(continuously last article )
Mixing qualified manufactured raw material proportionally, adding binder and making preperation for molding of biscuit.
5. Molding Biscuit
Machining Biscuit into certian shape. With the developement of molding technology, more and more molding method are invented. Compression molding is the most common technique. No matter what mloding method are applied, the final product should comply with following requirement: the size, shape, and precision of product should be manchined as designed. And then, final product should be high in density, uniform in structure, stratification, low in porosity, outstanding mechanical strength. By the way, chemical- physical property also should be qualified.
Shaped biscuit neet to dry for a while in the air, then by putting it into oven or chamber to dry it throughly and to dislodge free water content, after which product can continue to suffer final firing. Sometimes, people straightly convey raw material into kiln. Firing raw material under 140 ℃, then final firing succeed..
7. Presintering and Rough Machining on Biscuitre
Before the final firing, product should be fired under a lower temperature to remove various organic binder, especially wax. After presintering, product start to own sufficent mechanical strength. At this time, the product can be rough machined, such as triming size, cutting or drillingd. Because, in the last, the product which have suffered final machining become very hard.At that time, rought machining become very tough.
Sintering is the most important procedure. This procedure will decide thether the product can be produced successfully. Sintering have following function: first of all, it can exclude extra water content and organic in product; then, crystal form of product transform in allomorph way. Moreover, solid particles react with each other, which is called solid-phase reaction.. Next, stable product is manufactured.
9. Final Machining
Manufacturing procedure of graphite refractory products is complex. Under the influence of quality of raw material, manufacturing technique, operation, many errors exist among stable product. So, after sintering,the stable product should be machined advancely, which includes Cutting, cars, planing, drilling, milling, grinding, polishing, etc. Before the product leave factory, it should be inspected strictly.