Don Hemmelgarn
International TechneGroup Incorporated

Shortly after Gespard Monge wrote his 1801 dissertation "La Geometrie Descriptive", engineering drawings began to supplant physical models for engineers and manufacturers to describe their designs. This triggered a radical change throughout the manufacturing world --- putting into place a standard that would remain intact for nearly 200 years.

Even as computer-aided tools for design, engineering, and manufacturing evolved, engineering drawings would remain the standard for representing and communicating product data. Finally, with the emergence of the Internet as a reliable and instantaneous method to communicate intelligent electronic data, things began to change. Today once again sweeping changes are taking place as 3D CAD models are replacing engineering drawings as the standard in product definition throughout the manufacturing enterprise and its supply chain. The benefits are enormous. If�

The Cost of Interoperability

Just as Monge helped redefine manufacturing two centuries ago, the next industrial revolution will hinge on the effective use of master CAD models throughout the product development process. "Effective" is the key word as today CAD models are being created and re-created at unprecedented levels due to interoperability problems --- that is the inability to freely share a CAD model across dissimilar platforms, systems, and applications. And how big is the problem?

A recent study by ITI showed that manufacturers can typically spend from 25% to 75% of their time with the non-value-added task of reworking CAD models. Furthermore NIST (National Institute of Standards and Technology) recently released a report citing that time spent reworking or recreating CAD files costs the automotive industry alone in excess of $1 Billion each year. Take a closer look and you will likely find that redundant CAD model rework is draining time and money from your own organization. You may, like others, have come to accept CAD model rework as a standard part of the manufacturing process.

CAD models containing hidden errors or anomalies have a direct and detrimental impact on downstream analysis, data exchange, rapid prototyping, CNC programming, and other manufacturing-related applications. Those forced to try to import and work with problem CAD models are caught squarely in the middle of today's escalating "Bad CAD War" constantly walking the line between demonstrating technical competency and good business practices. But why should the burden be placed on the downstream CAD model user? Shouldn't it be expected that the files you receive translate cleanly and effectively into your in-house system? Shouldn't CAD model rework be the exception rather than the rule?

Making it Work

Manufacturers can and should continue to employ downstream CAD model repair and healing tools to address many data exchange problem areas. But sometimes data exchange gets a bad rap. If the model is unusable blame the translator, IGES, or STEP. It is not uncommon, however, for CAD models to contain geometry that is valid but not manufacturable --- such as thin edges, slivers, or unrealistic angles.

The answer is to identify and resolve CAD model problems up-front in the design stage. By adopting a CAD Model Quality initiative quality and interoperability are built into the model eliminating unmanufacturable conditions and downstream rework. Encourage your customers and suppliers to take advantage of some powerful technologies available today to maximize the CAD/CAM investments you've each made. Without this approach we might just as well return to the manufacturing practices of the past.