CNC ROUTERS REDUCE PRODUCTION TIME AND INCREASE ACCURACY
Switching from conventional power tools to a computerized numerical control (CNC) router helped reduce the time to produce automated wet process machines from 1900 to1000 hours. Poly Design, producers of a wide range of cleanroom equipment, were able to reduce their price for a three-position automatic transfer machine by 25% while increasing their profit margin. In the past it took five days to cut the parts for the eight cassette boats and two days for assembly. The CNC router automatically cuts the parts in only four hours and its accuracy is so much higher than power tools that assembly time is reduced from two days to one day. The time savings for producing one machine more than pays for the router at any reasonable hourly labor rate.

Each station is 4.5' wide, 12' long and 7' high. In the past, the panels and other components used to build the cabinets and tanks were machined using table saws, routers and hand saws. It took one person about 40 hours to cut out and prepare the parts for the eight baskets used for one machine. Cutting out all of the components needed for one machine took about 900 hours.

The polypropylene components are assembled using a welding gun. First, the joints are tacked together, then triangular polypropylene welding rod is melted into the joint to create the final weld. The relatively poor accuracy of the power tools used in the past meant that a considerable amount of touchup work and hand fitting was required during the assembly process. As a result, it took three to five people about 900 hours or a total of about 3600 hours to assemble and test the machine.

In an effort to reduce the amount of labor required to produce these machines, the fabricators evaluated a number of different CNC machine tools. First, they considered conventional machining centers large enough to handle the 4'x8' sheets used to produce the components but found they have a high price. Next, they looked at a new breed of gantry routers that interface with CAD systems, have a large cutting area, and a relatively low price.

They chose the Techno Series III from Techno-Isel. The machine's 0.0002" resolution and repeatability and 0.003" absolute accuracy ensure that plastic components are faithful representations of the designs created on the computer. The working area is 59" x 102", with a Z-axis height of 8". The machine also includes CNC software.

Now, the firm's engineers use the FastCAD or AutoCAD Lite software to sketch out their design on the computer. By manipulating their model on the screen, panning, zooming and rotating, they are able to validate all critical dimensional relationships before they begin to cut plastic. To provide a final validation step, they put a marker in the machine spindle and use it to trace the outline of the program on posterboard. Once the components for a machine are designed, they are nested together onto a 4' x 8' pattern to minimize waste. This optimization of the nesting process has saved a considerable amount of material relative to hand nesting.

It now takes only 4 hours to cut out the parts for all 8 baskets for one transfer machine. The increased accuracy and faster assembly have increased profit margins dramatically. The investment in CNC technology easily pays for itself every month.

For more information, contact Techno-Isel, 2101 Jericho Turnpike, New Hyde Park, NY 11040, 516-328-3970, FAX 516-326-8827, e-mail: techquestions@techno-isel.com.