Needless to prove that technical progress in mechanical engineering, electrical engineering, automotive industry, radio electronics, aerospace construction and nuclear engineering directly relates to application of precision tubes made of nonferrous metal

IMPORTS TAKE MORE MONEY than establishment of local precision tube-MAKING

Yuriy STASOVSKY, candidate of technical sciences

Needless to prove that technical progress in mechanical engineering, electrical engineering, automotive industry, radio electronics, aerospace construction and nuclear engineering directly relates to application of precision tubes made of nonferrous metals and their alloys. Neither there is a need to prove that the mentioned industrial sectors are well-developed in Ukraine. All the more illogical is the fact that, to cover the demand for precision tubes, Ukraine mainly imports precision tubes from Russia. This is happening although Ukraine possesses nonferrous deposits that have not been mined yet, as well as production waste containing nonferrous metals that have yet to be reclaimed.

The author intends not to discuss objective and subjective causes of this situation but to prove that there is a rather efficient way out, which requires relatively moderate investment. Research of the Ukrainian market proves that tubes made of many nonferrous metals and their alloys are still largely purchased abroad, primarily in Russia. This statement relates to tubes made of aluminum-based alloys, copper, brass, bronze, precious metals, oxygen-free copper and other nonferrous metals and alloys. Each year demands for some 60 ths. metric tons of these commodities remain unsatisfied. Shortage of semis (including tubes) made of copper comes to 30% of the total, brass – to 40%, copper-nickel alloys – to 65%, titanium – to 80%, oxygen-free copper – to 100%, aluminum and aluminum alloys – to 100%.

Open joint-stock company Nikopol Yuzhnotrubny Works is the most powerful Ukrainian tube company manufacturing a wide range of special-purpose tubes made of various steels and alloys. Being the one of its kind in Ukraine, open joint-stock company Artyomovsk Nonferrous Metal-Working Plant specializes in production of semi-finished products, such as tubes, rods, wires, sheets & plates, strips, bands, foil, etc. made of heavyweight metals (copper and copper-based alloys). Other Ukrainian tube plants are also equipped with the necessary facilities and make efforts to commence manufacturing of new types of semi-finished commodities including special-purpose tubes made of selected nonferrous metals and alloys.

The end-to-end approach to manufacturing precision commodities, including tubes, can be broken down to five large production stages, such as:

• smelting of charge metal;

• manufacturing of hollow and solid conversion billets;

• manufacturing of conversion sections with predetermined dimensions;

• finishing with application of auxiliary technological treatment affecting product quality; and,

• special unique processing to meet additional requirements posed to end product.

The first stage secures the desirable metal quality. Tube requirements determine the methods of metal smelting, as well as affect the quality of furnace charge and charge components. Quite a few most powerful Ukrainian mills are capable of providing the required metal quality.

The second stage determines quality and dimensions of conversion billets that will further be subject to various pressure treatment. The required tube material, dimensions, physical, mechanical and other properties affect the method of manufacturing conversion billets (sections). Several Ukrainian mills own the necessary facilities to complete this stage.

During the third stage, conversion billets are either transformed into conversion sections that are very close to dimensions of the final products or into the end tube. The functioning Ukrainian mills are equipped with press, forging, rolling and servicing facilities to manufacture conversion sections.

The fourth stage is production of a wide range of tubes made of nonferrous metals and alloys in compliance with the consumers’ requirements. As compared to the world tube making, Ukrainian plants fail to meet the product quality requirements owing to shortage of up-to-date equipment and end-to-end technologies complying with the international standards. First of all, the Ukrainian industry does very little to develop coil and long-drift drawing and other modern finishing methods. However, the Ukrainian mechanical engineering is potentially capable of manufacturing specialized up-to-date facilities to equip the new and the functioning Ukrainian plants. This relates to finishing equipment (various finishing mills), heat and chemical treatment units, thorough finishing equipment, etc. It would be useful to purchase certain types of foreign equipment as pilot samples for industrial testing in Ukrainian conditions.

The fifth stage gives the product a set of special properties ordered by consumer. Such properties may embrace non-corroding surface, extra-fine metal grains, extra-durability, etc. Ukrainian scientists and specialists have been conducting research in this sphere for many years. Several inventions have already proven effective in manufacturing.

Open JSC Artyomovsk Nonferrous Metal-Working Plant is the primary and the most powerful Ukrainian nonferrous mill specializing in working copper and copper alloys. This company owns special equipment for metal-making, ingot casting, tube and rod forging, tube rolling, tube, rod and wire drawing and copper wire rod production. The company applies pretty much the same end-to-end approach as mentioned above. However, due to lack of the required equipment and technologies, this plant is currently unable to manufacture precision tubes of copper and brass (in particular, thin-wall, capillary and flat-oval tubes).

