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The low profile of the Locator
Bar Attachment provides the space necessary to position the denture teeth
directly over the supporting bar structure
(FIG 6).
5. Spruing. Run the sprue at a 45 degree angle to the Cast-To
Bar Female so the molten gold will flow down along one side of the female, around and up to the other
side. The sprue should not be directed at the female that could possibly dislodge it when casting
(FIG 7).
6. It is recommended to use debubblizer to reduce surface
tension during investing procedures.
7. Investing. The most successful castings have been
accomplished by using Ceramigold Investment by Whip Mix Corp. or an equivalent High Heat Investment.
8. Mix a liquid/powder ratio of Ceramigold using 12ml to 60
grams of powder for each packet of mix needed. Hand mix for 15 seconds and vacuum mix for 90 seconds at
350-450 RPM. The investment material should be carefully painted into each attachment cavity
to avoid trapping bubbles and to prevent gold from going inside the female. The remainder of the
investment poured into the ring will stabilize the female during burnout. Place the ring in a water
bath for one hour, then bench set for a half hour.
9. Burnout. Place ring in a cold furnace (sprue side down) and
raise the temperature to 1500° F maximum. Use a rate of climb of 0° F to 1500° F maximum over a
time period of one hour. Hold at 1500° F maximum until burnout is complete. (Refer to investment
manufacturer's instructions for suggested burnout duration.)
10. Casting. Use only precious or semi-precious alloys for
casting the stainless steel female into a bar.
Non-precious alloys should not be used. Cast the bar using
recommended temperatures of the alloy manufacturer. The stainless steel Cast-To Bar Female will
withstand a temperature of up to 2000° F without any dimensional change.
Do not allow casting temperature to raise
above 2000° F which will melt the stainless steel Bar Female!
11. Divesting. After casting, allow the casting to bench cool
for 20 minutes. Be careful to push out the casting and investment with proper tools. It is not
recommended to hammer or bang on rings that may distort the castings. To remove the investment material
from the Cast-To Bar Female without damage to the stainless steel, use an acid-free
investment and porcelain remover solution in an ultrasonic unit for a period of 30-45 minutes.
(Do not use a bur to remove the
investment, sandblasting with aluminum oxide, or an acid pickling solution,
all of which can damage the retention surfaces of the Bar Female attachment.)
Clean the bar containing the Locator Cast-To
attachment in an ultrasonic cleaner solution, shell
blast, bead blast, or use a
Fibgerglass or Brass Pencil.
12. Finishing and Polishing. When polishing with a rubber wheel,
use caution not to damage the Cast-To Bar Female attachment. Polish the surface of the bar to make a
smooth surface. The Locator Parallel Post can be placed on the female to protect the attachment while
polishing. [If additional polishing of the female attachment is required, it is recommended to only
use glass beads at a low pressure (40 PSI) or a fiberglass or bristle polishing brush.]
13. After polishing the bar, place a Locator Processing Cap Male
onto each Cast-To Bar Female and check for proper fit. Clean again in an ultrasonic solution and
deliver to the dental office. |