Peter Ulintz Peter Ulintz
Technical Director

Advances in Automotive-Stamping Technology

February 17, 2021

Technologies in metal stamping continue to advance and mature―as they always have done,―but today this occurs more rapidly than in the past, and with technologies profoundly more complex.

Hot Forming―Amazing but Complex

Hot forming provides a good example. In common practice today: forming automotive components from boron-steel sheet metal at very high temperatures (approximately 900 C) in a die that simultaneously quenches the stamping—essentially heat treating the formed part in the die. 

Hot forming differs greatly from a traditional deep drawing process. Hot forming employs no blankholder; instead, special clamping units hold the part material in position and prevent the formation of wrinkles. And, the process often requires cooling lines located close to the die surface to facilitate the quenching process, which requires special die steels with high strength and heat-transfer rates. Strong ejector systems also must be designed and built to facilitate part removal. These represent only a few critical features that must be addressed when designing and building hot forming dies, which makes hot forming an amazing accomplishment considering that most die engineers and toolmakers never were trained in this technology.

Big Gains on the Materials End

Material evolution represents another example of complex technology. Advancements in steel technology has led to a new class of high-tensile-strength materials called advanced high-strength steel (AHSS). Except for the boron-based hot forming grades, these materials are designed to be cold formed in traditional stamping dies and press lines at room temperature. These materials may exhibit two to three times the tensile strength of traditional high-strength low-alloy steels, placing unprecedented demands on new tooling and older press lines.

A third generation of AHSS materials features tensile strengths approaching those of hot formed stampings but with enough ductility to be cold formed at room temperature. These ultra-high-tensile-strength materials surely will push existing press lines beyond their designed-for capacity limits.

Beyond steel, automotive and transportation applications of sheet aluminum alloys have increased greatly within the last decade. Processing aluminum stampings can be challenging, especially when working with new or unfamiliar alloys. Producers have developed new alloys for ultra-high-strength hot forming applications, with other existing alloys successfully warm formed and a few others super-plastically deformed. In addition, refinement of more-common alloys has delivered better cold forming properties. The best opportunity for success demands that the process engineer and die designer understand the differences and limitations between the various aluminum alloys and their tempers.

Lube and Tool Advances Abound

Advances in forming lubricants, application methods and thickness-measurement technologies have become increasingly more important and prevalent, especially considering the arrival of third-generation AHSS materials and the potential elimination of some types of chlorinated paraffin.

Modern stamping dies must withstand an ever-increasing array of stresses, temperatures, chemical attack, shock and vibrations. So―no surprise here―that metal stamping dies are prone to all kinds of in-process failures. Constantly improving tool-steel composition, heat treating methods and engineered surface coatings seek to meet the increasing demands placed on stamping dies. 

Tool designers and builders often choose carbide materials for stamping operations requiring long production runs. These materials exhibit high compressive strength, resist deflection and retain their hardness values at high temperatures—a physical property especially useful in high-speed cutting, punching and forming applications. Some processes, such as perforating small-diameter holes in hard, tough materials, may only be possible using tungsten carbide punches.

Also emerging: process developments such as double-sided incremental sheet metal forming. This novel manufacturing process utilizes two generic tools to manipulate sheet metal to produce free-form parts without the need for dies. The process potentially achieves a design-to-product cycle time of only a few hours or days as compared to the typical period of weeks or months required for conventional sheet metal forming processes.

Digital Evolution Lends a Big Hand

The digital world also works hard to keep pace with advancing stamping technology by delivering more accurate sheet metal formability analysis; improving springback prediction and responding to variations in the stamping process; and simulating programmable servo-press slides in combination with programmable servo-transfer systems to optimize strokes per minute. The digital evolution also includes optical scanning technology (white light and/or blue light scanners) to capture and digitize dies and parts produced off of dies in order to assess and appropriately modify the tooling; and morphing solutions that enable rapid and repeatable development of compensated die surfaces.

Are We Ready for This?

These and other recent advancements in automotive-stamping technology, and the impressive speed of change, prove fascinating. But what about the workforce? Are young workers equally fascinated with the rapid changes in manufacturing, and do employers’ training programs keep pace with this speed of change? MF

Industry-Related Terms: Alloys, Die, Drawing, Ductility, Forming, Lines, Quenching, Surface, Tensile Strength
View Glossary of Metalforming Terms

Technologies: Stamping Presses


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