Aluminum casting at home: making molds, technological process. Making molds for casting aluminum Aluminum plate casting technology

Aluminum casting at home is an excellent hobby that will help you pass your free time and can help you out at the most unexpected moment. There are several methods of such casting, many of which are used in industrial production, but some are also suitable for home use.

Aluminum has gained great popularity among home craftsmen. This is due to its performance characteristics, light weight and ease of casting. Using casting, you can easily and quickly produce various parts needed for household needs.

The most common methods are: injection molding and die casting. The first method requires special equipment, so the second is more popular. This is very simple technology, which can be used at home.

Characteristics of aluminum

Aluminum is a silver-gray metal that is distinguished by its ductility and lightness, can be stamped very well and bends well. The melting point of aluminum is about 660 degrees and the boiling point is 2500 degrees.

This metal has a high degree of heat conductivity. It is characterized by active interaction with oxygen, due to which an oxide film is formed on the surface of aluminum. It differs in color and physical characteristics, protects the metal from complete oxidation under the influence of an aggressive external environment. It has a high melting point, exceeding the temperature of aluminum, which affects the final result.

This metal has the property of changing its structure after melting. Its sudden cooling is not advisable, as it can lead to shrinkage of the resulting product. This property should be taken into account when casting aluminum products at home.

Technology

The technology for casting aluminum parts at home is quite simple, but requires careful fulfillment of the requirements and a lot of attention to the details. The simplest technology is to pour molten aluminum into prepared molds. In this case, it is necessary to have a minimum set of necessary equipment.

The main task is to melt the wax or paraffin inside the mold and replace the voids with aluminum, after which the cooled part can be easily removed. The first thing you need to do is prepare the formwork, which can be any cardboard box, for example, from under shoes, or make it from plywood. Paraffin or wax is poured into it.

When working with paraffin, some features should be taken into account:

1. Paraffin poured into a mold cools very quickly, so this process should not be accelerated. The part must cool on its own, this will maintain a homogeneous structure. For complete cooling, you need to wait about a day, after which you can proceed to processing it.
2. Paraffin can sag significantly in the center of the workpiece, so you need to take this fact into account when assessing the required dimensions of the workpiece.

Cutting the correct shape from a workpiece is a very difficult task. Therefore, a person who does not have the proper experience will not be able to cope with it.

The mold for pouring aluminum should be made of plexiglass, which is firmly held together with sealant. After this, at the bottom of the prepared “aquarium” there is a blank that needs to be secured so that it does not move during the process of pouring plaster. This can be done using plasticine.

Then you should prepare a gypsum mixture, which is prepared with the addition of fine-grained sand (in a one-to-one ratio). This is very important, since pure plaster contains a lot of moisture, which evaporates when the part is cast and affects the quality of the finished product.

The mixture should be homogeneous, the thickness should resemble sour cream. It is important that the mixture completely covers the paraffin workpiece.

It is worth remembering that gypsum hardens very quickly, so work must be done at a fast pace. After filling the mold completely, shake it to get rid of air bubbles.

After the plaster has hardened, the plexiglass form must be removed. This is followed by removal of paraffin. This can be done by placing the mold upside down on a hot sheet of iron heated over a fire. You can also boil the mold in water, which will remove the paraffin more thoroughly. After this, the plaster mold must be dried.

There are several ways to melt aluminum, but home casting technology involves self-production crucible furnace or using a muffle furnace. The crucible furnace is made only from refractory bricks.

Once the metal is melted, the aluminum casting process can begin. Using a spoon from of stainless steel the oxide film should be removed. You can try to melt the metal using gas burner, which will be sufficient for a small volume.

After hardening, the mold is removed from the plaster, cleaned and polished.

The technology may change depending on the requirements for the finished product and the available tools. Through trial and error, you can achieve the optimal technology.

Preparing parts

Home casting requires special preparation, as well as the availability of certain tools, among which we should highlight:

1. Aluminum scrap. Many products can be used as scrap, including wire. But you should choose a softer one, as it contains less oxides.
2. Gypsum. Molds for casting aluminum at home are best made from sculptural plaster. But its cost is quite high, so ordinary white plaster is quite suitable. It is easy to find at any hardware store. The main thing is not to confuse it with alabaster, which looks like white plaster, but is absolutely not suitable for casting.
3. Wax or paraffin. Wax is the best option, but paraffin is cheaper and easier to find. You can use regular candles by removing the wick and melting them.
4. Melting containers. To melt paraffin, you can use ordinary tin containers, but for melting aluminum it is recommended to use containers made of stainless steel or cast iron.
5. Source of high temperature. You can use either specialized muffle or crucible furnaces, or conventional gas burners. The choice of heating source is individual and depends on the volume of molten metal required.

Basic mistakes when casting aluminum

Many beginners make simple mistakes when making aluminum castings, so it is recommended that you familiarize yourself with them before performing work. The following basic errors should be highlighted:

1. The plaster mold must be carefully prepared. It is very important that all moisture evaporates completely. If this does not happen, then during the pouring of the metal the moisture will evaporate, leaving pores and voids. This significantly affects the quality of the finished product.
2. Insufficient heating of the metal can lead to poor mold fillability, which may leave unfilled voids.
3. There is no need to further cool the metal; the cooling process should occur naturally.

By preventing the occurrence of the above errors, you can get a high-quality result.

Melting of aluminum, like other substances, occurs when thermal energy is supplied to it, from the outside or directly into its volume, as happens, for example, with induction heating.

The melting point of aluminum depends on its purity:

• Melting point of ultra-pure aluminum 99.996%: 660.37 °C.
• With an aluminum content of 99.5%, melting begins at 657 °C.
• With an aluminum content of 99.0%, melting begins at 643 °C.

