Narrowing the Lean viewpoint
A 30-inch view of manufacturing will improve productivity and quality
By Mike Wynn, Humantech, Inc. -- Plant Engineering, 7/15/2007 1:00:00 AM
Many manufacturers passionately pursue Lean thinking. They drive waste from their manufacturing processes and encourage a culture of continuous improvement.
And why not? Toyota has demonstrated that Lean is more than a fad – it’s a sustainable, competitive advantage. As Jim Womack and Dan Jones said in their 2000 book, “The Machine That Changed the World: The Story of Lean Production,” Lean production has allowed Toyota to provide affordable, high-quality cars, in configurations that customers want. No wonder they are the world leaders in automobile production.
Lean manufacturing allows customer demand to pull production. Nothing is produced until it is needed, eliminating vast amounts of waste associated with work-in-process and finished goods inventory.
However, manufacturers often make a critical error when instituting Lean. Many fail to appreciate that for a Lean production process to flow smoothly, each individual operation must be stable, allowing workers to interact efficiently with their workstations. To focus on the needs and opportunities at this level, companies should embrace a 30-inch view of business.
Thirty inches is essentially the distance that a person’s arm extends from the shoulder to interact with others and the work environment. Once empowered to adopt a 30-inch view of people and performance, companies can expect to realize significant – 20% to 40% or more – improvements in profitability, operational efficiency, Lean practices, worker morale and reductions in injuries and workers’ compensation costs.
Stabilizing operations
Stability of operations can be described as consistent availability and predictability of the 4Ms, the basic building blocks of manufacturing: machine, methods, materials and man, Art Smalley wrote in his Lean Enterprise Institute article, “Basic Stability is Basic to Lean Manufacturing Success.” An individual operation is stable if these four aspects can be relied upon to support the process flow with consistent delivery and optimum quality.
Stability leads to consistent cycle times and reliable quality, with quick changeovers to minimize disruptions between product variations.
In contrast, an operation in which any of the four building blocks cannot be relied upon is at risk of becoming unstable, with inconsistent delivery and poor quality results. Without stable operations, more 'safety stock’ is needed, running counter to the goal of reduced work-in-process. Even worse, instability in individual operations reverts a work force back into the mode of 'fire fighting’ and distracts from continuous improvement efforts.
Many companies find out the hard way that trying to create a flow between unstable operations is a recipe for disaster. Stories of production processes that were 'Leaned out,’ falling back into old mass manufacturing habits within months are all too common. Flow exposes disruptions from unreliable processes, and no operation can run long with routine disruptions.
The Lean toolbox contains many tools that contribute to stable operations. These tools tend to focus on machine, methods and materials, with an assumption that skilled and reliable manpower will be available. Companies with mature Lean initiatives have come to understand the criticality of embracing safety and ergonomics, in addition to the traditional Lean tools listed (Fig. 1), to stabilize individual operations.
Designing for human performance
An interesting thing happens when you shift your view from optimizing production flows to ensuring stability of individual operations. The key constraint changes from materials to people. When you map out your value streams to find barriers to production flow, you are viewing the workplace from 30,000 feet, or perhaps 3,000 feet, and individual operations are just blocks in your diagram. But when you shift to the 30-inch view of individual operations, every part presentation, tool location, reach distance, etc., is critical to stability. This is because people are the key constraint to Lean and optimized manufacturing at the 30-inch level.
Toyota has understood this for a long time, and it embraces design for human performance in pursuit of continuous improvement. The Toyota Website states that, “The Toyota Production System organizes all jobs around human motion and creates an efficient production sequence without any Muda,” or waste.
Stabilizing machines, methods and materials is important, and the Lean toolbox typically offers tools to address these issues. However, many organizations miss tools to stabilize the people – or more accurately, to smooth out the interface between people and their work environment. Many operations are not designed for human performance. Typically, the fit between people and machine (reach distances, manual force requirements, sight lines, etc.) and the fit between people and materials (part presentation, manual material handling requirements) are not optimized (Fig. 2), creating barriers to productivity, quality and safety.