Since the 1960s Ukraine has traditionally developed production of semis (mainly precision tubes) made of refractory alloys at the facilities of Pilot Tube Plant with the State Tube Institute. It is quite a unique plant established solely for production of special-purpose tubes made of precision refractory alloys for the needs of aircraft and spacecraft construction, shipbuilding and other priority industries. Possessing all the necessary manufacturing facilities, the plant has been somewhat of a monopolist in this business for many years. The Pilot Tube Plant has tested and introduced new production technologies for manufacturing various precision tubes made of niobium, tantalum, vanadium, hafnium, titanium, molybdenum, tungsten, chromium, zirconium and other alloys. By the way, the author has taken an active part in this process. Since 1993 the plant has commenced production of copper and brass tubes (primarily, thin-wall and capillary ones).

In addition, in 1994 the experimental production division of the State Tube Institute commenced studies on technological adjustment and introduction of new types of nonferrous tubes and commodities. The division is equipped with 5,000 kN and 16,000 kN presses, numerous cold rolling mills, linear and drum drawing mills (140 kN, 80 kN and 10 kN ones), heat-treatment facilities and other devices.

Nikopol Yuzhnotrubny Works has recently launched production of various cold-finished seamless tubes made of copper and brass applying new technologies, including processing of unconventional conversion sections, such as empty brass shell cartridges.

The works has also commenced output of a wide range of tubes made of AD1 aluminum-based alloys with application of an alternative technology involving high metal consumption. Besides, the works has already introduced or currently tests the technology of making precision tubes of titanium and zirconium-based alloys.

Other tube plants in Dnepropetrovsk, Yevpatoriya, Kiev, Donetsk and Kharkov have also started small-scale manufacturing of tubes made of nonferrous metals and alloys, such as copper, brass, aluminum, silver, platinum and others. For many years, Brovary Structural Aluminum Smelter has been the sole manufacturer of tube shapes and certain dimension-types for tubes of ADZ1 wrought aluminum alloy. This smeltery is capable of manufacturing over 500 dimension-types of such commodities. Open JSC Kharkov Bicycle Factory has set up a division manufacturing merchant aluminum shapes. The employed equipment can produce extruded tubes, 10-100 mm in external diameter, up to 6 m long, 1.0-12 mm in wall thickness. If the existing production line is equipped with a coiler device, it will become possible to place extruded tubes in coils. This is very important for successful industrial cooperation aimed at supplying conversion strips and hollow sections. Open JSC Artyomovsk Nonferrous Metal-Working Plant has commenced producing tubes made of A6 primary aluminum. The plant is equipped with drum drawing mills, which can be used to manufacture various thin-wall tubes from coiled extruded sections.

The author would like to emphasize that although there are many unresolved problems, Ukraine has a weighty potential and enjoys certain progress in precision tube manufacturing.

At present, Ukraine does not produce tubes made of scarce, rare-earth and radioactive metals. Ukraine manufactures insignificant quantities of tubes made of precious metals. Several plants have lately started small-scale manufacturing semi-finished products (tubes, bars, wires, sheets, strips, etc.) made of recycled platinum, gold, silver and their alloys. However, these steps cannot completely resolve the issue of production and consumption of nonferrous semis.

Ukraine still tries to cover the unsatisfied demand for certain types of precision tubes by engaging in imports. In most cases, products manufactured by Ukrainian plants are mainly noncompetitive in terms of quality and price, which depend on the cost of raw materials, fuel and power, freightage rates and running production costs. Companies have to waste excessive financial resources owing to obsolete and deteriorated equipment, deficient power-consuming and laborious technologies. The available raw materials and production capacities are still used inefficiently. Thus, one can conclude that the cure to the problems is in the following steps. The operating and the new manufacturers must be adequately supplied with raw materials (preferably with those mined in Ukraine). The functioning capacities, as well as idle production space, ought to be used more efficiently. Manufacturers should make efforts to introduce modern resource-saving environment-safe end-to-end technologies that would boost competitiveness of Ukrainian commodities as regards quality and financial figures.

In author’s opinion, one of the ways to achieve these objectives is to set up mobile mini-mills equipped with up-to-date efficient facilities and resource-saving technologies. The mini-mills can use computer-based control systems to regulate the manufacturing process. The control system will be based on a comprehensive mathematical apparatus, which will consider all the main technological parameters and will give timely response to possible malfunctions.

