Test & Inspection: Leak Test Process: Using Lean and 5S to Drive Manufacturing Process Improvements
August 29, 2011
Leak testing is a mandatory step in the production of many industrial and consumer products. Its criticality is particularly acute in the area of medical devices, security equipment and other X-ray-based systems. When these systems are used, patients, the general public and system operators spend time in close proximity to the sources of radiation. Inside these systems, liquids dissipate the heat created by X-ray generators. To ensure systems are leak free, manufacturers require stringent inspections and suppliers charged with leak-testing develop robust procedures to perform these tasks.
Today, inspectors are likely to find they face a double challenge: First, conduct flawless leak tests. Second, satisfy expectations for improvements in testing efficiency.
For organizations with leak-testing operations, customer demands are best addressed through an established lean-manufacturing environment. The commitment to continuous improvement at the core of lean makes this an ideal approach for improving manufacturing processes. When applied, it also can significantly strengthen an organization’s quality-assurance efforts. Typically supported by 5S, a lean effort begins the never-ending process of capturing potential improvements. After the initial 5S event, with clutter out of the way, cell leaders and team members can examine process flow more clearly, identifying areas for next-step improvements.
Start with a StrategyFirms seeking improvements should do more than simply go down the 5S checklist (sort, straighten, sweep, schedule, sustain). Start with lean principles and use 5S as the primary tool to kick off the effort.
Companies ask: How much can we accomplish with lean? The answer is: A lot-particularly for those companies whose initiatives are guided by metrics of customer satisfaction and productivity. With this approach, the quality and production departments have something they can measure, track progress against, use as a common improvement language and align to support an organization’s broader strategic goals.
SortDisorganization and clutter are the enemies of efficiency. The sorting stage is the time to get ruthless about removing anything from the work environment not required to perform leak tests. “If you don’t need it, it needs to go,” is the mantra. When the clutter is cleared from a test room, the actual process flow is revealed.
There are two reasons why it is almost impossible to overdo the sorting step. First, removing every nonessential item will help boost the efficiency of every future leak test. There will be no clutter between employees and their work, so there will be no time wasted sorting through nonessentials.
Second, every future step in the 5S process builds on the thoroughness of this first step. The better the sort, the more effective each subsequent “S” step can be.
StraightenThe idea that there is a place for everything and everything in its place is one of the most powerful components of 5S. One helium-test room took this task a step further. Management decreed that tool-kitting had to be available for every setup. That meant that management required all test tools-O-rings, hoses, connectors, clamps, plugs and so on-be present in each kit. The department also took steps to ensure that no kit was ever put back in its place on the shelf if parts were missing.
The introduction of shadow boards is critical to the success of this step. This innovation creates a hanging spot on a board for all the hand tools needed for test setups. Every screwdriver, wrench or pair of pliers has a place on the board, complete with an exact “shadow” of its size and shape. Shadow boards facilitate the return of tools to their proper place. A good sort begins the process of cutting test cycle time. Adding heightened visibility for every well-marked toolkit and every hand tool further reduces the time an operator requires to begin a test.
SweepSometimes also called shine, this “S” is vital for creating an atmosphere where excellence can thrive. Cleanliness in test rooms is important not just for parts that need to stay clean, but also for establishing and maintaining a culture of quality. Where dirt is tolerated, other short-comings will find a place to hide. Cleanliness requirements promote the right mindset for the entire department.
One quality department credits a steady decline in customer complaints to this serious commitment to cleanliness. In this department, performance reviews and decisions about raises are influenced by ratings of departmental cleanliness. The environment is closely monitored and is sustained through the daily actions of employees. The company believes that when everything is spotless, it is a lot easier to spot a potential problem.
ScheduleA schedule that establishes a timetable for lean-related housekeeping chores makes sure that the test room does not drift back to the status quo that existed before the initial 5S effort. The schedule dictates how often the test room is cleaned, how often the shadow boards and tool-kitting are checked to make sure procedures are being followed, and whether a decision needs to be made about re-arranging the shelves to accommodate additional tool kits for new part numbers. Setting a schedule and following it is one way organizations communicate and enforce a commitment to quality.
The schedule is the solution to problems that arise in the dynamic environment of a test room. Change is normal and predictable. Unchecked, however, change brings the slow accumulation of clutter, promotes disorganization and undermines gains. Establishing and following a schedule, on the other hand, holds the gains and keeps the work path unobstructed for further progress.
For example, the water-testing area of one quality department revamped a significant part of its environment to apply innovative scheduling ideas as broadly as possible. The test room physically separated parts to be tested, from parts in test, from parts already tested. Paperwork modifications, including a test-serialization system based on start dates and FIFO (first in, first out) scheduling, was a subsequent step. That was followed by a policy prohibiting the cherry-picking of parts to be tested. Within one month throughput for the test room and downstream operations was improved.
SustainingMany organizations view the fifth “S” as the key to hold the gains achieved by the 5S process. When employees see improvements are permanent, they are motivated to make contributions. Because the best source of improvement ideas for leak testing will always be the people performing the leak tests, the sustaining effort can pay dividends. Over time, the sustaining effort results in a different attitude among employees and a different culture within a company. These conditions facilitate the flow of good ideas.
The process of sustaining continuous improvement will have many by-products. At one company, improvement ideas included the development of quality alert notices. Generated by corrective actions, these notices become a permanent part of inspection protocols. Another innovation was a kanban-type system for reordering customized O-rings-a key piece of tooling for virtually all of that organization’s helium and water testing. These relatively simple steps now ensure that customers never have to make the same complaint twice and that needed components of tool kits are always present.
MetricsWhat are the benefits of following lean and 5S? One firm that tracked cost-of-quality (COQ) discovered that it reduced the COQ an average of 7% per year over a four-year stretch. This represents a phenomenal success for that company’s lean effort. If a company sells $1,000 of new work, only a small fraction of that amount will be converted into profit. However, reducing COQ by $1,000 can flow 100% of those saved dollars right to the bottom line.
When the quality and production departments work closely together using lean and 5S, productivity improvements can be dramatic, particularly during the early years of establishing a lean operating environment.
Lean, supported by 5S, is an effective approach for driving manufacturing process improvements both company-wide and in the leak-test room. Because it is intolerant of disorder, waste, poor quality and human error, the lean-manufacturing approach tends to strengthen the quality-assurance system at companies that follow its principles. Reductions in customer complaints, COQ, returned parts and safety metrics confirm this. The increases in productivity, throughput and financial performance that are the other side of the continuous improvement coin confirm it further still. Q
Tech TipsThe idea that there is a place for everything and everything in its place is one of the most powerful components of 5S.
A schedule that establishes a timetable for lean-related housekeeping chores makes sure that the test room does not drift back to the status quo that existed before the initial 5S effort.
Lean, supported by 5S, is an effective approach for driving manufacturing process improvements both company-wide and in the leak-test room.