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The Influence of Machining and Assembly on the Tungsten Carbide Moulds |
| Author : Date : 2012-1-6 18:30:29 |
The Influence of Machining and Assembly on the Tungsten Carbide Moulds
The same grade of tungsten carbide blanks ,its service life is different after machined into moulds, some ones with long service life ,but other ones is very short. As a result of anatomy analysis,we found the problems caused by design, machining ,assembly and welding .
The size and geometry precision of tungsten carbide moulds are achieved by grinding .Meanwhile the grinding forces on tungsten carbide moulds is 2~3 times than on the steel ,so they require the engine is large but its rigidity is high.However ,for the current machines level,actually we do not have the special grinding machines for tungsten carbide.So the processing errors happen usually ,meanwhile the moulds service life will be serious influenced by the cumulative of the errors.In the EDM processing ,the microstructure changes happen on the mould surface layer due to the tungsten carbide material suffered as high as 10000℃ temperature and liquid medium influence in the moment of electricity discharging ,in addition ,cementation(carbon in liquid),metal-oozing(copper and tungsten electrode),even emerging with micro-crack ,they also influence tungsten carbide mould service life definitely .Insetting-sleeve with aim to make the tungsten carbide die withstand greater shock and extrusion loading ,whether it is hot-pressing insetting die or cold-pressing one ,the requirement on its clearance is very high .Generally,the interference for cold-pressing insetting mould is 0.03~0.05mm ,but for the hot-pressing one is 0.08~0.10mm,the processing temperature for sleeve is 700~800℃,but for tungsten carbide die is 300℃,meanwhile we have to put them in the 600℃ box-furnace to keep temperature for some time in order to eliminate stress .
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