Automating Lean Tools
Automation suppliers have adapted their products to lean principles, making automation more useful than ever in getting lean
By Bruce Morey
"There is a school of thought that would say that lean is about simplification, and is inherently anti-automation," says Jamie Flinchbaugh, a founder and partner of the Lean Learning Center (Novi, MI). Though a minority, according to him, this community does influence the debate. Their thinking is rooted in the belief that lean is essentially a manual process.
"The healthy thing about [thinking of lean as only manual] is the emphasis on 'creativity before capital,' meaning one should attempt lean solutions before automatically spending on capital equipment," Flinchbaugh observes. "On the other hand, there are also a group of people—perhaps less educated on lean—who believe a lean process is better, and to be better, you need a big capital budget. They want all new equipment to implement a new process. I fundamentally disagree with that approach."
Whether to use automation or not starts with looking at the problem through the filter of a lean mind-set, drawing a value stream map, and identifying the right places to use automation. Automation is not a goal in and of itself, according to Flinchbaugh, but a solution to a goal identified in the value stream analysis, such as eliminating waste or reducing production lead times.
"Oftentimes, people confuse automation with lean," adds Doug Ruffley, a one time lean implementation specialist for De-Sta-Co (Auburn Hills, MI). "Others even look at automation as a substitute for lean. They are only trying to take labor expense out, and are not necessarily looking at the big picture." He cautions that this can lead to islands of automation. Such islands may not lead to an improved process that shortens product lead times or reduces WIP inventories. In this scenario, automation sometimes increases waste through overproduction. "Automation is an effective tool in a lean process built around the pull concept," says Ruffley. "The islands of automation that lead to bottlenecks are difficult to create if you build a system around the principle that an order triggers the build sequence." Lean principles influence the design of equipment from De-Sta-Co, particularly the lean-process-driven need to build equipment that is agile and flexible. Robotic tool changers, robot end effectors, and clamps, for instance, all have maximum flexibility built into them, according to Ruffley.
Kevin Gingerich, a director at Bosch Rexroth Corporation, Linear Motion and Assembly Technologies (Buchanan, MI), acknowledges hearing objections to automation coming from some manufacturing engineers schooled in lean. The Bosch Rexroth division he represents provides automated conveyors, positioning equipment, and Cartesian robotics. "The biggest objection I have heard is automation of waste, and [how automation leads to] overproduction. You certainly do not want to automate at all costs," he says. He believes that companies should focus on the least wasteful way of processing, which may include automation. "Every assembly situation is different. Automated assembly is sometimes the only way to achieve the desired quality and productivity improvements. For example, high-precision, repetitive assembly operations may require conveyors for positioning repeatability, and robotics for assembly speed. In other circumstances, handling of sensitive components may be too difficult to achieve with manual assembly."
In a sense, choosing the right level of automation may be independent of lean principles. A helpful approach Gingerich developed to aid in choosing the right assembly technologies is to think in terms of production volume and product mix charted in a matrix. In the most unpredictable assembly environment—low volumes, high product mix—manual assembly is usually the reasonable choice. Recouping investment in sophisticated automation would be difficult in this scenario. Automation in the high-volume, predictable product mix case increases efficiency and quality while reducing waste, according to Gingerich's matrix. "Automated production is the right choice when it helps increase process reliability and cut costs in comparison to a manual solution," he says.
Replacing manual assembly with automation may be getting easier. Hendrick Christiansen, director of robotics and intelligent machines at the Georgia Institute of Technology (Atlanta) points to trends that include improved sensors like vision systems that can tolerate some variation in tasks.
Building flexible automation to contain future changes is also getting easier. "Lean manufacturing requires high efficiency coupled with flexibility. Lean systems produce highly customized products," says Christiansen. "You cannot afford to do expensive setup for every product or every machine anymore. This is true whether it is a robot or a CNC machine or 'hard automation'," asserts Christiansen.
Trends he sees supporting greater flexibility include automated systems that are easier to program. This means lowering the cost of changeover for small production runs. "We are starting to see new ways in which systems are programmed, such as storing library routines that can easily be reused." He points to easier integration of off-line programming software with CAD data as another key enabler, coupled with the ability to quickly modify existing part programs to create new ones.
The move to smaller lot sizes and flexible manufacturing affects the business of automation integrators like Edgewater Automation (St. Joseph, MI), according to President Rick Blake. "We need to focus on delivering adaptable, flexible automation to our customers. Lean concepts to reduce waste like Single Minute Exchange of Die [SMED] force us to design-in adaptable technologies like toolchangers." He agrees that automation components, from robots to slides, are more easily programmed. "It used to be too expensive even five years ago to bring that level of adaptable automation into a system. Where we used an air cylinder, we may now use a programmable slide or actuator." He describes each component as having their own, brand-specific user interface that allows integrators like Edgewater to program without extensive, specialized knowledge. "Even some sensors are programmable, ranging from simple pressure sensors to machine vision. We need this programmable capability to achieve the flexibility and rapid changeover demanded by our customers today. After all, for some safety-critical items like air bags or brakes, we can spend more money verifying that they are correct than we do when assembling them."
