Pit furnaces are top-loading furnaces that are used in wide range thermal processes compared to other heat-treating furnace designs and configurations. Most commercial and captive heat-treaters use or have used a pit-type furnace for one or more of these applications: tempering, aluminum-solution treating, nitriding, steam treating, annealing, hardening, carburizing, and vacuum heat-treating. Pit furnaces offer temperature ranges from 500° C to 1150° C. MAAN GLOBAL INDUSTRIES is among the leading Pit furnace manufacturers in India, gas-fired pit furnaces manufacturer and electrically heated pit furnaces manufacturer in India. Pit furnaces are fitted with retorts for several applications, can cool products in place, and provide the best design for long parts or heavy loads than typically supported with an overhead loading device. They also use the least amount of valuable floor space, which is a key consideration in today’s industrial manufacturing companies across the world.
What is a Pit Furnace?
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A Pit furnace is a type of furnace used for metallurgical processes which require low temperatures; mostly used to harden alloys like steel and evenly heat them. Pit furnaces are used to treat large metal objects with heat. Pit furnaces have been used for tempering (550° C to 750 ° C) and aluminum heat treating (250° F to 1,100° F) for many years due to the easy loading and unloading of parts, which is done by lifting the lid away and hooking the parts out of the furnace. Parts are often forced-air cooled or quenched in water as is the case for aluminum castings. Pit furnace manufacturers in India design and manufacture electrically heated pit furnaces, gas fired pit furnaces and oil fired pit furnaces.
Here’s a very insightful article on maintenance of Vacuum furnace.
What are the different Types of Pit Furnaces?
Gas nitriding Pit Furnace Manufacturers in India
Product Specification for Gas Nitriding Furnace
|Furnace Type||Gas Nitriding Pit Furnace|
|Material Loading Capacity (kgs.)||1000 kgs, 2000kgs, 5000 kgs, 10,000 kgs.|
|Power Source||Electric Heating|
|Type Of Furnace||Pit Type Furnace|
|Heat Treatment Process||Gas Nitriding|
|Temperature Range||1100 Degree C Max.|
|Price||Rs. 15,00,000 – Rs. 45,00,000|
Gas nitriding (700° F to 1,100° F) is the most popular heat-treating process in today’s heat-treating market. This process provides a thin coating on the steel parts used for high wear or corrosion in the gear market. The lower temperature of about 1,000° F has a very low distortion level on the part compared to gas carburizing in atmosphere with oil or vacuum carburizing with 20 bar quenching where straightening is often required or press quenching is needed.
Carburizing Heat Treatment Furnace
|Furnace Type||Carburizing Furnace Pit Type|
|Material Loading Capacity||500kgs, 1000kgs, 2000kgs, 5000kgs, 10 Tons|
|Max Temperature||500-1000 degree Celsius|
The carburizing process (1,600° F to 1,800° F) in pit furnaces is widely used by companies in the power-transmission, movable-machinery, marine, mining, wind-power, and gear markets along with a few commercial heat-treaters. These companies typically have very large capacity units from 16 feet in diameter to 20 feet deep for loads up to 50,000 pounds which makes the pit furnace the only choice.
These furnaces are mostly electrically heated with fully automated temperature controls, carbon probes, ramp and cooling features, etc. Slightly smaller carburizing furnaces also are used since case depths can be up to 0.250 inches deep for carburizing followed by a slow cool required for some specifications prior to further hardening. The enclosed (Figure 5) shows a typical carburize load, special fixture, and stop-off paint prior to loading. These furnace cells typically have a companion re-heating or hardening furnace, oil quench tank, washer, and temper furnaces with an atmosphere generator. By using an overhead crane or gantry device, these cells can provide a very high output and require very little maintenance.
Hardening and Annealing Pit Furnace Manufacturers in Mumbai, Hyderabad, Bengaluru, Delhi, Kolkata, Pune, India
The hardening (1,500° F to 2,000° F) and annealing (1,300° F to 1,800° F) processes are typically performed in radiant-heat-type furnaces where the heating method is no longer convection. The radiant heat is provided by gas-fired tubes or metallic-rod-type elements. A typical radiant heating element design shows the furnace heating chamber with the wall-mounted element attached.
