Part 4 of the Investment Checkoff List Series we will cover the burnout process.
This is meant to serve as a reminder or quality-control list. The information in parenthesis is a possible condition which may result from lack of, or improper control of the parameter.
Burnout:- Calibrated oven.........................................Don't exceed 1450°F, burt investment causes dark, rough castings
- Heat distribution in burnout oven..............Too hot a flask causes porosity; too cold incompletes
- Loading methods in oven...........................Too hot a flask causes porosity; too cold incompletes
- Air flow through the oven..........................Too hot a flask causes porosity; too cold incompletes
- Actual cycle time and tempretures.............What the dials say isn't always so; calibrate regularly
- Wax residue burn out complete..................Black spots, shiny spots, incompletes all may result from varying carbon deposits
- Time flask is held at pouring temperature...Too short a time at final cycle and the flask will be hotter than your oven causing porosity or brittle fractures
- Final temperature of flask...........................Too hot a flask cause porosity; too cold incompletes