The melting point of aluminum increases with increasing pressure. The dependence of the melting temperature of aluminum on pressure is presented in the graph below.

Melting point of aluminum alloys

Adding other elements to aluminum, including alloying elements, reduces its melting point. Thus, for some cast aluminum alloys with a high content of silicon and magnesium, the melting point decreases to almost 500 °C. In general, the concept of “melting point” applies only to pure metals and other crystalline substances. Alloys do not have a specific melting point: the process of their melting (and solidification) occurs in a certain temperature range.

Solidus and liquidus temperatures of aluminum alloys

When an alloy melts, the temperature at which melting begins is called the solidus temperature (or slidus point), and the temperature at the end of melting is called the liquidus temperature (or liquidus point). “Solidus” means, of course, solid, and “liquidus” means liquid: at the solidus temperature the entire alloy is still solid, and at the liquidus temperature it is all already liquid. When this alloy solidifies from a liquid state, the temperature of the beginning of crystallization (solidification) will be the liquidus temperature, and the end of crystallization will be the same solidus temperature. At an alloy temperature between its solidus and liquidus temperatures, it is in a semi-liquid-semi-solid, mushy state.

Eutectic temperature of aluminum alloys

Not all alloys have a range between solidus and liquidus temperatures. Such alloys are called eutectic. For example, in an aluminum alloy containing 12.5% ​​silicon, the liquidus and solidus points are reduced to a point: this alloy, like pure metals, has not an interval, but a melting point. This point and temperature is called eutectic. This alloy belongs to the famous cast aluminum-silicon alloys - silumins with a narrow solidus-liquidus interval, which gives them the best casting properties.

In the Al-Si binary alloy, the solidus temperature is constant and amounts to 577 °C. As the silicon content increases, the liquidus temperature decreases from maximum value for pure aluminum 660 °C and until it coincides with the solidus temperature of 577 °C with a silicon content of 12.6%.

Among other alloying elements of aluminum, magnesium lowers the melting point the most: the eutectic temperature of 450 ° C is achieved with a magnesium content of 18.9%. Copper gives a eutectic temperature of 548 °C, and manganese - only 658 °C! Most alloys are not double, but triple and even quadruple. Therefore, with the combined influence of several alloying elements, the solidus temperature—the beginning of melting or the end of solidification—can be even lower.

Melting temperature range of aluminum alloys

The table below presents the liquidus and solidus temperatures of some commercial wrought alloys. It must be borne in mind that the concepts of temperatures solidus and liquidus are defined for equilibrium transformations of the liquid phase into the solid phase and vice versa, that is, for infinite duration of the processes. In practice, corrections must be made taking into account the rate of heating or cooling.

Sources:
Aluminum and Aluminum Alloys, AMS International, 1993.
Handbook of Aluminum: Vol. 1, ed. G. E. Totten, D. S. MacKenzie

As is known, the melting point of aluminum is over 660°C. Using home heating appliances such as an iron, oven or gas stove, it is unlikely to achieve such a temperature. Therefore, smelting aluminum at home becomes possible with the appropriate equipment and, of course, the raw material for smelting - aluminum.

For aluminum melting, crucible melting is usually used. I described the manufacturing process in detail in my Dimanjy TechnoBlog. The peculiarity of this furnace is the top loading into the working chamber of the so-called crucible - a special ladle for melting aluminum, into which the raw materials are placed. The compact dimensions of the muffle furnace with vertical loading make it easy to store and use it at home on the balcony, in the garage or in the country house.

Now let's talk directly about the process of melting aluminum at home.

As already mentioned, for melting aluminum in muffle furnace needed. It is usually made of a fire-resistant material or a metal with a much higher melting point than aluminum. Corundum, graphite, porcelain, quartz, cast iron or steel are used to make crucibles. I managed to make a crucible from steel myself. You can buy a crucible made from other materials ready-made, but one made from steel turned out to be much simpler and more practical, especially if you have a welding machine and basic welding skills and operating a grinder.

The crucible size should be selected based on the amount of aluminum you want to melt. Heat must be transferred evenly from the hot crucible to the raw material. In turn, the crucible should also be heated evenly. For a muffle furnace of my design, I plan to make several crucibles of different volumes to work with one or two heating elements at the same time.

The aluminum is packed into the crucible as tightly as possible. To do this, it is advisable to grind the raw materials and slightly compress them. I used regular aluminum wire for melting, so I just cut it with wire cutters and pressed it tightly with pliers.

When melting, aluminum significantly decreases in volume compared to the original material (after all, in principle, we then melt it), so in the process of melting aluminum at home, we will need to periodically add raw materials to the crucible.

It should be noted that this can be extremely dangerous! The whole point is that moisture can linger somewhere in the raw materials we add, and when water gets into the molten aluminum, a sharp splash occurs, and the metal can splash out of the muffle furnace, damaging you with serious burns. And there will be absolutely disastrous consequences if molten metal gets into your eyes. Therefore, always monitor your safety - work exclusively in protective glasses or a mask, and even better - in a special fire-resistant metallurgist suit.

During the process of melting aluminum at home, an oxide film will form on the surface of the molten metal and any slag will float to the surface. The amount of slag depends on the quality of the raw materials used to melt aluminum. Somewhere it was tinted, somewhere it was stained - all this will leave the metal in the form of slag. Immediately before casting molten aluminum into molds, it is recommended to remove the slag using a special device.

