 United
Precious Metal Refining, Inc.
800 SERIES NICKEL WHITE ALLOYS
FOR 10 TO 18 KARAT WHITE GOLD
SHEET, PLATE & WIRE FABRICATION
Thank you for using UNITED'S alloys.
United #800 Series White Alloys are formulated for I 0 to 18
karat white gold sheet, plate, and wire fabrication giving a white
color. The #800 Series White Alloys can also be used for investment
casting if desired.
MELTING
The #800 Series White Gold Alloys and fine gold should be
melted together in a clean crucible. Put the alloy in the bottom of
the crucible and the fine gold on top. Initial melting temperature
should be 1070° C / 1958° F. Drop the temperature somewhat before
pouring as listed below. Boric acid flux should be used to keep the
metal clean during the melting process. The molten metal should be
mixed well with a stirring rod before pouring to assure a good mix.
A neutral or reducing cover gas is very helpful in melting white
gold alloys.
POURING TEMP. FOR INGOTS
10K - 1040°C / 1904°F
14K - 1010°C / 1850°F
18K - 1015°C / 1860°F
POURING
Metal should be poured into a preheated, vertical
graphite, or lightly lubricated iron mold. A steady even pouring
motion should be used, slowing down at the end of the pour to
prevent shrinkage in the top of the ingot. Use a round rod mold for
wire, and a 2 piece L shaped mold for plate and sheet.
DON'T QUENCH
Remove the ingot from the mold and allow to air cool
- don't quench. Nickel white gold rolling alloys will be much softer
if allowed to air cool after pouring and after annealing. Soak ingot
in a hot pickle solution to remove surface oxides.
FABRICATION
The metal ingot should be cleaned of all adhering
oxide or fluxes before rolling. The ingot should be rolled or drawn
to a 50% reduction in size before annealing. Too small of a
reduction can cause ingot to crack during anneal. After annealing
continue the reduction at 50% before annealing again. Clean the
ingot after each anneal in hot pickle solution. Keep the rolls,
dies, and metal clean to prevent defects in the finished stock.
ANNEALING
Annealing temperature 732° C/1350° F for 2O minutes. DO
NOT QUENCH INGOT, allow ingot to air cool. A boric acid fire coat
should be applied before annealing in an open atmosphere oven to
protect the metal from heavy oxidation. Clean the ingot in hot
pickle solution to remove surface oxidation after annealing. Avoid
over-annealing wire, plate or sheet stock as this can cause
excessive grain growth creating orange peel surface or poor strength
in finished goods.
REMELTING
Use a 30% scrap to 70% fresh mix on nickel white gold
alloys. White gold alloys have about 1/3 the re-usability of yellow
gold alloys.
INVESTMENT CASTING
Pre-Alloy #800 Series White Alloy and Fine
Gold pour into water to make shot.
PRE-ALLOYING TEMPERATURE
1060° C 1940° F.
CASTING TEMPERATURE
10K - 1040°C / 1904° F.
14K - 1000°C / 1832° F.
18K - 1010°C / 1850° F.
FLASK TEMPERATURE
Use somewhat hotter flask temperature.
QUENCH TIME 8 to 12
Minutes for invested flasks.
TECHNICAL ASSISTANCE
Always available…
Call 1-800-999-3463 / 1-800-999-FINE
E-mail / doc@unitedpmr.com
Web-Site / www.unitedpmr.com |