Tuesday, June 27, 2017

Quick Facts About Welding as a Profession

Welding is the most common way of permanently joining metal parts. In this process, heat is applied to metal pieces, melting and fusing them to form a permanent bond. Because of its strength, welding is used in shipbuilding, automobile manufacturing and repair, aerospace applications, and thousands of other manufacturing activities. Welding also is used to join steel beams in the construction of buildings, bridges, and other structures and to join pipes in pipelines, power plants, and refineries.

Welders work in a wide variety of industries, from car racing to manufacturing. The work that welders do and the equipment they use vary with the industry. Arc welding, the most common type of welding today, uses electrical currents to create heat and bond metals together—but there are more than 100 different processes that a welder can use. The type of weld normally is determined by the types of metals being joined and the conditions under which the welding is to take place.

Welders, cutters, solderers, and brazers typically do the following:
  • Study blueprints, sketches, or specifications
  • Calculate dimensions to be welded
  • Inspect structures or materials to be welded
  • Ignite torches or start power supplies
  • Monitor the welding process to avoid overheating
  • Maintain equipment and machinery

The median annual wage for welders, cutters, solderers, and brazers was $39,390 in May 2016. The median wage is the wage at which half the workers in an occupation earned more than that amount and half earned less. The lowest 10 percent earned less than $26,800, and the highest 10 percent earned more than $62,100.

In May 2016, the median annual wages for welders, cutters, solderers, and brazers in the top industries in which they worked were as follows:
  • Specialty trade contractors - $42,900
  • Repair and maintenance - $39,340
  • Manufacturing - $38,200
  • Merchant wholesalers, durable goods - $37,790
Wages for welders, cutters, solderers, and brazers vary with the worker’s experience and skill level, the industry, and the size of the company.

Most welders, cutters, solderers, and brazers work full time, and overtime is common. Many manufacturing firms have two or three 8- to 12-hour shifts each day, allowing the firm to continue production around the clock if needed. As a result, welders, cutters, solderers, and brazers may work evenings and weekends.

Friday, June 23, 2017

Process Heating: Induction

Induction Heater
Induction heating coils around large pipe
in preparation of welding.
The principles of induction heating have been applied to manufacturing operations since the 1930s, when the first channel-type induction furnaces were introduced for metals melting operations. Soon afterward, coreless induction furnaces were developed for melting, superheating, and holding. In the 1940s, the technology was also used to harden metal engine parts. More recently, an emphasis on improved quality control has led to increased use of induction technology in the ferrous and nonferrous metals industries.

In a basic induction heating setup, a solid state power supply sends an alternating current (AC) through a copper coil, and the part to be heated is placed inside the coil. When a metal part is placed within the coil and enters the magnetic eld, circulating eddy currents are induced within the part. These currents ow against the electrical resistivity of the metal, generating precise and localized heat without any direct contact between the part and the coil. 

An induction furnace induces an electric current in the material to be melted, creating eddy currents which dissipate energy and produce heat. The current is induced by surrounding the material with a wire coil carrying an electric current. When the material begins to melt, electromagnetic forces agitate and mix it. Mixing and melting rates can be controlled by varying the frequency and power of the current in the wire coil. Coreless furnaces have a refractory crucible surrounded by a water-cooled AC current coil. Coreless induction furnaces are used primarily for remelting in foundry operations and for vacuum refining of specialty metals.

Induction heating power console
Induction heating power console (Hotfoil-EHS)
Channel furnaces have a primary coil wound on a core. The secondary side of the core is in the furnace interior, surrounded by a molten metal loop. Channel furnaces are usually holding furnaces for nonferrous metals melting, combined with a fuel- red cupola, arc, or coreless induction furnace, although they are also used for melting as well.

The efficiency of an induction heating system for a specific application depends on several factors: the characteristics of the part itself, the design of the induction coil, the capacity of the power supply, and the degree of temperature change required for the application.

Induction heating works directly with conductive materials only, typically metals. Plastics and other nonconductive materials often can be heated indirectly by first heating a conductive metal medium that transfers heat to the nonconductive material.

With conductive materials, about 80% of the heating effect occurs on the surface or “skin” of the part. The heating intensity diminishes as the distance from the surface increases, so small or thin parts generally heat more quickly than large thick parts, especially if the larger parts need to be heated all the way through.

Induction heating can also be used to heat liquids in vessels and pipelines, primarily in the petrochemical industry. Induction heating involves no contact between the material being heating and the heat source, which is important for some operations. This lack of contact facilitates automation of the manufacturing processes. Other examples include heat treating, curing of coatings, and drying.

Induction heating often is used where repetitive operations are performed. Once an induction system is calibrated for a part, work pieces can be loaded and unloaded automatically. Induction systems are often used in applications where only a small selected part of a work piece needs to be heated. Because induction systems are clean and release no emissions, sometimes a part can be hardened on an assembly line without having to go to a remote heat treating operation.

Friday, June 9, 2017

Hotfoil-EHS Attending the 2017 Global Petroleum Show in Calgary

Hotfoil-EHS is pleased to announce our products will be on display at the Global Petroleum Show on June 13 through 15, 2017 at the Stampede Park in Calgary, Canada.

Hofoil-EHS will in exhibiting as a guest of Stein Industries in London, Ontario. Stein will be exhibiting its high quality, custom designed, affordable induction heaters built to withstand harsh environments with wide applications.

