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Hitachi Demonstrates Japan’s First CO₂-Free Gear Manufacturing Process
Hitachi Construction Machinery, in collaboration with industry partners, pioneers atmospheric pressure smart carburizing technology to eliminate direct CO₂ emissions in gear production for hydraulic excavators.
www.hitachicm.com
Carburizing furnace equipped with atmospheric pressure smart carburizing technology
Hitachi Construction Machinery, Nihon Techno, Koatsu Gas Kogyo, and Dowa Thermotech announced that they have demonstrated the effectiveness of "Atmospheric Pressure Smart Carburizing Technology", which can eliminate direct CO2 emissions generated by carburizing furnaces during the manufacturing process for gears incorporated in the reduction gear units of hydraulic excavators, for the first time in Japan.
Carburizing is a technique for heat treating metal which introduces carbon into the surface of a low-carbon steel part that has been heated to a high temperature (approximately 850 to 950°C) and then rapidly cools the part to harden the surface. The carburizing technique is widely applied to parts used in automobiles, machinery, etc., for its ability to improve wear resistance and fatigue strength as well as increase durability.
A typical gas carburizing (Figure 1) uses a hydrocarbon-type gas (propane, methane, butane) as the source gas and a converted gas (carbon monoxide, hydrogen, nitrogen) generated from the atmosphere to carburize metal. Under this method, CO2 is emitted from the carburizing furnace due to the carburizing reaction and the exhaust gas combustion reaction. In the manufacturing process for hydraulic excavator reduction gear units and other types of equipment, CO2 emissions are highest in the heat treatment process for metal parts with gas carburizing accounting for the largest proportion of those emissions.
Figure 1: Typical gas carburizing
The technology jointly developed by Nihon Techno and Koatsu Gas Kogyo (Figure 2) directly introduces carbon into the surface of steel by controlling the flow rates of acetylene gas and nitrogen gas with an acetylene gas concentration analyzer manufactured by Horiba, Ltd. Since the technology does not use converted gases, which are the source of CO2 generation, it eliminates direct CO2 emissions and reduces the annual CO2 emissions of each carburizing furnace by 56 tons. Furthermore, since gas conversion furnaces typically operate for 24 hours a day, electricity charges and maintenance costs can also be reduced. In addition, this technology can be used with existing carburizing furnaces, so there is no need to install new equipment, and reductions in initial investment can be expected.
Figure 2: Atmospheric pressure smart carburizing
In the recent demonstration experiment, the four companies applied the technology to gears incorporated in the reduction gear units of 20-ton class hydraulic excavators and demonstrated that the improvements in wear resistance and fatigue strength were equivalent to a typical gas carburizing process.
Going forward, the four companies will continue developing the atmospheric pressure smart carburizing technology with the goal of implementation.
Gears incorporated in the reduction gear unit of a hydraulic excavator
Hitachi Construction Machinery, Nihon Techno, Koatsu Gas Kogyo, and Dowa Thermotech announced that they have demonstrated the effectiveness of "Atmospheric Pressure Smart Carburizing Technology", which can eliminate direct CO2 emissions generated by carburizing furnaces during the manufacturing process for gears incorporated in the reduction gear units of hydraulic excavators, for the first time in Japan.
Carburizing is a technique for heat treating metal which introduces carbon into the surface of a low-carbon steel part that has been heated to a high temperature (approximately 850 to 950°C) and then rapidly cools the part to harden the surface. The carburizing technique is widely applied to parts used in automobiles, machinery, etc., for its ability to improve wear resistance and fatigue strength as well as increase durability.
A typical gas carburizing (Figure 1) uses a hydrocarbon-type gas (propane, methane, butane) as the source gas and a converted gas (carbon monoxide, hydrogen, nitrogen) generated from the atmosphere to carburize metal. Under this method, CO2 is emitted from the carburizing furnace due to the carburizing reaction and the exhaust gas combustion reaction. In the manufacturing process for hydraulic excavator reduction gear units and other types of equipment, CO2 emissions are highest in the heat treatment process for metal parts with gas carburizing accounting for the largest proportion of those emissions.
Figure 1: Typical gas carburizing
The technology jointly developed by Nihon Techno and Koatsu Gas Kogyo (Figure 2) directly introduces carbon into the surface of steel by controlling the flow rates of acetylene gas and nitrogen gas with an acetylene gas concentration analyzer manufactured by Horiba, Ltd. Since the technology does not use converted gases, which are the source of CO2 generation, it eliminates direct CO2 emissions and reduces the annual CO2 emissions of each carburizing furnace by 56 tons. Furthermore, since gas conversion furnaces typically operate for 24 hours a day, electricity charges and maintenance costs can also be reduced. In addition, this technology can be used with existing carburizing furnaces, so there is no need to install new equipment, and reductions in initial investment can be expected.
Figure 2: Atmospheric pressure smart carburizing
In the recent demonstration experiment, the four companies applied the technology to gears incorporated in the reduction gear units of 20-ton class hydraulic excavators and demonstrated that the improvements in wear resistance and fatigue strength were equivalent to a typical gas carburizing process.
Going forward, the four companies will continue developing the atmospheric pressure smart carburizing technology with the goal of implementation.
Gears incorporated in the reduction gear unit of a hydraulic excavator
www.hitachicm.com
