If the events of July’s Semicon West show are any indication, now is the time to be in the solar-cell business. One of the few hot spots of activity at Semicon was the InterSolar part of the exhibition, where show floor traffic was sometimes shoulder-to-shoulder.
Among the solar-themed equipment was a conveyor adapted by Bosch Rexroth, Farmington Hills, Mich., to move solar modules through an assembly process. The modules ride on belts powered by gearmotors operated from variable-speed drives. Capacitive prox sensors detect when modules near the end of the run, and a pneumatic machine raises or lowers modules when they need to turn corners or exit onto a different conveyor. The belts are specially made to ensure they shed as few particulates as possible. The whole apparatus is a modification of a conveyor designed to handle flat-panel displays.
Also new from Rexroth were eLINE Compact Modules, preassembled linear systems for handling small items and packaging operations with loads up to 60 kg. Target applications are those where cost is a big consideration and where users would otherwise be tempted to just throw something together themselves. Features include easy programming and start-up, a stepper motor with positioning control, factory pre-lubrication, and a configurable online 3D CAD generator. Modules are available as ball screw-driven (eCKK) or belt-driven (eCKR) versions, in profile sizes of 90 and 110 mm. They use two aluminum ball/rail hybrid guideways with hardened-steel inserts.
The modules typically get handled with air grippers. SMC Corp. of America had a variety of noncontact lifting devices that use what it calls cyclone flow to create suction for lifting modules. A layer of air escaping around the edge of the lifting pad prevents equipment from touching the module.
The moving cables that attach to such equipment need special qualities: low particulation and long flex life are just two. Several firms have offerings in this area.
W. L. Gore & Associates, Newark, Del., uses a PTFE jacket that lends itself to high-flex, low-outgassing cables that slide smoothly without generating particles. The company has boosted manufacturing capacity and can now make flat cables up to 300-mm wide so that one self-supporting cable can replace several discrete wire runs for stroke lengths of 500 mm or less.
Similarly, high-flex silicone cables from Cicoil, Valencia, Calif., now have what’s called a StripMount option. Here wire conductors or air lines are encased in an extruded silicone jacket along with a fiberglass-reinforced flexible ribbon. The ribbon provides an area through which users can screw in fasteners or punch holes so the flexible cable can attach to, say, a housing or panel. The idea is to eliminate the need for cable conduit or cable ties as attachment points. The fiberglass-reinforced strip molded into the silicone has 250 lb of holding force.
Pneumatics supplier Festo, Hauppauge, N.Y., gave show-goers a heads-up on saving energy with judicious monitoring of air supplies. Festo engineers have noticed that many manufacturers have a lackadaisical attitude about the air lines that run through their plant. At one plant they checked, engineers found the air supply contained rust, oil, dust, and water. Moreover, the whole plant hissed — there were air leaks everywhere. An energy audit in such cases can save thousands of dollars, says Festo. One customer cut its electricity bill by 55% after fixing problems the audit identified. Further economies are available through use of software that monitors machine operation, showing pressures and flow rates, to make sure actuators are properly sized for best efficiency, and through use of ultralow-leakage products which lose under 2 liters of air per hour.
Enfield Technologies, Trumbull, Conn., demonstrated additions to its LS-System line of pneumatic valves and electronics that provide high-resolution pressure control. Enfield’s demonstration replicated a semiconductor application with precise control of pressure in a 330-cc chamber. The command profile changed rapidly and was nonlinear, bringing the system from vacuum through 125 psi of an inert gas over a 5-sec period, with accuracies of 0.014% of full scale during all changes. The final set point was accurate within 0.0036% of full scale.
It’s tough to get quick, precise control in such a small chamber, Enfield says. Standard electronic pressure regulators — and even high-performance versions — can’t faithfully follow the changing command and settle within the target range. The Enfield equipment smoothly tracked the rapidly rising wave pattern. The end user in this demonstration selected a specialized pressure sensor and used an Enfield LS-C41 closed-loop controller, valve driver, and LS-V05c high-speed proportional valve.
The LS-C41 is an analog controller implementing real-time PID control. It also has deadband elimination features to boost system accuracy and cut hysteresis. The LS-V05c valve is also analog, meaning it can hold partially open to provide variable flow control rather than pulsing. Only marginal moves are needed to change the flow rate. For example, if the valve must open or close just 5% to adjust flow, the marginal bandwidth is nearly 8 kHz. This minimizes excessive full-stroke shuttling. The valve is rated at up to 150 psi and internally pressure balanced so it can source different pressures with little effect on performance.