System
description
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2019-10-16
4
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4.17
Determination of the powder / water partial quantities
Determining amount of powder per flask this formula is helpful:
Volume of flask in cm³ 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 amount of water according to the instruction manual of investment ma-
terial:
Ratio, given by instructions: 100:40
100:40 = 570:x
40 x 570:100 = 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.
