Meeting the Challenges of Lean Flow
An industry consultant provides guidance on implementing a basic Lean plan.
David McPhetrige, FlowVision LLC
Medical device manufacturing presents unique challenges, including regulatory compliance and
Businesses in most industries have reaped enormous benefits by im-plementing and sustaining Lean Flow as a foundational business strategy. Benefits of this strategy include:
• Increased—or protected—market share
• Increased unit selling price
• Improved customer service, fill rate, on-time delivery
• Reduced manufacturing lead time
• Reduced operational costs that eliminate non-value-adding work and improve productivity
• Increased capacity—better floor space and equipment utilization
• Decreased inventory levels–components, work in progress and finished goods
These benefits may then fund new product development and protect operations from “low-cost country” competitors. And, depending upon a company’s experiences, this list can—of course—be expanded. Lean Flow is a time-tested, industry-proven methodology to provide these benefits.
Lean Flow Defined
What is Lean Flow? Ask 10 people, and you may get 10 answers, illustrating the need to select and employ a consistent Lean Flow methodology. “Lean” is a solid, proven set of progressive techniques, tools and calculations to identify and eliminate non-value-adding work, delays, queues, space, assets and risks.
“Flow” also is a set of math-based, fact-driven techniques, tools and calculations enabling a company’s work force to advance its products with minimal interruption from order to fulfillment—and even enabling cash to flow back to the firm more quickly from fulfillment to payment. Once a Lean Flow methodology is selected, it is important to determine the scope of the first implementation. Some businesses implement Lean Flow “wall to wall.” Many instead choose a smaller target area. Why?
To reap the full benefits, Lean Flow must become a way of life—a fundamental business strategy. It must guide daily operations, business execution and quality documentation. In the regulated, quality-focused medical device manufacturing industry, Lean Flow’s learning curve may be less daunting with a limited initial implementation scope. Additionally, regulatory requirements may direct companies to verify significant physical changes to layout and processes.
Many product families or manufacturing lines are candidates for a Lean Flow implementation. Go where the money is—the processes or products offering the most benefit. The typical medical device manufacturing Lean Flow implementation includes:
• A 50,000-square-foot manufacturing footprint
• Less than a 200-person work force
• Approximately 25-50 processes
• Fewer than 500 end items
Often, manufacturing operations are fed by batch processes—molding or machining, for example. Operations then feed into another batch process, often provided by a third-party, such as sterilization. Will you include these batch processes in your initial Lean Flow implementation scope? There is no right answer, though many focus first on “getting their own house in order.”
Now that a Lean Flow methodology has been selected and the scope of the first effort defined, remember: Lean Flow is a set of progressive, math-based, fact-driven techniques, tools and calculations. These are broken down into three basic categories:
• Data collection and validation
• Calculation and analysis
• Layout—conceptual and physical
Data collection and validation enables the company’s implementation team to make decisions using agreed-upon, verified facts—not emotions. The team will experience “emotions” as data is collected and validated by observation as required. Before progressing to calculation, analysis and physical layout, the team should be unified and free of “second-guessing.”
Within these three Lean Flow categories, there are 12 progressive implementation steps—and how they apply to medical device manufacturing.
Step 1 (Data): Create Process Flow Charts
Start with the highest-volume product within the defined Lean Flow implementation scope. From that
product’s perspective, what process does it go through first? Second? Third? Continue until all the product’s processes have been listed.
Represent these sequential processes graphically in a flow chart. If the product has processes that occur in parallel, not just in sequence, the process flow chart will have both a vertical and a horizontal dimension. What if the product has optional processes? Rework? Scrap? Those processes will have more than one connecting arrow and option, rework or scrap percentages. Validate options, rework and scrap figures, using sales-analysis, statistical process control, run chart and other available data.
What’s a process? It is work that is fundamentally different or requires different skill set qualifications from other work. Assembly is different from test. Test is different from autoclave. A clean-room process, even assembly, is different from its non-cleanroom counterpart.
