a distance of approximately 1.5 cm from the finished model, the corners must be screwed to the chipboard around the entire perimeter with screws.

It is important, after screwing, to carefully walk with the help of silicone sealant at all joints and corners, once again double-checking the reliability and tightness of the structure. Otherwise, flowable polyurethane or silicone, which has the ability to penetrate even the smallest gaps, will leak out of the matrix. In order for all the material to dry thoroughly, it is better to leave the matrix to dry (about 12 hours). We recommend the use of aquarium silicone sealant. Its main feature is the elimination of shrinkage or cracks that often appear after drying. A matrix treated with such a sealant will last for many years without problems.

After making sure that the almost finished matrix is ​​completely dry, the next step will be to lubricate it with a specialized separator. This mixture can be purchased in any building stores... Almost all of it has a wax base, and differs only in manufacturers. English is considered the best separator. After application, it completely dries up, dissipates and after a few hours, polyurethane, formoplast, gypsum or silicone can be poured into the prepared matrix. Any formulation used to create shapes will do.

Stage 3. The rule of pouring polyurethane into the matrix in the manufacture of polyurethane mold

First, one should decide with the choice of the substance itself. For example, if we are talking about a non-natural stone, then it would be correct to make molds from polyurethane. And so, it is allowed to fill in with any material adapted for such work. At large factories and enterprises, specialized equipment is used that makes the task easier. But, you can fill the form with your own labor. How to do it correctly?

There are unnatural stones with a different number of angles. Such a stone looks beautiful and is very popular. For him, the polyurethane mold is the most the best way... It is convenient and practical, easy to clean and will not create any unwanted errors. The pouring process is a delicate matter and here you need a table or some other object that will stand clearly in level. Ready-made silicone or polyurethane (how to prepare it, the manufacturers themselves write on the packaging of the material) must be poured in a slow stream, excluding the ingress and formation of air bubbles. At the same time, it is important to tilt the matrix slightly to one side.

When the solution reaches the bottom wall of the matrix, the entire structure can be lowered and the material can be continued to pour. Left for a day, the matrix will harden and take on a suitable shape.
When completely dry, the die is ready for disassembly. It is too early to use it for the production of unnatural stone. For better fixing, it is advisable to leave the product in a warm place for a while. This is necessary in order for the form to exclude irregularities on the walls or surface. This is especially true of polyurethane, as this material has a memory and, if bent and left like that for a short time, it stays that way. Having stood in a warm room, the service life of such forms increases, regardless of what solution they will be poured with.


Also read:

Silicone is a quality material for flexible injection molds. Technology self-made silicone molds

How to make silicone molds yourself and how to make epoxy resin products yourself

Silicone cures without shrinkage at room temperature to form silicone rubber. Two-component liquid silicone for mold making, silicone molds are suitable for epoxy resin casting. How to make a silicone mold yourself for casting an epoxy product at home. How to make a mold for gypsum or for casting epoxy resin from molding silicone at home without having experience in mold making.

The technology of self-production of silicone molds from elastic two-component silicone.

Making silicone molds at home, followed by casting epoxy into a silicone mold. In this topic, the production of silicone molds for the manufacture of products from epoxy resin, we will try to master the simplest technology of self-production of molds from silicone for pouring products from epoxy. Two-component silicone is used for casting molds and making impressions. I offer you a free master class on making epoxy resin products. Manufacturing technology of silicone molds and methods of manufacturing products from epoxy resin.

All about raw materials for self-production of molds at home.

How to choose a material for making molds and casting from gypsum, concrete, polymer concrete, polymer resins. In addition, the production of forms and sculptures can become independent profitable business... How to choose a material for making an elastic mold for castings from plaster or other materials. Casting into silicone molds using the example of making a simple product from epoxy resin.

Silicone compounds and rubbers are easily processed into molds even at home and do not require any additional equipment, since they have the ability to self-pour them manually. After reading carefully step by step instructions You can easily make your own silicone molds. The same self-made molds will cost about half as much as you can buy them, in addition, you can make any mold yourself and will not depend on mold manufacturers and the assortment that mold manufacturers offer you and you will be able to make that range of molds for products that are not on the market, so you will have absolutely no competition in your assortment.