Also, after the aluminum has melted and formed a uniform shiny drop, as the liquid terminator did in the movie “Terminator 2,” it is recommended to keep the crucible in the oven a little longer to give the molten aluminum greater fluidity. This will greatly simplify further casting.

What's next? Obviously, you need to pour molten aluminum into a specially prepared casting mold. I wrote a separate article about this in my TechnoBlog Dimanjy, which is called “”. Let's study, train, gain experience!

Aluminum is one of the most common metals on earth. It is present even in the human body, so what can we say about the surrounding reality. Every home or personal car has aluminum functional elements, parts or assemblies that, alas, break quite often. This is furniture and window fittings, guides for doors and shutters, lock latches and other necessary little things.

They can be replaced with purchased new products, repaired, or made independently. In the last two cases, you may need to melt aluminum at home.

Characteristics of aluminum

It is not necessary to know all the characteristics of metal for homemade projects. But there are several points that can become significant or even dangerous in the work.

Aluminum lends itself well to casting and melts at a relatively low temperature of 660 °C. For reference: cast iron begins to melt at a temperature of 1100°C, and steel - 1300°C.

Therefore, melting aluminum at home on a gas stove is difficult to achieve, since home gas appliances cannot provide such a temperature. True, domestic “Kulibins” can do anything, but more on that later.

You can reduce the melting point of aluminum by grinding it into powder or using a finished powder product as a raw material. But here another property of aluminum becomes important. It is a fairly active metal, which, when combined with atmospheric oxygen, can ignite or simply oxidize. And the melting point of aluminum oxide is more than 2000 °C. When melting, oxide is still formed, but in small quantities; it is this that forms scale.

The same activity can play a bad joke if water gets into the molten metal. An explosion occurs. Therefore, if you need to add raw materials during the smelting process, you need to make sure that it is dry.

Raw materials for smelting

If you have to melt aluminum at home, it is not used as a raw material due to the complexity of working with powdered metal.

You can purchase aluminum ingots or use regular aluminum wire, which is cut into small pieces with scissors and pressed tightly with pliers to reduce the area of ​​contact with air.

If a particularly high quality of the product is not expected, then any household items, tin cans without a bottom seam or profile trimming, can be used as raw materials.

Recycled raw materials can be colored or stained, this is not a problem, the excess components will come off as waste. You just need to remember that you cannot inhale the fumes of burnt paint.

In order to obtain high-quality aluminum smelting at home from recycled materials, it is better to purchase ready-made fluxes, the task of which is to bind and bring to the surface of the molten metal all impurities and contaminants. But you can make it yourself from technical salts.

The coating flux is prepared from 10% cryolite and 45% each of sodium chloride and potassium chloride.

Another 25% of the total mass of sodium fluoride is added to the refining flux to obtain aluminum without porosity.

Personal protective equipment when melting

Melting aluminum at home is an unsafe process. Therefore, you need to use personal protective equipment (PPE). Even if such melting is needed once on minimal equipment, then at least you need to protect your hands, for example, with special welding gloves, which perfectly protect against burns, because the temperature of liquid aluminum is more than 600 ° C.

It is also advisable to protect your eyes, especially if melting occurs quite often, with goggles or a mask. And ideally, you need to work in a special metallurgist suit with increased resistance to fire and high temperatures.

If you need very pure aluminum using a refining flux, you should work in a chemical respirator.

Casting shape

If you only need to cast pure aluminum for solder, then a casting mold is not needed. It is enough to use a steel sheet on which the molten metal will cool. But if you need to cast even a simple part, you will need a casting mold.

The casting mold can be made from sculptural plaster, namely gypsum, not alabaster. Liquid plaster is poured into an oiled mold, allowed to harden a little, shaking occasionally to release air bubbles, the model is inserted into it and covered with a second container of plaster. IN convenient location you need to insert a cylindrical object into the plaster so that a hole appears in the mold, the so-called channel, into which molten aluminum will be poured. When the plaster has completely hardened, the two parts of the mold are separated, the model is taken out, and the mold with the finished cast is connected again.

A casting mold can also be made from a mixture of 75% foundry sand, 20% clay and 5% coal sand, which is poured into a special box made of boards and compacted. The model is pressed into the compacted earth, the resulting imprint is sprinkled with talcum powder and graphite (coal dust) so that the cooled aluminum part can be easily separated from the mold.

Melting crucible

Melting aluminum at home requires a special container with a spout made of refractory material. This is the so-called crucible. Crucibles can be porcelain, quartz, steel, cast iron, made of corundum or graphite. At home, you can use a purchased crucible or make one, for example, from a piece of steel pipe of sufficiently large diameter. True, for this you need a grinder, welding machine and skills in using these tools.

The dimensions of the crucible depend on the required amount of aluminum to be melted. This ladle should be heated evenly, and its heat should be transferred to the raw materials.

Melting furnaces

The technology for melting aluminum at home is quite simple. In a special ladle, scrap aluminum is heated to a temperature exceeding the melting point of this metal, the melt is kept in a heated state for some time, slag is removed from its surface, then the pure metal is poured into a mold to cool. The melting time depends on the design of the furnace, that is, the temperature that it can provide.

If a blowtorch or gas torch is used, they heat the aluminum from above. True, the oven is still made of bricks in a well without a binding solution, inside which coals will burn to heat the container from below and maintain it in a heated state.

The design of the furnace looks approximately the same if the crucible is heated from below using ordinary firewood and a hair dryer. Only in this case, the firewood is stacked in a brick well not on the bottom, but on a grate located on the first row of bricks, and in this row there is a hole left for a metal pipe placed on the neck of the hair dryer and secured to it with electrical tape. The crucible in this case is tin, naturally, not aluminum, in which diametrically opposite through holes are made at a short distance from the top. A steel rod is threaded through these holes, by which the can must be suspended in the oven. A hair dryer is needed to pump hot air into the space between the bricks and the crucible. Sometimes a metal barrel is used instead of bricks.

