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At present, silicon nitride ceramic tool materials have been used for the efficient processing of cast iron, and have excellent performance in terms of processing safety, stability and economy. The new SiAlON tool material developed by SPK Tool Company of Germany has added a new member to the family of silicon nitride ceramic tool materials.
The general silicon nitride tool material composition is ßSi3N4, and the newly developed SiAlON tool material composition is α/ßSiAlON. By improving the metallographic structure of the material, fine carbide hard particles are distributed between the SiAlON grains, thereby improving The hardness and thermal shock resistance of SiAlON tool materials give them higher oxidation resistance and better chemical stability.
Due to the above-mentioned excellent properties, α/ßSiAlON tool materials can be used in a wide range of machining applications, from roughing to finishing, from continuous cutting to interrupted cutting, and even to cutting with severe vibrations; It can be used for both turning and milling; its machinable materials include grey cast iron and ductile iron. When processing gray cast iron, it can be used in various processing occasions; in the processing of ductile iron, in addition to milling, it can now also be used for interrupted machining of turning.
For the milling process, the tough α/ßSiAlON material should be used. The SL808 grade was specially developed for this purpose. It shows high processing efficiency when processing gray cast iron. For example, the MJ9090 face milling cutter is used to rough-mill the GJL250 gray cast iron box, the cutting speed can reach 1200m/min, the feed per tooth is 0.275mm (feed speed 10000mm/min), and the milling width is 5~12mm. Change between. Despite this high cutting throughput, the tool life can reach 50m/blade.
The cutting performance of α/ßSiAlON and ßSi3N4 materials was compared by processing a compressor housing. First, the ribs and planes are machined. When the feed per tooth is the same as that of ßSi3N4, the SL808 of α/ßSiAlON can use a higher cutting speed and shorten the processing time per piece. Due to the good wear resistance of α/ßSiAlON and longer tool life, the economics of processing are further improved. Compared with the ßSi3N4, the cutting speed of the SL808 is increased by about 15%, the tool life is increased by about 63%, the cutting amount used is 0.20 mm per tooth feed, the cutting speed is 900 m/min, and the axial depth is 5.0 mm.
Then compare the performance of the two tool materials when roughing the flange face and the screw face. Due to the better heat resistance of α/ßSiAlON, the cutting speed can be increased from 500m/min to 800m/min, and the feed rate can be increased from about 3000mm/min to 4000mm/min, thus reducing machining time by 20%. Tool life is doubled and machining costs are reduced by 30%.
Comparing α/ßSiAlON with Al2O3 coated cemented carbide tools also proves that the former has better cutting performance in various processing applications than the latter. For example, when milling the side of the crankcase, the axial depth is 3 mm and the radial depth is 40 mm. The larger diameter 7-tooth carbide milling cutter originally used is replaced by a 50 mm diameter α/ß SiAlON five-tooth MKS88° milling cutter. Since α/ßSiAlON has good heat resistance, the cutting speed is 1000m/min, and the feed rate is 3600mm/min, which is about 3.6 times of the original. Therefore, the economical efficiency of processing is greatly improved, and the processing cost can be reduced by about 70%.
When machining a bearing block made of GJL400 cast iron with a MKS90° right-angle face milling cutter with a diameter of 80mm, the diameter of each diameter is machined by circumferential milling in one clamping. The radial cutting depth is 40mm and the axial cutting depth is 10mm. . Compared to the Al2O3 coated carbide tool, the feed rate is increased from 550mm/min to 3000mm/min, and the machining time is reduced from 6.8 minutes to just 1.25 minutes.
The development of α/ßSiAlON materials is regarded as a development direction of silicon nitride ceramic materials. Its high temperature and wear resistance performance is significantly improved compared with ßSi3N4, but the toughness has not decreased. The above examples of processing cast iron are a good example of these advantages. .
widely used in instrumentation, communications, magnetic switches and various sensors.
Unlike cated Alnico Magnets, sintered Alnico magnets(sintered Alnicos) offer lower magnetic properties but better mechanical characteristics. Mixes of metal powders are pressed to shape and size. The sintering process is well suited to large volume production, and results in parts that are structurally stronger than cast Alnico magnets. Relatively close tolerances can be achieved without grinding.
Application of Sintered Alnico magnets:
•Electronic ignition systems
•Volt-amp meters
•Industrial motors
•Generators
•Vending machines
•Watt bour meters
•Medical instruments
•Magnetic reed switches
As an efficient tool material, ceramics are ideal for high speed machining and efficient machining. Since the cutting speed and the feed rate can be significantly increased, the metal removal rate can be increased and the processing time can be shortened, thereby improving the economics of the cutting process and even reducing the investment cost.