Copying products, self-production of silicone molds and pouring epoxy resin into a mold is what you can do on your own at home or in an industrial environment, after carefully studying my step-by-step lesson on making silicone molds and mastering the methods and technology of pouring epoxy resin.

The proposed methodology is a detailed description of this technology for copying products.

Step 1. Let's take a copy of a simple product as an example. We will cast this part from epoxy resin into a split silicone mold, consisting of two parts.


Step 2. To apply the described technology for the manufacture of silicone molds, we need the following materials, two-component silicone for self-production of the mold and epoxy resin for pouring into the mold for the manufacture of the product.

Step 3. Silicone. This is the material from which the casting mold will be made. While a common and inexpensive silicone sealant is fine for this purpose, it is much easier and more convenient to use a two-component silicone specially designed for mold making. In the example below, we will use just such a silicone from Pentasil, any other two-component potting silicone will do.

Step 4. Epoxy resin. There are a great variety of such resins on the market, and most likely many of them will be suitable for our casting. The main requirement for the resin is that the polymerization time should not be too short. I, in particular, stopped for the manufacture of our product as an example on a product called Finishing Resin. This resin, after polymerization, is quite elastic and resembles polyurethane resin in physical properties.

Action 5. Release agent. If the mold material is two-component silicone or two-component polyurethane, the release layer is only needed to separate the halves of the mold. There are many release products specifically designed for this purpose, usually in the form of a wax-based aerosol, but if you do not yet have the opportunity to find such a release, regular petroleum jelly or melted candle wax is fine.

Step 6. Plasticine. It will serve as our main building material. Before proceeding with the manufacture of the form, it is worth checking the selected materials for compliance with each other. If you neglect this stage, you can not only not get a copy, but also lose the original. First, make sure that the chosen silicone, after curing, is easily removable from a surface made of the same material as the part to be copied. If this is not the case, the copied part will have to be covered with a release layer or another silicone should be used. Second, make sure the cured epoxy separates well from the silicone and that the physical properties of the cured resin are satisfactory.

Step 7. Making silicone molds. To begin with, on a flat solid base (I use a compact disc for this purpose), apply an even layer of plasticine and slightly press the copied part into it.

Step 8. If the part is relatively flat, you can press it into the clay to the level where the border of half of the future shape will pass. In the case of a more voluminous part, instead of pressing the part to the full depth, we apply another layer of plasticine around the perimeter of the part.

Step 9. After that, you need to walk along the perimeter of the part and press the plasticine against its wall, thus forming a clear border. To do this, I use improvised gadgets made of matches and toothpicks covered with silicone sealant. Since plasticine does not stick to silicone at all, it is very convenient to process it with this particular material. Please note that in the future casting, a small seam is formed at the place where the joint of the halves of the mold will pass, so the location of the border must be chosen in such a way that this seam can be removed without damaging the parts around it.

Step 10. It is important to make sure that the clay is tightly adhered to the copied part everywhere, so that the silicone cannot leak under it when casting the mold.

Action 11. Now we will make the walls of the future container, for which the easiest way is to use the same plasticine. The distance between the wall and the part should be 5-7 mm, and the wall should be the same amount higher than the highest point of the copied part. The junction of the wall with the floor of the container is leveled using all the same devices covered with silicone.


Step 12. After that, it is worth making several small indentations in the floor of our container. They will serve as locks to prevent the halves of the future shape from moving.


Step 13. So, the container is ready to pour silicone. The silicone that we are currently working with when creating our product consists of two components of a thick white mass, reminiscent of condensed milk in consistency, and a dark blue liquid catalyst, there are catalysts of different colors that must be mixed in a ratio of 10: 1 (in the instructions not specified by weight or volume; I use a scale for dosing). The bright color of the catalyst helps to achieve complete mixing of the components - the finished mixture should have an absolutely uniform blue color. Avoid skin contact with silicone and especially catalyst. It is advisable to work with gloves (by the way, this also applies to epoxy).

