August 2022 Volume 4

MATERIALS

The maximum effective tool stress for the top die was output onto a contour surface (Figure 3). It was found that increasing the top die angle in the first operation yields a lower tool stress in the second. Very small folds were observed in the simulations with the lowest pin recess shapes. In Figure 3 on the right, the middle sample represents the lowest tool stress without forming a defect in the part. However, this optimal value is adjacent to runs that may have defects in the forging. If process control is not tight, the pin recess may need to be decreased slightly (toward the upper bound) to reliably avoid forging defects while still providing a reasonably low tool stress. – Courtesy of Scientific Forming Technologies Corp.

Figure 1. Preform and two-hit gear forging Preform top and bottomdie geometry features were varied inDOE by modifying the top die angle and the recess depth of the bottom ejector pin. Five samples were defined for both variables, and a full factorial sampling (25 simulations) was applied.

Figure 3. Analysis of gear tool stress

Figure 2. Variable 1 (left) and Variable 2 (right)

Conclusion Computer simulation software platforms available to forgers are one of the great technological advances from which the commercial forging industry has benefited. Especially during the last half century, simulations have helped elevate forging processes, optimize product design activities, as well as enhance die life. Forging dies are affected by mechanical and thermal stresses and fatigue. Studying these effects on the tooling can yield important insights on why, where, when and how dies can fail in service. These are important points to consider when it comes to product pricing, planning for die replacements, etc.

Author Dean M. Peters has covered metal working markets, including the foundry, welding & industrial gas, heat treatment and forging industries for more than 30 years. His journalistic credentials are enhanced by his BS in metallurgical engineering, MBA in finance and a decade of experience in market research. He can be reached by e-mailing ForgeOpEd@gmail. com.

FIA MAGAZINE | AUGUST 2022 28