Instruction manual

OPERATING_MANUAL_MC20V.DOC 18.03.11 KS Seite 29
3.18. Determining volumes of investment powder and water for
Investment
determining amount of powder per flask this formula is helpful:
Volume of flask in ccm x 1,4 = amount of powder in grams
For example flask ø 8 x 8 cm
r² x x h x 1,6 = amount of investment powder in g
4² x 3,14 x 8 x 1,4 = 570 g
Or on flasks ø 5 x 5,5 cm
2,5² x x 5,5 x 1,4 = 150 g
This is gross weight, volume of cone and wax pieces must be subtracted!
To find out proper the amount of water according to the instruction manual of
investment material:
Ratio, given by instructions: 100:40
100:40 = 570:x
40 x 643:100 = x = 228 g water
Please take notice:
More water makes investment material more permeable for gases = better form
filling. If the manufacturer gives a mixing ratio 37 .. 39 : 100, use for filigree items
39:100, on standard items use 37:100!
Make very precise measurement, use water with exact 20°C Too cold or too warm
water can strongly change properties of the investment material like mixing time etc.
Short cut:
For standard MC20V flasks there are some recommendations:
gypsum bonded investment powder like Goldstar XL, XXX, Kerr Satin Cast 20 etc.
100 : 40 powder : water
flask size
investment powder
in grams
water in ml
mixing time in
min:sec
Ø 30mm x 55 mm
60
24
4:00
Ø 50mm x 55 mm
150
60
4:00
Ø 65mm x 55 mm
270
108
4:00
Ø 80mm x 55 mm
390
156
4:00
Ø 50mm x 80 mm
220
88
4:00
Ø 65mm x 80 mm
370
148
4:00
Ø 80mm x 80 mm
560
224
4:00
phosphate bonded investment powder like Goldstar Platincast, H.T.
100:35