If melting must occur quite often, then you can make a muffle furnace with your own hands with vertical loading of the crucible or buy a ready-made one.

Melting with a blowtorch

Melting aluminum at home with a blowtorch should not take place indoors. In addition to raw materials, a blowtorch, crucibles and bricks, you need to prepare firewood, pliers and a steel rod.

So, a small well was made from bricks so that a ladle with aluminum and a small steel sheet could be installed on top. A fire is lit in the well, which must burn out a little to form coals.

Next comes the actual melting of aluminum at home. Step-by-step instruction process:

A container with raw materials is placed on the bricks. It needs to be heated for about 15 minutes.

After this, the burner of the blowtorch is turned on at full power and the aluminum is heated from above.

The process begins within a few seconds, but in order for the heating to be uniform, the metal in the container must be carefully mixed with a steel rod, holding it with pliers (remembering to wear gloves). You can do without a rod by periodically shaking the bucket using the same pliers, but very carefully.

When the liquid becomes homogeneous, you need to take the container with pliers and pour the contents onto the calcined steel sheet so that all the resulting scale remains in the ladle, and only clean metal gets on the sheet to harden.

This is how pure aluminum is usually obtained from recycled materials if aluminum parts need to be soldered with it.

Melting with wood or gas

Aluminum smelting at home using wood occurs in lightweight collapsible furnaces. The disadvantage of this method is the uncontrollability of the process. It is not possible to increase or decrease the heating temperature. It is possible to intervene in the process only by removing the container with aluminum from the heat.

Melting aluminum at home using gas is the only possible option for an apartment. The container needs to be heated for a long time, periodically draining the molten metal. In this case, casting is performed in layers. To work, you will need two metal containers of such diameters that one fits over the other. The smaller one serves as a crucible. It is placed with a crowbar, for example cut aluminum wire, on the burner from which you need to remove the flame divider of a household gas stove. A larger capacity will have to be worked on first. About a dozen small holes are made in its bottom. Bolts are screwed into two or three of them, which act as handles, by which the hot container can be lifted with pliers.

This container is placed upside down on the crucible. This design allows aluminum to be heated. Periodically, the upper container must be removed and the scrap mixed with a metal rod or knife. Before draining the molten metal, the slag must be removed from its surface.

Melting aluminum in a muffle furnace

A muffle furnace is already quite a serious piece of equipment for producing high-quality molten metal. Therefore, when melting, flux is used to clean aluminum from impurities. And this is almost a production process, and not smelting aluminum at home.

The step-by-step instructions also include several points for preparing raw materials:

• First, flux is melted in a crucible, which must be taken in an amount of 2 to 5% of the weight of aluminum, and then scrap is added to it.
• How active the flux is can be determined by the surface of the melt - it should be mirror-like. If this is not the case, a little more flux is added to the melt, then it will be necessary to add it before the end of the melt to make it easier to remove the slag from the surface of the metal with a steel spoon.
• Melting should be carried out at approximately 700-750 °C. This is the temperature of the red glow.
• During the smelting process, it may be necessary to add raw materials to the crucible, since the molten metal is greatly reduced in volume.
• Refining flux is added, if necessary, at the end of the melt in an amount of 0.25% by weight of the molten metal. Maintaining such a proportion at home is not an easy task. After adding flux, the melt must be mixed with a spoon, let stand for about 5 minutes, then remove the slag.
• When, as a result of heating, the aluminum has turned into a homogeneous shiny drop, the crucible must be kept in the oven for some time so that the metal becomes more fluid.
• Then the aluminum from the crucible through the spout (at this moment it becomes clear why such a ladle is needed) is poured into the mold in a thin continuous stream.
• After complete cooling, the mold is carefully divided into halves, the finished part is removed from it, which still needs to be finally processed: drill holes, if necessary, clean and sand the surface with sandpaper. That's all. The process is complete.

So don’t be alarmed in advance if you have to melt aluminum scrap at home in order to get pure metal or make a part to replace a broken one. Serious professional skills are not at all needed to organize such a foundry. The desire and skillful hands of an ordinary amateur craftsman can work wonders.

Many people perceive the term "foundry" as something associated with large production and professional skills and abilities. But, in fact, casting a part yourself at home is possible even for the most humanist who knows nothing about casting technology.

How to cast an aluminum part

Metal characteristics

Aluminum is one of the cheapest, most common and accessible metals, which can be easily machined and cast. The main features of aluminum are high electrical and thermal conductivity, as well as increased corrosion resistance. The boiling point of this silvery-white metal is 2500 °C. Pure aluminum melts at a temperature of 660 °C, and technical aluminum - at 658 °C. Home heating devices are unlikely to be able to provide such a temperature, so it is better to use a crucible muffle furnace to cast an aluminum part.

Muffle furnace and its purpose

A muffle furnace is an indispensable device for heating various metals yourself at home. Such a device is capable of melting not only aluminum, but also copper and many non-ferrous metals, as well as drying and firing ceramic products.

Types of muffle furnaces

Muffle devices for melting metals are of the following types:

• vacuum;
• air;
• gas;
• electric.

By design they are divided into:

• tubular;
• vertical;
• horizontal;
• bell-shaped

A muffle furnace consists of a heating chamber and a special heat accumulator.

