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The Exponential Nature of CAD Knowledge

By Stephen M. Samuel

When design engineers use high end CAD tools well, there is an exponential benefit. The difference between someone good with CAD and someone who’s just OK can mean a huge variation in how fast the product they’re working on gets to market and therefore millions of dollars in opportunity cost. It also makes a great impact on product quality.

Computer Aided Design is design automation. The programs that we use these days are the culmination of millions of man-years of programming and wisdom. When we extrude sketches and sweep shapes along a guide, we take for granted, the myriad of calculations that are going on behind the scenes. Most of us have lost sight of how difficult it was to get a simple thing like the center of gravity and the weight of a sculpted shape such as a turbine blade. Millions of little tetrahedrons are reconciled in the blink of an eye. This is how we become more competitive.

The nature of competition requires us to continually improve what we do knowing that our competitors are doing the same. If our competitors are good, they spend a considerable amount of time trying to figure out how to optimize what they do down to the last detail. When you see someone win the Indianapolis 500 you know that the driver has insane skills, but the car is also a huge part of the competition. The car is the culmination of massive amounts of research and development, and special tricks that come from years of experience. You can’t win without the great driver and the great car.

In the design space, the situation is similar. In order to be competitive, you must first have the top people – the real drivers. The top people come to you with a lifetime of practical experience, plus a great education. The top people must practice their art constantly to stay on top. Their employer must continually expose them to the latest techniques and upgrade them with education. It’s costly, but it’s worth it.

When a design engineer goes to do something difficult, that’s when the real magic happens (or not). For example, designer A is a good user of CAD system X and designer B is great. The task is to develop a new design for a tire that reduces rolling friction as it displaces water on wet roads. Designer A comes up with a new idea for a design and laboriously creates that design on the round surface of a revolved profile of the tire. It takes a long time because each measurement has to be translated onto the surface of the tire and then built with a combination of surface techniques. It takes designer A about three days to complete the entire design and about 2 more days per design iteration. Designer A also knows nothing about the kinematics package or finite element analysis, so when he’s done with the design, he has to wait until the separate kinemtics group and the analysis group make room in their schedule to attend to his job. This adds even more time onto the overall process. Designer B is not necessarily smarter than designer A but he knows his CAD and CAE. Instead of translating his ideas to the round face of the tire then creating surfaces from there, he uses the “wrap” technique followed by a thicken and a subtract. Designer B sketches his idea in a flat pattern where it’s easy, and then he can iterate design changes in about 20 minutes. He also knows the associative finite element code so he can easily get the centrifugal stresses and validate the design. When designer B want’s to iterate on the design, he tweaks the underlying parameters, the model is automatically re-meshed, and the new stress results are soon available. Designer B insures that the product gets on the market a full month earlier.

  • A) Designer B sketches the basic tread contour on a tangent plane
  • B) The contour is wrapped onto the round surface of the tire
  • C) The wrapped contour is thickened and propagated to fit the width of the tire
  • D) The thickened solids are instanced all around the tire
  • E) The solids are subtracted from the tire solid
  • F) The tire model is brought associatively into the finite element analysis package

The company enjoys a full month of selling the new product they wouldn’t have had otherwise. This effect could mean increased market share and hundreds of thousands more units sold. The investment made in designer B, the extra days of training, paid off by orders of magnitude.

In many engineering offices there is a common situation. There’s this one guy – we can call him Harry. Harry seams to do the work of five people. Harry bangs on the keyboard as if he were playing a jazz saxophone. When you watch him it’s like watching a computer macro. He’s focused and the work gets done well. He’s passionate about it and knows the CAD program backward and forward. If there’s ever a command that he doesn’t know, it bothers him and he eventually finds out exactly what it does. He does the research and he tries a million new commands even before there’s a need. He’s plugged into a network of like-minded individuals that are also passionate about the CAD tools and share what they learn about the system. Harry even knows tips, tricks and techniques that aren’t necessarily published in any formal resource.

Companies will do best if they try to ensure that every designer has Harry’s skills. The fact is that Harry is a bit of a freak of nature, but there are plenty of ways to bring everyone else up to a higher level of skill, and reap the benefits of having many Harrys.
Here is a partial list of actions that companies can take to ensure that they’re really getting the biggest bang for the buck spent on CAD tools:

  • Make sure that people are well trained by someone who understands the company-specific processes.
  • Make sure that the software’s abilities are used to create part-specific techniques. In other words, the process must be continually upgraded along with the user’s abilities.
  • Make sure you are using a software package that is continually improving and becoming more capable.
  • Make sure your work force has access to extremely responsive and knowledgeable experts.
  • Make sure there is an internal user group and people are rewarded for creating and publishing their home grown techniques.
  • Make sure you have a library of legacy tips and techniques.
  • Give people room to fail if they must try something extremely innovative.
  • Optimize the use of the CAD tool by supplying the best hardware. This may include two monitors, and a space ball device.
  • Hire the right people with the right skill set. This may include testing their CAD skills before they are hired.

Using these techniques will truly ensure that the best use will be made of CAD. They comprise the best ways to ensure that a better product is created and arrives in the hands of the consumer in the shortest possible time. This in turn makes the entire product life cycle less expensive.

Author Stephen M. Samuel enjoys an exciting carrier as President of Design Visionaries. He lives and works in San Jose, California where Design Visionaries was founded.

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