REPLICAST Unfilled II
Unfilled II is a low viscosity, fast setting polyurethane casting
system that is useful for a variety of casting applications. Its low
mixed viscosity makes it ideal for casting prototype or production parts
where very fine detail must be duplicated. It is also well suited for
potting and encapsulating uses, as well as general tooling and fixures.
REPLICAST Unfilled II is often used with bulk fillers to extend its use to different and more demanding applications. Bulk fillers have traditionally been used with unfilled materials to provide better machining of the finished castings, and often they improve other handling and cured properties.
PTM&W’s PA0738 is a white, high purity treated alumina material in a fine powder form that is very easy to add to REPLICAST Unfilled II. The particle size and shape of PA0738 gives it a very free-flowing consistency, and also allows high loading of the REPLICAST Unfilled II, while maintaining a good pouring viscosity. The cured material is a medium tan color. Castings made with REPLICAST Unfilled II and PA0738 have very little shrinkage and are easy to machine.
HANDLING & CURING
REPLICAST Unfilled II is a fast setting material! The working time
before gel is less than 5 minutes at 77°F, so it is important to plan
ahead to allow sufficient time for mixing and pouring. Proper sealing of
the pattern and application of release agent are very important to
insure acceptable castings. Silicone release agents can have a reaction
with the REPLICAST Unfilled II system, leaving pinholes on the cured
surface. For best results with this system, use PA0801 non-silicone
paste wax release to avoid the silicone-related problems.
The mix ratio for REPLICAST Unfilled II is 88 Parts A to 100 Parts B by weight. It is best to use two containers to separately measure out the Parts A & B, and a third container to combine and mix them in. Carefully measure out proper quantities of Part A and B, then mix them thoroughly in the third container for 30 seconds. Be sure to scrape the sides and bottom of the container while mixing, and take care to minimize the air entrapment. Pour the mixed material into the previously prepared mold or pattern. Do not scrape the sides or bottom of the container to get out the last bit of material, as unmixed material could be scraped into the casting, making soft spots.
If a bulk filler such as PA0738 is used, certain benefits are derived. The working time of REPLICAST Unfilled II was developed for the unfilled material. Therefore, when bulk fillers are used, the material is slowed down, allowing a longer working time to add the fillers and make the casting. This aids greatly in avoiding trapped air caused by trying to mix fillers into an exceptionally fast gelling system.
NOTE: PTM&W supplies the combination of REPLICAST Unfilled II and PA0738 filler in kits for convenience as REPLICAST 112.
TYPICAL MECHANICAL PROPERTIES
|REPLICAST Unfilled II A/B||ASTM Method|
|Mix Ratio, by Weight||88 A to 100 B||PTM&W|
|Mixed Viscosity, @ 77°F||275 cps||D2393|
|Working Time, 4 fl. oz. Mass @ 77°F||3 – 4 minutes||D2471|
|Cured Hardness, Shore D||75 Shore D||D2240|
|Shrinkage, in./in., Mold # 1, Vol: .053 Gal||.002 in/in||D2566|
|Specific Gravity, grams, cc||1.07||D1475|
|Density, lb./cu. inch||.0386||D792|
|Specific Volume, cu. in./lb.||25.8||D792|
|Tensile Strength, psi||4900 psi||D638|
|Elongation @ Break, %||30 %||D638|
|Flexural Strength, psi||6000 psi||D790|
|Bashore Rebound||37 %||D2632|
|Quart Kit||Gallon Kit||Pail Kit||Drum Kit|
|REPLICAST Unfilled II A||1.75 lb.||8 lb.||40 lb.||400 lb.|
|REPLICAST Unfilled II B||2 lb.||9 lb.||45 lb.||455 lb.|
|Kit||3.75 lb.||17 lb.||85 lb.||850 lb.|