Knowledge of the company’s processes and products will guide the team’s intuition on what a process is, so don’t over-think it. As one Lean Flow expert said, “if it’s the same, call it the same; if it’s different, call it different.”
Create a process flow chart for each product in the scope. Most likely there will be fewer—probably far fewer—process flow charts than products, because of process commonality. Use existing documentation—(catalogs, for example) to include all products, and device master records (DMRs) to include all processes—to validate all process flow charts.
Step 2 (Data): Develop Standardized Work
For every product and process in the process flow charts, another level of detail is required: Task-level work, with associated work-content times, quality verifications, worker qualifications and value-add/non-value-add evaluation.
Medtech has a head start—DMRs represent standardized work. The next step is to determine how long it takes to do each DMR work task. Not how fast it can be done, but how long it takes—reasonably, repeatably, day in and day out. Observe it; measure it; validate it. This data collection and validation step, though tedious, is crucial to founding a data-driven, math-based, emotion-free Lean Flow implementation.
Your DMR work tasks include recording data on the Device History Record (DHR). These critical steps also require reasonable time estimates.
As the team develops standardized work, look for opportunities to take quality to the point where the work is done. Can end-of-line inspection/test be reduced or yields improved by using progressive, in-line check/double-check verification of critical work tasks? Now is the opportunity to do so.
Standardized work forms a basis for sustained continuous improvement. For each work task, identify whether the task is value-add or not—in the eyes of your customers. Customers include regulatory agencies and the International Organization for Standardization, in addition to doctors, hospitals and patients. Nonetheless, customers, not process capabilities, determine value-add.
Step 3 (Data): Develop Product/Process Matrices
Step 2 generates a lot of data. Now it’s time to organize, manage and prepare to analyze it. This data forms a product/process matrix: products on the vertical axis and processes on the horizontal. At every intersection of product and process, this matrix, or spreadsheet, records the total reasonable, validated work times from Step 2. Each product-process combination may have from one to three total times, as applicable: One for labor, one for machine and one for setup.
During Step 1 option, scrap and yield data were collected and validated. Each of these gets its own matrix, or spreadsheet “tab,” using the same products and processes. This data is important for Lean Flow. It affects how often a process must be performed in order to achieve the prime Lean Flow goal—taking care of your customers better than the competition does.
Step 4 (Data): Create the Multi-Product Process Flow
Fundamental to Lean Flow is flexibility and process commonality. When a mix of products using common resources is produced, resource utilization is maximized and operations costs are minimized.
Combine process flow charts from Step 1 into a multi-product process flow. Your intuition will help determine what products and processes may be combined—more than one multi-product process flow may be needed. In any case, the multi-product process flow provides the first conceptual glimpse of what a Lean Flow facility will look like. The following steps provide guidance for turning this conceptual flow into a physical reality.
Step 5 (Calculation): Calculate Takt Time
Takt, a German word, literally means beat, pace or rhythm. Your business must march to the beat of your customers, and must keep up with their pace.
In Lean Flow, takt is a calculation: work time per day ÷ customer requirements per day.
Takt represents how often each process must be performed, at capacity, to take care of your customers.
Work time per day may vary by process, and it must be reasonable. It must exclude, for instance, the realities of cleanroom gown-ups, equipment planned and unplanned downtime, area or line clearances and other real-world interruptions to DMR product work. Customer requirements must reflect the one Lean Flow “guess” you must make: forecasted mix and volume during perhaps a three-year time period.
Takt is important. If a person, or a machine, has more than a takt time of work, you will not keep up with your customers’ pace.
Step 6 (Calculation): Weighted Standard Time, Resources
Product/process matrices, with validated data, enable the company to calculate average work-content times, weighted by product volumes, for each process. A simple, powerful calculation, applied to each process, provides crucial results—how many people, how many machines, how many products in process: Weighted Standard Time ÷ Takt.