Making a muffle furnace with your own hands

To make the device we need the following tools and materials:

• wire;
• Bulgarian;
• brick (7 pcs.);
• protective glasses;
• hammer;
• metal bucket;
• piece of iron, etc.

Furnace construction stages:

For greater functionality it is allowed installation of two electric heaters, which can be turned on one by one or simultaneously. For example, for soldering a small amount of raw materials, only one lower heater is turned on, and if the scale of melting is large, two devices are used.

The muffle furnace with vertical loading is very compact, which allows you to store it in the country house, in the garage or on the balcony.

The principle of operation of the furnace is quite simple: the soldering container (crucible) with the raw materials placed there is installed on the working surface of the furnace where it is heated to the required temperature (660 °C). The heated metal is poured into a pre-prepared casting mold, which can be made from plaster or some other non-flammable material. To make the mold, it is recommended to use white or sculptured plaster, which can be purchased at any building materials store.

As mentioned earlier, for soldering aluminum in a furnace need a special bucket(crucible), which is made of a metal that has a melting point higher than that of aluminum or from a refractory material. Porcelain, graphite, corundum, quartz, steel or cast iron are used to make containers for melting aluminum. The ladle can be purchased at a specialized store or made independently. The size of the crucible is determined by the expected amount of raw material to be melted.

The metal must be laid as tightly as possible and slightly compressed. Since aluminum loses significant volume during melting, raw materials should be periodically added to the ladle.

Important. The added raw material must be absolutely dry, since even a small amount of moisture entering the hot aluminum can cause a sharp splash, as a result of which the metal splashes out of the furnace and can cause severe burns, especially dangerous if molten aluminum gets into your eyes.

Therefore, before starting work, you should take care of your safety: purchase safety glasses or a mask, or better yet, get a special fire-resistant metallurgist suit.

During the process of melting metal at home, an oxide film will appear on the surface of hot aluminum, as well as various slags form(old paint, particles of dirt, etc.). Its quantity directly depends on the quality of the raw materials. Before pouring the molten metal into molds, it is necessary to remove the slag using special devices. Then it is recommended to keep the aluminum in the oven for some more time to give the metal greater fluidity. This will greatly simplify its further casting.

Casting an aluminum part yourself

Let's look at the easiest way to solder a part at home.

We will need:

• metal scrap;
• smelting ladle;
• molds.

Process steps:

• Prepare a container for melting aluminum at home. For this purpose you can use a piece steel pipe.
• Make a mold. For parts with a complex structure, the form may consist of several elements. The mold can be made from plaster (sculptural). Do not use alabaster under any circumstances!
• To prevent the plaster from sticking to the mold container, you must first lubricate it with oil.
• During the process of pouring gypsum, the container must be shaken periodically to prevent the formation of bubbles.

Important. Since plaster hardens very quickly, try to install the model of the part in plaster as soon as possible. It is also recommended to install a small object (for example, a stick) in the plaster, which will serve as a channel for pouring the future part.

A good owner always wants to fix any problems in his home as soon as possible. Therefore, immediately after the breakdown of parts of some structures, for example, sliding doors, he is wondering how to melt aluminum at home on his own. This process is generally simple, so it will be enough to try the entire procedure once so that no more questions arise about how to melt aluminum at home correctly. First of all, you will need to prepare a mold for the liquid material. It is best to make it from boards and flasks. After the mold is formed, clay, molding sand and coal dust are added to it. Their ideal percentage ratio is: 20% to 75% to 5%. Next, you will need to press the compacted mixture into an object, following the example of which the required part will be made. The clearer the print, the better the result. At the end it is sprinkled with talcum powder.

Even scraps of old ones are suitable for melting. aluminum profile. You can also purchase aluminum ingots in a hardware store at the lowest cost (about 60 rubles per kilogram). If the high quality of the product that you plan to create is important, then it is better to pay attention to more expensive material and refuse to use scraps. But the tips on how to melt aluminum at home will be the same for any chosen option. The easiest way is to use a ready-made furnace in the process, for example, a muffle or a small forge, which will also perfectly replace it. The pieces of metal are placed in a convenient container with a spout, made of cast iron or steel, and then sent to the oven and heated. After melting, the aluminum should be kept at high temperature for another 6-7 minutes. Only after this can it be removed from the oven and slowly poured into the mold without interrupting the flow.

But you can make a furnace for melting aluminum yourself. To do this, you will need to take any refractory container (for example, a regular scoop), a gas burner and a pre-heated steel plate. The base of the furnace will be created from bricks. They will need to be laid out with a miniature well, under which a fire will be lit. If you don’t have bricks at hand, you can replace them with ordinary skewers. Next, a fire is lit; it is necessary to heat the metal in the lower part, as well as to maintain a high temperature when the burner is turned off. When a sufficient amount of coal is formed under the “stove”, it will be possible to install a refractory container with the required amount of aluminum on bricks or skewers. It should warm up for about 17-20 minutes. After this time, the burner is turned on to maximum temperature and directed to the container from above.

If all stages are completed correctly, the melting process will begin in a couple of seconds. But for an excellent result, you must ensure that the heating is uniform. To do this, the hot mixture is periodically stirred with a steel wire or gently shaken. The main thing is to reliably protect your hands at this stage with special gloves from possible serious burns. It is best to use the uniform of professional welders. In addition, do not forget that when melting not a new aluminum ingot, but old profile scraps, the paint from them can evaporate. Therefore, in this case, care should be taken in advance to protect the respiratory tract. As soon as it is possible to achieve homogeneity of the liquid metal, you will need to carefully take the container with pliers and pour its contents into the previously prepared form. If it is not required, then simply pour aluminum onto a steel plate.

