Equipment Focus: Car Shredders

Today’s high-tech automobile shredders are “smarter” and more automated than ever, enabling recyclers to be smarter in operating them.

By Kent Kiser

A South African scrap company had a problem—its 4-year-old car shredder was operating below capacity, producing about 67 tons an hour, and the company wanted to increase the machine’s production. But how?
   The answer came in the form of a new shredder-automation system. This system included upgraded programmable logic controller technology for directing basic shredder functions. It also featured diagnostic sensors to monitor the physical health of key components. Plus, the system included a shredder-management software package that enabled the company to store and review its production data.
   These technology upgrades boosted the shredder’s production to 90 tons an hour—a 37-percent improvement. Problem solved.
   In this high-tech world, such success stories should come as no surprise. After all, industrial equipment of all kinds has steadily become more automated, so why not scrap processing equipment such as automobile shredders?
   Indeed, since their creation in the late-1950s, car shredders have evolved technologically through the greater automation of basic functions, increased use of sensors for diagnostic monitoring, and—most recently—the development of specialized software programs to store and relate operating data.
   The shredder-automation trend has been driven by the goals to:
• control operating functions to achieve the steadiest, highest production and, hence, the lowest cost per ton in the time the shredder operates;
• monitor the physical condition of critical components for maintenance purposes—and to prevent significant downtime; and
• record and analyze data that can be used by management to improve productivity and efficiency.
   The key to achieving these goals, the theory goes, is automation, not people. The rationale is that shredder personnel are only human, which can mean all kinds of inefficiency, mistakes, oversights, and more. In other words, the shredder can only be as good as the people running it—and all too often that isn’t good enough.
   In contrast, the latest automation features enable shredder operators to reduce or eliminate the human inefficiencies in many parts of the system. “People who are heads-up in the shredding business understand that the more they keep their operators off the controls, the better the shredder is run,” says a shredding-industry consultant. The fact is, he asserts, that “automation can simply monitor and adjust variables better than a human operator.”
   Here’s a look at how shredder automation reached its current state and where it could be heading in the future.

Progress Through PLCs
Shredder automation began humbly enough with simple on/off relays that controlled basic mechanical functions.
   It wasn’t unusual for early shredders to have 50 to 100 relays, which—among their drawbacks—had to be modified manually, a time-consuming and tedious practice. Such old control systems were also bad at warning of potential problems and identifying the cause of problems when they did occur.
   In the 1980s and early 1990s, programmable logic controllers (PLCs) began replacing relays for controlling a shredder’s logical functions—such as its start/stop sequence—as well as other traditional operator functions.
   A PLC system is composed of a processor and input/output modules (electronic switchboxes with blinking input/output lights). In a modern shredding plant, each part of the system—from the infeed conveyor to the downstream components—are connected to one or more input/output modules in the shredder’s control room. These modules continuously send input data to the PLC processor, reporting in on the status of each component. The PLC processes all of these inputs and determines which outputs should be turned on or off, thus continuously tweaking the shredder’s operations for maximum performance. Based on incoming data, for instance, the PLC can send a signal to start or stop the infeed conveyor, increase or decrease the motor’s torque, shut down the downstream conveyors, and so on.
   In contrast to old relay controls, PLC systems can be changed easily and quickly via computer. Among their advantages, PLCs can interface with other information systems, such as sensors attached to the motor or scale. More modern PLC systems can transmit information continually through a high-speed ethernet network to other computers—in the shredder’s control room, the manager’s office, or elsewhere. In this way, the PLC enables the operator and others to view operating data in real time and, thus, keep an eye on critical parameters as well as respond to any problems that develop. To be sure, PLCs make it easy to know the status of any part of the system, identify the source of problems, and respond if necessary. If the PLC detects an alarm condition, for instance, it sends a descriptive error message to the operator’s computer screen. The operator must then decide what to do, responding by using the computer’s touchscreen.
   Another notable benefit of today’s PLC systems is that they can be connected via phone modem to the shredder manufacturer or technology vendor, thus allowing remote troubleshooting of virtually any shredder problem.