Step 14. Pour the resulting mixture into a plasticine container with the copied part. This should be done slowly, in a thin stream, and try to pour silicone into the far corner of the container, and not onto the part, so that the silicone flows around it gradually, from below, without forming voids and the air has time to come out, otherwise I will be in the form of a hole. There is no hurry - this silicone remains fluid for almost an hour, but we must remember that mainly silicones have fluidity, that is, a life time of 10 minutes. At the end of the filling, the container should be left alone until the silicone is completely cured.

Step 15. After the silicone has hardened, remove all the plasticine. This must be done very carefully, so that the copied part remains in the silicone, from which it is very willingly separated. First, carefully remove the side walls, then remove the floor.

Step 16. As a result, we have the finished first half of the form with the copied part in it. If traces of plasticine remain on the form or part, they must be carefully removed, again not allowing the part to separate from the silicone.

Action 17. Place the finished half on the same disk and build plasticine walls around it, the height exceeding the highest point of the part by 5 mm.

Step 18. Using the above method and tools, we will achieve a more or less tight joint between the mold and the plasticine walls (this is not so easy, because the plasticine reluctantly sticks to the silicone mold, but absolute tightness is not so important here).

Step 19. Be sure to cover the surface of the first half of the mold with a release layer of petroleum jelly, or apply a separator or paraffin, in order to prevent the halves of the mold from sticking together (the silicone sticks to itself tightly). To do this, you can use a brush, applying Vaseline very thin layer, and only on the silicone, and not on the copied part.

Step 20. The container for the second half of the mold is ready. Silicone is prepared and poured in the same way as for the first half. It remains to be patient.

Step 21. After the silicone has cured, remove the mold from the disc and remove the plasticine walls.

Step 22. Now we have to separate the two halves of the finished silicone mold. Despite the release layer, the halves may be stuck together at some points, so some force may be needed to separate them. In this case, it is important not to damage the copied part inside.

Step 23. So, our self-made two-component silicone mold is ready!

Step 24.Epoxy resin casting
First, let's prepare the epoxy. The epoxy components are usually mixed in a 1: 1 ratio, and it is advisable to adhere to this ratio as closely as possible. For the resin, at least the one that we took for training in production, the scales will not work. Components have different density, so it is better to use special measuring cups. Recently, I have been adding a third ingredient to the resin: a small drop of special coloring pigment (a mixture of black and white). In this case, the casting is not translucent, but has a more familiar gray color.

Step 25. Mix the epoxy resin thoroughly, not only in the center, but also along the edges of the container, but at the same time carefully, trying to introduce as few air bubbles as possible. Alas, the formation of these air bubbles is almost inevitable, while you cannot put up with them, where the bubble is close to the surface of the part, a hole is formed in the product. There are several ways to deal with bubbles using vacuum and high pressure, but we will use a simpler method. The resin, already mixed in the tank, should be heated, for which an ordinary hair dryer is suitable. After heating the resin, it should be left for a couple of minutes, during which time most of the bubbles will come out. Take a look at the following photos. On the first resin, immediately after heating, bubbles rise violently to the surface. In the second photo, most of the bubbles have come out.

Step 26: Of course, this method is only applicable for resin with long cure times. The fast-setting epoxy resin with which experienced manufacturers are already working will most likely harden before we have time to finish all these manipulations, especially considering that heating accelerates polymerization. Now we will apply resin to both halves of the silicone mold. For this I usually use a toothpick or match. The resin is laid out on the silicone surface in a thin layer, while, again, you need to try not to introduce bubbles or create voids.

Step 27 Epoxy is applied to each mold half with a slight excess with a crust. At this stage, you can once again heat the resin, already in the mold, forcing the majority of the remaining bubbles to come out and making it thinner, which will reduce the thickness of the future flash.

Step 28. Put the halves of the shape together. In this case, the excess resin will simply be squeezed out. Sometimes it is recommended to provide channels or cavities in the form to drain excess resin, but I did not notice any special advantages of them and eventually stopped making them.

Step 29. Press the halves of the mold firmly against each other, for example, clamp between two hard plates, fastened with rubber rings, or place under a load. This is important, because if the mold halves are loose, the flare will be thicker, not to mention the fact that the resin may simply flow out. On the other hand, you should not be too zealous either, since the form is elastic, and strong compression can deform it and the future casting.