It is important to note that during the melting process of aluminum, scale is formed. This is the oxide of the metal in question. It is impossible to avoid its appearance, so the uniformity of the result should be assessed taking into account this very grin. When liquid metal is poured into a mold or onto a plate, the container will need to be tilted so that the aluminum oxide remains in it. In general, this is not difficult to do if you perform all the steps as carefully as possible. In cases where metal is melted to further create any parts or decorations, you should also stock up on a special grinding tool or regular sandpaper in advance. In order for the result to be worthy, the finished product, after it has hardened and cooled, will need to be carefully processed on all sides with the selected tool.

There are several aluminum casting techniques that are used in production on an industrial scale. But if we are talking about work at home, then the most acceptable way is to pour liquid aluminum into homemade molds. This is the technology we will talk about.

Before understanding the nuances of casting, it is advisable to remember some of the characteristics of this metal. at a temperature of about 660 ° C (depending on its purity), and boils at 2,500. Another feature that needs to be taken into account is rapid oxidation upon direct contact with air.

There are quite a lot of different “engineering solutions” that can be implemented when casting aluminum yourself at home. " Craftsmen", knowing its characteristics, they select it themselves necessary equipment and materials. One of the main problems is what and how to make a mold for pouring. This is where people who have no practical experience most often stumble. Therefore, we will consider only one of the simplest options, since it is unrealistic to cover all the methods in one article.

Let's start with what you need to prepare for casting:

Aluminum scrap

Each of us has encountered this metal. But has everyone noticed that, for example, aluminum wire can be different? One bends easily, like plasticine, and the other is harder, less pliable. For casting, it is advisable to choose the one that is softer, since such a material, relatively speaking, contains less oxides and more “pure” aluminum.

Gypsum

The easiest option for working from home. Its best brand is sculptural (marked “G - 16”). But it has yet to be found, and the cost of such quality product quite high. Therefore, in domestic conditions, white gypsum (designated “G - 7”) is more often used, which is not in short supply. It can be purchased at any specialized store that sells building materials.

He's appearance very similar to alabaster and the two can easily be confused. In addition, the seller, not knowing why the buyer needs plaster, may offer this “analog” instead. In the construction industry, materials often replace each other, since many of their characteristics are similar. But alabaster is definitely not suitable for making molds! This needs to be taken into account.

Wax

This material is mentioned in almost all recommendations for do-it-yourself metal casting. Indeed it is the best option, but only if we are talking about the manufacture of small parts. Pure wax is quite expensive, and there is no point in buying it in large quantities. Moreover, it is unlikely to be reused.

In practice, you use ordinary candles, which are found in any household goods department. Whether they are stearic or paraffin is not important. The quantity depends on the dimensions of the required part, the “blank” of which will be prepared from them.

You'll need a few more things as you go along. This will become clear when considering casting technology, and the choice of specific materials depends on the ingenuity and capabilities of the craftsman.

Melting containers

You can also melt candles in a regular tin. But for aluminum, the cookware needs to be stronger, since it will have to be heated quite strongly.

Heat source

What can I use? Muffle furnace or homemade crucible/. The main thing is to achieve the required melting temperature. As for the last “device” (crucible), it is clear from the picture how it works. You just need to take into account that the brick must be fireproof.

When using a sufficiently powerful stove to heat materials, it is necessary to include some kind of temperature regulator in its power circuit (if it does not exist). Such modernization will save time, nerves and electricity. It is enough to install a simple rheostat or an adjustable transformer (LATR). Otherwise, you will have to constantly turn on/off the device so as not to “drive” the temperature.

Casting technology

Making a blank

The task is to melt the paraffin and pour it into a mold with certain linear parameters. After it has cooled, it is easy to cut out an exact copy of the required part from the hardened mass. The easiest way is to take a shoebox. In principle, such “formwork” can be easily made from cardboard or plywood, securing the entire structure with adhesive tape.

Features of work

• The poured mass cools down for a very long time, and this process should not be forcibly accelerated. Hardening should occur naturally, then the structure of the blank will be uniform throughout its entire thickness. You will have to wait at least a day, since the top hard crust is not yet an indicator that the paraffin inside has hardened.
• The material used is characterized by significant shrinkage. In other words, in the central part of the mold the mass will “sag” somewhat during the cooling process. When calculating the dimensions of the required workpiece, this should be taken into account and paraffin should be poured with some reserve in volume.

Since you will have to manually cut out a part from a finished sample, it is clear that in the absence of experience (and perhaps even ability), it will not be possible to do everything accurately the first time, especially if you need to cast something of a rather complex configuration. But a rejected “blank” has only one path – to be melted down.

In order not to waste time, it is advisable to prepare two of them. If the first one is spoiled, then with the second one, taking into account the experience gained, the work will go more successfully. Considering that candles cost pennies, this will not “hit your pocket.”

Mold making

There are enough recommendations for its preparation. One simple way is to make it from plexiglass. This “aquarium” is assembled by fastening cut pieces of hardboard using plasticine. They also seal all joints.

Making a part template

A “blank” is placed at the bottom of the “aquarium”. To prevent it from moving during the process of pouring the solution, it is fixed with the same plasticine.

It should be taken into account that all other work is done quickly, since the plaster sets well. But this material is not used in its pure form. Its mixture with sand of the smallest fractions (50 to 50) is used. Otherwise, water will remain in the gypsum mass, which will begin to evaporate after pouring aluminum. This will cause pitting in the finished part.

The mixture is diluted to a medium-thick sour cream, after which the solution is loaded into the mold. You need to cook it so much that the “blank” is completely covered with it. In this case, it is not worth saving on material, especially since its price is low. To remove air bubbles, if there is no vibrating table, the mold must be shaken thoroughly by hand.

