Metal casting to order. Jewelry casting Centrifugal jewelry casting

• from our raw materials. A prerequisite for casting from non-ferrous metals, since their price is always included in the cost of the service. Also, at the request of the client, when working with silver, we can use our own material;
• from customer-supplied raw materials. Mandatory when casting from gold. At the same time, the transferred raw materials must meet a number of strict requirements. If a client requires silver casting, he can provide his own metal if necessary.

• "from gum" - is a combination of casting into metal and creating wax models from any molds made by the company's specialists or provided by the client, including non-standard sizes;
• "from a 3D file" - a combination of 3D prototyping and metal casting. The choice of the prototyping method is determined on the basis of the specifics of the further production of the simulated products, the recommendations of the technologist and the wishes of the client.

Jewelry casting (LUI) is one of the varieties of investment casting (LPIM). However, it has specific features and therefore is a special direction in the casting of art products. The accuracy of castings is ensured by the use of elastic molds, the use of finely dispersed gypsum-based molding materials and forced metal casting - in vacuum or centrifugal installations. The LUI technological process consists of the following technological transitions: model making, assembly of a model set, molding, melting of models, annealing, setting and forced casting of molds, separation of castings from the gating system, heat treatment, control, finishing and assembly of jewelry castings.

Let's consider each technological operation in more detail. First, a master model of the future casting is obtained. If a piece of jewelry needs to be obtained in a single copy, then the artist makes it mechanically, i.e. cuts from thermoplastic materials with a low solidification temperature (from 68 to 98 ° C). These materials are paraffin, shellac wax, ethylene-vinyl acetate copolymer, ceresin.

For serial production of jewelry (JI), hot curing elastic molds are used. They include raw rubber, which is vulcanized during the mold making process.

Master-modsl is made of metal by machining followed by chromium plating and together with a feeder. The vulcanization operation is carried out on a vulcanizing press at a pressure of 5 kN and a temperature of 150-160°C for 30-45 minutes. Use raw rubber brand SKI-3 and SKN-40M. The material in the form of a crumb is placed in a vulcanizing device, inside of which there is a master model. From above, the device is covered with a punch and placed in a vulcanizer. The resulting elastic mold is filled with a fusible mass using an injector. Domestic masses are used, consisting of shellac wax with paraffin (in ratios 20: 80, 40: 60, 60: 40, 80: 20) or copolymer-ethylene with paraffin in ratios 5: 95, 10: 90, 20: 80, 30 : 70). The optimal ratio is a mixture consisting of 65% paraffin, 20% shellac wax and 15% ethylene copolymer. The production of models and model blocks is carried out similarly to the LPVM using an injector and a wire soldering iron. The cleaned and finished model is attached to the middle of the riser model by connecting the melted feeder to the gating system using the heated end of the soldering iron. Then, with the same soldering iron, all the influxes and irregularities of the resulting joint are leveled.

When casting jewelry, molds are made from single refractory mixtures containing electrodinas or cristobalite (the latter in imported mixtures), non-stick additives and gypsum. The shell, as in the LPVM, is missing. Domestic refractory mass "Jewellery - 2" consists of 80-88% dinas powder, 12-20% gypsum and up to 5 ml of orthophosphoric acid, which is added to increase the setting time of the molding mass and its fluidity. The water-mass ratio applied is 0.32-0.42/1, i.e. for 0.32-0.42 l of water, 1 kg of dry mixture is given. When using imported mixtures, mixtures of Sati hiccup, Supercast, K-90 and Inversright are used. In these mixtures, dynas is replaced with cristobalite and non-stick additives are added. All ingredients are of high purity and constant chemical composition. Import mixtures consist of 70-75% /?-cristobalite, /?-quartz, 20-25% a-gypsum CaS0 4 and 5% H 2 0. Particle size

The production of a casting mold begins with the preparation of a refractory slurry. To do this, the powder of the refractory mass (1 kg) is poured into 0.3 - 0.4 l of water and mixed with a mixer. Then the resulting mass is installed in the window of the vibro-vacuum installation and stirring is continued for 3-4 minutes. At this time, air bubbles are removed from the mixture. Next, this smssyo is poured into a flask with a model block, which is installed in a vibro-vacuum installation on a special rubber stand, and vibro-vacuum treatment is continued for 8-9 minutes at a residual pressure in the installation of 1400 Pa.

The hardening time of the molding compound depends on the dimensions of the flask: in a flask with a diameter of 75 mm and a height of 140 mm, the molding compound hardens within 40–60 minutes. In large flasks, the hardening time increases to 3 hours. After 3 - 4 hours, the model composition is smelted in a steam bath or furnaces in air at a temperature of 150°C. With further calcination, the model alloy remaining in the mold burns out. This operation is carried out in calcining furnaces according to the regime indicated in table. 7.

Thus, the total calcination time should be approximately 10.5 hours.

If the mold is poured with copper-based alloys (brass, bronze, nickel silver, cupronickel), then its cooling after calcination and pouring with metal is carried out at a temperature of 600 ° C.

Table 7

The duration of the calcination of the model composition

YUI is poured forcibly on centrifugal plants or vacuum suction machines. Domestic installations P51, D161 or imported ones are used - Modular 80vac, Laminate 600/150, S10 / GA1000, etc.

On these machines, filling is carried out at a residual pressure of (0.4-0.6)-10 Pa. Extraction of the filled block from the mold is carried out by dissolving the model mass in water, followed by hydrotreatment of the YuI block in the P24 hydrotreater. This makes the cleaning process easier.

All other operations in the manufacture of JI, starting from the separation of castings from the gating system to finishing and control of products, are carried out according to the LPVM.

Jewelry casting is formally a type of investment casting. At the same time, jewelry casting has a number of specific features and is one of the leading trends in artistic casting. Therefore, the authors of the textbook considered it possible to devote a separate chapter to it.

The high quality of the surface and the accuracy of reproduction of the openwork pattern is ensured by the use of elastic rubber molds, finely dispersed molding materials on a gypsum binder, and forced filling of the molds with metal.

In the CIS countries, the leading developer and manufacturer of specialized equipment for the production of jewelry is the design bureau SKTB-6 JSC Russian Gems (St. Petersburg).

8.1 MASTER MODELS

The first stage of serial production of a piece of jewelry is obtaining a master model. The artist sculpts or cuts it out of thermoplastic materials (Table 8.1).

The composition of materials subjected to mechanical processing includes paraffin, shellac wax, ethylene-vinyl acetate copolymer, ceresin.

Modeling materials include wax, rosin, paraffin, oxidized polyethylene wax.

