HEAT PROCESSING NEWS
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February 2008, Volume 66, Issue 1-AV |
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In this Issue: |
NEWS & EVENTS
Mr. Grzegorz Paluch named new President of ELTERMA S.A. (Poland)
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Jeffrey Boswell, Group President for SECO/WARWICK S.A. has named Grzegorz Paluch Company President for ELTERMA S.A.
effective January 1, 2008. Mr. Paluch brings over 18 years of experience in engineering, metallurgy and business management to the 55 year-old provider of heat treatment equipment and contract manufacturing services.
In 2005, he was appointed a Managing Director of Inter Stal Centrum Ltd. Commercial Heat Treatment Shop seated in Mysłowice, which belongs to BŐHLER-UDDEHOLM Group. From 2001 to 2005, Mr. Paluch served as Vice President of Nitrex-HTC Ltd. in Częstochowa and Member of the Board of Directors for Castelli Nitrex Ltd. in Zabrze.
In 1996, during his tenure at Nitrex Metal Inc., Montreal, Canada, Mr. Paluch launched Nitrex-HTC Ltd., the first network of commercial heat-treating shops in Poland as General Manager. The business was started with one heat treating shop located in Częstochowa (South of Poland), and successfully expanded to additional commercial HT shops in Poland - in Grodzisk Mazowiecki, in Chełmo (near Toruń) and in 2004, the Nitrex-HTC shop in Świebodzin was established.
From 1989-1996 he worked for Polmo, the Automotive Assemblies Company in Praszka, Poland (formerly Visteon S.A., currently, Tedrive Poland Ltd.), starting his career as a technologist and finally serving as Manager of Technology Dept.
Grzegorz Paluch holds a Master of Science, Metallurgy from Technical University in Częstochowa, Poland, Specialty: Metal Science and Heat Treatment.
ELTERMA’s Thermal Process Team designs and manufactures a wide variety of heat treating equipment configurations with and without the addition of protective atmosphere. Specialists in applications for automotive and aerospace components, tube and pipe manufacturing, electrical steel components and other unique and divergent applications, the Team can offer many types of quality furnace systems including roller hearth, rotary retort, rotary hearth, mesh belt, specialty box, bell and pit furnaces along with custom designed furnaces, all developed specifically to meet each user’s plant, process and energy requirements. For more information, visit http://www.elterma.com.pl/en/products/Heat_Treatment_Equipment.html
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Thermal Process
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Roller Hearth Furnace Line |
Gulf States Tube has installed a new roller hearth annealing furnace system to process 10,000 pounds (4500 kg) per hour of 1” (25 mm) diameter tubing to increase production at their Texas facility. The tubing will vary in size from 5/8” to 2” (16 to 50 mm) outside diameter, with output rates varying with process requirements of the tubing being processed. This is the second system purchased from SECO/WARWICK, the first system was originally installed in 1968.
Controlled atmosphere annealing eliminates cleaning and assures scale free work. SECO/WARWICK roller hearth furnaces heat quickly and uniformly. No matter what the length of run or size tubing, SECO/WARWICK furnaces provide even heating - end to end - as the work progresses through the furnace.
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The atmosphere generator unit is positioned over the furnace cooling section to conserve space. |
The complete system including furnace, load/unload tables, control system, Exogas® (exothermic) generator and refrigerant dryer was designed and manufactured in the SECO/WARWICK Pennsylvania facility.
About The Thermal Process Team
SECO/WARWICK’s Thermal Process Group builds heat treating equipment using protective atmospheres in a wide range of configurations for most heat treating processes including annealing, fastener, brazing, carburizing, carbonitriding, forging, forming, hardening, nitriding, quenching, tempering and stress relief applications. We offer auxiliary system components including material handling equipment, quench systems, protective atmosphere systems and cooling equipment to create a complete manufacturing cell. Visit the Thermal Process Team at http://www.secowarwick.com/thermalprocess.html
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Vacuum Furnaces for Brazing Applications
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| Typical 2 Bar Vacuum Brazing Furnace |
Two types of vacuum furnaces are available for brazing applications depending on material used for construction of hot zone. The choice of hot zone construction (heating elements and insulation) depends on the vacuum level requirement, compatibility with base material and braze filler metals, temperature requirements, and cooling speed.