Step 30. When choosing the position in which we leave the mold with the liquid resin inside, it makes sense to take into account the following consideration. Despite our efforts to combat air bubbles, one or two of the most stubborn bubbles are likely to remain in the resin. What will happen to them next? Most likely, they will rise up and remain on the surface, forming tiny holes in the finished casting. But where the casting will have the upper hand is up to us. It makes sense to position the shape so that the top is the part where the bubbles will be less noticeable, or where it will be easier to close them.

Now all that remains is to wait. By the squeezed out resin, one can judge the readiness of the casting. Do not hurry! If the resin has not yet cured completely, the casting may be damaged if it detaches from the mold. In my case, I do not touch the resin mold for 24 hours. After this time, the halves of the mold can be gently separated and removed.

Step 31. Dried streaks are carefully removed with a match or a toothpick, after which the remaining insignificant seam can be treated with a fine sandpaper.

Act 33. That's all, actually. Our epoxy resin casting, absolutely identical to the original, is ready.

As you can see, everything is quite simple and modern, having gained experience on such small products, you will be able to make serious products that are in demand on the market, and you will also be able to independently make silicone molds to expand your activities and expand the range, and most importantly, you will be able to make molds from silicone and not depend on that range which is proposed today.

Here is an example of pouring silicone into open matrices.

An example of a silicone mold and a finished product from silicone molds. Silicone molds

Removing the silicone mold from the finished product. How to remove a silicone mold from a finished product


You can ask and discuss all questions on our forum.

More and more craftsmen are willing to try their hand at working with this relatively new material, but from the very first steps they face difficulties, not knowing where to start, which silicone to use and how to handle it. Here I will try to summarize the main points, based on my own experience and information obtained from the Internet. I must say right away that I will not tell you anything fundamentally new - everything that will be discussed is well known to professionals working with silicone, but I hope that the information gathered in one place will help beginners overcome the first difficulties.

What silicones are needed for casting?

So, first of all, the silicone itself. When creating dolls, I use platinum-based compounds (two-component silicones) from Smooth-On made in the USA, so we will talk about them. For work, you will need two types of silicones: for casting the dolls themselves and for making a mold. The first ones are not so many, first of all, these are the Dragon Skin Series and Ecoflex Series. They have a high degree of elasticity and allow you to most realistically convey the effect of human flesh.

The silicones of each of these series have different specifications: softness, pot life (the length of time when the silicone retains fluidity), setting time, viscosity, etc. What kind of silicone is the best to use when creating dolls? I can't say anything concrete here - it all depends on ultimate goal master. In my opinion, it is most correct to follow the path of experiment, trying different series, in order to find in practice the very one material that allows you to achieve the desired effect.

The silicones of the Dragon Skin Series and Ecoflex Series are colorless and translucent, therefore, to obtain a realistic color for the doll, they must be dyed using special Silc Pig pigments.

The second type of silicones is used to make molds. Be careful - platinum-based silicones can only be cast into molds made of platinum-containing silicone. Tin catalyzed silicones must not be used. Otherwise, the casting will not solidify. Mold release silicones have a lower degree of elasticity and a higher hardness, as a rule, they are painted in bright colors or transparent. A bright color of one of the components allows you to evenly mix components A and B before pouring, and transparent ones allow you to see the model in the mold (this is convenient if the mold is cast entirely and then cut into parts). Mold release silicones include such series as: E-Series, Mold Star Series, Equinox Series, Rebound Series, etc.

The shape can be made by pouring, or by gradually applying layers of silicone with a brush. The first method is simpler and faster, but requires more silicone. The second one is more laborious, moreover, it requires a variety of additional materials. You can clearly see the process of creating a "smeared" form on the official video of the company:

A little about forms

The finished silicone mold remains elastic, this is its undoubted advantage, however, we must not forget that it can be easily deformed, so it must be placed in a special protective casing cast from ordinary plaster.

Before pouring silicone into a silicone mold, it is imperative to use a special Ease Release compound, otherwise the mold and casting will firmly stick together. The separator layer must be thoroughly dried, as in some cases it prevents the silicone casting from completely hardening.