The wax model made by the artist goes through the entire cycle of technological operations necessary to obtain a master model (see Chapter 7). Master models of jewelry castings are usually made

They are made of copper-based alloys (bronze, brass, nickel silver). Sometimes the master model is electroplated with a corrosion-resistant tin-nickel alloy.

8.2 Elastic molds

In the manufacture of jewelry of complex configuration with particularly thin elements, elastic molds are used from special vulcanized rubber. To do this, raw model rubber blanks are placed in a metal holder. Master model, the internal cavities of which are filled with pieces of raw rubber,

placed on the prepared layer. The remaining rubber blanks are placed on top of the model. Then a punch is inserted into the holder. The clip is placed in a vulcanizing press.

Vulcanization occurs at a temperature of 150-160°C for 30-45 minutes. The temperature is maintained within the set limits automatically.

Desktop small-sized vulcanizing press D159 (Fig. 8.1) consists of two heating plates, a traverse mounted on two columns, a screw pair with a flywheel, and a thermal control system.

Technical characteristics of the press D159

Nominal pressing force of mold covers, kN

(at least) ............................ 5

Size of heating plates, mm............. 110x140

Maximum distance between plates, mm....... 70

The maximum heating temperature of the plates, ° C ........ 175

Temperature control error, ° С....... ±5

Mains voltage, V................ 220

Power consumption, kW (no more) ........... 0.8

Vulcanization time, min................... 30-45

Mass of the press, kg (no more) .................. 22

In addition to the D159 SKTB-6 press, the PV-1 vulcanization press was developed with heating plates dimensions of 142x172 mm.

After cooling in water, the rubber mold with the master model sealed in it is cut, forming a complex relief of the part, so that when wax models are obtained, the halves do not move relative to each other. In some cases, additional inserts are cut out, which facilitate the extraction of waxes. To improve the filling of thin sections in the cavity of the molds, cuts-bulges are made.

The rubber used for the manufacture of molds must not cause corrosion of the master model, not stick to the model composition and have high physical and mechanical properties (elasticity, resilience, etc.).

These requirements are met by materials based on polar rubbers and a mixture of highly elastic SKI-3 rubber with polar nitrile butadiene rubber.

Rubbers for the manufacture of molds, in addition to rubbers, include a filler (silicon dioxide, titanium white, carbon black, etc.), a plasticizer (paraffin and petroleum oils), and a vulcanizing agent.

Peroxides of organic compounds can be used as a vulcanizing agent (Table 8.2).

Rubbers based on SKN-40M rubber have sufficiently high elasticity and resilience, but are distinguished by high hardness. They provide high surface quality of products, almost do not stick to the model composition and can be used in the manufacture of massive products. Rubbers based on a mixture of rubber SKI-3 and butadiene-nitrile rubber are not inferior in physical and mechanical properties to imported rubber "Gold label".

For the manufacture of small plastic and souvenir and gift items, you can use the rubber unvulcanized mixture LPO "Red Triangle", which has the following properties:

Conditional tensile strength, MPa, not less than ......... 12

Elongation at break, %, not less....... 750

Residual deformation after rupture, %, no more....... 20

Hardness ТМ-2, arb. units, not more than .............. 42

These properties are provided with the following vulcanization mode: temperature 150± 5°С, time 45±5 min, pressure 10 MPa.

In the manufacture of jewelry of a relatively simple configuration and souvenir and gift products, molds from viksint - rubber sealant are also widely used. At the same time, the best performance was achieved in the case of the use of viksint U-1-18 siloxane sealant, which exhibits the following properties:

Vitality, h ............................. 0.5-6.0

Conditional tensile strength, MPa, not less than....... 2.1

Elongation at break, %, not less than..... 160

Shore hardness, arb. units .................... 50-60

For the manufacture of wixint molds, U-1 paste and catalyst No. 18 are used. The paste is thoroughly mixed with the catalyst and applied with a brush to the metal master model. For 100 mass parts of U-1 paste, it is necessary to take 0.4 mass parts of catalyst No. 18. The curing time is 72 hours at a temperature of 25 ° C.

After vulcanization of the first layer, it is covered with a gauze pad to strengthen the walls of the mold and the next layer is applied. The number of layers depends on the configuration of the master model and is selected empirically.

Jewelry is cast from gold, platinum and silver alloys. Alloys suitable for products are called foundry. Special requirements are imposed on them - they must have good casting properties, be minimally saturated with gases, which determines their non-porosity, and ductile. Most gold alloys of the 750th test, gold alloys of the 583rd test with nickel and zinc content, with silver-copper ligature can be attributed to the category of foundries; 950 platinum alloys and 916 and 875 silver alloys.

Making jewelry by investment casting is the most progressive method that has recently become widespread in the jewelry industry. It made it possible to increase labor productivity, reduce the loss of precious metals, and also use semi-skilled jewelers in the manufacture of complex jewelry, and low-skilled jewelers in the manufacture of products of medium complexity. The actual process of casting products and the processes preceding it take place in specially equipped workshops of jewelry enterprises, foundry and molding, respectively.

Modern investment casting equipment is a complex consisting of several units (installations). Such a complex includes: a vulcanizing press, an injection unit, a compressor, a vibrovacuum unit, a melting and pouring unit. There are two types of melting and pouring plants with centrifugal forced pouring of liquid metal into a mold and vacuum suction.

The most common installation of centrifugal casting.

The essence of the process lies in the manufacture of castings by pouring molten metal into thin-walled, one-piece, one-time casting molds made from a special refractory mixture according to one-time models. One-time investment models are made in molds from model compositions. Before pouring, the model is removed from the mold by melting, burning, etc. To eliminate residues of the model composition and hardening, the mold is heated and calcined. Pouring is carried out in heated molds to improve filling.

The main technological operations for the manufacture of molds and castings.

Ш Preparation of the model composition.

Ш Production of casting models and elements of the gating system or section of models.

Ш Assembly of models or sections of models into blocks.

Ш Production of a casting mold.

Ш Preparing casting molds for pouring and pouring metal into a hot mold.

Ш Solidification and cooling of the casting in the mold.

Ш Removing the mold from the casting.

The sample for the mold is made from non-precious metals (cupronickel, brass, bronze) with subsequent nickel plating or rhodium plating. Otherwise, the metal surface will stick to the mold. Casting in a mold inevitably gives casting shrinkage, so the sample is made with an adjustment for shrinkage, i.e., the thickness of the metal is made in all proportions "full" than the true dimensions by 5-6%.