If a process weighted standard time is greater than takt, more than one person and/or machine must perform that process in order to keep up with your customers’ requirements—at capacity, not necessarily today.
If a process time is less than takt, perhaps a flexible employee can perform both this process and another process and still keep up with the customers’ pace.
Step 6 is a reality check—a sanity check—of the prior five steps. Calculated resources should be pretty close to current staffing and equipment levels, using current demand in the calculations.
Step 7 (Calculation): Define Cells
Cell definition is a complicated and demanding—yet satisfying and powerful—analysis. A cell is a grouping of process resources optimized for a subset of products. In other words, products may flow better through several similar cell paths than through one combined line.
Typically, cells result from large work-content or setup time differences, dramatic component differences, number of product changeovers and associated line/area clearances, and very short takt times.
Step 8 (Layout): Review Actual versus Design Requirements
With the Lean Flow facts and data calculated and analyzed, you now apply your expertise, intuition and experience to the results so far. The implementation team will “walk” products in the customers’ typical order patterns through the calculated resources, cells, takt times and work-content times.
Remember, takt and resource calculations are averages. As the saying goes, “you can drown in a pool averaging 6 inches deep.” You may determine to split a line into a “deep-end” cell and a “kiddy-pool” cell. Thorough review of Lean Flow design calculations, in the light of real-world demand patterns, will trigger some cell-definition iterations.
Steps 9-12 (Layout): Create the Block Diagram, Develop Standard Operations, Facility Layout, Design IPKs
The focus of the block diagram, a non-scaled, conceptual floor layout, is Flow. Flow techniques ensure
that products move continually toward customers. Apply those techniques using a block diagram.
The block diagram is based on the multi-product process flow, resource calculations and cell definitions. The block diagram determines:
• Standard operations: Balance to takt time—define exactly which work tasks will be performed at each workstation or operation
• Parallel or serial work
• In-Process Kanbans (IPKs): Work signals—when to work, where to work, what to work on next, how many units between operations and processes
The more work applied to the block diagram, concentrating on clear, intuitive, visual work signals and balance, the easier the actual scaled physical layout will be—and the more Lean Flow benefits the actual new manufacturing layout will provide.
Because of the conceptual block diagram, scaled physical layout is much easier. It’s easier to determine exactly how many workstations, what tasks occur and materials are consumed at each workstation, how many machines, how many units in process at and between workstations and processes. You know where power, air, hydraulics, controlled environments, laminar flow, etc., are required.
The challenge is to fit the conceptual block diagram into the facility’s available footprint. Even this may be a pleasant surprise. Because the goal of Lean Flow is about maximizing flow—keeping product moving toward the customer and process commonality—the new Lean Flow lines may require less space than they used to.
Planning, Materials and Lean Procurement
For sustainable Lean Flow benefits, the implementation must bridge the gap from project to business practice. Quality documents—procedures, policies, measures —must reflect and drive Lean Flow as a way of life.
Planning and procurement drive daily Lean Flow execution. Lean Flow manufacturing is more responsive, with shorter lead times and greater mix and volume flexibility. You must change your planning to take full advantage of Lean Flow.
Lean Flow lines use simple kanban demand signals. The signals that drive the line also should drive procurement—materials replenishment. Instead of acquiring materials based on an unreliable forecast, Lean Flow kanban techniques enable companies to replenish only what they consume, while maintaining a statistical safety stock that ensures target service levels. Procurement kanban may be simple and visual, and it may also be incorporated into your business system’s MRP (material requirements planning) logic.
Issues Unique to Medical Device Manufacturing
Though Lean Flow implementation benefits are clear, and they apply across all industries, there are issues unique to the medical device industry that Lean Flow can help to solve—as well as provide opportunity. The issues listed below are not all-encompassing. They demonstrate that Lean Flow can provide a solution and still achieve phenomenal business performance.