After the poured mass has hardened, the “aquarium” is dismantled. All that remains is to remove the paraffin from the plaster. It's easy to drown it out. For example, place a plaster template, bottom up, on a sheet of iron, and place it on an open fire. But this does not guarantee the “cleanliness” of the insides of the form. If the part is not just a metal plate or something similar, but has protrusions, cutouts, and so on, then a different method is used.

An unnecessary metal container is taken, into which a plaster template is placed and water is poured. The dish is placed on the fire, and when the liquid boils, the paraffin will begin to collect at the top (float). But it’s unlikely that you’ll be able to wash the container afterwards.

After the melting process is completed, the gypsum is dried. The temperature should be low, otherwise the material may “burn out” and become deformed, especially thin parts of the template.

Pouring aluminum

There is nothing complicated about this, just one nuance. It is necessary to keep a stainless steel spoon ready, which will immediately remove the resulting oxide film.

A few notes

• The “aquarium” shape can be made from any available materials. The main thing is that it does not fall apart during pouring of plaster, and that it can be easily disassembled later.
• It is not necessary to look for a muffle furnace or install a crucible as a heat source. You need to try whether the prepared aluminum scrap will melt, for example, from a gas burner. Perhaps argon will be sufficient. Everything that is on the farm is sampled.

When casting yourself, it is necessary to experiment, since the essence of all operations is presented quite clearly, and the examples given on equipment and materials are not dogma.

Casting aluminum at home is a process that can be done home handyman, however, it must be performed in accordance with a certain methodology. You need to know the characteristics of the material itself and understand how to work with it correctly.

Features of aluminum

Aluminum - material, widely used in different types industry, it is also suitable for home casting. Its advantages are:

1. Versatility in use;
2. Good performance characteristics;
3. Relatively light weight;
4. High indicators of ductility and malleability.

It also has disadvantages. In particular, metal does not lend itself well to certain types of processing.

Casting process

Thanks to casting, you can quickly make various devices based on aluminum for domestic or industrial needs.

The process can be performed under pressure or using molds. In the first case you will need:

1. Special equipment;
2. Specialized technological knowledge;
3. Press forms.

The process is also performed using conventional molds, which are made on the basis of a special homemade mixture. The production technology is quite easy to master. Aluminum has high ductility, thanks to which it can take on any shape. Its melting point is more than 600 degrees.

Previously, to make aluminum parts they used molds that were inserted into the ground, then homemade plaster molds began to be used. Now there are special molds from which parts are made under pressure.

At large enterprises, casting is carried out under high pressure and shrinkage is practically absent. For work, special cars and equipment. The technological process is quite complex:

1. The required working pressure is created due to the operation of the piston, and it is driven by compressed air;
2. Oil and emulsion help speed up movement;
3. The material, heated to the melting temperature, quickly enters the mold under pressure and fills it completely.

Products produced in this way rarely have any defects and are highly accurate. This technology is relevant in the manufacture of parts for aircraft manufacturing and instrument making. Molds allow you to use molten metal of any temperature.

Necessary equipment

To produce aluminum parts for various purposes with high precision under pressure, you will need special equipment: an automatic machine and durable molds. For aluminum casting, they are usually made from steel alloys.

Their casting surface must be almost ideal; no distortion of the geometric configuration and size is allowed. The mold must be equipped with a mechanism thanks to which the finished part can be removed from it without difficulty. In addition, it must also contain movable metal rods, with the help of which the internal cavities of the workpieces are formed.

Future products that you will pour into special molds will need to be given one or another configuration, which mainly depends on the molds themselves. This type of foundry process also uses specialized machines and other equipment.

Casting machines can have a cold or hot chamber in which the mold pressing process is carried out. Typically, hot chamber metal melting machines are used to produce predominantly zinc-based alloys. The required pressure is pumped into them using a piston or compressed air. Under pressure, the molten mixture is slowly forced into pre-prepared molds.

And machines that use cold pressure are mainly used when castings need to be made with the addition of copper and magnesium alloys. In this case, the molten mixture during the casting process enters the molds under very high pressure, sometimes it can be about 700 megapascals.

Thanks to injection molding, it is possible to achieve high performance, there will also be no need to subject the parts to additional machining. The machines differ by model depending on their operating parameters.

Production of molds

Special casting machines are practically not used at home. This is not advisable not only due to the high costs of purchasing them, but also because the process is quite technically complex. Moreover, the equipment that operates under pressure is very large.

At home, aluminum-based lost wax products are given the required shape manually. You can also make the form yourself. Many home craftsmen use the “in-ground” casting technique, thanks to which they can ultimately obtain the necessary aluminum parts without special equipment.

You can give the models of forms that you have to work with a certain configuration, and the forms themselves are made using scrap materials with your own hands. In particular, the form can be obtained from simple cement mortar. In such a situation, the lost wax can be given a rectangular or square shape. On the Internet you can find video tutorials on how to properly pour aluminum into cement.

Often used for casting plaster molds. In such a situation, plaster models can be given almost any configuration. A very important indicator when working with molds is the shrinkage of the material. When it hardens, it should be minimal.

When pouring aluminum, models can be given the desired configuration through the use of wax. But here it must be said that only small parts can be made using wax using aluminum. Thanks to a number of performance characteristics, wax models can be given even complex configurations, but parts can only be manufactured in this way once.

Using the foundry method, you can easily produce parts on a predominantly duralumin base. Dural is a material consisting mainly of aluminum alloy with a number of other components. But you need to know that the blanks that are smelted on its basis take a long time to harden.