Making rubber molds. Raw rubber mixtures are used as raw materials for rubber molds. The preparation of the rubber mixture consists in pressing out in a vulcanizing press at a temperature not exceeding 100 ° C for 1-1.5 minutes. To do this, a piece of raw rubber compound is placed between two polished steel plates, lubricated with silicone fluid to prevent the mixture from sticking to the metal. Limiters are installed between the plates, allowing you to adjust the required gap. Withstanding 1--1.5 min under the pressure of the upper plate, the mixture is cooled under running water and separated from the plates. It is better to press out the raw rubber mixture immediately before making molds. In order to fix the rubber plates relative to each other when assembling into a package (several layers of rubber), rubber locks are made - ribbed on one side of the plate. To do this, the pressed raw rubber is cut to the size of the molds and cleaned with a cotton swab dipped in gasoline. The mold is wiped with organosilicon liquid. The assembled package is placed in a vulcanizing press, heated for 5 minutes; then for 40 minutes they are vulcanized under pressure at a temperature of 140 ° C. After vulcanization is completed, the package is cooled under running water and the rubber plate is removed from the mold.

For the manufacture of detachable molds from pressed rubber, plates are cut out according to the shape and size of the metal frame. The plates are cleaned with gasoline and stacked in packs. The number of plates in a pack depends on the thickness of the model. Rubber locks are placed on the lower pack, the reverse side of which is cleaned with a file and moistened with gasoline. The model (original) is also placed between the locks. It is positioned in such a way that the locks provide fixation of one half of the mold relative to the other, but do not interfere with the extraction of wax models. The surfaces of the upper and lower rubber packs facing the model are rubbed with talcum powder, and the edges of the future connector are lubricated with silicone oil. After applying the top pack to the bottom pack, an additional plate is placed on top, on which the press plate will exert pressure. The assembled package is placed in a metal frame, inserted into a vulcanizing press and pressed against the top plate of the press. After the temperature of the upper plate of the press reaches 140--150°C, it is lowered to the limit, and vulcanization is carried out under its pressure for 30--45 minutes. After this period, the heating is turned off, and the frame with the mold is removed and cooled. Excess rubber is cut off and the mold is separated at the place of the connector and the model is removed. On the working surface of the mold should not be bumps and damage.

For the manufacture of split molds, as well as for the manufacture of split molds, plates of pressed raw rubber are cut out in the shape of a metal frame, moistened with gasoline and placed in packs. The thickness of the packs, as for split molds, depends on the height of the model.

The jewelry model is placed between two packs of raw rubber, and the cavities of the product are densely filled with pieces of raw rubber. The package thus assembled is placed in a metal frame and placed in a vulcanizing press. Further, the process of pressing and vulcanization proceeds similarly to that described. After removing the mold from the frame, it is cut into two halves, carefully cutting the parting line with a scalpel. The cut line is chosen uneven (hilly) for better fixation of the halves of the molds. To extract a complex wax model from them, additional cuts are made. The manufacturing quality of the mold is determined by the experimental casting of the wax model.

Making wax models. The material for investment models is a special wax model composition, which is loaded into the melting pot. The lid of the boiler is closed and pressed with nuts. After that, the heating of the boiler is turned on, the temperature is set (60--70 ° C) for the model composition and the pressure of compressed air is regulated depending on the size and shape of the wax model. A layer of talc powder or sprayed silicone fluid is applied to the working part of the mold. Then the mold is installed in a special fixture. The model composition heated to a certain temperature is fed from the boiler into the mold by pressing on the nozzle. For models with a complex configuration and large flat models, the composition is supplied by strong or repeated pressing.

The halves of the rubber molds should be pressed tightly against each other, but not too hard and not too loose. Excessive compression of the halves of the mold prevents air from escaping from it and leads to an underfilling of the model, and weak compression leads to overfilling of the mold. The mold filled with the model composition is kept for 1-2 minutes until it cools, after which the wax model is carefully removed from the separated mold.

To assemble models into blocks, sprues are used - wax risers with a metal rod inside. They are made from model composition waste from model smelting. Wax waste is melted in a sand or oil bath and poured into a special mold, into which a weighted metal rod with a diameter of 1.5 mm has been inserted in advance. After cooling and removal from the mold, the sprue is subjected to a thorough inspection, cleaning (with a special scraper) of seams, flash and other defects.

To assemble models into a block, the wax riser is fixed in a special fixture. Fusing the connecting parts of the models and the riser with a thin blade of an electric soldering iron, solder the models to the riser. As a result, a block is formed - a "bush". Each block can contain up to 60 models. The block is installed on a rubber stand (the mass of the stand, however, as well as other parts, is fixed), and then washed in a 5% solution of sulfanol or in detergents for synthetic products. Dry the blocks with a stream of air, using a fan for this purpose, until the moisture completely disappears from the surface of the models.

Mold making. Distilled water is poured into the rubber cylinder and placed on the vibrating table of the vacuum unit. With the vibrator turned on, gradually, with continuous stirring, the molding mass is poured into the cylinder at the rate of 2.5 hours per 1 hour of water. The molding mass is mixed with water for 1.5-3 minutes, after which the cylinder is covered with a lid and a vacuum pump is turned on to suck air from the cylinder. The vacuum is brought to 0.8--0.9 at pressure and the mixture is evacuated for 5--7 minutes. Then the cylinder with the evacuated mass is removed from the vibrating table, and on the vibrating table, with moderate vibration, a flask with a model block is placed (the flask is mounted on a rubber stand). Carefully, so as not to damage the model block, the molding compound is poured into the flask, closed with a lid and the air suction is turned on again. At a vacuum of 0.8 - - 0.9 atm, as soon as the mixture begins to spray, the pump is turned off. Vibration lasts 1--2.5 minutes. After 2 hours, the rubber support is removed and dried in air for at least 6 hours.

Meltdown of wax models. For melting wax models from molds, a drying cabinet equipped with a thermometer and a tray for collecting the melted wax mass is used. The casting mold is installed in the chamber of the drying oven on the grate down with the gating cup and kept in it for 6 hours at a temperature of 150°C, after which it is subjected to calcination.

Ignition of a flask with a mold. The flask with the casting mold is installed in an electric furnace heated to 100°C on a special grate vertically, with the sprue down. Heating is carried out stepwise according to a given program up to 700°C with periodic exposures after 200 and 400°C. After that, the furnace is turned off and the flask is cooled together with the furnace to a certain temperature, at which the flask is transferred to an electric melting machine for centrifugal casting. The temperature of the flask is calculated depending on the casting alloy according to the formula t° heating of the flask.

