Vacuum Furnace Classification
Vacuum furnace is mainly used for sintering metal powder products, metal injection forming products, cemented carbide, ceramics, Nd-Fe-B, stainless steel non-woven fabrics, etc. The structure of the high temperature vacuum sintering furnace is basically the same as that of the vacuum heat treatment furnace, except that appropriate changes are made according to the sintering process.
Vacuum sintering furnaces are divided into double vacuum sintering furnaces and single outdoor pressurized gas-cooled vacuum sintering furnaces, which have two identical sintering furnaces, a common set of vacuum pumping system and electrical control system. In operation, the two furnaces are used for heating and cooling respectively and alternately. The furnace has the functions of degreasing, pre-sintering and sintering in the same furnace at one time. The degreasing system includes external pipelines, vacuum valves, condensers, collectors and mechanical pumps. In order to meet the requirements of Nd-Fe-B sintering process, a vacuum unit with high vacuum and large pumping speed should be equipped in a single outdoor circulating pressurized gas-cooled sintering furnace. The structure of the furnace is the same as that of a single-chamber outdoor circulating pressurized gas quenching vacuum furnace.
1. Prepare before start-up:
(1) Check whether there are tools or other conductive substances in the control box of electrical appliances. If there are forgotten workpieces in the furnace, they should be removed in time.
(2) Check whether the switch contacts are normal after closing.
(3) Check whether the temperature control instrument works properly and open its switch to keep it in working state.
2. Open-up production:
(1) Set the temperature of the automatic temperature control instrument according to the technological requirements.
(2) Put the control "handle" in the position of automatic control to raise the temperature.
(3) The cold furnace can be heated for 2 hours and then be loaded into the workpiece. Continuous production allows continuous charging.
(4) Workpieces should be placed evenly and smoothly in the furnace, and no contact between workpieces and electric heating wires should be allowed.
(5) Operating in strict accordance with process regulations.
3. Shut off the instrument switch and open the power supply knife gate.
4. Notices for Vacuum Furnace Operation:
(1) When the temperature of the furnace is higher than 400 C, it is not allowed to open the door of the furnace for intense cooling.
(2) The maximum operating temperature should not exceed 950 C.
(3) The charge quantity should not be too large, and the temperature reduction should not be greater than 50 C.
(4) Don't use too much force when loading the furnace, so as not to damage the bottom of the furnace.
(5) Always pay attention to whether the electrical work of the instrument and the electric control box is normal.
(6) For newly installed or overhauled furnaces, place them at room temperature for 2-3 days and nights after decoration. The resistance of three-phase electric heating elements to the ground (furnace shell) should be greater than 0.5M by checking with 500V megohm meter for electricians, and then supply electricity and bake according to the following process. The cover plate of the furnace shell is removed during the process of closing the oven door at 750-800 8h, closing the oven door at 550-600 8h and closing the oven door at 750-800 8h at 100-200 15-20h, so that the water vapor in the masonry body is easy to disperse.
(7) After a month of use of the newly overhauled or newly installed furnace, the state of diatomite at the top of the furnace should be checked, and if it sinks, it should be filled again.
5. Maintenance of vacuum furnace:
(1) Always pay attention to the lining and resistance wire bracket tiles, find out the damage and repair it in time.
(2) Frequently check the situation of the electric heater wires. If it is found that there is contact between the two wires, it should be separated in time.
(3) Check clamp tightening of resistance wire lead rod monthly, remove oxide skin and tighten clamp in time.
(4) Clean the furnace every week to remove oxides and workpieces thrown into the furnace.
(5) Frequently check the use of lifting steel wire for furnace door, find out that damage should be replaced in time.