Untapped opportunities
Designing the workplace to optimize human performance has many benefits that contribute to Lean production. First and foremost, extending Lean to the 30-inch level addresses wasted motion, one of the 'seven deadly wastes’ first identified by Taiichi Ohno, the chief architect of Lean manufacturing at Toyota during the 1950s. Even today, careful consideration of the man-machine and man-materials interfaces can create double-digit improvements in productivity, as illustrated by these examples:
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Honeywell commissioned the design of a work cell for high-volume production of turbochargers. Through careful consideration of the operator interface, Honeywell achieved a 37% improvement in productivity over the previous generation work cell, which had not been designed with human performance considerations.
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Toyota addressed a problem operation involving the installation of spoilers on its highest-volume automobile. Once observers determined the root causes of the challenges workers were facing at the human-machine interface, Toyota corrected problems relating to reach distances and tool selection, achieving a 67% improvement in productivity.
A second important contribution to Lean production is the impact that designing for human performance can have on developing a culture of continuous improvement and employee engagement. Operating with a 30-inch view of Lean improvement helps you achieve a culture of continuous improvement in three self-reinforcing ways:
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Individuals will 'own’ improvements when they see that they will personally benefit from them while the company gains. Challenges in the man-machine and man-materials interfaces are often troublesome to individual operators, creating hassles in their work and often contributing to pain and fatigue. Addressing them can improve the operators’ quality of work life.
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Driving waste out at the 30-inch level requires us to respectfully engage the operator as the expert in the process. It is not uncommon to identify a dozen or more no-cost and low-cost improvement opportunities within a single operation. This is because operators, when treated with respect, will share a wealth of knowledge on both problems and practical improvements that will drive out waste. This respectful engagement creates lasting bonds with the Lean team, boosting continuous improvement activities.
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Improvements at the 30-inch level can be accomplished quickly and bring visibility to the continuous improvement process. The types of improvement opportunities that arise can be addressed in hours or days, rather than the weeks or months that most workers are accustomed to. The immediacy of the improvements further reinforces that continuous improvement is real, it can benefit them personally and they can contribute in a meaningful way.
Improving quality, delivery and costs
Designing the workplace for human performance is good manufacturing management. Once you have smoothed out the interface between people and their work environment (man-machine) and extended efficient material flows to the end user (man-materials), you have established the basis for flowing production and continuously improving operations for the long term.
One example that illustrates the collection of benefits comes from Corning’s Goose Creek, SC, facility. The company was anticipating challenges with a glass lens machining work cell, which consisted of four operations, because part weights were projected to increase from 20 or 30 pounds to as much as 70 pounds. Operators were struggling with a poorly designed man-materials interface, and the increased parts weight would surely impact quality and the bottom line.
Corning designed a material-handling assist that allowed operators to continue positioning the glass lenses in machining fixtures – a critical step for quality – while eliminating the need to manually handle the parts. The project team estimates that a 50% reduction in issues that hampered quality allowed them to meet a demanding delivery schedule while saving the company $3.6 million per year.
Companies that overlook the issues in the 30-inch space between employees and their workstations do so at their own risk. In fact, this 'last mile’ of performance improvement is critical to deriving ongoing and increasing value from companies’ Lean initiatives.
| Basic building block of manufacturing | Tools to ensure stability |
| Machine – Equipment, workstation and tools used to complete the operation | Total Productive Maintenance |
| Methods – Procedures and standards to complete all aspects of the operation, including routine and none-routine tasks | Standard work, quick changeovers |
| Materials – Raw materials, work-in-process and components needed to complete all aspects of the operation | Visual controls, the Japanese 5S system of organizing and managing the workspace, Kanban inventory systems |
| Man – Trained personnel are available to complete the operation, and the human-workstation interface is designed for human performance | Safety, ergonomics |
| Interface | Workplace design issues |
| Man-Machine | Reach distances, work heights, fixture design, tool selection, lighting |
| Man-Materials | Container selection, part presentation, in-station material handling, part weights |
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Mike,
I liked your article a lot nd agree with what you said. It is however depressing to me that a Japanese car company continuously leads US companies and they continue to look and act stupid. But I definitely digress, I look forward to seeing you in Orlando at AEC 12. Maybe I'll see you in Vegas.
Yours, Bill
William Lenharth, Ph.D. - 10/25/2007 5:51:00 AM CDT
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