Metal is poured into molds in a special installation for centrifugal casting. For casting jewelry, installations with a capacity of about 13 kW, a crucible capacity of 1.5 kg (for gold) are used. The temperature control interval is 700...1200 °C and the rotational speed of the melting unit is 220 rpm. To pour the metal, the crucible of the installation is heated to 700 ° C and dehydrated boric acid is poured onto the bottom of the crucible as a flux at the rate of 1.5 ... 2.0% by weight of the charge. Then the crucible is heated to the melting temperature of the alloy and the metal is loaded in parts according to the weight of the casting. The molten metal is deoxidized with zinc for gold and phosphorous copper for silver at the rate of 0.1 ... 0.2% by weight of the charge, stirring the melt, excess flux is removed from the surface. The casting mold is transferred from the furnace and installed in the pouring unit. The machine is turned on for a set rotation time of 2 ... 3 minutes and pouring is carried out. The mold removed from the pouring unit is cooled in air to 60...70 °C. Separate the block from the molding mass with light blows of the hammer on the metal flask and the core of the block. The block is then cleaned with a stiff brush. The castings are finally cleaned from the molding sand in a 20 ... 40% hydrofluoric acid solution. After etching, the castings are washed in running water and, if necessary, clarified in chills: gold in 10% nitrogen, silver - 10% sulfur. After washing and drying, the block is ready to separate the castings from the gating system.

Separated castings, even when models of the whole product are made, are not yet ready. They go to the mount for surface treatment, adjusting the size of rings, assembling lock knots in earrings and brooches, soldering the ears of pendants, etc., and only after the final mounting are ready for fixing stones and polishing.

Lost wax casting for jewelry production

Introduction

Chapter 1. Materials and tools

1 Jeweler's workplace

2 Tools and equipment for making jewelry

3 Safety precautions for manual jewelry making

Chapter 2

1 Investment casting

2 3D jewelry modeling

3 Molds, Christmas trees

4 Types of casting

5 Centrifugal casting

6 Vacuum casting

Conclusion

List of used literature

Applications

jewelry casting centrifugal vacuum

Introduction

Jewelry has been known since ancient times. A man, having met gold on his way, was fascinated by its beauty, amazed at the ability to retain its sunny color and brilliance in any conditions, and is easy to process; using these amazing qualities of metal, combined with the harmony of lines and shapes, a person created one of the inimitable types of folk art.

At first, people used only gold to make jewelry, then gradually began to use silver, precious and semi-precious stones, pearls, amber, and today stones grown in special installations, which, in terms of external characteristics and physico-chemical properties, are not inferior to natural ones: emerald , pomegranate, turquoise, opal, malachite, etc.

Jewelry created by craftsmen is designed to serve not only as decorations and household items; they are able to carry an educational principle: to satisfy the aesthetic needs of a person, to form his artistic taste and culture, to arouse interest in creativity. Jewelery in Russia arose from time immemorial. The most important stages in the history of its development are the following stages: jewelry art of Kievan Rus, jewelry in Rus' in the 16th and 17th centuries, jewelry in the 18th and 19th centuries, jewelry in the Soviet period. The centers of Russian jewelry art at different times were Kievan Rus, the Vladimir-Suzdal principality, Novgorod, Pskov, Yaroslavl, Nizhny Novgorod, Kostroma, Kazan, Kaluga, Vologda, Veliky Ustyug, Moscow, St. Petersburg, a number of cities in the Urals. Jewelers of Kievan Rus were famous for their products made of gold with champlevé and cloisonné enamel. This time is characterized by such adornments as cauldrons, which were hung from both sides to a woman's headdress, barmas - precious mantles painted with images of a religious nature, hollow earrings in the form of a crescent, hryvnias - neck ornaments in the form of a hoop, pendants made of twisted gold threads, beads of all kinds. Niello, granulation, enamel, filigree (filigree), embossing, carving, gilding were successfully used in decor. The main motive for the ornamentation of products is clearly stylized plant forms.

A similar style of ornamentation, but more accurately reflecting wildlife, was preserved in the jewelry of Russia in the 16th and 17th centuries, although their shape, size, decor indicate a change in the living conditions and life of Russian people: the products have become more democratic and to a much greater extent than earlier, they displayed the characteristic features of their time (much less pretentiousness in the drawing, more concise and clearer in its intent and content).

Beginning of the second half of the 18th century. for master jewelers of Russia was marked by the discovery, development and development of domestic deposits of semiprecious raw materials. In 1688, the ores explorer Mikhailo Tumashev found semi-precious stones in the Urals near the former Churzinsky prison: agate, topaz, etc. Soon, deposits of many other precious and semi-precious stones were discovered, which began to be widely used in jewelry. Moreover, in the XV-XVII centuries. the most fashionable gems were an unusually bright and elegant emerald with its greenery, as well as cherry-red almandines and rubies and spinels scarlet as the dawn. In those days, jewelers liked to decorate their products with enamels of bright, rich palettes, repeating the range of colors of precious stones.

Chapter 1. Materials and tools

1 Jeweler's workplace

Workplace of a jeweler - a workbench complete with a chair-chair for sitting (Annex 1). Outwardly, the workbench looks like a regular single-pedestal table with a segment cutout (working cell) in the top plate-cover. The workbench consists of a frame, a top plate or cover (table top), a pallet, sliding wooden drawers, and a number of auxiliary devices. Workbench dimensions (height X length X width) 900X1 YuOH X700 mm. Each workplace is equipped with a chair-chair for sitting, swivel, adjustable in height, portable, always with a rigidly fixed back.

Tabletop. Designed to permanently place some auxiliary devices on it and temporarily, for the period required by the work process, tools and fixtures. In order to avoid unnecessary loss of precious metals, the countertop must certainly have a completely smooth, even surface, for which its top is finished with heat-resistant continuous cut plastic. A segment-shaped cutout (radius 300-350 mm and depth up to 300 mm) in the table top is necessary for unhindered entry of sawdust onto the pallet; besides, it sort of outlines, defines the immediate working area, within which the jeweler performs almost the entire amount of work. To the end of the tabletop (in the center, right in front of the worker sitting on the chair) there is a finagel - a wedge-shaped protrusion made of hard wood and extremely necessary (as an emphasis) when performing the operations of filing, sawing with a jigsaw, and scraping. In the process of collecting precious metal waste, the jeweler often has to remove and re-install the finagel, so the nest holder must be designed in such a way that the removal and installation of the finagel can be done easily, quickly and reliably. Along the entire contour, excluding the immediate working area - a segmental cutout, the tabletop is sheathed (with a small allowance for the side) with a strip of corrosion-resistant steel. The side is necessary to retain waste, and its absence in the working area allows the performer to easily and quickly sweep the sawdust into the pallet. In order to prevent a possible fall of workpieces or products on the floor, especially when scraping, a plastic fence should be installed along the edges of the tabletop (left and back sides).