These furnaces typically require a protective atmosphere to keep the components free from scale or from de-carburizing when hardening. Both endothermic and nitrogen-methanol blends are used in this type of furnace. Often times, a top-mounted fan is used for better temperature uniformity or mixing of the protective atmospheres. The gas-tight shell and lid provides a perfect seal against any oxygen penetrating the heating chamber. Overhead lifting devices are commonly used to remove loads into a quench tank or companion washer and tempering furnace. Special fixtures, baskets, and center-post devices are common for large loads when hardening. The pit furnace offers a large work capacity for large, long, or heavy loads that other furnace types cannot.
Bright Annealing Heat Treatment Furnace
Bright Annealing is a process of heating or cooling metal objects in an inert atmosphere so that these objects can go through the process of oxidization. During this process the surface becomes bright and shiny. If Bright Annealing is improperly done, the objects will have poor finish. The surface of these objects may crack, can be stained or can be ruined by being corroded very easily.
Pit Furnace for Wire Annealing
Wire drawing lines that reduce diameters of the wires to the desired thickness often require annealing to remove internal stress induced during the drawing process. Annealing is done at temperatures upto 750 degree C for upto 6 hours in annealing furnaces. Electrically heated Wire annealing Pit furnaces are the most efficient in carrying out annealing process on wires due to uniform heating at low energy consumption and slow cooling rates of the furnace chamber.
Stress Relief Pit Furnace Manufacturers in Africa, Kenya, Dubai, UAE, Europe
Pit furnace are also widely used for Stress Relief purposes in Steel Alloys and Metal structures where stress gets induced in metal components due to work hardening such as cutting, bending, rolling or welding. Due to high uniformity in heating in Pit furnaces, Stress can be removed easily at 550 Degree C to 650 Degree C by holding the metal pieces for upto 2 to 4 hours (different metals have different soaking times).
Electric Pit Furnace
Electrically Heated Pit furnaces offer high temperatures upto 1100 Degree C at low power loads which means your electricity consumption remains low while thermal efficiency remains high. These electric pit furnaces are capable of inert atmosphere for various heat treatment processes such as Carburizing, nitriding, vacuum annealing, Stress Relief and Bright Annealing. Electric Pit furnaces for Normalizing are widely used in Railway and Locomotive manufacturing industry. Electric heat treatment furnace manufacturers in Africa, Kenya, Dubai, Oman, Ghana, Kuwait, Uganda, Sri Lanka, Europe, USA, Australia, Malaysia, Indonesia, Philippines.
Gas Fired Pit furnace
Gas fired pit furnace manufacturers in India offer most versatile heat treatment furnace running on fuels such as LPG, CNG, LNG, PNG that keeps heat treatment costs low while providing optimum production rates. In a gas fired pit furnace, retorts of AISI 304, AISI 310, 330 and Inconel are used for heat treatment in a sealed enclosure. Bureau of Energy Efficiency (BEE) conducted a study on efficiency of Gas Fired Pit furnaces.
What is the cost of a Pit Furnace?
Pit furnace costs range from Rs. 500,000 to Rs. 25,00,000 Lacs depending on the size, capacity, mode of heating etc. Due to their high heating efficiency, Pit furnaces are often preferred over box type and chamber furnaces.
What is the advantage of using Pit furnace?
Pit furnaces provide a wide range of thermal processes for typically far less cost than other types of furnaces. They are favored when dense loads or a wide range of parts need to be processed. These furnaces also provide a smaller footprint than a batch or mechanized box-type furnace and require much less service time. Often times, they have the unique ability to provide more than just one thermal process. Lastly, pit furnaces are the only choice when very large, long, or heavy loads require heat-treating.
MAAN GLOBAL INDUSTRIES is the leading Pit furnace manufacturers in India. Our engineers design and manufacture wide range of industrial pit furnaces based on the application requirements and heat treatment process. We manufacture Electric Pit furnaces and Gas fired Pit furnaces that are inert atmosphere capable and carry batch load of upto 20 tons. We are the pioneers in Pit Furnace Manufacturing and Industrial Heat Treatment furnace manufacturing in India. Top Pit Type Furnace Suppliers in Africa, Oman, Kuwait, Dubai, Kenya, Uganda, Europe, Indonesia, Malaysia, Australia and Sri Lanka.
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