Springing Into Action - NHK Spring Company Ltd - Brief Article

Automotive Manufacturing & Production, Sept, 2001

"We are looking for methods to increase our quality and reduce time-to-market," notes Ken Okura, assistant to the manager, Research and Development Dept., NHK Spring Co., Ltd., a manufacturer of springs for, among other things, suspensions and even seats.

One of the ways that they are looking to do both is through using simulation technology for modeling the molds that are used to produce the springs. One of the key things that simulation permits is determining where the stress loads may be in the mold-as-designed. As Okura explains, "We have to know where the stress loads are so we know if the mold is maintaining its shape under load." The objective is to make that determination while the mold is still being designed so that modifications can be made. When the real mold is made, the testing is, then, ideally, nothing more than a final check.

The company is using MSC.MARC/AutoForge nonlinear simulation from MSC.Software (Costa Mesa, CA) along with a NHK Spring-developed software package, Design Director. The latter is based on the Statistical Design Support System, proposed by Dr. M. Shiratori at Yokohama National University; it uses a Design of Experiments methodology combined with finite element analysis (FEA) simulations that are made by MSC.AutoForge.

What happens is that the MSC.MARC/AutoForge software is used to model the punch and die and to simulate the process. The software features automated contact analysis, a material database, and kinematics, as well as an autoremeshing feature. The last-named is particularly beneficial in terms of minimizing the need to generate physical prototypes and also minimizes the amount of time that engineers need to spend working on that aspect of things. Instead, they are busy working on improving the actual design of the springs.

Engineers take information related to responses and a defined range of design variables and upload the information to DesignDirector; this then generates a series of design factor value combinations; a series of FEA simulations are then performed and calculated by MSC.MARC/AutoForge. Explains Okura, "Then the response surface equation is generated for each design factor automatically, which is used for the optimization, reanalysis, sensitivity analysis, and evaluation of dispersion."

It would hard to find a better testimonial to the performance of a product than this one: "MSC.MARC/AutoForge is indispensable; it has made it possible to know the stress of metal molds and workpieces and enabled us to predict workpiece flatness, reducing design time and physical testing," says Okura. Which is what it is all about.