"Robotic systems readily lend themselves to automating batch sizes of one," says Mark Handelsman, of Fanuc Robotics (Rochester Hills, MI). "The lean principle that gets our customer's attention besides overproduction is—paradoxically—idle equipment. Efficient use of capital is the key motivation in reducing equipment idle time, and they look to our [robotic] systems to help maintain utilization rates of CNC machines or stamping equipment. Quick changeovers and flexibility facilitates that goal." Fanuc offers a variety of tools to put the burden of flexibility in the automation, as Handelsman describes it, including easy-to-use off-line programming and simulations. "Practically every quote we do today involves us getting a CAD description of the part and simulating the robotic workcell. It reduces wasted motion of the robot and ensures the right-sizing of the robots and cell."
Another key to flexibility is how robots are deployed. Many robots, including those made by Fanuc, are now mounted on overhead rails, reducing their footprint while maintaining unit agility and increasing flexibility. "The top-loader is great for matching the layout of a process most efficiently, something not always easy to do with a pedestal robot," explains Handelsman.
Manual versus automation may not be the way to think. Rather, how best to blend the two may be the way to frame the problem. Guy Morgan, managing director and North American operations advisory group lead for BBK (Southfield, MI), suggests taking this view of matters. BBK is an advisory group that helps turn around manufacturers that face challenges, and their techniques include the use of lean tools.
"The focus on lean is to both eliminate waste and support the operator, Morgan comments. He believes automation makes obvious sense in applications like improving safety or employment in hazardous environments. "But automation offers its greatest added value when it works in concert with a human who adds tactile sensory capability. For example, in a workcell that machines castings, a human could be loading castings into a configured nest, ensuring that they are loaded correctly. A robot could then take over, and move the parts into and out of the machining operation. Finally the operator can unload the pallet, using his human senses to inspect the parts for quality and completeness."
This blending of human labor and automation requires a higher skill level in production operators than has been the norm, according to Morgan. "In a truly lean environment, that operator is responsible for his cell as if it is his or her own business. That includes using and maintaining the automation correctly." Proper training is vital to a successful lean automation implementation, he cautions.
Technology used for error-proofing—the lean concept of poke-yoke—is especially impressive to Morgan. "Technology like light curtains, electric eyes, or machine vision that ensure parts are properly placed or tools properly set is an effective trend in automation," he says. By no means is this new technology. He believes, however, that reductions in cost coupled with increasing capability and better-trained engineers are leading to its more frequent application. "If you are serious about 'no defect forward,' you will want to use these tools."
Fanuc delivers machine vision systems, including 3-D laser equipment, integrated with their robots. That company's Mark Handelsman agrees that there is a sharp increase in the number of machine-vision applications the company delivers. "Increasingly our robots are used for error-proofing. For example, robots used in machine-load-ing operations with vision attached. There is usually time in a machine loading cycle to do quality checking."
Flexibility, while a mainstay of lean, remains a challenging concept. "I would caution users to think about the future. Many times, they do not pay attention to the next level of processing, or the next design iteration. Try to design your automated system for that next opportunity, the next level," says Edgewater Automation's Blake.
"Manufacturers need to build as much flexibility as possible into their assembly and manufacturing systems," agrees Gingerich of Bosch-Rexroth. "People want to buy their equipment and forget about it. What people in the US are discovering is that lean does not allow them to do that." He cautions that manufacturers cannot buy equipment and then let it remain in its original configuration. Lean means constantly revisiting manufacturing strategies, including how best to use automation as it develops in capability.
Safe, Lean, and Automated
"What is fundamentally not lean in many companies right now is automation safety and compliance," states Craig Torrance, a manager with Pilz Automation Safety L.P. (Canton, MI). "Safety and engineering functions are in their own silos. Engineering is concerned with efficiency, safety with regulatory compliance; they do not talk to each other."
"As a result, there is a huge amount of waste in some of these safety procedures," claims Torrance. For example, robot workcells require fencing around most of the cell to prevent unsafe entry into the work zone. According to robot safety standard RIA 1506, the fencing requires 18" (457-mm) of space between the maximum extent of the work envelope and the fencing to prevent injury to someone trapped in the work zone. "That represents 12 ft2 (1.1 m2) of wasted space in a typical workcell," explains Torrance. "By looking at the problem through a set of lean goggles, we developed technology that eliminates that wasted space." The result was the SafetyEye. Introduced in February 2008, it features a 3-D machine-vision device that sits above a work cell, monitoring a zone to ensure compliance with standards. It does this while eliminating guard fences and buffer zones.
"The most effective time to deploy a machine safety strategy is in the upfront design," cautions Kelly Schachenman, a manager for safety automation with Rockwell Automation (Milwaukee). "Many hazards can be designed out and effective procedures designed in when the machine is first being laid out. A strong commitment to a rigorous process that includes a Safety Risk Assessment and Safety Requirements Specification will lead to machines that are the most likely to deliver lean solutions and protect employees."
This requires as much a change in mindset as a change in tools, designing safety in the early stages of development, as well as using safeguarding technologies that enable flexible solutions. Rockwell Automation's GuardLogix suite of integrated Safety PLCs combines safe and standard control into a single platform and design environment. This packaging eliminates integration work such as error trapping and data conversion, enabling diagnostic and machine status information to be provided to operators and maintenance personnel, and allows manufacturers to deploy flexible safety solutions that can improve both employee safety and machine productivity. To help in this integration, Rockwell Automation provides a Safety Accelerator Toolkit for their GuardLogix Systems.
This article was first published in the July 2008 edition of Manufacturing Engineering magazine.