Casting Dimension Repeatability.

In a presentation titled, "Reproducing Casting Dimensions in Green Sand(01-163)," G. DiSylvestro, DiSylvestro Videography Service, Park Ridge, Illinois, looked back upon research performed by 12 ferrous foundries 25 years ago. The original investigation into the reproducibility of casting dimensions was the work of the AFS Molding Methods & Materials Div.'s High Density Molding Committee. "Although the results of the initial investigation were presented, recommendations were never offered by the committee," said DiSylvestro. In his Silver Anniversary Lecture, DiSylvestro provided such recommendations as he updated the research for today's foundries.

"The entire casting process from design to final cleaning can affect the reproduction of acceptable casting dimensions," said DiSylvestro.

Following is a summary of the 15 recommendations he provided:

1. Correct for poor casting design before foundry tooling.

2. Mount patterns firmly and audit frequently to overcome the possibility of shift, ram-off, excessive wear, etc.

3. Design appropriate gating and risering geometry.

4. Develop and maintain correct bond and/or sand additives with enough latitude to accommodate the casting, moldmaking and sand transportation equipment.

5. Audit meaningful sand properties and establish molding sand profiles to maintain consistent physical and thermal properties for the castings produced.

6. Strive to achieve uniform mold compaction to obtain sufficient density conditions on all patterns in the mold.

7. Monitor setting of cores, core assemblies or chaplets before close-over and use alignment templates when necessary to ensure critical casting internal dimensions.

8. Use correct mold and core venting strategy.

9. Assure sufficient cope height of the mold to maintain adequate ferrostatic pressure during pouring.

10. Check pins and bushings for excessive wear and prevent rough mold handling prior to and after pouring.

11. Control metal chemistry and pouring temperature to have sufficient fluidity, and avoid excessive shrinkage or expansion pressure.

12. Manage pouring speed to avoid pouring shock and prevent cope raise, surge and/or mold dilation.

13. Prevent extreme processing variables that may interrupt consistency from normal practices and preplan casting production whenever possible.

14. Practice preventive maintenance to keep equipment in good working order.

15. Develop direct communication vigilance and action-oriented corrections procedures with employee training and apply applicable new technology for continued excellence.