Precision, uniformity and value in everything we build and sell.
L&L Special Furnace Co. has been in business for decades, and our reputation speaks for itself. Our expertise lies in designing and manufacturing a broad line of heat treating furnaces, ovens and quenching equipment for a diverse range of customers, from industrial manufacturers to testing laboratories. We provide expert, professional service in support of our superior American craftsmanship and highly sophisticated engineering in both our products as well as the processes they are used for. Our base of satisfied customers is extensive and growing rapidly.
That is an important aspect of doing business with L&L. Whether you’re just looking for some general advice on what type of equipment you need, or if you have a challenging and complex engineering question requiring broad and deep expertise, we can help you.
Our product line is also very flexible, so we can easily adapt a particular model to unique or specific design requirements. Some of the more common applications that we support are ferrous and non-ferrous heat treating, hydrogen brazing and sintering, and forging. For more information about our equipment and the solutions we provide, please give us a call so we may provide detailed and specific information about how we can address your particular needs.
We remain firmly committed to the principle that American craftsmanship is the best in the world, and our products reflect that commitment. Our entire team works out of our plant, located just south of Philadelphia. From there, we provide comprehensive service and support to our customers worldwide. Our fully stocked parts department understands the industrial heating business in great depth and detail, and we pay meticulous attention to every facet of industrial and laboratory ovens and related equipment, including assembly drawings, wiring diagrams and general support information.
In addition to repairing existing installations, our expertise also extends to startup environments where our expertise is often called upon to assist with both site and process-engineering planning.
Following are some of the heat treating applications that our products are used for, along with our recommendations for which of our products represent the best solution for each process.
Process: Neutral Hardening
Process Industry: Heat Treat / Tool and Die
Specific Applications: Neutral Hardening of Tool Steels
Description of Process: L&L manufactures furnaces that can be used for neutral hardening of tool steels, such as those used in tool and die applications. The furnace uses an inert gas such as nitrogen or argon. Once the furnace is heated above 1,400℉, natural gas or propane is introduced at a predetermined setting. This enriches the atmosphere, and the natural gas or propane “cracks”. The cracking causes the atmosphere to become neutral. The parts are then loaded into the furnace for the heat treating cycle. After soaking in the elevated temperature for a set amount of time, the parts are removed and air-cooled or quenched in oil depending on the alloy of the steel. The neutral atmosphere produces a part that is virtually decarburization free.
Furnaces to Use:
Process: Hardening
Process Industry: Machine Shop
Specific Applications: Small Batch Hardening of Various Tool Steels
Description of Process: L&L manufactures small benchtop furnaces that work well in a machine shop environment and can be used in general heat treating processes, including surface hardening of materials such as tool steel. In a typical hardening process for a tool steel, the furnace would be heated to a temperature of 1,800-2,200℉. The parts would be left to soak in the furnace for a specified time (based, along with temperature, on the type of material involved and the desired effects) to achieve the phase change to austenite. After soaking, the part is then either air-cooled or oil/polymer quenched to achieve the final martensitic crystalline structure. The result is an increase in the Rockwell hardness of the part. The parts can also be wrapped in a stainless-steel foil or have an inert blanketing system to lower the amount of decarburization that takes place. Parts are typically surface ground or bead blasted post heat treating and quench.
Furnaces to Use:
B86
Process: Heat Treat, Anneal and Temper
Process Industry: Aerospace Manufacturing and Maintenance
Specific Aerospace / MRO Applications:
Aluminum Heat Treat
Stress Relieving
Heat Treatment of Steel
Heat Treatment of Titanium
Description of Process: L&L manufactures furnaces that are designed specifically for aerospace manufacturing and MRO heat treating facilities. These versatile furnaces can be used for heat treatment processing of materials, including aluminum, steel and titanium alloys. Typical applications for these ovens would include solution heat treatment of aluminum parts, stress-relieving welds, surface-hardening components made from tool steels to achieve a durable martensitic crystalline structure, and annealing steel fasteners.
These furnaces are also available with pyrometry packages that allow for easy calibration with no field modifications necessary. They are specifically designed to meet and exceed AMS270D class I, II, III and IV equipment.
Furnaces to Use:
XLA Series
FNA Series
Process: Heat Treating Knife Blades
Process Industry: Hobby
Specific Applications: Heat Treatment and Tempering of Steel Used to Make Knives and Decorative Knives
Description of Process: L&L manufactures a series of furnaces that can be used to heat treat steel knife blades, including those fabricated from stainless steel. The steel blanks for the blades are formed, machined, and then sharpened prior to heat treating. A basic heat treatment for a knife blade would involve hardening at a temperature around 1,850℉ followed by cooling or quenching.
