CAD/CAM increases sheet metal manufacturer's abilities

Modern Machine Shop, Jan, 1994

When Westport Precision, Inc. speaks of working to precise measurements, they mean a standard tolerance of five-thousandths (0.005) of an inch for the parts that they produce in sheet metal. The company produces parts in aluminum, cold-rolled steel, brass and copper.

"CADKEY allows Westport Precision to create 3D wireframe models from the 2D drawings that their customers supply to them. They then place all the holes and notches that need to be cut into the part. Being able to create a 3D model straight-away has allowed Westport Precision to eliminate the need for sophisticated knowledge of geometry and trigonometry on the part of the designer. The CAD/CAM system (from CADKEY, Windsor, Connecticut) takes care of all of the calculations." Michael Pagett, Vice-President of manufacturing states, "Bench mechanics with a solid mathematical knowledge of geometry and trigonometry still used to make errors in math.

"After our programmer, John Del Vecchio, has completed the 3D model CADKEY, we inspect the model against the customer's original 2D drawing," Mr. Pagett continued. "This checking process data as a quality control. In my opinion, this ability to inspect the 3D model and its dimensions against our customer's drawings, before starting any production work, is probably the most important overall benefit of using CADKEY. We now have the capability to work with our customer at an engineering level, taking their 2D drawings to build a 3D model to verify for the customer that their parts fit properly."

"We transfer the design as a CADL file to the unfolding and programming software, such as ProFold and ProFab." The computer unfolds the 3D model into a 2D flat pattern, using the user-defined material thickness, bend radii and what is called the "K" factor as defaults. The "K" factor is a mathematical formula which calculated the amount of metal that needs to be subtracted from the flat pattern to compensate for the bends in the material represented in the 3D model.

"Once we have a flat pattern, we always verify its dimensions in the X and Y directions to make sure that the outside dimensions are correct," Mr. Pagett added. "Based on our experience, if the outside dimensions are correct, all the holes and notches to be cut out of the pattern will also be in the right places."

A major benefit of using CAM software to layout the flat pattern and program the parts is that a sheet-metal manufacturer can work faster and smarter. After the 3D model has been unfolded into a flat pattern, it is clear what is going to be cut out of the sheet of metal. If there are other parts for this job, or even if the company has another job for a different customer, that requires the use of the same type and thickness of metal, some or all of these additional parts can be frequently be fitted into the areas of the metal sheet which are going to be removed during the first job. This nesting of parts for more than one job results in optimal usage of both time and material.

"I don't see how anyone in manufacturing today can be effective without a CAD/CAM system," Mr. Pagett said. "The sheet metal mechanics of a few years ago don't exist anymore. Computers allow us to get our work done employing people with lesser skills."

"However," Mr. Pagett added, "in moving into CAD/CAM, you need to work with a knowledgeable dealer who will be there to provide you with service and support. Steve Kidd of Cimtech has helped us, from the beginning to determine what hardware and software we needed in order to become a more productive company."

"Four years ago, prior to using the CAD/CAM system," Mr. Pagett concluded, "we employed two full-time and one part-time sheet-metal programmers. We now have one. Plus, we have removed almost all downtime from out Strippit CNC turret punch presses." He adds, "Our business has changed greatly in the last few years. Our lead times have been cut in half. We have had to change the way we do business. Our CAD/CAM system has allowed us to respond quickly to our customers' needs. We also do CNC machining, plating, screen printing, cable and electro-mechanical assemblies."