Indutherm MC60V - Recommendations for Flasks; Preheating of the Flasks

System
description
sales@romanoff.com | www.romanoff.com
2019-01-08
4–20
4.17 Recommendations for flasks
For standard MC60V 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 phosphate: water
flask size
investment powder
in grams
water in ml
mixing time in
min:sec
Ø 30 mm x 55 mm
60
21
3:00
Ø 50 mm x 55 mm
150
52
3:00
Ø 65 mm x 55 mm
270
95
3:00
Ø 80 mm x 55 mm
390
136
3:00
Ø 50 mm x 80 mm
220
77
3:00
Ø 65 mm x 80 mm
370
130
3:00
Ø 80 mm x 80 mm
560
196
3:00
4.18 Preheating of the flasks
After investment process the flasks have to undergo a firing process. For this purpose the
flasks have to be placed in the furnace with the button (opening) down to ensure a com-
plete flow-out of wax.
The firing cycle of gypsum bonded flasks has normally 3 phases:
 Phase 1. Melting out of wax and steaming out remaining moisture of flasks very
slowly. This steaming out process should be done very gently to prevent gypsum
against cracks. In case of the flasks for MC60V (comparatively small) we recom-
mend to reach a temperature of 300 °C (= ramp of 2.5 °C/min) in 120 minutes. On
bigger flasks, we recommend to go to 150 °C – 180 °C in 120 minutes.
Investment powder is a good insulator, that’s why the heat takes time to reach the
core of the flask. To ensure that the flasks heat up homogeneous, let the flasks
have a rest at the hold temperature of 30 minutes on small flasks and up for 60
minutes on bigger flasks. After this time the wax should be fully flowed out.
 Phase 2 Burning process of flasks. This process is like a sintering process: single
particles bake together (bonding) and the investment material becomes much
stronger. Gypsum bonded investment materials need 730 °C for this bonding pro-
cess. To reach this temperature starting at 300 °C, ramp should be 4 °C/min =
process takes around 2 hours. On bigger flasks (starting at 150 °C, we recom-
mend to select ramp 5 °C/min. Duration in the furnace: for small flasks like MC60V
around 1 hour, on bigger flasks up to 5 hours.