Models that are used for metal casting must be prepared: they will need to be cleaned and oil applied as a lubricant.

Algorithm for working at home

Making aluminum parts using the foundry method at home is not that difficult; the process does not require expensive special equipment. Those models that will take part in foundry work will need to be cleaned from above and lubricated from the inside. Preparation will also be required when you practice the “in-ground” casting method. Be sure to check that the technological recess along its contours strictly corresponds to the contours of the future part.

As mentioned, the shrinkage of molten aluminum is an important parameter during operation. When filling, it should be minimal, otherwise the part will not correspond in size to those that were specified.

In order for the shrinkage to be minimal when the metal hardens, it will be necessary to make a small clay edging on the mold, along which molten aluminum is poured into it.

To melt the metal, a steel container and a special stove are usually used. At the same time, when performing work, do not forget about safety rules. If you decide to engage in the foundry process at home, you must follow personal safety rules. Be sure to wear special clothing that will protect your skin from possible burns.

Below have been discussed key aspects related to the aluminum casting process in both industrial and domestic settings. As you can see, anyone can do this at home; the work does not require expensive equipment; with the help of improvised tools, you can learn how to make all kinds of aluminum parts without leaving home.

Casting aluminum at home using the example of making a souvenir.

Hello!
Today I will tell you about my experience in sand casting using a burnout model.
Why does this method deserve attention? Everything is very simple! Literally easy! The fact is that there are many types of casting. And since we are talking about casting in sand (earth), we will consider its options.

You can watch the entire process in the video at the end of the article!

Sand casting is the most common casting method due to its simplicity and low cost. So you can easily cast something from aluminum at home or in. Still in modern world this is the prevailing technology. The key difference between all the options is whether we have a disposable model that is burned out during the pouring process, or whether we have some kind of master model that is made of solid materials and cannot be destroyed.

A cheaper option is casting using burn-out models, but provided that the model is not very complex and you can cut it out of foam plastic (polystyrene).
Casting using a non-burnout model requires some preparation of the mixture (I will talk about this in future articles), while casting using a burnout model requires only dry sand.

The main disadvantage of sand casting is that the casting is rougher and rougher (the finer the sand, the better the casting will be) and requires machining.

And now directly about casting using a burnt model.

We will need:

• molding container;
• sand;
• Styrofoam;
• oven with ;
• tool for processing foam and finished castings.

First of all, we start working with a template or drawing; I will tell you using the example of casting a souvenir.
Prepare the template and cut it out. This is necessary in order to quickly transfer it to our foam. If you draw well, then you can draw the detail directly on the foam, it doesn’t matter. After which, we need to cut out our blank. This is what it takes most time, since the work is painstaking, and the defect is practically impossible to fix (you can cut out the damaged part and glue a piece of new polystyrene foam with glue and try to cut it out again).

Then I used an engraver and processed the edges more clearly, cut out holes and the product acquired a recognizable appearance. Here, by the way, I didn’t succeed the first time, since the cutter cuts the foam like a knife through butter and, due to torsion, is pulled further into the depths, so be careful and don’t overdo it. Otherwise you will have to start from the beginning, which is what I had to do!

When the workpiece is ready, put it aside and go get sand. If necessary, sift it and prepare it for molding. We take a container prepared in advance (it doesn’t matter what it is, as long as it can be used to completely drown the part and fill it with sand). First, we pour a little sand on the bottom so that the workpiece does not touch the mold, and then we begin to add sand and periodically shake the box so that the sand evenly fills all the irregularities and holes.
I couldn’t fit the tail of the knife into the mold, so I had to “extend” the mold with another jar. I already made the sprue out of wet sand so that it would hold its funnel-shaped shape.

That's all! Preparation for casting is completed, all that remains is to melt the aluminum and pour it in!

Aluminum melts at a temperature of 600 degrees, so a simple fire will do for us.
A metal can will do as a crucible. Even a can can is suitable for one-time melting, just make sure that it is iron and not the same aluminum, otherwise the can will melt faster than metal and everything will end up in your fire or even cause you damage. Be careful and follow safety precautions!

When the aluminum has melted, you can add a little borax or a simpler option - soda and salt. This will help remove toxins from the metal and make it more fluid. Therefore, we make a ball of soda and salt from foil and throw it directly into the molten metal, while it is good if you have a steel spoon nearby, or a wooden stick on the edge. We push the ball to the bottom of the melt and the melt begins to gurgle a little. All debris that floats to the surface must be removed. It is also convenient to do this with a spoon or other metal object similar to a spoon. After this procedure, the surface of the molten aluminum should be smooth and mirror-like. Now we can pour metal into our mold!

Carefully pour into the mold. If you do this in indoors, it is worth taking care of the hood. In general, when working with fire you should take this very seriously. When poured, the foam will ignite and begin to burn out. Be prepared and attentive! We spill our casting with a reserve. So that the excess metal in the sprue gives up weight and there is a reserve for metal shrinkage. All this will improve its final quality.

After pouring, you need to wait a little before removing the workpiece; the metal needs time to cool and set. There is no need to wait a day until it cools completely, 10-15 minutes is enough.

During my casting, I noticed that a thin layer of sagging appeared. This is probably due to the fact that I rubbed the sand poorly and left some kind of cavity into which the metal flowed. But all this turned out to be fixable.

I treated the outer sides with a grinder, and the inner ones with a drill.
And this is how I ended up with a souvenir, from which I later made a spoon!

You can watch the full process in the video, at the end there is also an epic crash test of our casting and all this is accompanied by a bit of humor.