Die Face Design next Generation

Nowadays die face design is moving towards CAD environment. Iterations are done directly inside CAD and on native CAD data. The tool used for die face design must support the user in all phases of the process design cycle: from the very early conception phase, through feasibility studies until the final validation. An optimum with respect to performance and accuracy needs to be established for each of these separate steps. Die face design should be based on B-Spline geometry in order to keep the solution fast, powerful, flexible and compliant to the automotive industry standards. Any possible hold due to required changes in geometry must be removed. Surfaces must be accurate to guarantee an accurate description of contact surfaces and accurate simulation results – as early as possible

Customer Challenge

Automotive sheet metal forming parts come from the design department and often consider only aesthetics (outer panels) or functionality (reinforcements, beams etc.). Normally no, or very little, consideration is given to manufacturability. This is the job of the process design department or toolmaker: find ways to create the part in a robust and cost-optimized way. In most cases the time-pressure is huge (and ever increasing), but still many variants of the die face design and process need to be considered before an optimum (manufacturability and cost!) is found.

Typical Workflow

• Starting from the part geometry, a first die face design for the first draw die is quickly drafted and evaluated for general feasibility like occurrences of cracks and wrinkles. As the first design will not normally fulfil all criteria, iteration loops are run to optimize the die face design and stamping process parameters. These iterations normally consist out of the following:
• Complete or partial part modifications coming from the design department
• Geometrical addendum modifications to eliminate wrinkles, cracks or to optimize the trimming conditions
• Process modifications to overcome cracks and wrinkles and improve the general robustness of the process
• Reduction of blank size for material cost optimization
• Propose part modifications in case a feasible or robust process cannot be guaranteed

After proof of concept of the general feasibility for the first drawing stage, the following operations are included in the process design (trimming, hemming, flanging, restrike…), both geometrical design and simulation validation. Next to the crack and wrinkle analysis and press force estimation, other criteria also become relevant at this stage, e.g. analysis including cosmetic defects for outer panels and springback compensation for the forming dies. Finally, the last step, after full validation of the process design, milling of the production tools will be carried out.

Key Capabilities        

Integration of a dedicated solution for die face design into CAD environments will offer huge advantages over standard CAD usage and mesh-based die face design solutions:

• Compared to standard CAD usage, it minimizes the tool designers’ workload by implementing tool design & process knowledge, and following the natural process of tool face design.
• The integration offers a set of powerful interactive tools and functions, which provide guidance and support for part preparation, binder development and die addendum and provides quick access to important process information like trimming angle conditions and developed trimline geometry.
• It combines the convenience and speed of rapid die face design with the quality of the native CAD surfacing. Therefore highest quality simulation results can be expected – right from the beginning.
• Full CAD based design eliminates the need to regenerate a mesh model in CAD and thus doing the same work twice. The same model can be used throughout all phases of the development process,  from the early (feasibility) stage up to the milling of the model
• Due to the CAD integration all native CAD functionalities can be used to reach an optimal design without need for compromises due to limitations of the mesh-based die face design software
• Easy and fast iterations due to dedicated part replace functionality: in just a few minutes, the original part geometry can be exchanged with the latest version of the part. There is no need to reconstruct manually the full die any more.
• By providing a strong dedicated link to the simulation environment, quick and easy simulation iterations can be carried out without the need for much user interaction and  without loss of geometrical accuracy

Major Benefits

• Reduction of costs, by using the state-of-the-art die face development methods to deliver right the first time
• Ensuring success in prototyping and manufacturing by testing the virtual prototype first: production problems avoidance strategy
• Gain time: no need to rebuild die face designs in CAD environment based on a mesh reference
• Also in the last phase of the development process new part variants can still be easily and quickly investigated by integrated intuitive replace functionality for CAD data
• Fast learning curve for new users: with only very little training also non CAD experts can become extremely efficient in creating production ready die face designs
• The die face design product can be easily integrated into the existing host PLM structure