Assembly in Action:Tester Ensures PCB Assembly Machine Reliability
For servicing and supporting its Siplace machines, Siemens chose the ScopeMeter 199C from Fluke Corp. (Everett, WA). The ScopeMeter 199C ensures that testing and calibration of the Siplace machines is carried out accurately.
The Siplace series includes compact and modular pick-and-place machines, with interchangeable component feeders, placement heads and spare parts. Complete Siplace lines can be reconfigured, and production capacity can be quickly shifted to other lines or factories. The platform has an operator interface that handles a stand-alone machine, as well as full production lines. A complete Siplace line consists of a high-volume screen printer, surface mount placement machine, a transport handling system and a high-volume reflow oven.
A team of more than 20 technical support engineers services Siplace machines in the United Kingdom and Ireland. The engineers provide regular maintenance, and they also respond quickly to service calls.
"When we visit a site, we want to be able to access any part of a machine to work on it, and we want to be able to service it or replace parts as quickly as possible to maintain the manufacturer’s productivity. If we need to test or calibrate a machine’s PCB, it is not feasible to move it to a workshop for testing on a bench oscilloscope or another meter. The ScopeMeter 199C provides our engineers with the ideal solution for electrical measurements in one portable, handheld test tool," says Ken Martin, service manager.
The handheld ScopeMeter190 Color series combines the functions of a digital multimeter with a dual-input digital storage oscilloscope with bandwidth up to 200 megahertz. The bright, backlit color screen enables viewing in dark recesses.
For Martin, one particular function of the Fluke 199C has proved particularly useful. This is being able to plot changing signals simultaneously on the X and Y axes of the oscilloscope using the dual-channel capability. "High-precision placement means that the positioning control electronics of the pick-and-place heads has to be extremely accurate," he explains.
Along the two axes of movement, there are registration markings etched on copper strips, which are detected optically for exact positioning of the head during placement. Within the machine are axis drive cards controlling the movement of the head along the X and Y axes. On some occasions, it may be necessary to replace a drive card, drive motor, optical reader or track on which the head moves. If a part is replaced, recalibration is needed to accommodate the tolerances of the new part. Once calibrated, the machine’s servo system maintains placement accuracy.
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Exact equality of linear movement along the two axes is vital. A signal is captured from each of the axis drive cards, controlling the head movement forward and sideways. These signals are fed into the two channels of the ScopeMeter 199C, and a classic Lissajous figure is displayed on the screen. If the output signal strengths are unequal, the figure is elliptical and its shape indicates which axis drive card needs to be adjusted. When the signal strengths are equalthe required settingthe figure is a circle.
"Fluke instruments always top our list because of their reliability and ruggedness. For servicing these flexible machines in particular, the ScopeMeter is proving a vital tool," says Martin.
For more information on the Scope-Meter test tool, call 800-443-5853or visit http://www.fluke.com.
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