Pallet. Represents an opportunity for the jeweler to minimize, prevent the loss of precious metals. For the duration of the work on the pallet, the jeweler has items or parts (on the left - unprocessed, on the right - processed), as well as brushes for sweeping (collecting) waste. The pallet is made of sheet corrosion-resistant steel; installed directly under the working area; has the appearance of a large scoop with a non-pointed concave front; Its edges are covered with plastic for the safety of the worker.

The use of the pallet as a drawer is ensured by the presence of guides. A special recess (cutout) in its front side is made to ensure the tightest possible contact between the pallet and the worker's overalls, which creates conditions for the most complete ingress of waste into the pallet. Drawers. There are only four of them. They are located in the first part of the workbench - in the cabinet under the tabletop. Drawers are designed to store tools. To avoid cases of mechanical damage to the instrument, the boxes are made of wood. In the first box on top, jewelers store files, needle files, in the second - wire cutters, pliers, tweezers, scissors. In the third, deepest - hammers, rentrigels, finagel (paired instrument). At the very bottom - overalls (robe, slippers). Auxiliary devices. These include a lighting lamp, a drill, flexible lines of a parallel gas-air outlet with a holder for a burner. A lighting lamp is necessary to create such lighting conditions for the workplace that would fully contribute to the productive and high-quality work of a jeweler. The lamp-lamp is installed on the opposite edge of the worktop from the working edge. The position of the lamp-luminaire in the vertical and horizontal planes can be freely adjusted due to the movable stand. The light from the luminaire lamp should be soft and even, if possible, like daylight, and fall on the working spot (finagel area), and not on the workplace in general. Light flickering or directed into the eyes of the worker is not allowed. Drill - a special mechanical tool for processing labor-intensive and hard-to-reach areas of the Products. The drill consists of an electric motor, a flexible drive hose, a foot rheostat and a set of cutters. The principle of operation of the "jewelry" drill is almost the same as the medical drill used in dental offices. One end of the flexible hose is connected to the motor shaft, and a tip with a collet clamp for mounting cutters is mounted on the other. The rotation speed of the burs is regulated by a foot rheostat. The flexible hose provides the worker with the necessary operational space - the installation of the tool in any position. The drill is suspended on a rod, which, in turn, is rigidly mounted on a flange fixed to the side (right) side of the tabletop. Flexible lines of parallel gas-air branch with a holder for a burner are gas-air fittings complete with a burner. The workbench is equipped with such devices only where it is possible to perform soldering work on it. This workbench has a special panel located to the right of the jeweler above the drawers. The panel has two handles. Above each of the handles is the corresponding inscription "Gas", "Air". By rotating the handle in the direction of the arrow pointer and thus changing the pressure of gas and air, the required temperature and size of the burner flame are constantly maintained. There are taps for supplying gas and air. They are located on the back side of the workbench. Soldering is performed on an asbestos sheet, tightly laid on a metal base with a flanging. A soldering tool is stored under the worktop on rails. The ignition of the burner is carried out either with the help of an alcohol lamp, or from the flame of a special gas burner, constantly burning. Workbench frame. Perform welded metal, non-stationary. The non-stationarity of the frame of the workbench is achieved due to the fact that its legs from below have rubber pads. Such pads increase the stability of the workbench, eliminate damage to the floor, and most importantly, they significantly reduce and dampen vibrations, which is very important for high-quality assembly operations. From the side and back sides, the frame is sheathed with steel sheets. The framework is intended for installation of fastening on it of all component parts of a workbench. Parts of the workbench, constituting one whole - the workplace of a jeweler, are noticeably distinguishable in design and are designed, each separately, to perform unambiguous tasks in the overall process of making jewelry. During this process, a number of similar to metalwork, but very specific mounting operations (marking, bending and straightening, soldering, bleaching, filing, sawing with a jigsaw, drilling, scraping, pinning) and the use of a variety of tools and devices. During the execution of the work, the jeweler's workbench should contain only what is needed at the moment. The jeweler must ensure that the tool is always fit for work (does not deteriorate or fail), as well as the service life, its timely sharpening and editing. The jeweler is obliged to constantly monitor the collection of waste precious metals. The work practice of jewelers shows that there are four main conditions for ensuring the most complete collection of precious metal waste, four main components for reducing their losses: cleanliness at the workplace, accuracy in the work of the performer, conscientiousness of the performer himself and, finally, scrupulous accounting. Waste collection is carried out by the jeweler as necessary after each individual operation and always before leaving the workplace (lunch, other necessity), as well as after completion of all work, at the end of the working day. The collection procedure is as follows: after sweeping over the mounted products or parts and putting them away in a special metal box, often called a goft, the worker sweeps over the tool used in the work, especially files and needle files; then sawdust is swept into the pallet from the countertop, hands and clothes are swept over. Sweeping tools, hands and clothes should be done with a stiff brush; sweeping sawdust from the countertop and sweeping the pallet with a soft brush or brush. With the help of this brush-brush and the Jewelry Scoop, the waste from the pallet is then collected in a special jar with a tight-fitting lid, commonly referred to as a biksa. Brushes and scoops are always under the hands of a jeweler: brushes - at the right side wall of the pallet, scoops - in the opposite from the working part. Jars-biks with waste are stored in a box-goft. The waste of precious metals accumulated during the month is remelted. The resulting ingot is weighed, registered in the register and handed over to the workshop's storeroom of precious metals. After the end of each working day, a goft box sealed with the personal seal of the jeweler is delivered to the pantry of precious metals.

2 Tools and equipment for jewelry production

Ruler. (Appendix 2(a)) Ordinary, but certainly metal, 100-150 mm long. The dividing scale of the ruler should be clear, well visible. Notches of the working edge are not allowed. A ruler is used when carrying out the necessary measurements, as well as when applying direct marks with a scriber.

Vernier caliper, micrometer standard. Caliper (Annex 2(b)) make measurements of external and internal dimensions, the depth of holes and protrusions. The accuracy of measurement with a caliper is higher than with a ruler, because, firstly, the division value of its scale is more accurate (0.1 mm), and secondly, the caliper is in closer and more reliable contact with the object being measured. Micrometer (Annex 2(c)) necessary for a jeweler in cases where special accuracy of the determined size is required, primarily when measuring the thickness of workpieces or parts. The division value of the micrometer scale is 0.01 mm.

