?
Fig. 1. After examining your flasks, create an inspection report and drawing and include a photo of the actual flask. Flasks are critical to ultimate casting quality and should be inspected regularly.
ramming, squeezing, and impact or impulse. It must have sufficient struc- tural integrity to maintain proper mold dimensions during these mold filling functions. Equally important, a flask is a carrier frame, providing a secure fix- ture for the transportation and manipu- lation of its mold during pouring and solidification. As horizontal green sand tight flask molding lines have become more sophisticated, the dimensional and mechanical properties of the flasks also have become more critical.
What Inspection Program Should I Use?
Flasks have become a major capital
investment for metalcasting facilities. Flasks often are used in a set rather than individually, so the assembled stack-up dimensional data is ulti- mately the most crucial information about them. However, attention should be paid to each individual flask in the set as well.
Most tight flask molding line
manufactures today number their flasks and pallet cars for tracking and accountability. Regardless of the number of flasks on a molding line, the amount of wear on each flask is
typically consistent, except in the case of severe molten metal damage. One method of keeping track
of serviceability and dimensional characteristics is an annual program of sampling flasks on the molding line. Testing about 2% of the molding flask sets on the line once per year is suf- ficient sampling for tracking this data. Inspection of the flasks, preferably by a coordinate measuring machine, can be limited to the dimensions that are critical and functional. Manual inspection also is accept-
able, if the procedural steps are consistent for each inspection. A written procedure with photos is recommended for ensuring accuracy of manual inspections. If a 2% sample represents four sets of flasks, one set should be checked every four months. At minimum, one set should be checked per year regardless of the total quantity of flasks on the molding line.
How Do I Inspect My Flask? Ideally, the metalcasting facility has
a copy of the original as-manufactured final dimensional inspection reports for its flasks (and the pallet cars, as well) to use as a benchmark for inspec-
tions. If not, equipment still can be evaluated for serviceability without any starting point data. Te goal for collecting data is to
determine the amount of wear per cycle, annualized, on the critical surfaces and points of the flasks and hardware. Exclusive of material defects in the flasks, this data can be an indication of the longevity of the flasks before repair or replace- ment is required. Te following procedure is a good
starting point. • Make sure your flasks are per- manently numbered (i.e. C-001, D-001) and record all data by flask reference number (Fig. 1).
• Start and maintain a program to measure a sampling of your flask’s critical dimensions.
• Let casting and mold qual- ity dictate what is necessary to record. Flasks are components of a system. Know the points of your flask handling in the mold- ing system that can affect mold quality, such as pins and bushings that can cause mold misalign- ment. Generically, the following processes can affect the mold and
October 2011 MODERN CASTING | 41
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