Staying LEAN – Why LEAN needs SPC

In the quest to eliminate every NVA, some go too far. Why going LEAN doesn’t mean living without the insight afforded by process monitoring.

In terms of popularity, the numbers for LEAN are staggering; LEAN is extremely popular. Yet, it’s evident that it has yet to fully achieve its promise even after three decades of broad implementation. LEAN programs fail to meet their objectives as often as 95% of the time. In truth, only a handful of companies have been successful in fully implementing LEAN.  Names like Toyota, Danaher, and Honda come to mind.

Most firms that start the LEAN journey ultimately abandon it, only coming back to it now and then before the program fades into history. While 80% of manufacturers claim to have implemented LEAN, less than 1% of these leverage fully LEAN practices, often leading to the failure of their LEAN implementations. So, why do most companies that try to leverage LEAN fail to achieve what they set out to do?

At the initial stages of LEAN implementations, manufacturing companies often see some quick wins and gains with fresh education and organizational funding to transform their processes. However, over time, the effort can get bogged down as it demands continued support from all levels of the organization for needs that are often under supported and possibly even unmet.

In many of these organizations, the top leadership is often not educated in the process or unwilling to follow through with continued funding for the implementation. Attrition of program champions and people familiar with the LEAN philosophy leads to a lack of investment and possible shutdown of the program if it cannot continue to deliver results.

Thus, the program must remain successful and sustainable even with the increasingly limited ongoing attention of resources.  How do the remaining champions focus on only the highest risk needs for continued performance of the process?

Enter statistical process control (SPC).

SPC is not a LEAN replacement so much as a performance enhancer and process auditor. SPC eliminates the confident blindness of the LEAN approach. Companies use SPC to ensure consistency, predictability, and stability of processes, and to protect the reputation of the products and services they offer. It alerts stakeholders to changes that are not expected so the team knows where to focus its limited resources.

Unpredictability and Inconsistency are Bad for Business

Obviously slight variations are inevitable when delivering value at an acceptable cost, but variations that defy expectations make customers uncomfortable and perhaps prompt a rethinking of vendor. Real or perceived unpredictability is bad for business.

SPC’s control charts help businesses identify variation that goes beyond expected or acceptable variability (referred to as special cause variation) so a producer knows where to act before it results in bad outcomes for customers. SPC monitoring flags special cause variation, which are changes resulting from something that needs to be addressed.

 

 

Control charts are one of several tools available in SPC to improve LEAN implementations by providing live monitoring for change on your behalf, so you can focus your limited resources on areas of highest risk or benefit and ignore false alarms.

You can use SPC to monitor:

• Changes in materials or supplier flows that underpin your performance assumptions
• Changes in physical attribute trends such as dimensional differences
• Changes to the variation of fill with respect to target levels
• Growth in labor content, cycle time, processing or waiting throughout the process
• Unexpected deviance among machines or fill heads from the expected variation
• Frequency of defects and defect types (through scrap, rework and additional processing)

The purpose of SPC is to continuously improve your processes by reducing issues that destabilize them, all in the endless pursuit of zero defects. You can use real-time SPC to track these dependencies and provide your LEAN implementation team with critical process stability and improvement information.

One of the reasons SPC is often not implemented within LEAN is that some incorrectly consider it to be a non-value-added (NVA) process. In the pursuit to eliminate all NVA processes, some people assume a trustworthy process has no need for monitoring. In truth, thinking you no longer need to bother with monitoring is both foolish and arrogant. The mere fact that change is possible should be enough to convince you of the need to keep monitoring your processes to ensure you are not losing control — before such changes embarrass you.  SPC is cheap insurance against hidden change.

Sensitivity to Changes in Your Processes

Consider the following scenario:

An enterprise establishes a working relationship with a certain trusted supplier. The enterprise has done due diligence by scrutinizing this supplier and rigorously testing the materials they deliver. The enterprise concludes that the supplier qualifies to be added to its “partner” or “preferred” list of vendors. Moving forward, the company no longer scrutinizes these sources for consistency and quality. There’s a foregone conclusion that these inputs will never deviate in a way that compromises your process performance or product.

 However, sometime later, this supplier, in an effort to improve delivery, increase yield, or just save cost, changes its raw material source. Without SPC, there’s no way of identifying if this change by the supplier will result in special cause variations that the enterprise will need to address in its own manufacturing. Because of the supplier’s “partner” status, the variations could go unnoticed until unpleasant changes appear in process variation or finished goods shipped to your customer.

 Without a way to detect upstream changes that might result in unexpected deviance from the expected, the company might fail to require another thorough scrutiny of the process until problems occur.  Your goal should be to detect process stability changes before problems occur.

This is true for any improvements to production that might turn out to be less reliable or to have unexpected consequences. SPC is designed to detect these kinds of situations, ensuring that your implementations are sensitive to changes that impact process reliability and outcomes.

SPC works by sampling a process regularly to create a picture of measurable performance over time. It constantly compares past and present data to assess whether the current process behaves similarly to previous periods. Every time new data fails to statistically fit earlier data, alerts can trigger an investigation into what may have happened to cause a change in performance.

Introducing SPC to your LEAN implementations will warn you of trends and changes before they turn into performance, output, or quality problems.  Thus, SPC often tells you about a pending problem before it occurs. SPC also keeps you from overreacting every time there’s a slight fluctuation in performance or an out-of-specification product. Not every defect is statistically significant. Such overreactions could prompt you to make unnecessary and costly process adjustments to parameters that were performing as expected, resulting in degraded rather than improved outcomes.

This is a common problem when operators are asked to manually tune a machine in response to current output values.  This operator ‘tweaking’ can represent an unwanted ‘ringing’ in the output values that appear like a series of necessary corrections, but are in fact wasteful changes.

Continuous improvement is important for any manufacturing company that wishes to remain competitive. WinSPC software is designed to help manufacturers make the most of their processes in order to consistently produce quality products at the lowest possible cost. It helps you monitor all process steps and helps you to prioritize and focus your people and technology on the best actions to achieve the desired results — including higher profitability and better customer satisfaction.

When seeking to understand your manufacturing process, continuous information and testing is not a Non Value Added operation.  It might just be the investment that prevents you from accruing unexpected costs or customer loss due to unforeseen process breakdowns.  It is incredibly cheap insurance for your peace of mind, allowing you to focus wherever you need to be.  And it could be just what makes your LEAN operation stay LEAN.

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Based on original source by Solomon Ndungu