Monitoring the Situation
A more recent shredder-automation trend has been the use of sensors to monitor the physical condition of specific components for diagnostic purposes. Unlike the PLC system, these sensors don’t tell the shredder what to do or stop doing. The sensors simply monitor various conditions of critical parts—for instance, the vibration and temperature levels of the motor and rotor bearings—and send this data to the PLC processor and, in some cases, other computer systems linked to the shredder.
   By tracking such conditions, the sensors can reveal operating trends and suggest when maintenance is required. They can also help operators prevent catastrophic problems from developing and, thus, spare the shredder from significant downtime. For instance, it’s possible through the PLC system to set acceptable/unacceptable levels for the data collected by the sensors, such as a temperature range for the motor bearings. If the sensor indicates that the low or high level has been exceeded, the PLC alerts the operator or simply shuts down the system.
   One specialist in this niche is Motornostix (Pty) Ltd., which is notable for the Web-based features of its condition-monitoring system for the scrap shredder and shear markets.
   The firm’s system works like this: Data is collected through a Motornostix-designed data logger called a Canary unit, which samples data every minute. Aside from monitoring the vibration and temperature of motor and rotor bearings, the Motornostix system can track motor current, motor speed, ambient temperature, and any three “process variables” (such as conveyor belt scales, downstream components, power meters, additional temperatures, and so on).
   The Canary unit, which is locally networked to a PC at the shredding operation, can send its data to the PC through a cable network or via wireless transmission based on a 2.4-GHz spread spectrum radio running a proprietary Motornostix protocol.
   The PC then acts as a bridge to the Internet, sending the data collected by the Canary to a central Motornostix database in Cincinnati. From there, authorized shredder personnel can securely access the information via a simple Web-browser interface and, thus, keep track of the shredder’s status at all times and from virtually any location. (This Internet feature is particularly helpful for shredding operations that run at night and for managers responsible for reporting on production at remote sites, Motornostix notes.)
   Among its features, the Motornostix system includes a “proactive” alarm capability. If any of the monitored components exceed their preset parameters, the system notifies the appropriate shredder personnel by sending an alert message to their respective mobile phones. If the personnel do not respond to this alarm message, a representative from Motornostix’s 24/7 call center follows up with a phone call.
   While the Motornostix system is primarily designed for condition monitoring, it can also serve as a management tool, the company says, by presenting the collected data in various charts and graphs, covering such information as shredder run time, uptime per day/week/month, motor current draw, and more. The system’s graphing capability enables users to correlate between any measured data, such as motor current draw against tonnage of shredded scrap produced. The system can also perform spectral analysis of the motor’s vibration, with spectral data being sampled according to predetermined conditions. Such information can help shredder operators identify poor operational practices as well as machinery problems that could be developing.

Getting ‘Relational’
While the PLC system and condition-monitoring sensors are great for collecting data on a shredder, they generally aren’t designed to store and analyze such data. Yet access to such data and the ability to review it in various ways is just what shredder operators need.
   That’s where specialized shredder-management software programs come in. Such programs offer the best of two worlds: They display real-time operating data (from the PLC) for the shredder operator, and they store this and other information for future analysis by the shredder’s managers and owners.
   This ability to store information solves a shortcoming of older PLC systems, which generally gathered data for 24 hours then purged the previous day’s data to make room for the current day. This practice required shredder operators to print out the PLC-collected data every day or lose it forever.
   More recent PLCs were an improvement in that they could save daily operating data in a spreadsheet file. The drawback here, however, is that each day is saved as a separate or “flat” file—a format that makes it more difficult for management to relate the data in different ways.
   Today’s most-sophisticated shredder-management programs have resolved that problem by storing information in a relational database, which enables shredder managers to easily and quickly “relate” the data in whatever way they wish.
Suppose, for instance, that your software program compiled a year’s worth of data on your shredding operation. You could then sort the data to determine, say, what was the most-frequent operating delay in the first six months of the year, which operator had the highest (or lowest) production in a given quarter, or which material gave you the highest recovery in the previous month. 
   While today’s shredder-management software programs draw most of their data from the PLC system, they sometimes add to this data by requiring the operator to respond via touchscreen to certain conditions. One program, for instance, has a “compulsory delay feature” that stops feeding the shredder if a problem arises and won’t continue until the operator responds by touchscreen to the situation.
   In such instances, the system notifies the operator that there’s a problem by displaying a screen with icons for the most-common shredder problems, such as blocked infeed rollers, an unshreddable, a gap in the feed, and so on. Once the operator selects one of these icons, the system allows the shredder to continue. In some cases—such as when the problem is less common—the operator must respond by touchscreen to another query or two until the problem has been pinpointed.
   Having access to and control over this and other data enables shredder managers to know (not just guess) how their operation is doing, discern operating trends, reduce or eliminate inefficiencies in the process, learn from previous mistakes, identify developing or impending problems, and know precisely where to make improvements—all of which can yield a competitive advantage and move the operation a step closer to achieving maximum production.

The Retrofit Issue
While the latest shredder-automation features are great news for those buying new shredding systems, what about the vast majority of recyclers who operate older, less-automated shredders?
   The answer can be summed up in one word: retrofit. Virtually all existing shredders can be outfitted with up-to-date PLC features and management software—it all just comes down to a cost/benefit analysis.
   As one shredder manufacturer notes, “Operations in which every production minute is critical will definitely benefit from the ability to analyze the productivity of their machine.” The shredding-industry consultant agrees, noting that “if you’re looking to maximize your equipment—and your investment—it makes sense. The only time it doesn’t make sense is if you don’t want to fully utilize your shredder.”
   Turning a low-tech shredder into a high-tech one is “probably the best money you could spend on your shredder,” says another manufacturer, because it can yield an immediate boost in production. How much of a boost? “In 90 percent of shredders,” the consultant notes, “a good automation package will result in a rise of 20 percent. That’s not taking into account the gains in terms of material density, copper reduction, and other factors.”
   And what can a shredder operator expect to pay to give their older shredder a technology facelift? About $50,000 for a minimal retrofit, sources say, up to $75,000 for a “full-blown” control package that includes such features as an upgraded operator chair, a new touchscreen PC and PLC computer, management software, and new wiring.
   Motornostix, meanwhile, offers a novel payment approach for its condition-monitoring system. Rather than making a major capital investment upfront, shredder owners simply pay for the installation of the Motornostix system, then a monthly service fee, with contract terms available from six to 60 months, the company says.