Marking circle. Represents (Annex 2(d)) two metal rods connected by a spring ring and a set screw. The spring ring provides the working ends of the compass with the ability to move apart, diverge in different directions, and the locking screw is necessary to fix the distance between the rods. The working ends of the compass rods are made pointed. A marking compass is used when dividing lines into segments, constructing angles, dividing a circle, marking circles and arcs, as well as when transferring linear dimensions from a drawing to a material.

Nutromer and calipers are standard. Nutrometer (Annex 2(e)) measure the inner diameter of the product and parts, and calipers (annex 2(e))-external.

File. Used in jewelry. Files vary in size, profile and notch. According to the profile, files are trihedral, semicircular, round, flat, rhombic, differently convex (Annex 3(a)). Jewelery files, unlike locksmith's, as a rule, are sharp-nosed. File cuts are indicated by numbers: 0, 1, 2, 3, 4, 5. The higher the cut number, the finer the file tooth. Files with a large notch (numbers 0, 1,2) are intended for preliminary (rough) filing, files with a finer notch (numbers 3, 4, 5) - for the final (finishing). Files are made from tool steels. To ensure safe and convenient work, a wooden handle is mounted on the file shank. Needle file. It differs from a file in a smaller sectional plane and in that the file shank is also a handle. Like files, needle files (Annex 3(b)) differ in size, profile and notches. The profile of the needle files is the most diverse. Files are trihedral, wedge-shaped (knife), rhombic, flat, square, round, semicircular, differently convex, grooved, oval, needle-shaped. The notch of the needle files is indicated by numbers 1-6. Needle files with a notch of numbers 1, 2, 3 are used for rough filing of relief, contour, solder joints. Needle files with a notch of numbers 4-6 are used for fine finishing: removing small scratches, processing prongs. Needle files are attached in handles with a collet or screw clamp.

Riffel. Unlike most needle files, the riffles have a shortened, curved working part of a biconvex, round and semicircular profile with bends of various configurations: annular, two-radius, ski-shaped. As a rule, the reefs (Annex 3(c)) one-sided notch. Corrugations are used for processing concave surfaces, finishing the internal surfaces of hollow products. cutter. The method of filing using a drill and a set of burs-mills (Annex 3(d)) allows you to work faster and more productively. The following types of cutters are most often used: conical, cylindrical, face, combined, ball, cavity, shaped.

Jigsaw or jigsaw. By design and principle of operation, it is similar to a conventional hacksaw. (Annex 3(e)). Fixing the cutting file and stabilizing it in the working position, as well as removing it, are carried out by rotating the wing screw and clamping cheeks in one direction or another, the holding surfaces of which are marked with teeth marks. The size of the jigsaw along the length is freely adjustable and fixed with the help of guides and a lamb screw, which allows the use of saw blades of both standard length and shortened (broken) ones. Jigsaw files are a hardened rectangular wire of a certain length with an oblique-toothed notch on one side. The saw is attached with the direction of the cutting teeth down, since the working position of the jigsaw is usually vertical. Drill. Consists of a working part and a shank (Annex 4(e)). The section of the working part in the form of a cone formed by the cutting edges is called the cutting one, and the angle of this cone is the angle of sharpening the drill. The optimum value of this angle when drilling gold and silver alloys ranges from 125 to 140°. The helical grooves in the working part of the drill are necessary for the passage and removal of sawdust. The shank is used to fasten the drill in the spindle chuck.

Scraper. Consists of a rod with a working part and a handle (Appendix 4(g)). The working part of the scraper (very short for safety reasons - 20 mm) has three blades - three ribs formed by a trihedral conical sharpening, the angle at the top of which is called the sharpening angle of the scraper. Scrapers are made from tool steels, they differ from each other in cross-sectional dimensions and sharpening angle. The working part of the scraper is hardened.

Chasing. This is a steel (alloy steel) rod with a length of 9 to 12 cm of round, square, rectangular, octagonal sections. The working end of the coinage must be hardened, the middle part is not hardened and has a thickening to increase stability in operation (during shocks) and reduce vibration. The shank of the coinage is made relatively soft and viscous to protect it from flattening. On the working surface of the coinage there should be no sharp corners and edges, in order to exclude punching through. The stamps are distinguished by the shape of the working part, which can have the most diverse notch pattern. Assortment of coinage in accordance with the implementation of new specific coinage work is constantly changing and growing. The main types of coinage (Annex 4(h)) have the following names.

Consumable. This coin (Annex 4(h-2)) used for reproduction, embossing the general outline of a drawing or font; the shape of the working part (strike), as a rule, is linear in the form of a slightly rounded wedge and resembles a screwdriver blade; also happens with a curved striker.

Purushnik and boboshnik. The working part of these coins (Appendix 4 (h-3))- hemispherical and oval; they are used to obtain all kinds of bulges, provide a deep drawing of the relief.

Lochatnik. The mint of this variety (Appendix 4 (h-4) has a striker of flat shapes; used to flatten and smooth out flat areas of an image. A distinction is made between polished polishers to obtain a brilliant image and matt polishers with various degrees of roughness.

Cut. They are used for knocking out a thin linear pattern and for one-sided stepped displacement of metal; has the shape of a single-sided sharpened flat chisel (Annex 4 (h-5)).

Stichel. This is a kind of steel cutter 100-120 mm long, fixed in a specially shaped wooden handle 30-70 mm long. Stichels are distinguished by the shape of their cross section and the shape of the cutting part (annex 4(s)). The shtikheli of a certain profile are also divided according to the thickness by numbers.