Molds for casting dolls can be made not only from silicone, but also from plaster. It is advisable to use special dental plaster for this purpose, such as Fuji Rock, which have increased strength, perfectly convey small relief details and dry quickly enough. Compared to silicone molds, gypsum does not require a release agent and absorbs excess silicone oil during the casting process. However, plaster forms also have significant drawbacks - it is almost impossible to remove the master model from the plaster without damage, the forms open with great difficulty and loosen up rather quickly, losing the accuracy of aligning the halves. Also, in comparison with a silicone mold, a plaster mold has to be made from a larger number of parts, which increases the number of seams on the finished casting.

Basic rules for working with silicone

So, we figured out the materials for casting, now let's talk about the process itself. To avoid marriage and failures when working with silicone, two golden rules must be observed, which greatly facilitate the life of the master:

      1. Always strictly and meticulously follow the instructions, not allowing any initiative.
      2. Always test new materials that come into contact with silicone for compatibility.

For work, it is advisable to purchase a vacuum chamber with a pump that evacuates air from the mixture before filling. Some types of silicones can be used without preliminary degassing, but the risk of air bubbles remaining in the solidified mass is quite high.

It's also a good idea to have an oven or drying cabinet for post-curing. finished products... The heat-treated silicone more quickly acquires the physicochemical properties declared by the manufacturer. Heat products in an oven designed for food products I would not risk it, despite the fact that platinum-based silicones are considered non-toxic materials.

I note that the manufacture of silicone dolls requires significant financial costs, however, it is impossible to save on materials and equipment, looking for cheap analogs and doing self-activity - the result of such experiments is usually deplorable and leads to inevitable damage to castings and molds.

It is only necessary to work with silicone with vinyl gloves, latex gloves cannot be used.

The casting room needs to be heated, the temperature in it should not drop below 22-23 degrees. The required temperature regime is one of the most important factors - at temperatures below 18 degrees, the silicone may simply not solidify, and a higher air temperature slightly reduces the life of the finished silicone mixture.

But it is impossible to store silicone in the heat. The material has a limited shelf life, which shrinks as the temperature rises. An open can must be used quickly, as contact with environment can also affect its properties. The algorithm of actions when working with silicone should be as follows: we take out cans of silicone from a cool place, wait for it to warm up to the prescribed 23 degrees, mix the contents of each can thoroughly, combine components A and B in exact proportions, subject the finished mixture to degassing, fill into the mold and return the remaining silicone to the cold room.

In general, it should be remembered that silicone is a very capricious material that does not allow liberties in handling.

Silicone vagaries

In principle, the process of making silicone castings is elementary, but this simplicity is deceiving. Silicone constantly brings unpleasant surprises, not allowing the master to relax and make mistakes. The main danger for uncured silicone is inhibition (poisoning) by various substances incompatible with it. The most formidable and at the same time the most common "enemy" of silicone is plasticine containing sulfur. To work, you only need to buy plasticines marked Sulfur Free, such as Monster Clay or Chavant. It is better not to keep the doubtful plasticines in the workshop at all - even an accidental touch of the hand to the sulfur-containing material can "infect" the silicone mold.

The second "enemy" of silicone is latex. Do not use latex gloves, syringes with rubber nozzles on the pistons, or any other instrument that has latex parts in its construction.

Use with great care wooden sticks for mixing the mixture. Some silicones do not tolerate wood contact and may be inhibited. To hedge against unpleasant surprises, it is advisable to stir the silicone with metal stirrers.

Freshly cured polyesters, epoxy and polyurethane rubbers are also dangerous. As I wrote above, before using any new material, you need to test it by filling it with a small portion of silicone. If the mixture completely cures within the usual time allotted for full polymerization, and the silicone surface is not sticky, it can be considered that the new material has successfully passed the exam and can be used in further work.

That is, in fact, all that I wanted to tell about the techniques of working with silicone. I myself often made mistakes, experienced many unpleasant moments and I hope that this hard-won experience will help novice craftsmen not to step on painfully familiar old rakes, save nerves, time and money. Good luck with your creativity!