Toward Artificial Intelligence
Given the steady gains in shredder automation over the years, a logical question at this point would be: How much more automated can car shredders become?
   While shredders have definitely evolved, there’s still room for technological improvement, experts note. For starters, “shredder operators aren’t making the best use of the PLC capabilities that they have,” says the shredding consultant. The shredding business still relies on PLCs for simple on/off tasks and some linear curves, but PLCs can do more. Specifically, PLCs can be programmed to use mathematical algorithms to variably control shredder functions. “A PLC is a small computer that has the ability to work these functions out continuously,” the consultant says. “You put algorithms in there that say, ‘If this is the case, do this…’ or ‘If this is the case, do that…’ You’re trying to put the brain of a great shredder operator into the PLC, so you’re basically trying to put some artificial intelligence in there.”
   While this idea may come to pass, shredding is currently a “very human process,” the consultant says, noting that the scrap business hasn’t “turned the corner to maximize the use of the mathematical functions of the PLC. There’s definitely a big jump to come. You have to turn the corner from PLC on/off control to artificial intelligence.”
   Turning that corner, however, does not mean that shredders will become totally automated in the future, say shredder experts. On the contrary, several shredder employees—such as infeed crane personnel and the main operator—would be difficult or impossible (not to mention cost-prohibitive) to replace with technology. What’s more, such jobs need the human touch. Good crane operators, for instance, can ensure that just the right mix of scrap is presented to the shredder. Similarly, a skilled operator can adjust the infeed rollers just so to prevent material jams and ensure steady production. 
   While such personnel may remain essential, their job responsibilities will likely change. “Eventually,” the shredder consultant says, “the operator could become what I’d call a ‘minder’ who meshes the shredder manager and operator functions.” Rather than sitting all shift at a console in a control tower, for instance, the person could work from an office in the shredder building, monitoring operating data on a computer screen, viewing actual operations via infrared and standard surveillance cameras, tweaking the infeed rollers (if necessary) using remote-control technology, and responding to problems by touchscreen. “Shredding’s a big enough process that it needs to be watched,” the consultant says. “So, in the future, I think shredders will become mostly automatic with the ability for someone to step in and make decisions when necessary.” 
   This approach will prevent shredders from becoming what one manufacturer calls “overautomated.” A totally automated shredder, for instance, might shut down immediately when, say, a bearing temperature exceeds a specified level. Depending on the situation, though, the operator might prefer to stop feeding the shredder, finish processing the material inside the chamber, then shut it down. “We found that it’s better to alert the operator of a change in status, and then let him decide how quickly he deals with it,” the manufacturer says, noting that such operating flexibility is important.
   What all of this means, he concludes, is that “you’ll always have a human element in shredding, but their role will be limited to what they do best.” 

The Car Shredder Crew
The following 11 companies manufacture automobile shredders with different automation/control packages. Contact each firm to learn precisely what its shredders include in terms of the PLC system, condition-monitoring sensors, and shredder-management software.

American Pulverizer Co., 314/781-6100, www.ampulverizer.com
Harris Shredders, 800/373-9131 or 770/631-7290, www.harriswaste.com
Henschel Recycling Technik GmbH, 49/561-801-6885, www.henschel-recycling-technik.de
Innovative Recycling Systems Inc., 440/498-9200
Lynxs Shredder Corp., 877/980-9980
Newell Riverside, 866/764-7567 or 210/227-9090
Magnatech Engineering Inc., 913/845-3553, www.magnatech.org
Metso Minerals, Metal Recycling, 800/995-9149 or 319/558-0160, www.metsominerals.com 
The Shredder Co., 915/877-3814, www.theshredderco.com
Texas Shredder Inc., 800/531-5927 or 210/491-9521, www.texasshredder.com
Wendt Corp., 716/873-2211, www.wendtcorp.com 

In addition to shredder manufacturers, there are companies that specialize in providing automation technology to the shredding industry, including:

Motornostix (Pty) Ltd., 513/791-7807, www.motornostix.com 
Smart Recycling Solutions Ltd., 44/1375-482-896, www.smart-recycling-solutions.com 

Kent Kiser is editor and associate publisher of Scrap. •