Assembly In Action: Automated Production Line Increases Speed, Precision
March 29, 2011
When Prüfrex received a major new contract to produce small engine ignition control systems for forestry and garden machines, the company decided to replace its existing semiautomated production line with a faster, more powerful alternative-one that could handle a volume of approximately 3 million units per year.
A critical part of the application included resin casting the ignition controls in a way that would ensure both their high-voltage insulation and resistance to outside factors, such as temperature, humidity and vibration. To achieve this goal, Prüfrex worked with Scheugenpflug, a supplier of automated mixing, metering and dispensing systems.
After evaluating the application requirements, Scheugenpflug designed a fully automated production line to support the resin casting of electronic components in countless different configurations. With a 45 by 20-foot footprint, the system includes a linear transfer mechanism, various process and measurement units, and several preheating and curing ovens loaded in turn by a four-axis linear motion system.
Once activated, the system conveys ignition controls in part bins from preproduction to a test cell for camera inspection and to record their model type and exact position. Then the system automatically selects and sets the precise resin dosage for each component, before ferrying it to a preheating station.
From there, all parts make their way to a two-chamber vacuum dispensing station. In the first chamber any remaining moisture and air bubbles are effectively eliminated. Next, the parts are transported under vacuum to the second, main chamber where the actual casting and sealing takes place.
Once the resin has been dispensed, the parts are moved to a sensor-controlled unit, where the casting levels are measured with an accuracy of up to 0.004 inch. Sometimes, additional resin may have to be dispensed into the assemblies to top them off. This is due to tolerance differences in the injection-molded parts or slight reductions in resin levels as a result of the pressure difference after leaving the vacuum station. The extra resin is dispensed by an individually controlled two-fold piston metering system.
After recasting and final control, the parts are forwarded by a four-axis linear transfer to one of three double-chamber curing ovens.
Throughout the process, the precision linear axis system must remain rigid in a completely horizontal position and guarantee vibration-free, smooth handling, since the delicate, fully filled components would be ruined by the slightest impact.
By offering maximum quality, speed and precision, the system is helping Prüfrex meet the rapidly rising demand for its ignition systems. More importantly, the system is fully upgradable and well-suited to support the company’s future growth.
For more information on dispensing systems, call 770-218-0835 or visit www.scheugenpflug-usa.com.