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Article | January 31, 1998
A window into the packaging line
Amway's graphical human-machine interface for an entire packaging line reduces troubleshooting time by 75%.
Faster troubleshooting The number one benefit of providing such extensive information to the operator and mechanic is faster troubleshooting. "From a troubleshooting standpoint the HMI can typically save us 75 percent of the time it takes to identify what and where a problem is on the packaging line" says Jay Mol electrical engineer at the personal care plant. "Over time" Mol adds "an operator will begin to understand 'Hey when I get this fault message maybe 50 percent of the time it's this problem and I need an electrician and maybe 20 percent of the time I need a mechanic.' So he can build a history about reacting to what he's seeing." The second benefit of the HMI is reduced labor. Because the HMI allows the line operator at the filler to monitor and control other machines on the line there's less need to staff up the line. (Amway designates one "operator" per line with additional production people added as needed.) The extent of the labor savings however depends on the product being packaged. Generally Mol estimates labor savings of "a person or two" on the line. Another benefit is the ability to easily and inexpensively modify what the operator can see and do. For example say an operator wanted to see when a particular drive has stopped working. "Traditionally we'd have to run a wire from the VFD [variable frequency drive] to the input module [on the PLC] then wire an output module [on the PLC] to a light on a control panel and do some programming changes in the PLC. With an HMI and the network I can create a button on the screen assign a Wonderware tag to a PLC address and modify the ladder logic in the PLC if necessary." He says it's a 15-minute software change versus four to eight hours running wires and modifying a physical control panel. HMI is a window It's important to understand that Amway's HMI is not performing any logic functions itself. It merely acts as a conduit between the operator and the PLCs on the line. In fact information from multiple PLCs can be combined onto a single screen in a way that makes sense for the operator. However all logic decisions for actual machine control continue to be made in the PLCs themselves. The HMI itself is actually an industrial-grade Pentium 133MHz-based computer with a color LCD touchscreen and keyboard from Touch Controls (Oceanside CA). Spotted by Amway at a trade show the computer "has a pretty rugged screen and a very hard case front" says Mol. The washdown-grade screen is mounted in a washdown-duty stainless-steel cabinet. Although the HMI is located at the filler it is not connected to the filler's PLC. Instead it connects directly to the PLC network. The computer runs Wonderware's HMI software under Microsoft's Windows(TM) 95 operating system. All of Amway's Wonderware screens were programmed by Engineering Solutions (Grand Rapids MI) a firm that specializes in programming such HMI software environments. Amway's Mol however is capable of making any subsequent changes to the HMI's screen by creating new buttons or symbols from scratch or modifying existing ones used on other HMIs at Amway. "We've been trying to develop some standard buttons and symbols for a common look and feel for the operators. That's our ultimate goal." Justifiable through efficiency According to Mol the investment in the HMI-including the hardware software and consulting time to program it to Amway's specifications-totaled in the neighborhood of $20. Mol says the payoff is increased line efficiency due to shorter downtimes. Amway says it hasn't tracked specific before/after efficiency comparisons since plans call for swapping some of the equipment with other lines. Nor did Mol have to cost-justify the upgrade. "We as a corporation have taken a stance that we know that these technologies help us do a job more efficiently and make it easier on the people doing the work" he comments. Mol acknowledges a $20 HMI isn't warranted for all packaging applications. For simpler applications like on Amway's CIP system it uses Allen-Bradley's (Milwaukee WI) PanelView(TM) operator interfaces. Those consist of a touchscreen display as well as A-B's PanelBuilder(TM) programming environment to put graphics and text on those screens. He also says that companies contemplating an upgrade similar to Amway's Line 2 HMI can save money by choosing a non-touchscreen computer for $2 to $3 versus the $7 Amway spent for its high-end industrial-hardened touchscreen computer. Ultimately though Mol says Amway feels the investment is warranted. "Obviously the initial costs would have been lower [with a traditional hard-wired control panel] but you lose the efficiencies and flexibility you gain from putting in an HMI."
Imagine being able to see at a glance the operational status of any packaging machine on a line-right down to every sensor actuator limit switch valve and drive-just by calling up a real-time graphical animation of that machine on a touchscreen display. Further in the event of a machine stoppage imagine an operator being able to look at the screen to quickly pinpoint the cause of the problem relaying detailed information to the appropriate engineering support personnel (even informing them which tools to bring) for a fast fix. That would shrink downtime and send line efficiency soaring. That scenario is precisely why Amway invested in a custom human-machine interface (HMI known also as an operator interface) for Line 2 in its Personal Care Manufacturing Facility. Located at Amway's Ada MI headquarters campus the line is used to package lotions shampoos and other products. The HMI based on softwarefrom Wonderware (Irvine CA) was part of a controls upgrade initiated a year ago when the line was relocated from a different Amway facility. Amway's control strategy for this line was two-pronged. First management wanted to network all the packaging machines' programmable logic controllers (PLCs). That's so they could exchange information more freely with one another to better react to fault conditions that may crop up anywhere on the line (see story p. 30). The second objective was to leverage the free-flowing communications of the PLC network by adding an HMI that can grab information from any PLC on the network and present it in a graphical format for the operator. The HMI becomes in effect a window into the heart of the packaging line.
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