Brief background. The task before us was to make a certain number of rubber buttons from the car keys according to the sample. We tried to print them on a 3D printer from a rubber filament, but the quality did not suit. It was then that the idea came to reverse the technology of casting in silicone. What came of this, read under the cut.
There are a lot of photos.

Technology overview

Plastic injection molding

Not exactly rubber, but the essence is the same: a special machine - an injection molding machine (TPA) - brings the raw material (2) to the melting temperature and through the outlet die (3) injects the melt into the mold (4,6). Typically, thermoplastics are used as feedstock.

Pros: manufacturability, high speed receipt of the product, the widest list of materials, high final quality, the highest degree of detail. Cons: here - manufacturability, unjustifiably high cost for home use, high energy consumption, payback only on large circulations.

Silicone casting

The technology is simple and elegant, those who want to get acquainted in more detail can follow the links in the title, but here I will give a short description. The master model is placed in a bath and poured with a liquid silicone mixture, after a while the silicone hardens. The resulting one is cut and the master model is taken out of it. Due to its physical properties, the silicone immediately takes on its original form with a hollow in the form of a master model, into which anything hardening should be poured. Anything hardened is removed in the same way as the master model. Pros: simplicity, cheapness, repeatability. Cons: not everything is so simple, bubbles in the product, sometimes a rather lengthy process, a limited range of materials, dirt - then you walk around and stick to everything.

So let's go! After practicing a little on cats, it was decided to make a matrix not based on silicone, but on the basis of the same plastics that are poured into these very silicones. The principle is the same here: we mix the two components of thermosetting plastic with each other and pour into the finished matrix until curing. There are a number of reasons why I decided not to use silicone as a matrix. Firstly, even when using a large amount of separating lubricant, it was not always possible to normally tear the model off the matrix; several pieces had to be thrown away. Secondly, silicone matrices quickly deteriorate, especially if they are boiled to accelerate the polymerization process. Thirdly, the silicone still deforms, especially if you squeeze out the air bubbles by hand, and not with a compressor. Fourthly, I had a lot of plastic and little silicone, however, after several unsuccessful attempts to pour the mixture into the matrix before its polymerization, the situation changed to the opposite. And fifthly, I just wanted "like at a factory." A classic mold consists of a die (usually the lower part) and a punch (usually the upper pressure-generating part). I decided to start with making a matrix, into which the master model will be "poured". I immediately apologize for the possible hidden advertising on business cards, I tried to remove everything from the kata, initially the goal was not to post here. As you can see, the part itself is small, which means that laminated business cards can be used as formwork. Lamination, in addition to an aesthetically smooth surface, makes it possible to dispense with the use of a release agent. Based on previous experience, I decided that the model would not just lie with its back on the business card, but on a small plasticine platform. As a result, the product will be, as it were, recessed in the tray, which will give an additional opportunity to avoid bubbles.

I glued it with superglue to the plasticine, otherwise it won't stick. The bath is inside out. We glue the holes. Result To press the punch, I decided to "pour" four pins along the edges into the matrix. The bottom line is this: the back of the buttons, the one that is glued to the plasticine bath, is a counterpart for the punch, to which it will be pressed. Accordingly, we will "pour" the thread into the same part.

In the photo, part of the thread is closed with a tube, this is the counterpart of the punch. Since it is very difficult to set the parallelism of the pins by eye, on another business card I drilled holes in the same places and assembled something like this frame: As you can see, the threaded ends are facing the inside of the matrix ...

The result with the formwork will look like this: As a direct pouring material, I used what the seller recommended with the words: "Holds 120 Celsius and hardens in three minutes." Actually, this is a cardboard box with two jars of yellow and blue colors, half a liter each. The liquid in the jars is transparent, one thinner than the other. Well, that is, the contents of the blue jar are thicker, and the contents of the yellow jar have a yellowish tint. After polymerization, the composition loses its transparency and becomes, I don't even know how to express it otherwise, but softly white. The chemical composition is not really known, the yellow one says: 4,4'-Methylenebis (phenyl isocyanate) and a warning of urgent and inexorable death in the most terrible agony, if suddenly something. But the blue jar tells us that "No hazardous ingridients", but there is still WARNING on it. One way or another, but children Soviet Union do not intimidate with such trifles, which means we will work with what we have.

