Alfa Ceramic 4 – Användningsinstruktioner
Alfa Ceramic 4 is a palladium-silver based precious metal ceramic alloy (57,8% palladium: 30 % silver).
Wax-up: Minimum thickness of wax should be no less than 0.3mm. for single units and 0.4mm. for bridges and multi-units. Sprues should be no smaller than 8-10 gauge, (3.3-2.6 mm diameter) and no longer than 1/4" (6 mm) with adequate reservoirs.
Investing and Burnout: Recommended Investment: Phosphate Bonded . Follow the manufacturer's instructions. To prevent air entrapment in mold during casting, no more than 1/4" (6 mm) of investment should cover highest point of wax pattern. Ring should be burned out at 820°C /1500° F for a minimum of 45 minutes or according to manufacturer’s recommended time. Place the ring(s) in a room temperature oven and raise the temperature to 820°C / 1500°F for 1 hour plus 10 minutes for each additional ring. If you are using a rapid fire investment, follow the manufacturer's instructions.
Alloy Quantity: Required Alloy Quantity = 11,4 g/cm3 * (Wax Weight). For reusing cast alloys use only clean buttons and at least 30 percent new alloy.
Casting: Centrifugal type casting machines should be wound 3 full turns. Use a standard alumina or ceramic type crucible that has not been previously used for a different alloy. Avoid graphite crucibles or the use of carbon, asbestos or flux in contact with the metal during melting. If an automatic induction-casting machine is used, do not use a graphite insert in the crucible.
A hot gas-oxygen torch with a multi-orifice tip should be used with the inner cone of the flame at least 1/2 to 3/4 inches long to avoid excessive oxidation during melting. The fuel proportions should be one-part fuel to two-parts oxygen. Maintain the tip of the inner cone at a minimum distance of 1/2 inch from the metal. The metal should be heated to approximately 1420°C before casting. At the casting temperature, the metal appears like fluid and will vibrate if the casting machine arm is tapped gently. Every casting machine is different. The casting temperature may require adjustment based upon the alloy and the amount of metal being cast. Do not overheat; if oxide vapours get visible it is to hot.
For cooling, allow the casting ring to cool to room temperature. DO NOT quench in water.
Cleaning and Finishing: Grind the metal surfaces for porcelain application with non-contaminating aluminium oxide stones in one direction. The investment should be removed by sandblasting (50 micron aluminium oxide at no more than 2 bars of pressure (30psi)). All traces of chemicals should be removed by rinsing in tap water followed by cleaning in distilled water in ultrasonic cleaner. All surfaces to which porcelain is to be applied should be rough ground with an aluminium oxide disc or red stone. Do not use heatless stones or steam cleaners. After grinding, metal should be cleaned in distilled water in ultrasonic cleaner.
To minimize the reaction between the metal and constituents in porcelains that may cause porcelain discoloration, it is recommended that a metal surface conditioner.
Degas at 1950°F for a total of 5 minutes. The first 3 minutes should be in air and the final 2 minutes in vacuum. CAUTION! After this step avoid contact between the metal surface and fingers or other foreign object that could leave a contaminant deposit on the surface.
Presolder: Solder joints should be large (at least 5 mm²). Soldering gap about 0.05-0.2 mm. Invested units should be preheated and pressure blasted with 50 micron just before soldering.
Post Soldering (After Firing): Solder joints should be large (at least 5 mm²). Soldering gap approximately 0.05 - 0.2 mm. Cover ceramically veneered units with wax before investing.
Recommended Solders: Alfa Lod 1030
Hardening: Heat treat for app. 15 min. at 550°C
Alldental Q & Co. AB CE 0413
120 06 STOCKHOLM
Tel. +46-(0)8-694 80 25
Fax +46-(0)8-694 80 26