Tungsten Carbide Pellet Dimensional Accuracy

From the technology point of view, tungsten carbide pellets subject to granulation, vibration sieving, drying, and isostatic pressing processes. Differ from other tungsten carbide products, tungsten carbide pellets forming not by molding tolls, which rub through sieve procedure using particle weight on a rotating granulator powder adhesion and continuous scrolling and raised molding, and finally by isostatic pressing, so it has a certain density and strength. However, before the isostatic pressing, the density of each carbide pellet is relatively uneven, which makes the sintering step, and after the isostatic pressing, the pellets of the larger size of the deviation, inconsistent shrinkage factor is different.

Tungsten carbide pellets size controlling has a direct impact on its density, semi-finished products grew scroll speed pellets and pellet density showed a decreasing relationship. When the grains grows fast, the corresponding density pellets products decreased by optical observation can be found isostatic pressing pressure can effectively reduce the porosity of carbide pellets inside, but the density has been improved, although the size has changed small, and further reduction in size after sintering shrinkage occurs over negative tolerance of waste. By metallographic observation can be found isostatic pressing pressure can effectively reduce the porosity of carbide pellets inside.

Take YQ3 tungsten carbide pellets as example, YQ3 mixture rubber solution 80-90ml added to gasoline and glue seepage uniform mixture in a mixing vessel, after glue seepage into the stainless steel tray into the drying cabinet for drying, and steam pressure control in a certain time within the appropriate range. After the particles strike-through screen wipes material into the granulator rolling a certain time, and then glue seepage abrasive powder sieved added granulator particles adhered to the surface so that it will roll up, by size requires careful observation confirmed pellet density, shape and size, until the pellet surface emit. After several experiments, the semi-finished pellet size upper and lower tolerance limits to control the shrinkage factor for the average size of the finished product plus finished lower limit value to determine the dimensional tolerance limit endorsement pellet product size.

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