The most popular choices for insulation and heating elements are graphite and a refractory metal such as molybdenum. Molybdenum will not absorb moisture, will heat faster and is still recommended in the aerospace industry for materials made from titanium, aluminum or materials having high content of these metals. Graphite is a more economical material with lower maintenance requirements. Graphite material purity has improved over the last several years, and can now be considered for many vacuum brazing applications. A furnace using graphite will need a larger pumping system to operate at the same vacuum levels as the furnace with a metal hot zone because graphite is a hygroscopic material. Generally, graphite furnaces heat more slowly compared to an all-metal hot zone furnace.
Why Vacuum Brazing?
Vacuum brazing is usually a high temperature (typically 1700°F/927°C - 2250°F/1232°C), fluxless process using nickel-base, pure copper and less frequently precious BFM. There are several advantages to brazing under vacuum conditions:
- The purity level of the atmosphere (vacuum) can be precisely controlled. Atmospheres of much higher purity can be achieved than can be obtained in regular atmosphere furnace, in effect; there is less residual oxygen to contaminate the work piece.
- The vacuum condition at high temperature results in a decomposed oxides layer, and by doing so improves the base metal wetting properties. Improved wetting will result in better joint properties (e.g. increased strength, minimum porosity, etc.)
- Reduced to a minimum distortion because all parts are heated and cooled uniformly at precisely controlled heating/cooling rates.
- Repeatability and reliability of the brazing process in modern vacuum furnaces, ideally suitable for Lean/Agile manufacturing system.
Click here to read the full text version of our technical article "Issues in Vacuum Brazing" published in Heat Treating Progress Magazine.
SECO/WARWICK’s Vacuum Team provides custom engineered, quality Vacuum Furnaces for most processes including hardening, tempering, annealing, solution heat treating, brazing, sintering, carburizing, carbon/carbon composites, CVD–graphitizing, high pressure quench and degassing. Visit the Vacuum Team at http://www.secowarwick.com/vacuum.html
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Maintenance Tip: Diagnosing and Repairing Water Leaks in Vacuum Furnaces
The chart below is from a vacuum furnace showing a classic example of the pressure curve in a furnace with a water leak. When the pressure in the furnace is reduced to a point below the vapor pressure of the water, the water begins to boil, causing the pressure to rise. The boiling action removes the latent heat of vaporization from the water, causing its temperature to drop. The vapor pressure of water, as with most substances, is lower at lower temperatures. When the temperature of the water goes low enough that its vapor pressure is higher than the furnace pressure, the boiling stops and the vacuum level starts down again. The vacuum level will continue to drop until the vapor pressure of the water at the new temperature is reached when it will start to boil again.
This cycle is repeated several times with the vacuum level required to boil water becoming lower with each cycle due to the heat which was taken out of the water. This process is represented on the graph as peaks and valleys going from left to right, with each peak being slightly lower than the previous one. With this particular furnace, the pressure rose to a point where the control system shut down the heating system, causing the saw tooth shape of the heating curve. When the pressure dropped to an acceptable level, the control system allowed the heat cycle to resume, resulting in the ‘saw tooth’ pattern being reflected in the heating curve. Eventually sufficient heat is removed from the water that it freezes, resulting in the leveling out of the pressure curve.
Small water leaks may not be large enough to cause the heating system to cycle on and off. The pumpdown will slow until the water freezes, and the pumpdown will continue. It may not seem that there is a problem, because the required vacuum level can be reached, but this is misleading. The leak is still there and it needs to be fixed.
Possible sources for leaks include:
- Welds
- Older vessel inner wall corrosion
- Heat exchanger (internal or external)
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Thank you for reading Metal Minutes. Feel free to contact me with your questions, comments and suggestions.
Beth
Ryan, Metal Minutes Editor
bryan@secowarwick.com
+1-814-332-8437
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