Safety belt

The reasons for a rupture of the muffles can be very diverse, and the damage is considerable. In the end, the dental technician has to start the work all over again, which costs working time and new material. The trouble is always quite big and can now be avoided. The AP seat belt functions, as the word suggests, as a "safety mechanism" that prevents microcracks from spreading in the investment material. The mass is held together and the pressed-in ceramic remains dimensionally stable. The conical ring is placed over the muffle only immediately before the pressing process, after the muffle has been filled with the ceramic pellets and the press ram. This does not affect the expansion of the muffle! It is not necessary to preheat the ring. Thanks to the specially developed conical geometry of the AP 200 and AP 300 muffles, this shape allows the inner surface of the safety belt, which is also conical, to be accommodated! Removal of the safety belt: After removal from the press furnace, the muffle is turned upside down with the muffle tongs and loosened with a light tap on a refractory surface. If the seat belt cannot be loosened, the muffle can be trimmed down to the edge of the metal ring. The investment is then blasted off and the pressed object is removed from the muffle. The material of the seat belt consists of a hardened steel, which leads to the formation of soot outside the furnace. After removing the investment ring from the press furnace, it should be placed in a safe place to cool down. The seat belt is milled conically on the inside. The wall thickness is on average around 2-3 mm. There is a fillet at the wider end of the ring to mark the thicker side. The height of the seat belt is 3 cm for the AP 200 muffle and 3.5 cm for the AP 300 muffle. Devesting: After removing the muffle from the furnace, it can be devested after 20 minutes. Indications that his muffle must be lukewarm have not been confirmed in practical use.