High quality of end products can be reached via dividing manufacturing of precision commodities (including tubes) into stages. Quality control is conducted at all the manufacturing stages, which allows timely adjustment of the product’s parameters.

A modern mini-mill uses the continuous manufacturing approach and directly links all the conversion stages, thus lowering power consumption and transportation costs within the manufacturing cycle. Besides, manufacturing is extremely flexible and easily adjusts a product to meet requirements of the rapidly changing market situation. Management over the manufacturing process is also flexible, which enables saving power and lowers the investments needed. Equipment is arranged into an assembly line for piece processing. Moreover, substandard products are efficiently recognized and removed from the production line, along with simultaneous correction of the appropriate technological parameters. Production based on these principles requires lots of scientific efforts to ensure stability of technical performance on all the conversion stages.

Ukraine has two examples of partial implementation of the mini-mill concept. Ukrainian-Spanish joint venture Intersplav, Sverdlovsk town of Lugansk region, converts scrap and waste aluminum alloys into pigged secondary aluminum alloys. A mining equipment plant jointly with Yugchermet company, Dnepropetrovsk, manufactures extruded semis (shapes, tubes and bars) using ADZ1 aluminum-based ductile alloy. These two companies have proven all the economic advantages of mini-mills.

There is an important and tempting proposal to establish a mini-mill to reclaim nonferrous metals from various weaponry and convert the recovered metals into a wide range of thin-wall, capillary and flat-oval precision tubes. It proposed to locate such a mill at the grounds of a tube plant in Pridneprovye region. In the long run, Ukraine will have demands for 15 mln. meters or more than 700 metric tons of such tubes per year. At present, Ukraine has to import almost 100% of similar tubes.

Ukrainian companies have already developed and tested several interesting technological approaches to manufacture semis using empty shell cartridges or various cylindrical hollow, solid or flat cast billets (obtained via recycling and continuous casting of weapon metal).

Nikopol Yuzhnotrubny Works employs the technology of reprocessing unconventional hollow sections (empty brass shell cartridges). However, this technology features rather poor technical and financial performance (metal consumption coefficient comes to 2.0, while cost of producing tubes, 16×1 mm, is 3.2-5.4 times as high as the cost of the utilized unconventional hollow sections).

The first scheme for weapon metal reprocessing is targeted at production of tubes from unconventional hollow sections. The objective of this technology is to efficiently salvage high-quality weapon metal, lower power consumption, improve tube quality, reduce production costs via application of efficient technologies and improve the environment at the sites of Ukrainian plants. This technology considerably boosts technical and economic performance of manufacturing process (e.g. metal consumption coefficient totals 1.09, i.e. metal losses come to approximately 8.3%). Both the first and the second weapon metal conversion technologies produce standard conversion sections that can be used for subsequent cold-finishing of various tubes.

When arranging the mini-mill-type tube production using the power-saving environment-safe end-to-end technology, one should keep in mind that there are two groups of the necessary manufacturing facilities.

The first group comprises two independent production lines:

• cold-working of unconventional hollow sections (it takes an average of 6 seconds to convert one empty shell cartridge into a standard conversion section);

• remelting of waste metal and continuous casting of billets and sections.

The production costs of converting empty brass cartridges into continuously-cast sections, 57×12 mm, are as follows:

• raw materials and feedstock make up 61% of the total costs;

• fuel and electric power – 3%;

• wages and salaries – 1.8%;

• depreciation expenditures – 4.7%;

• transportation expenses – 1.4%.

The second group embraces the currently functioning equipment (cold-rolling mills, etc.) and new facilities (mills to draw tubes on moving or stationary mandrels, heat-treatment facilities, etc.).

The equipment of the second group performs finishing of the standard conversion sections manufactured using the first group of equipment. Standard sections are converted into a wide range of thin-wall, capillary, flat-oval and other types of precision tubes. Mini-mills require labor inputs that do not exceed 2.4 man-hours per 1 tonne of end commodities (as compared to more than 4 man-hours at large tube plants). The planned rates of return are estimated at 45%. It is calculated that 1 tonne of manufactured products will cost 30-40% less than the imported commodities. Once again, this proves that Ukraine spends more money on imports than on development of local technologies.

Thus, Ukraine can set up a mobile mini-mill to reclaim brass shell cartridges and other industrial waste and convert them into a wide range of competitive tubes. The initial outlay to set going the first group of mini-mill’s facilities (including design, manufacturing of equipment, assembling and putting into operation) is estimated at USD 2.2 mln. The payback period does not exceed 2 years, whereas life span of a mini-mill using Ukrainian raw materials comes to at least 30 years. These main organization principles are also applicable in arrangement of manufacturing for other precision products at Ukrainian companies.

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