Presses more than 10 yr. old may include a manual proximity switch to signal positioning on reversal, a critical process for producing accurate parts.  This manual switch is only as accurate as your hand is steady, and parts may eventually fall out of tolerance. In addition, many older presses were designed with small proportional directional valves that provide a slow pressing speed into the part, in order to achieve an accurate reversal position. With today’s servo-quality proportional directional valves, metalformers can achieve positional accuracy and very high flows, due to the rapid response time of the valves.  Aging pumps, motors and even hydraulic fluids are not as efficient by today’s standards. In addition, due to enhancements and new options, older power units may not be as economical as new equipment. And, as shops grow and add larger presses, the amount of power needed increases.  Last but not least, metalformers must address safety and update their older presses as needed. Upgrading to ANSI B11.2-1995 (R2010) and adding light curtains allows a press to be run by an auxiliary piece of equipment such as a feeder or foot switch, to reduce cycle time. 

Today’s hydraulic presses are faster and more reliable than ever. In the last decade, the technology has experienced constant upgrade. PLCs and other electronically based controls have improved speed and flexibility.  To reduce cycle times and improve part quality, better valves and highperformance PLCs provide faster speeds and excellent positional accuracies.  Servo-quality proportional valves offer fast response times, even in larger-size valves that can handle the required flow and faster cycle times.  Proportional valves offer an improved level of control over older servo valves, without the sensitivity to contamination that can lead to maintenance issues. And, today’s PLCs have scan times fast enough to achieve ±0.001-in. positional accuracy with a D08-size valve, and provide monitoring of the linear transducer to achieve the reversal/positional accuracy of the press.  The controller’s high-speed ramping functions provide the ability to manage the increased pressing speed.  Using today’s valves and PLCs, cycle times can be improved with simpler and easier-to-troubleshoot circuits.

Barcodes in the Pressroom

Quality control is further improved with the use of barcode readers, a growing trend during the last 5 yr. Metalformers use barcode readers to scan the tool and the work order to automatically upload the new parameters for that component. Scans also can be used to validate the press and die against the work order, to ensure that the proper press is being used for the job. An employee’s badge also can be scanned to check for permission to operate the press.  New PLCs enable process automation by controlling multiple presses within a line, or by integrating a press with auxiliary equipment. This automation provides consistent control over all press operations. Typical applications include adding roll feeders for advancing sheetmetal in a press, or integrating rotary-index tables into a pressline.

 Motors are much more efficient today than they were 10 yr. ago. They offer a reduced rotational mass and higher-quality copper for improved winding technology. Pumps are more efficient as well, as improved seals and stronger hoses and couplings have virtually eliminated leaks and greatly minimized maintenance. Even hydraulic fluids exhibit increased effectiveness due to new additives, promoting improved pump performance. Also, state-of-the-art pumps and motors operate more quietly than do their aging counterparts, and they use offthe-shelf replacement parts, whereas replacing components of older pumps and motors can take 12 weeks or more.  Another recent development is the use of soft motor starters or variablefrequency drives (VFDs). These devices allow the motor to ramp up to full speed, decreasing the inrush current. A hydraulic press with a VFD will start the motor when the press is ready to perform work, and then shut the motor off when platen movement is not required, including during press idle times. This technology can run the motor at slower speeds when the press is idle, to allow for accumulators to be charged and the oil to be cooled or filtered.