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Akrovest Premium Instructions

Weigh the investment powder and measure the mix water at a ratio of 40 to 42 parts per 100 parts powder. (40 to 42 ml water per 100 gms of investment).
NOTE: Colder mix water temperature will increase working time, while warmer temperatures will shorten working time. For best results adjust water temperature to 75- 85 degrees F (24-29 degrees C).
·Add the investment powder to the water.
·Using a spatula, mix by hand until the powder is thoroughly wetted.
·Using a mechanical mixer, mix on low speed for one minute, then on medium for an additional two minutes.
·Place investment mixing bowl under a bell jar with a vacuum table pump down capacity of 29 inches of mercury.
·Vacuum the investment slurry in the mixing bowl until it rises, the bubbles break and it begins to boil vigorously. Continue to vacuum for one minute.
·Pour the investment down along the inside of the flask allowing it to flow up, around and over the patterns leaving a minimum of ?” space at the sides and ½” at the top and bottom.
·Place flask under vacuum and de-air for 1 ½ to 2 minutes.
As with all Gypsum bonded investments, keep all mixing equipment clean when processing.
NOTE: Small amounts of set investment from previous mixes may accelerate the set time of the mix, thus shortening the available working time.
·Top off flask with investment if needed and allow to sit undisturbed for a minimum of 1-2 hours.
·Remove sprue base.
·Load into burnout oven sprue end down.
·Follow general burnout cycle.

WATER/POWDER RATIO (W/P)= 41/100)
Powder   Water     Water    Water
    lbs.          ml.           lbs.       lbs.+oz.
1
186
.41
7oz.
2
372
.82
13 oz.
3
558
1.23
1# 4oz.
4
744
1.64
1# 10oz.
5
930
2.05
2# 1oz.
6
2.46
2# 7oz.
7
2.87
2# 14oz.
8
3.28
3# 4oz.
9
3.69
3# 11oz.
10
4.10
4# 2oz.
11
4.51
4# 8oz.
12
4.92
4# 15oz.
13
5.33
5# 5oz.
14
5.74
5# 12oz.
15
6.15
6# 2oz.
BURNOUT PROCEDURE

Follow the burnout cycle best suited for the size  flask indicated on the burnout cycle chart.

For best results do not overload oven.
BURNOUT CYCLES

6 HR. CYCLE 2 ½” x 2 ½”
FLASKS
8 HR. CYCLE 3 ½” X 4”
FLASKS
12 HR. CYCLE 4” X 8”
FLASKS
300 Degrees F
2 HR.               149 Degrees C
300 Degrees F
2 HR.               149 Degrees C
300 Degrees F
2 HR.               149 Degrees C
700 Degrees F
1 HR.               371 Degrees C
700 Degrees F
2 HR.               371 Degrees C
600 Degrees F
2 HR.               315 Degrees C
1350 Degrees F
2 HR.               732 Degrees C
1350 Degrees F
3 HR.               732 Degrees C
900 Degrees F
2 HR.               482 Degrees C
1350 Degrees F
4 HR.               732 Degrees C
           1 HR. HEAT SOAK AT MOLD CAST TEMPERATURE              2 HR. HEAT SOAK AT MOLD CAST TEMPERATURE       


After the metal is cast and solidified, the investment may be removed by plunging the hot flask into room temperature water or with a deflasking machine using a hydraulic cylinder to push out the investment core.



PHYSICAL CHARACTERISTICS
Water/Powder
40 to 42/100
Working Time
9 min.
Set Time
12 - 14 min.
Green Crushing Strength @ 2 Hours
450 PSI
Set Expansion @ 2 Hours
.55

*Contains no asbestos

TROUBLE SHOOTING GUIDE

CASTING DEFECT:   Non Fills
CAUSES/CORRECTION:   
Incomplete burnout/insufficient time at peak burnout temperature.
Pattern improperly sprued/ too thin or long.
Metal too cool when cast.
Mold too cool when cast.
Insufficient metal by weight.



CASTING DEFECT:   Flash or “Finning” on castings
CAUSES/CORRECTION:  
Water to powder ratio too high/decrease water to within a range of 40-42/100.
Investment processed past recommended working time.
Flask disturbed while investment setting up.
Investment burnout cycle started before material was completely set. (Hold a minimum of 1 ½ hours.)
Burnout cycle too rapid causing thermal shock of investment.
Flask allowed to dry and not remoisten before burnout.

CASTING DEFECT:   Dark rough castings which do not deoxidize in pickling solution.
CAUSES/CORRECTION:
Burnout temperatures too high, do not exceed 1350 degrees F/732 degrees C peak burnout temperature.
Metal overheated/Adjust to proper casting temperature.

CASTING DEFECT:   Nodules or bubbles
CAUSES/CORRECTION:
Investment not properly mixed and vacuumed (consult mixing instructions).
Poor adhesion of investment to wax or plastic patterns. Use a suitable wetting agent.
Full vacuum not obtained. Check vacuum pump for proper oil level.



CASTING DEFECT:   Rough casting surface
CAUSES/CORRECTION:
Improper water/powder ratio/Adjust to 40-42/100.
Flask heated too rapidly/Slow down rate of heating.
Surface roughness on wax patterns/Check original models and polish if necessary.
Pattern material trapped in mold cavity/Patterns may be improperly sprued causing pattern material to boil within mold.

CASTING DEFECT:   Watermarks
CAUSES/CORRECTION:
Investing cycle too rapid. Keep working time within 9 minutes.
Water too cold. Adjust to 75 degrees to 85 degrees F.
Excess water in mix. Stay within the required 40 to 42/100 water/powder ratio.

CASTING DEFFECT:   Investment Breakdown
CAUSES/CORRECTION:
Too high water/powder ratio.
Metal too hot.
Mold too hot.
Flask placed in oven with insufficient setting time.

CASTING DEFECT:   Blowout
CAUSES/CORRECTION:
Water to powder ratio too high/decrease water to within a range of 40 to 42/100.
Flask heated too rapidly. Slow the rate of heating of the burnout cycle.




Akrovest™ Premium Investment was designed to be mixed at a water/powder ratio of 40 to 42 parts water to 100 parts powder by weight. When mixed and invested properly, it provides its user with super smooth casting surfaces and exceptional reproduction of detail which results in less finishing time.