Stop Pulling Wires

If you're going to survive as a made-to-order manufacturer, your production processes had better be adaptable. In the made-to-order world, customer requests result in hundreds, if not thousands, of permutations of items in the catalog. Good luck trying to predict too far in advance how best to arrange your production environment to meet those varying orders. You'd do better to make your shop floor endlessly flexible, ready to respond at a moment's notice (well, a day's notice, anyway) to alterations in the production landscape.

Made-to-order office furniture manufacturer HON INDUSTRIES Inc. (Muscatine, IA) has long been committed to embracing changes that improve efficiency and productivity. "We're very much disciples of the Toyota lean production system," says CIO Malcolm Fields. "Changes on our factory floor are driven by what we call RCI - rapid continuous improvement - events." During an RCI event, which typically lasts for a week, a HON RCI team studies a particular aspect of the production process. For example, it might study the standard work, or defined set of steps, required of employees at a particular production cell or station. The RCI team looks for bottlenecks and considers factors related to employee health. "We might discover that the standard work as documented doesn't allow for adding or subtracting assembly people based on fluctuations in demand," Fields explains. "Or, the work might not be ergonomically correct."

In response to RCI findings, HON frequently reconfigures its production lines, even to the extent of completely reversing the flow of a line - or several lines. Unfortunately, until recently, moving a line was an expensive, labor-intensive chore. HON's shop floors were saddled with a legacy IT infrastructure stitched together with serial cables. As a result, each time a production line had to be moved, so did the cabling. So, to respond more quickly to the results of RCI events, HON decided to go wireless.

Bend Without Breaking
At HON, the "lean" concept extends to its use of technology on the shop floor. The only place where data collection equipment sits is at the packing stations at the end of each production line. There, HON traditionally used wired workstations, which included stationary bar code readers and label printers. "What drives the factory is the production ticket, which includes directions about what to make and the options that go into the product," Fields explains. When a finished good comes off a line and heads for warehousing and shipping, the ticket is scanned, a label is generated for the box, and the data is sent to the central system that manages the warehouse.

If HON were content with the occasional process improvement, having wired data collection and labeling stations wouldn't have caused much grief. But, with more than a dozen factories, each with as many as 100 production lines, HON doesn't make only occasional changes. "At each factory, we probably have 40 RCI events each year," Fields says. "Some RCI events cause changes to multiple lines." Nearly every time a production line is reconfigured, the end of the line shifts to a new physical location on the shop floor. So, the wired data collection station has to be repositioned. In the past, rewiring packing stations in response to an RCI event took between 6 and 20 hours, causing significant downtime. Fields also notes that, even when stations weren't being moved, there was downtime stemming from the old cabling. "Stretching serial cables around in a factory can make them unstable," says Fields.

Addressing the inefficiencies, the new wireless system from Intermec Technologies Corp. (Everett, WA) includes multiple RF (radio frequency) antennas and ceiling-mounted RF access points. These devices relay information to and from Intermec 5055 wireless touch screen-based PC workstations. The wireless workstations still have bar code scanners and bar code label printers attached for use at the end of production lines. However, for faster warehouse putaway, HON relies on Intermec's ScanPlus 1800 Vista wireless handheld bar code scanners.

Build In Redundant Wireless Access
According to Fields, the wireless system has reduced downtime, as well as maintenance costs stemming from working with cable. HON no longer has to pay outsourced contractors to come in and rewire facilities and data collection stations - a common and expensive occurrence in the wired days. And, the wireless infrastructure is resilient. "We put in redundant radios, and we have the access points and base stations connected to multiple data closets so there isn't a single point of failure," Fields says. "With the wired system, we often had to examine hundreds of feet of cable to trace the cause of a problem."

Most importantly, because changes to the shop floor can be enacted quickly and inexpensively, HON can be aggressive about responding to RCI-based recommendations. "If you take down the barriers to change, your cycle time is shorter, and you can try more things," Fields says.