Trimming the cost of cutting and drilling.

A Maine-based machinery manufacturer that last year introduced a series of cantilevered-arm robots aimed primarily at the wood-working industry is now offering the units as a low-cost alternative to CNC drilling and routing of plastics.

USA Robot of Portland says its Maxym (Movable Arm XY Machine) robots can cut or drill just about any plastic, including glass-reinforced composites, at speeds of 20-50 in./min. More important, the company says, a unit sells for about one-tenth the price of a CNC machine and is accurate to 1 mil at top speed. Driven by stepper motors and lead screws, the robots are especially suited to applications such as thermoforming, rotomolding and RP/composites, where secondary steps like routing and drilling are almost always required. With the ability to accommodate parts up to 24 x 48 in., the robots can handle about 90% of all plastic parts manufactured, the company says.

DRAW THE PROGRAM ON-SCREEN 

A drawing program designed by USA Robot president Tom Bryand lets the user sketch onto a computer screen the pattern to be cut or drilled. Patterns as small as 1/2-in. square up to 4-ft square can be programmed.

An on-screen menu then lets the user assign depth of cut and cutting speed for each line of the pattern. Individual cuts are identified on the computer screen by dotted and dashed lines. Once programming is completed, the user presses the "run" button and the cutting or drilling begins.

USA Robot says the lead screws on the units are accurate to 2 mils over the entire travel of the screw. This tops the accuracy of more expensive CNC machines, the company says, because the gantry arm on a CNC machine returns to its starting point after each cut and then has to travel a relatively long distance for its next operation, lessening the machine's accuracy. The software on the Maxym robots tracks the locations of the robot, says v.p. Jack Hanson, and doesn't move the cutting arm back to "square one" each time, ensuring greater accuracy.

Furthermore, Hanson says, Maxym robots take only about 15 min to program, whereas a CNC machine could require one or two days to program for the same job. The cost of the robots ranges from $13,000 for a unit that will cover an area 12 in. square to $19,950 for a model that can cut a 24 x 48 in. part. An optional fourth axis that allows parts to be jigged between two robots and permits 360|degrees~ cutting costs $5200 extra.

The robots are relatively lightweight and don't require dedicated floor space, Hanson says. The 1-ft-sq unit weighs 270 lb and the 24 x 48 machine weighs 450 lb. Each is mounted on a stand with lockable casters for easy mobility.