Design and Comparative Analysis of Deep Drawing without a Blank Holder under Varying Corrective Ironing Ratios

This experimental study investigates the influence of tooling and process parameters on the quality of deep-drawn cups. Focusing on the mechanical response and geometric characteristics of parts, experiments were conducted without a blank holder using mild steel (RRSt 1403), half-hard copper (SF-Cu H70), and annealed aluminum (Al99.5 W). Both conical and modified tractrix dies were utilized under varying punch–die clearances and simultaneous corrective ironing ratios. Key performance metrics, including punch load, displacement, limiting drawing ratio (LDR), fracture modes, work hardening, and dimensional uniformity, were systematically analyzed. The modified tractrix die significantly reduced forming effort, decreasing the maximum punch load by 3–9% and punch displacement by 22–32%. While mild steel and half-hard copper tolerated ironing well, annealed aluminum's LDR dropped substantially, confirming its susceptibility to failure. The use of a rough punch, however, significantly improved aluminum’s LDR to 2.77, underscoring the critical role of controlled friction and punch surface design. Three distinct fracture modes were observed, with their locations directly linked to the balance between material properties and frictional forces. Furthermore, simultaneous ironing was found to enhance cup quality by promoting uniform wall thickness and increasing hardness by up to 53% in aluminum, with comparable gains of 63% in steel and 58% in copper. These findings provide practical guidance for optimizing die design and process configuration to improve drawability and enhance product integrity in industrial deep drawing operations.