Case Study

A time-saving "machine"

Hofmann Werkzeugbau

NX Mold Design enables 20 percent design lead-time savings

Miniature to multi-ton dies

Hofmann Werkzeugbau GmbH is part of the Hofmann Innovation Group of five companies located in Germany, the Czech Republic and Spain. These companies offer a broad spectrum of services for the plastics processing industry ranging from product development, rapid prototyping and rapid tooling through die design, construction and production of injection molding dies to the assembly of small series. As the nucleus of this corporate group, mold die construction was founded as early as 1958. The group currently employs 450 people. With 250 employees, Hofmann Werkzeugbau is the largest individual company in the group.

“We design and manufacture injection molding dies within a very broad spectrum, from the genuinely miniature part to 40-ton dies for molding complete car roofs, for example,” says Hofmann Werkzeugbau’s managing director Günter Hofmann. At the same time, the company is not so interested in size itself, “but in implementing the highest level of technology possible,” emphasizes Hofmann. With an emphasis on quality, the company has received the “Die Construction of the Year 2005” award, conferred by the Fraunhofer Institute for Production Technology IPT and the machine tools lab WZL of RWTH Aachen University.

Experience turned to strategic advantage

Hofmann Werkzeugbau has been relying on CAD/CAM software from Siemens for 17 years now. “When we first started using Siemens software, there was practically no other system capable of implementing the complex surfaces in dies,” says Hofmann. “At that time, a 2D system was used for the surrounding design of the complete die. Today, it goes without saying that NX™ has all the abilities needed to design injection molding dies completely, down to the last detail and to create the required NC programs.”

Currently Hofmann Werkzeugbau uses a total of 53 NX workstations for die and model construction. Twenty more are in use at Hofmann & Engel in Dresden. “I consider it to be a strategic advantage to have worked with NX for so long and to have taken full advantage of all the possibilities the system has to offer,” Hofmann says. “We’re very satisfied with it.” Thus, it is no surprise that the company tested NX Mold Design practically from the very first moment it was available, and then introduced it step by step.

Automated mold design process

Reliable and fast design is ensured by built-in automation within NX Mold Design, such as an injection molding die design “expert” that prompts users through the design process. The software offers functions for the entire die creation process, including capabilities for automatic mold separation. It encompasses tools for process management, mold separation and individually adjustable libraries of standards and other repeated parts. The tools offered by NX Mold Design guide users through every important task when creating injection molding dies.

Before the software was implemented, it was tested intensively and tailored to the company’s processes. For example, this included customization of the user interface, the layer structure, color assignment and input of standard parts specific to the company. The libraries included in the expert system can be “used in practice to a wide extent,” explains Peter Michel, the design group leader at Hofmann Werkzeugbau.

Relieving users of routine work

For every task, NX Mold Design provides special screens and function menus which, once filled out, are processed automatically. This relieves users of a lot of routine work operations. In NX Mold Design, every item – part, standard, screw, etc. – is stored as a separate file. In this file, the part’s “properties” are defined as attributes, namely geometry, material, hardness, manufacturer and so on. Whenever a part is worked on, the entire knowledge base is always active in the background and does not need to be re-entered. This results in easy control of the attributes, as well as with improved standardization and design safety. The right parts are produced automatically.

Michel describes “clean data” as being the basic prerequisite for a mold design project. On this basis, designers use NX Modeling capabilities to heal imported geometry with only a few simple steps.

Due to the ability to easily document, transfer and view JT™ representations of tool designs, Hofmann has equipped workstations in the production facilities with viewers; this has resulted in a substantially reduced dependence on paper drawings.

“We have been using NX Mold Design globally, that is to say at every workstation and for all kinds of dies for around one and a half years now,” reports Michel. The result has been a significant reduction in design time. “In total we benefit from design time savings of around 20 percent,” says Hofmann. “I can already imagine us achieving a design time saving of about 50 percent in future.”

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