Actually, a photo of cans: It is necessary to stir the whole thing in a one-to-one ratio, which is damn convenient, unlike silicone, into which 3-4% of the catalyst must be poured. Go measure when the final product weighs half a gram!

Informative page

If you mix in any proportions different content options from all four jars (yellow, blue, silicone and silicone catalyst), then absolutely nothing will happen. For the phases of liquids do not coincide and they do not mix. But if you mix everything together, and even in the right proportions, we get an indistinct mass, similar to very fragile polyurethane foam.

So let's go!

We prepare the proportions: We mix: With the help of a can and a compressor we degas from the refrigerator (we get rid of gases, that is): And ... we don't have time to do anything. The mixture is solidified.

But now I have a beautiful, anyhow, minus one-fifth of the plastic: By the way, this is a very important point: you need to know exactly and be sure of what exactly you are going to do. If the whole process is carried out manually, including mixing, degassing, pouring back and forth, it must be understood that the pot life of the mixture must be sufficient to carry out all these procedures. Well, and a lot of small moments that are difficult to foresee without sad experience or experienced advice. For example, a degassing chamber. I collected it on my knee from the compressor from the refrigerator and glass jars with lid. It seems nothing complicated, but a lot of bugs immediately got out. First, it is impossible to get a hand out of the can if you hold a glass at this time.

This is how I looked when the first time I tried to do it: Second, the hose from the compressor enters exactly the center of the lid from the can, respectively, when the pressure is normalized, the air forcefully hits exactly the center of the mixture. As a result, minus the second fifth of the plastic and the white, opaque walls of the can. Third - the hose is short and hard, and strives to overturn a small and light jar of contents. Minus the third and fifth plastic. Of course, after that I began to think over all my actions in advance, with various scenarios. As a result, I was able to achieve something: I must say that in this case I decided to do without using a compressor. Next, you need to "strip" the matrix: Remove the plasticine and admire the result: Put the master model in place and assemble a new formwork: Here we will pour the mixture that will form the punch, this is the counterpart of the matrix. Of course, so that the pins are not flooded with plastic, they are fitted with tubes. If desired, they can then be pulled out of the punch. The insides must be lubricated with a release agent, for this I use a wax solution in the form of a spray.

Result after removing the formwork: A little processing and here's the result: A few words about plastic. During the polymerization process, the plastic can get quite hot, and heating speeds up the reaction. Accordingly, the larger the volume we mix, the more heat is released and the faster the mixture hardens. This must be taken into account. The intermediate stage - gel - lasts literally a minute, at this stage there is still an opportunity to correct minor flaws. After complete polymerization, a product is obtained that resembles ivory in texture. It is lighter than ABS and less durable, it seems to hold the temperature better. Easily processed mechanically, glued, painted (it is better to use a dye in the process of mixing the components), sinks in water, burns. With strong heating, it first passes into a less solid phase, then becomes very plastic. But not fluid! That is, it cannot be crumpled, otherwise it will simply crack. With destructive overheating, the plastic begins to crumble, suddenly turns into a fluid mass, becomes transparent and changes its color to the color of burnt sugar. Stinks and all that of course is present. Can it be used as a substitute for thermoplastics? It depends on why, but in general cases, yes, and given the fact that this is not the most durable option available on the market, it is definitely possible.
Well, now what this whole thing was started for is the production of silicone copies. Since I had only white silicone, ..

Personally: ... but the buttons need black, I had to improvise with the toner from a laser printer: I already mentioned the difficulties with the selection of the silicone / catalyst ratio, here the insulin syringe came to the rescue. I stirred the whole thing and smeared the resulting kaku first on the punch, and then poured the rest into the matrix, where the "bulge" I made from plasticine came in handy. After 10 minutes: Result after trimming: conclusions

The technology is working, there is nothing complicated, the materials are available. For home or small series, a great option. Suitable for large items in the same way as thermoplastics. A very serious disadvantage is the mud. Maybe I'm such a swine, but the fact that I screwed up my workplace, very frustrating.

 

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