מתכת אצילה צהובה - MAJESTIC
הרכב המתכת :
Au = 86%
Pt = 5%
הוראות עבודה:
WAXING AND SPRUING
Direct spruing: the direct technique may be used for spruing single units.Use a 10 gauge(2/6mm)sprue
indirect spruing: The indirect technique is always preferred for spruing bridges,multiple units, and single units.With bridges use 10 gauge (2.6mm) feed sprues (1,6mm)long.For multiple units use the same size feed sprue.Attach the feed sprues along the length of an 8 gauge(3.3mm) runner bar and connect the runner bar by two 6 gauge (4.1mm) indirect sprues to the crucible former
INVESTING:Use a phosphate bonded,high heat, ceramic investment.Both graphite containing anon-graphite investments are acceptable.Follow the manufacturer's instructions
BURNOUT:Place the ring in a cold furnace and run it directly up to 788C Heat soak the ring for one and a half hours.Allow additional time for large rings,multiple rings , and for very thin patterns
If there is any plastic in the mold , two stage burnout is required. Place the ring in a cold furnace and raise the temaprture at a rate of 6C per minute to 315C.Heat soak at this temaprture for 30 minutes.Raise the temparture to the normal burnout temparture at a normal rate and heat soak
CASTING:Preheat a high heat,quartz crucible.Use oxygen,at 10-20 psi, with natural gs,propane,or butane.Adjust the flame large enough to completely cover all the alloy in the crucible.Do not direct the flame stedily at one region on the metal,but reather keep the torch tip circling around it
Use a 1:1 ratio of old to new alloy.Melt the button,then add new metal ingots to the melt
Permit the casting machine arm to stop by itself.Allow the ring to cool 5 minutes on the bench then quench it
METAL PREPERATION: Grind the contour the surfaces of the casting which are to recieve porcelain.Use aluminum oxide stones or carbide burs dedicated for use only with a particular alloy
Sandblastthe casting with 50 micron, virgin aluminum oxide abrasive of 75-80 psi
Clean the casting in ultrasonic bath for 5 minutes using a general purpose cleaner, then rinse thoroughly under running water
DEGASSING:Place the casting in a porcelain furnace for at 649C and raise the temparture to 1038C.Fire the casting in air for 1 minute.To remove excess oxide,sndblast the casting with 50 micron,virgin aluminum oxide abrasive, or place in hydrofluoric acid
Clean the casting well before opaquing using ypur method of chice-steam cleaner,ultrasonic bath,alcohol,etc
Apply porcelain according to the manufacturer's instructions
RECOMMENDED PORCELAINS:Duceram plus,Ceramco,Ceramco 2,Ceramco 3,Ceramco 4, Ivoclar IPS classic,Vita VMK 95,Shofu vintage