Automobiles need to lose weight in order to cut their fuel consumption. More and more manufacturers are therefore beginning to use thin sheets of high-strength steel. Extremely hard and precisely shaped ceramic manufacturing tools will be presented at Euroblech 2006.
It only takes a few moments in the car shop to give the fender its attractive rounded shape. Fenders, doors, roofs and other car parts are mostly made on a conveyer belt using a sheet metal forming process: The metal runs off a huge roll and is pressed into a corresponding mold, the matrix, via a three-dimensional die. The high-speed method that enables the production of large numbers of parts is known as deep drawing. Recently, however, this method has begun to reach its limits: The conventional steel materials used in many of the metal parts are now being replaced by high-strength steel. Auto manufacturers are aiming to save weight in order to cut fuel consumption. By using high-strength steel, they can produce components that are thinner and lighter without losing any of their stability.
However, using high-strength steel complicates the forming process. Due to the heavy mechanical load, the matrix wears out more quickly than with conventional sheet metals. This is a high price to pay, because the molds have to be manufactured with extreme precision – and thus at great expense. A possible solution is to replace the tooling steel with high-performance ceramics in areas that are subjected to particularly high forces. Ceramic material is very much harder than steel, hardly wears out at all, and exhibits a high resistance to attritious wear. Working in cooperation with partners from research and industry, the Fraunhofer Institute for Production Technology IPT has demonstrated a way of producing such high-performance ceramic inserts.
The results of the “KeraForm” project are on hand. The advantage of the material, its extreme hardness, is also a drawback: High-performance ceramics are so hard that they can only be worked with diamond. “The complex shape of the inserts represents a special challenge,” says IPT project coordinator Andreas Weber. “This is where we need new process technologies.” The Fraunhofer crew has identified three conventional methods that are basically suitable for the job, and has optimized them for its own purposes. The best results were achieved with jig grinding, a method in which a small, very rapidly rotating grinding tool moves across the ceramic part to create the desired shape.
The use of ceramic-reinforced forming tools is particularly beneficial when large numbers of parts are to be produced. The Fraunhofer team intends to apply the experience gained from this project to open up further fields of application for high-performance ceramics.