Page 19 - MetalForming March 2012

• How do we control this risk?
Solid-state and PLC-based mechanical-press controls are at very high risk of obsolescence. These are the machine con- trols that run the press itself, controlling all aspects of the clutch-brake safety circuit and other electrical devices on the press, such as press lubrication and slide adjustment.
Not only do these units often contain aging electronic components, but today’s special safety requirements place a high burden on engineering and liability. These safety require- ments can render stop-gap repairs potentially dangerous and ill-advised. Botched repairs can lead to grievous injuries. This added burden results in higher-priced replacement costs and typically longer lead times to produce the controls, config- ure them for the press, and install them. To make matters worse, nearly all press controls developed since the 1980s either are dedicated microprocessors or PLC-based, which means most will have some level of obsolescence risk.
Lead Times
For small presses, lead times to receive replacement con- trol components can stretch as long as four to eight weeks just to receive the hardware after the order. It can be much worse for larger presses, 800 tons and up, where lead times can be extended by an additional four weeks. This occurs because the larger press’s electrical cabinets, starters, drives and dis- connects may not be off-the-shelf items, and can require cus- tom fabrication or extended delivery delays.
In addition, installation of the replacement components can easily take one to two weeks after the parts are delivered, assuming two experienced techs working full time on the installation. That timeline assumes the stamper already has the quotes prepared and has avoided delays in processing the order. Budget one or two weeks for preparing quotes.
To Mitigate Risk
...start by looking at your most important presses, and con- tact the press-control manufacturer(s). Be aware that in some cases, the press and control builder are one and the same, and that some aftermarket press-control specialists are actually the control provider. Either the press builder bought the control from them when the press was built, or a later end user changed the original control to one available from the press- control specialists after having run the press for some time.
If the investigation reveals a lack of support, begin to prepare for the worst by first asking: Should the control fail, is the press worth investing in? A “yes” answer implies that the machine is valuable, with a useful life ahead. In this case, go ahead and begin the investigation to identify the best after- market control provider to meet your needs, when the needs occur.
Immediately prepare quotes for your most-critical press- es—don’t wait until something breaks. Having this work done ahead of time can save weeks or months of downtime should an aging control fail. Also, be sure to investigate the support policies of your new or potential control vendors. Ask
Manufacturers of press feeds are quite busy these days retro- fitting aging mechanical push-pull feeds with servo-feed control packages. Shown here is a retrofit completed by Coe Press Equipment, which included replacing the drive’s original rack- and-pinion mechanical system with a servo feed. Other typical updates include new pneumatic valves and cable sets, and a new operator interface.
them how long they will support their product, to avoid future obsolescence issues.
Aging Servo Feeds at High Risk
Older servo feeds, purchased in the 1980s and ’90s in particular, are likely to no longer be supported with new parts. Servo drives themselves differ from variable-speed drives in their ability to not only control motor speed and acceleration, but to also turn the motor a very precise number of degrees of rotation. This control function allows the feed to index the strip a programmed feed length.
Press feeds represent a very specialized application of servo-drive technology. Stampers cannot simply purchase a new drive and motor package from a motion-control supplier. Specialized application knowledge and custom program- ming are required to apply the technology in a press-feed application.
Lead times for servo-feed drive and motor packages can be as little as in-stock to four days, if ordered from one of the larger original equipment manufacturers. If the OEM cannot support the equipment, some of the larger servo feed sup- pliers offer drive packages to support equipment made by other manufacturers. In this case, though, quoting may take a bit longer if the supplier lacks complete documentation for the equipment.
Mitigating risk begins as noted above. In some cases, a stamper can locate rebuilt drives or have repairs made using old parts sourced from used-equipment websites. However, as a better long-term solution, consider opting for com- pletely new drive-motor packages, providing state-of-the-art features and ease of use with current hardware support. Again, request quotes sooner rather than later for critical equipment, to enable your pressroom to react quickly in the event of a breakdown.
Straightener and Reel Drives
The risk of obsolescence is relatively moderate to low for straightener and reel drives, as its application in the pressroom
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