DESIGN
COMMENT
Michael Paloian, Integrated Design Systems, Inc.
Design Documentation: Do We Still Need It? We live in an age where everything is automated by computers and appears to be done perfectly within the blink of an eye. This is especially true in the design profession. When I first started working as an industrial designer more than 40 years ago, things were very different. I had to sit at a drafting table for hours, weeks, and months slaving over part drawings which were meticulously detailed with a pencil, calculator, and a skilled hand. The slightest design change would require the erasure of many hours of work and investing countless additional hours to incorporate the changes. All parts were detailed using conventional orthographic drawing methods to describe every feature of a part. Most parts required multiple drawing sheets to fully describe all the features in numerous cross sections and views. Part drawings were finalized by manually adding dimensions, tolerances, material specifications, and countless other notations. Finally, a tool maker would receive a set of blueprints which would then be manually programmed into an NC machine or interpreted by a patternmaker and made into a wooden pattern. Everyone of these steps provided an opportunity for human error, which could result in costly tooling revisions. Thank God those days are gone! Today most designers don’t even know what an orthographic drawing is, much less know how to create one. 3D CAD has completely changed the workflow and design process by enabling designers to create 3D models of an entire assembly and all associated parts with all the appropriate draft angles, radii, clearances, and dimensions. These individual virtual parts are then sent to a tool maker who simply enlarges them based on required shrinkage, designs a mold from the CAD files, and eventually cuts a mold directly from the data. The entire process from start to finish can theoretically be completed without ever physically touching a part or requiring any human intervention. However, the process is not completely automated yet and humans must intervene at various critical phases, which require some form of documentation. The documentation I’m referring to is a production control drawing. A wonderful benefit of 3D CAD is its ability to create a fully associative set of production control drawings for every part and assembly, which are automatically updated with design revisions.
Although tool makers cut molds directly from the 3D CAD files, production control drawings are primarily used to identify critical dimensions, materials, surface finish, color, and any other important parameters critical to product form, fit, or function. Production documentation should be treated as a legal document between an OEM and a molder. If parts deviate from the stated specifications within the documents, they can be legally rejected for non-compliance. Furthermore, if a product failure leads to litigation resulting from injury, production control drawings are often cited in arguments by the defense or plaintiff. It’s therefore extremely important for designers to be very deliberate in specifying every notation on a production control drawing. Careless omissions or incorrect specifications pertaining to assembly, materials, tolerances, and countless other important factors affecting a product could result in serious consequences. Next time you launch a new product don’t overlook the importance of production control drawings. Remember to consider them a very important legal document as well as an important source of information for the molder and tool maker. I look forward to hearing from you. Please feel free to contact me at paloian@idsys.com with your comments or questions. www.rotoworldmag.com 25