Product and component traceability: For Lean Flow, traceability is simply a DHR work task to be performed within takt time. Traceability requires a standard time and calculated resources. In this respect, traceability is no different from any other quality task.
• Technology offers many productive, reliable alternatives to traditional handwritten traceability. In Lean Flow, materials are presented to production using kanban techniques. Kanban can take advantage of scanning and printing technology to associate component lots to finished-device trace codes. Lean Flow implementation offers the opportunity to improve or automate component, finished-lot and employee traceability, and other DHR requirements.
Employee qualification and currency: In a regulated environment, of course, qualification and currency are mandatory to perform work on a for-sale device. A Lean Flow employee must qualify to perform a “home,” or starting-point, operation, plus that operation’s feeding and consuming operations, to ensure quality and product flow. Lean Flow expands on the typical definition of “qualified”:
• The employee must be able to perform the task with requisite quality, following the definitive instructions and within the reasonable standard work time. This ensures that the employee can keep up with the customers’ takt, or pace.
• The employee must be flexible—qualified, current and able to perform the operations immediately before and after his or her “home” operation. This ensures that product flows uninterrupted toward the customer, even when the line is staffed at less than capacity.
DMRs: Lean Flow does not change your fundamental product design and processing. It simply ensures that products move toward the customer, uninterrupted. Should significant Lean Flow product flow and quality changes need to be made during implementation, DMRs will need to be updated as required.
“Front-end” and “back-end” batch processes: Outside or in-house machining batch processes may feed into a clean room. In turn, the cleanroom output may go to a batch sterilization process, perhaps with out-gassing and a significant lead time. Batch processes mean queues, which in turn easily disrupt first in/first out, bloating inventory and triggering expedites.
• Lean Flow uses mathematically calculated, physically defined IPKs to minimize, control, organize and properly order the inherent queues of batch processes. This keeps your products flowing toward your customers, with minimal interruption and delay.
Cleanrooms, gown-ups, clean side/ dirty side, etc.: Lean Flow quantifies the impact that a controlled-environment work area has on work time available and in-process queues.
Cleanroom protocol decreases the time the workforce may work on product. Whereas a non-clean room production worker, for example, may be available to work on product for seven hours out of an eight-hour shift, medtech employees may be available for six hours or less.
• Lean Flow uses facts: A controlled-environment work area presents constraints, reducing work time available. Those constraints effectively decrease takt time, which in turn increases resources required. This is all measurable and verifiable, so the results are reliable.
• For example, in Lean Flow, “gown-up” is a set-up process. As such, you may document it as standard work. As you do so, you may find opportunities to make gown-up, and other clean room constraints, more efficient—more clean side/dirty side bench space, more wash stations, sufficient gowns and hair covers, timely laundry service, clear definition of break and lunch periods and so on.
• Product movement in and out of the clean room means limiting the number of moves and trips. Lean Flow uses a simple, visual technique—IPKs—to achieve this. Because Lean Flow uses data and math, you may build these effects into your line design.
• GMPs, QS, ISO, etc.: These represent work and quality tasks that require time to perform. Measure these additional time elements, add them to the work content for the processes they affect, and use them in the Lean Flow calculations.
Before You Begin Your Lean Flow Journey
The first step on the Lean Flow journey is management team education. Use an experienced, industry-recognized Lean Flow consulting and education organization that will put your team on the same path, using a consistent set of techniques.
The next step is to quantify potential Lean Flow benefits, and define an implementation timeline and roadmap. A Lean Flow consulting and education provider also can provide this business assessment. As a fundamental business strategy, Lean Flow requires a dedicated steering committee and an implementation team.
Can you implement Lean Flow on your own? The obstacles are: time from start to completion, learning curve and “re-inventing the wheel.” Bringing in a third party to aid in the process can reduce implementation time from years to weeks or months, vaults your team over the learning curve and steers around the Lean Flow obstacles that could otherwise serve to slow the process.