This is a great opportunity to see major welding equipment vendors and new technologies being introduced. If you plan on being at the Global Petroleum Show, please stop by the Stein Industries at booth 4404.

The Global Petroleum Show provides direct access to the entire supply chain, innovative technologies, products & services and a massive number of educational seminars within the energy sector. Global Petroleum Show is an industry leading event, where more than 50,000 energy professionals from more than 90 countries converge for three days to strengthen business relationships, network, and do business with more than 1,000 exhibitors. During this pivotal, evolutionary period for the oil & gas sector, it’s never been more vital to re-connect with your global industry. From upstream to downstream, GPS provides a forum where business gets done.

Wednesday, May 31, 2017

Resistor Controlled Welding Machines

resistor controlled welding machines
Resistor controlled welding machines by AFTEK.
Resistor control has been used in multi-operating welding systems in shipyards and heavy construction for decades. In the heyday of nuclear power plant construction in the USA, nearly all were built using multiple-operator systems. From the thirties until about 1990, nearly all multiple-operator systems were the designed similarly. They used a large bulk power supply with “grids” connected by cables to form a system of distributed power. This system minimized the use of high voltage primary power, distributing 75-80 volts of secondary voltage instead.

As these systems grew in popularity, the concept of “packs” became popular. These packs provided 2, 4, 8, and 16 arcs in a steel rack, and all being connected to a separate power supply. A now defunct company named Big Four developed the concept of connecting multiple-operator systems in a loop arrangement, which resulted in greatly improved voltage stability. In 1990, this loop concept was further refined into integrated, modular welding packages. These newly designed systems provided an internal power supply sufficiently sized to provide power to all the arcs without any interference.

Loop systems are still being used today. They are viewed as a very economical welding alternative. For example, for a loop that needs twenty MIG arcs, it is possible to use (4) 500-amp power supplies connected to a single 500 MCM cable which circles the work space. Twenty control modules can be connected wherever needed on the closed loop of cable. A huge cost savings is realized in having to establish just four (4) primary connections instead of twenty (20).

Most conventional arc weld­ers use a transformer-like device called a reactor to control the "heat" of the welding arc. If you examine the Voltage/Amperage (V/A) curve for a con­ventional constant current (or constant voltage) welding power supply, you’ll see spikes. This is inherent in the design of conventional arc weld­ers. The V/A curve of a resistor controlled arc welder, on the other hand, is a straight line.

Resistor controlled arc systems provide more consistency of power - if you shorten the arc, thus lowering the arc voltage, the current will increase, and maintain virtually the same power (heat). If you lengthen the arc, you raise the voltage, but the power remains virtually constant. Why is this important? In any welding process, increasing the amperage increases penetration and increasing the voltage widens and flattens the head (and reduces penetration). With a resistor controlled arc, if you are welding along the seam and it closes, shortening the arc length will increase penetration. If the weld opens, lengthening the arc will lessen the penetration and widen the weld. This provides excellent control right in the electrode holder.

AFTek, a US manufacturer located in Chattanooga, TN and division of Hotfoil-EHS, is the sole remaining manufacturer of resistor controlled welding machines in the USA. Their resistance welders are an acknowledgement of the superior design Big Four developed years ago, while improving performance with edge-wound coils for better heat dissipation (thus better current control) and rotary switches for current selection, even under load.

Wednesday, May 10, 2017

New Product: The ISG Wireless Heat Treatment Controller

ISG heat treat controller
The ISG heat treat controller.
The ISG heat treatment controller is a panel-mounted controller which can easily be connected to thyristor, electrical contactor, or induction/inverter driven power sources. The controller has 2 analog outputs, 5 digital outputs, 2 analog inputs and 2 digital inputs.

The ISG is capable of controlling two measurement points and monitoring two measurement points. If more measuring points are required, up to 14 controllers can be daisy-chained to the same heating process via cables or wireless, while all being managed from a single computer. The ISG communicates with PC's via Zigbee radio or with an RS485 Serial port.

All routines or process plans are created with ISPort software. After the process is started, the routine and the process data is saved to the PC, and also to the controller's memory. This enables the controller to work independently should the connection between ISG and computer be lost. The ISG includes a convenient LED process display and additional process status and alarm LED's.

For more information on the ISG heat treatment controller, visit http://www.hotfoilehs.com or call 609.588.0900.

Wednesday, May 3, 2017

Custom Built Heat Treat Furnaces

Custom Built Heat Treat Furnaces
 15'x15'x60' Custom Furnaces
Hotfoil-EHS has extensive heat treating furnace design and fabrication experience. From small, low-throughput furnaces, to much larger high yield furnaces, to rail-driven furnaces, Hotfoil-EHS Design Engineers and Fabrication Shop have done it all.

 Heat Treat Furnace
Capable of handling 45,000 lbs.
Recently Hotfoil-EHS provided a customer with a heat treat furnace that is 15'x15'x60' that accommodates up to 45,000 pounds of material. Two, 5 million BTU burners heat the furnace to 1650 deg. F. The furnace travels on a track, back and forth, to accommodate two beds for greater production.

 Heat Treat Furnace
Rail system with (2) beds

For more information, visit http://www.hotfoilehs.com or call 609.588.0900.