Delivering designs fast that cost the minimum while meeting targets for function, quality, and durability is what sets apart the expert engineer. The discipline of design for manufacturing (DFM) intends to aid engineers in doing just that. “Today, time to market and cost are the two critical factors that drive product development in industries such as automotive or off-highway. Product design takes around 5% of the total time in the product life cycle but has a 70% or more impact on the overall product life cycle cost,” explained Dr. Vinay Kulkarni, Vice President, and Head, Desktop Products & Technologies, Geometric Limited.
Employing DFM does not necessarily mean using advanced software technology. A variety of methods could be used to get it right the first time. One is employing expert engineers with years of experience in the process used to make their parts. Another is instituting a structured process of reviews that includes manufacturing input before releasing designs. “Some organizations have set up a 'standards department,' which is an intermediate between design and manufacturing to define design best practices in terms of manufacturability,” said Kulkarni. So, manual processes work. However, as Kulkarni points out, manual processes are error prone, time-consuming, and need design and manufacturing engineers to be close to one another.
To mitigate these problems, Geometric Limited provides its DFMPro to aid in applying DFM at the design stage. According to the company, it is integrated into two popular CAD programs—Pro/Engineer from PTC and SolidWorks from Dassault Systemes. Engineers use the add-on product to check design features for manufacturability as they create their CAD designs. Instead of referencing written standards or reviewing designs in meetings, the engineer validates the 3-D CAD model using these built-in rules for manufacturability. There are two modules available: one for machining and one for sheet metal. Processes checked include milling, drilling, turning, and sheet metal fabrication. Most importantly, the organization can modify existing rules and add new rules from its own proprietary standards. If such standards already exist in written form, it would be a matter of transferring that knowledge base to the DFMPro rule base.
How it works is simple. As the engineer or designer specifies the CAD model, they simply ask DFMPro to analyze the model. Using feature recognition technology, the software uses the available rule base to determine if the features it identifies meets the manufacturing rules. For example, a machining rule for drilled holes might be that the depth-to-diameter ratio should be less than 4. If a hole has a ratio of 4.38, the software will flag each instance as a failure. Categories for rule evaluations are success, failure, or nonapplicable. Online help documents explain the rules if needed. “DFMPro also acts like a training tool for new designers to acquaint them with design best practices and manufacturability,” said Kulkarni.
Highlights of the latest release, DFMPro V2.0, include new rules, reports generated as eDrawings in 3D, support for assemblies (not just individual parts), and support for feature count and parameter calculation so users can create their own templates to perform simple manufacturing cost calculations. Currently, DFMPro comes prepackaged with about 20 rules each for machining and sheet metal. The company reports a new module for injection molding will be available for plastics parts.
Adding one’s own rules and cost calculations is where the bang for the buck lies. Think of DFMPro as a framework requiring effort after purchase to get the most value from it. “An automated tool like DFMPro is useful for companies that deal with a large number of design changes and new designs frequently, such as large OEMs tasked with introducing frequent new products to the market. Also, suppliers who cater to multiple OEMs are typical users of DFMPro,” said Kulkarni.