Engraving chisel. It is very similar to a graver, but it is used only for rough work, i.e., if it is necessary to excavate a significant amount of metal. Nippers, scissors. Used for cutting (nibbling, cutting) material in the process of performing many operations in the manufacture of jewelry (Annex 4(k)). The main tool for bending - bending tongs (Annex 5(a)). They are usually made from tool steel; their shape has not changed for more than one century. The size of the forceps (length) ranges from 13 to 16 cm. There are also so-called small forceps. The length of these tongs is about 12 cm. They are rarely used - when performing “thin” work, where it is difficult to achieve the required shaping accuracy with ordinary tongs. All tongs differ in the shape of the working surfaces of the sponges. Auxiliary tools for bending include various mandrels and crossbars, hand vices, special devices, and for bending sheets and strips - metal and wooden base plates with a forming groove (Annex 5(b)). Dressing processes are carried out using the following tools: metal, wooden, textolite hammers, steel straightening (straightening) flakesen plates, anvils, spurs, pliers, crossbars, mandrels, drawing boards, special punches (Annex 5(c)). The main tool for soldering is a flame torch, tweezers and scissors are also used. (Annex 6). Gas from the network and bottled gas is used as fuel for the burners. Gas burners consist of two tubes (steel or brass): one for gas supply, the other for air. Each tube is equipped with a valve that simultaneously plays the role of shut-off and control. To mix air with gas, the end of the air tube is soldered into the gas tube, or two leading tubes are soldered into the third. The mixing tube ends with a nozzle in which the final mixing of air with gas takes place and which gives the torch a certain shape. Nozzle designs may vary. As a grinding tool in the manual manufacture of jewelry, abrasive whetstones (grinding stones), grinding rod-shaped files about 150 mm long, semicircular, round, square, rectangular, triangular cross-sectional shapes, various grain sizes, silicon carbide stones, pumice, slate, grinding coals (usually in in the form of square bars), sandpaper (sandpaper), woolen, felt, felt circles, various hair brushes, drills with replaceable rubber and ceramic circles. Stichel are hardened steel blades ranging in size from 100 to 120 mm. The upper part of the chisel is called the back, the lower part is called the blade. (Annex 7(a)). The non-working end of the engraver is mounted on a spherical wooden handle. Spitzshtiheli (cut-out shtiheli). The most common and most used cutting tool of the fixer. Pincers can have both straight and side (right and left) sharpening (Annex 7(b)); with left sharpening, the cutting edge is on the left side of the engraver, with right sharpening, on the right. The angle of the chisel blade ranges from 30 to 45°, and the sharpening angle is 45°. Flachstichels (flat gravers). They have a flat blade with a width of 0.2 to 0.4 mm. Stichel with a blade width of 0.2 to 0.3 mm are used for fine trimming with corner setting, trimming corners, cutting prongs; engravers with a wider blade are used for finishing casts and cutting with all types of setting, except glue, for glossy trimming (gloss, shine). Cutters for a drill, needle files, nippers, drills for fastening are used the same as when performing mounting operations. Sharpening of engravers is carried out using fine-grained bars. To improve the sharpening process, the whetstones are lubricated with oil. When sharpening, it is necessary to strive to ensure that the sharpening area is formed in one step. The blade is polished using GOI pastes, leather, rubber-based bars, and marble bars. The jeweler-tackmaker uses the following tools in the process of seaming and crimping metal: pressure gauges, crimps - metal punches (crimping punches), corner verters, corneters, knurling (meligraphs), bartacking hammers (Annex 7(c)). Support pad-anvil. It is used as a device in the process of minting. A simple support pad is a steel plate with a flat surface, without sharp corners and ribs. There are also special linings, such as anka (Annex 8(a))(steel plate of a cubic shape), having hemispherical recesses of various diameters, designed for knocking out spherical blanks of hollow products. In some cases, soft linings are used to weaken the force of blows during minting. Such linings are made of wood, rubber, cardboard, lead, resin mixture, special mastic. Handmade wooden vise. Consist of two equal semicircular wooden boards-sponges with a total diameter of 30-35 mm, interconnected by a fixing screw (Annex 8(b)), which regulates the compression force of the product and, accordingly, the movement (divergence) of the jaws, not exceeding, as a rule, 15 mm. Manual wooden vices are used for filing, sawing, drilling, scraping, engraving, back-tacking operations. Drill. It consists of a metal solid rod, collet clamp, flywheel, handle, belt. The rod is needed to secure the collet and the flywheel, in the upper part of which there is a hole for threading the belt (Annex 8(c)). A drill is used to perform drilling and reaming operations. Special clamping device. When engraving, it is possible to hold the product in hand only in rare cases, but usually it must be fixed. This is achieved using a number of devices: wooden hand vise, engraving blocks, mounting plates, ball vise, engraving pad. Engraving pads. They are two small (20X 100 mm) rectangular metal plates (Annex 8(d)), movably connected by clamping screws. Fixing products in them is carried out simultaneously with the use of soft cushioning materials (wood, leather). Ball vise shrabkugel. Made in the form of a cast iron ball (Annex 8(e)) with a diameter not exceeding 130 mm. The top of the ball is cut off. A groove is cut in the segment-shaped section, in which a plate with the product is fixed with the help of bolts. To ensure free maneuvering (moving the product), a leather ring is placed under the shrabkugel; as a shrabkugel, you can use the used lathe spindle chuck by adding a part in the form of a hemisphere to it. Engraving pillow. The simplest engraving device. It is a round pillow (Annex 8(e)) filled with sand. The material for the pillow is leather or canvas. The pillow is used as a lining for the fixing plate. It is not difficult to make such a pillow. Letkal. They are used as refractory devices in the process of soldering jewelry. Usually jewelers use asbestos letkal on a wooden base. For soldering products that need to be soldered in a vertical position, spring clips are strengthened on the letkal: products or parts are clamped between paired wire protrusions. For step-by-step soldering, a letkal-turntable is used, which is a metal base on which a rotating table is mounted on a leg (Annex 8(g)). The thrust square is simple and adjustable. Required to check the perpendicularity of a rack, ledge, product element, to determine the deviation of the surface from straightness and flatness (Annex 8(h)). Scriber. A metal rod resembling an ordinary pencil in shape and size, only with a lead (needle) more pointed than a pencil. The scriber is necessary for drawing marks on the surface to be marked both by hand and using a ruler, square, template. Marking plate. When marking, jewelers use a non-hardened metal bar of rectangular or round section with dimensions of approximately 150X100 mm as a marking plate. To reduce vibration, a proportional sheet of dense, elastic rubber is glued to its lower plane. The upper plane of the bar is even and smooth. Many jewelers use a dressing plate (flakeisen). Manual rollers. They are necessary for processing metal by pressure with a continuous change in its shape along the entire length or in some given section of the workpiece. Rolls (Appendix 8(i)) come with rolls in the form of smooth cylinders with cutouts of various profiles. Smooth rolls provide the rolling of sheets, strips, strips, plates, and profile rolls are used to obtain rolled products of round, square and other shapes. Drawing board. It is used to carry out the manual drawing process - pulling the workpiece through the conical hole of a tool called a die or die. It happens with holes drilled directly in it (Appendix 8(k)), but it can be equipped with a set of die-dies inserted into it. By drawing, a wire of the required diameter is obtained from wires of a larger diameter, and from a tape, tubular billets are used for the manufacture of swivel joints and frames for small stones. On annex 9 shows the types of blank profiles obtained by drawing, and annex 10 patterned surfaces of tapes and strips obtained by rolling.