The simplest approach to a hardening heat treatment process using these furnaces would be to simply place the blades in the furnace for the amount of time and temperature recommended for the material used. To prevent oxidation, the blades can be wrapped in stainless steel foil. To achieve a carburizing effect, the blades can be wrapped in newspaper before being wrapped in stainless steel. The graphite from the newspaper provides a carbon-rich atmosphere that results in case hardening (which reduces the brittleness of the final knife blade without sacrificing he hardness of the surface). An inert blanketing atmosphere is also available in some models. The result is an austenitic crystalline structure. As a final step, the blades are either air-cooled or submerged in an oil quench to achieve the desired martensitic crystalline structure. Any warping that may occur can be removed through stress relieving.
Furnaces to Use:
Process: Heat Treating
Process Industry: Military
Specific Applications: Heat Treatment and Tempering of Various Tool Steels for Military Applications
Description of Process: L&L manufactures a series of dual-chamber furnaces that can be used for general heat treating and tempering. These are typically a dual-chamber furnace with a high-temperature hardening/austenitizing chamber on the top and lower-temperature tempering chamber on the bottom.
An example of the type of application that is ideal for these furnaces would be the hardening of machined parts for use in combat tanks. Heat treatment is a key part of the manufacturing process for such parts, and usually involves hardening, annealing or drawing, as well as quenching of the machined parts. The hardening chamber would be used for the austenitizing step of the heat treatment process. The lower-heat tempering chamber would be used for the annealing, drawing or stress relieving of the steel. In these processes, the crystalline structure can be refined by bringing the temperature of the steel to just below its austenitizing temperature. The result is a reduction in brittleness and the restoration of some degree of ductility, and the relief of internal stresses that may have developed during heat treatment, welding or forming. An oil quench tank can be supplied with the furnace for facilitating the quenching step for achieving the final martensitic crystalline structure.
Furnaces to Use:
Process: Heat Treat / Anneal / Stress Relieve
Process Industry: Aerospace
Specific Applications: Thermal Processing Aluminum, Steel, Titanium
Description of Process: L&L manufactures a series of retort or muffle furnaces used in aircraft facilities for heat treatment processes, including hydrogen brazing, annealing and stress relieving. Typical materials heat treated in these ovens include aluminum, steel (including stainless steel) and titanium.
These furnaces use a high alloy insert and an inert atmosphere such as nitrogen or argon to displace all of the oxygen inside the retort. They can have a cold wall vacuum and then be backfilled with inert gas. Any heat treatment batch process that cannot tolerate oxygen or requires a significant degree of atmospheric reliability, a low dew point, and repeatability is an excellent candidate for this furnace model.
These furnaces are ideal for the general heat treatment of aircraft engine parts, including stress relieving of delicate, mission-critical aircraft engine components.
Furnaces to Use:
Process: Heat Treat and Temper
Process Industry: Machine Shop
Specific Applications: Small Batch Hardening and Tempering of Various Tool Steels for Military Applications
Description of Process: L&L manufactures a series of dual-chamber furnaces that are used to heat treat and temper various types of steel, including tool steels and parts for military defense use. These units consist of separate chambers for the hardening and tempering processes, with the high-temperature hardening/austenitizing chamber on the top and a recirculating tempering chamber located on the bottom. Note that this dual-chamber design makes efficient use of power and space.
As an example of how these dual-chamber furnaces might be used, consider heat treatment and tempering of tool steel. For the hardening step, the tool steel would be placed in the upper high-heat chamber for hardening and heated to the austenitizing temperature of the steel, up to 2,200℉. After heat treatment, the part can be moved to the lower-temperature bottom chamber for the tempering step, where it will be heated to below the steel’s austenitizing temperature. This process refines the crystalline structure of the steel to remove excessive brittleness and relieve internal stresses.
Furnaces to Use:
Process: Heat Treating
Process Industry: Manufacturing
Specific Applications: Heat Treatment of Various Tool Steels
Description of Process: L&L makes a series of furnaces that are well adapted for general heat treating and hardening processes found in the manufacturing industry, which can involve parts with a wide variety of shapes, sizes and materials. For such applications, one of our typical box furnaces would be used. These furnaces support a production environment extremely well. They can also be used for preheating, where the material is heated to just below it’s austenitization point to prevent thermal shock and volumetric changes during the hardening process. Additionally, they can be used for stress relieving of repaired parts. A typical example of how one of these furnaces might be used would be the hardening process for punches and dies made from tool steel, which usually occurs around 1,850℉.
Furnaces to Use:
Even if you do not see precisely what you are looking for, we invite you to get in touch with us. Our team of experts will help you figure out exactly what you need—and more importantly, how to integrate our equipment into your workflow.