3 Safety precautions for manual jewelry making

In the process of making jewelry, the performer must keep the following requirements in mind. Worker's clothing must be clean and neatly tucked in; the workplace must be kept clean. Work should only be done with the right tool. All tools with pointed ends must have handles. When marking, bending, straightening, filing, scraping, nailing, chasing, engraving, back-tacking, it is necessary to exercise special care and caution in handling the scriber, compass, files, needle files, scrapers, wire cutters, milling cutters, chasers, engravers; do not allow these tools to be located on the edge or close to the edge of the table; do not use them as tools for opening boxes and stirring sticks; do not touch the sharp and cutting parts of the tool with your hands; at the end of the relevant work, remove the tools in the drawers of the workbench. When cutting with a jigsaw, you must be extremely careful; do not apply excessive force to the file in order to speed up the sawing process, do not try to release the jammed file by force, do not direct it with your fingers to the cutting line. When performing a drilling operation, you cannot correct the drill on the go. When polishing the product, keep it with sharp edges in the direction of rotation of the circle. The polished surfaces of the product should be positioned relative to the circle so that the product is not picked up by the circle. Do not allow strong heating of the product to avoid burns to the hands. When sharpening tools, use a protective shield or goggles. Do not sharpen the tool with the side (thorium) surface of the wheel.

Do not wash your hands in oil, emulsion, kerosene and do not wipe them with cloth scraps contaminated with shavings. When carrying out soldering work, special attention must be paid to excluding the possibility of gas explosions, fires and burns; in the event of a gas leak, it is prohibited to: light the burner, turn on and off electrical appliances; the workbench should not contain flammable objects; products must cool on stands made of refractory materials; they should be carried with tweezers. When bleaching, contamination of the bleaches and the ingress of foreign metals into them should not be allowed; do not allow bleaching solutions to get on hands and clothes; do not lower completely uncooled parts and products into the chill to avoid splashing; when immersing products in the chill and removing them from it, use a special acid-resistant mesh bucket or copper tweezers. If necessary, perform work in overalls (gown, gloves) and with the use of personal protective equipment (glasses, lenses). Keep container with acids closed; in case of contact (during use) of acids on the body, wash off with water and consult a doctor.

After finishing work (especially before eating), wash your hands thoroughly; Do not eat or smoke while working.

Chapter 2

1 Investment casting

Investment casting is widely used in the jewelry industry. This method makes it possible to mass-produce products of complex configuration, while ensuring the required accuracy, as well as to obtain thin-walled castings with a deviation from the specified size of no more than 0.5% and a surface finish of 5-6 class. This makes it possible to use them as finished jewelry items without additional machining. More often, investment casting is carried out on centrifugal installations, from which the casting method itself received the name - centrifugal casting. Casting can also be carried out on vacuum plants using the vacuum suction method. At the same time, the schemes of both technological processes of investment casting are identical, only the processes of filling (pouring) the mold and the equipment on which this operation is performed differ. The lost wax casting method has become widely used even in small jewelry workshops. The equipment used is simple in design, small in size and can be mounted in a production facility with an area of ​​20-25 m 2 . At the same time, even workshops that do not have highly qualified fashion jewelers in their staff, by borrowing experience and using ready-made rubber molds, can produce highly artistic products and thus satisfy the demand of the population. The main stages in the manufacture of jewelry elements using investment models are the production of a reference sample, the production of a mold, the production of a wax model, the preparation of a casting mold, the casting of jewelry elements, and the cleaning of castings. Equipment. The following equipment is required to perform the technological process of casting jewelry using investment models: a vulcanizing press, an injection unit, a vibrovacuum unit, a muffle furnace, a foundry unit (a melting and pouring unit or a simple desktop centrifuge, a "vacuum-metal" unit), a drying cabinet, installation for electrochemical polishing, technical scales of the 1st class, equipment for melting, tanks for knocking out castings and washing out flasks, flasks made of heat-resistant steel, an electric soldering iron, as well as various tools and containers. Vulcanizing press (Annex 11) is intended for obtaining rubber molds according to the standard sample of the product by vulcanizing rubber. By design, the presses can be different, but they all have heating in the upper and lower plates. Injection plants (Annex 12) are designed to obtain melted models by melting wax and filling rubber molds with it. The installation consists of a wax tank, an electric heater and a temperature control device. Structurally, it can be made in various versions. The press is a portable structure. A bottom plate is installed on a rigid (cast) frame, in which an electric heater is mounted. On special guides, vertically standing and rigidly attached to the frame with the help of a worm gear, the upper plate moves, in which an electric heater is also mounted. Installed between the plates and pressed flask with raw rubber is heated to a certain temperature. Under the influence of pressure and temperature, the raw rubber plates are welded together. To regulate and maintain the temperature, the press has an automatic or manual control system. The most successful design of the injection unit is a vertically located cylindrical casing. A wax tank is mounted inside the casing, from which the wax, under the pressure of compressed air supplied from the compressor through the gearbox, enters the injector nozzle. Compressed air pressure is controlled by a manometer, which is installed on the top cover of the casing of the injection unit. Excess pressure in front of the reducer should not be higher than 19.62 * 10 4 -29.43 * 10 4 Pa ​​(2-3 kgf / cm 2), and when spraying - 1.96 * 10 4 -7.85 * 10 4 Pa (0.2-0.8 kgf / cm 2). The injection nozzle is equipped with an individual heating system. A chute is installed under the nozzle to direct the flowing wax into a special tray. Control handles are mounted on the front part of the casing of the injection unit. Wax heating rate is regulated by the power regulator knob (knob with a scale of 0-10). The heating temperature is controlled by a remote contact thermometer. The rubber mold is filled with wax through an injection nozzle, the individual heating temperature of which can be changed from 0 to 50°C using a specially provided heating regulator. Muffle furnace. Depending on the volume of production, various types of furnaces are used. In small-scale production, the drying electric laboratory cabinet SNOL-2.5-2.5-2.5 / 2M and electric resistance furnaces SNOL-1.6 * 2.5 * 1 / 9-M2U4 * 2 are most used; SNOL-1.6*2.5*1/11-M1U4*2. These furnaces provide for automatic adjustment of the set heating mode of the furnace inner shaft. The heater is made of wire of high ohmic resistance. The temperature is controlled and adjusted by a millivoltmeter. The heater is turned on with a magnetic starter. The space between the chamber and the cabinet body is filled with heat-insulating material.