Combining powerful improvement methods in process manufacturing

Six Sigma and Lean improvement methods have been used in a number of industries for quite some time. Read here to learn how you can use both in a chemical plant and reap significant benefits.

By Douglas R. Pratt, Dow Corning Corp.

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• It also helps ensure that changeovers get attention for engineering study and improvement.
 It results, given well-engineered changeovers, in shorter time to steady-state operation, which, in turn, decreases defects since processes generally produce fewer defects at steady state compared to startup or shutdown.

Continuous processes mirror batch processes; they simply are on a much larger scale. Instead of lift trucks moving materials to and from warehouses to batch process, large-scale continuous processing plants use miles of pipe to transport materials to dozens of storage vessels. The waste is the same, the effects are the same.

A continuous reactor, just like a batch kettle, might have catalyst beds that must be changed at regular intervals. Some processes foul with unreacted chemicals or residue that must be removed. Changeover time-reduction techniques apply. And, of course, many continuous processes include various batch operations.

Whether we are considering batch or continuous systems, there is a key element that cannot be overlooked. Lean can only be truly effective when the process is stable and consistently capable of meeting customer specifications and needs. Lean efforts to increase speed and reduce inventory without a stable and capable process in place will likely result in a disappointed customer when the process breaks down or experiences a quality upset. The statistical analysis inherent in Six Sigma plays a crucial role in identifying the root causes that prevent establishing stability, consistency and capability.

Maintenance and waste
Speed and variation in support activities, such as maintenance and quality assurance, can have a profound impact on the overall operating performance of any chemical process. If maintenance materials, tools and personnel are not properly staged for maintenance speed and to minimize waste, the whole manufacturing process will suffer extended downtime during a repair or shutdown (Lean). Likewise, if the quality of maintenance work varies, breakdowns or poor performance of the process will result (Six Sigma).

Other, similar factors can also compromise quality assurance and related efforts, like materials sampling activities. For example, cutting travel distance and time spent in testing (Lean) might be best addressed by giving plant operators the tools and training to do their own testing close to the manufacturing process. Batching of quality assurance tests might offer benefits to the central laboratory, but at the expense of delays to the process. Whether testing is done in the central lab or the process, repeatability and reproducibility of the test results must be understood and be acceptable (Six Sigma). Lean combined with Six Sigma statistical principles can eliminate these inefficiencies. 

Information technology, human resources, logistics, commercial development and other processes that support chemical operations can be similarly improved using Lean Six Sigma methodologies and tools. For example, some informational processes are batched overnight or on a set schedule. However, real-time information is critical to prevent defects and waste. Personnel practices, such as hiring and training, can also benefit from reduced variability and increased speed when waste and non-value-adding activities are removed.

As everyone knows, the company that wins is the one that has the most efficient commercialization process, delivering the shortest time to market with new, stable and capable products and services.
 Lean Six Sigma concepts help to keep the focus on the true goal, supplying and serving our customers and to avoid optimizing subprocesses at the expense of this higher goal. One of our Six Sigma Master Black Belts reminds us continually, “The main thing is to keep the main thing the main thing.”

Succeeding at integration
Whether your company is a Lean shop working to integrate Six Sigma, or vice versa, several issues must be addressed. Expect significant emotional energy and commitment in support of whichever methodology was deployed first. For this reason, it is essential to employ change-management principles to bring the second methodology in place.

Impacted employees will need to understand the details of the second methodology and power of the two together. The combination will require framing. Training must be offered. Some companies relabel their initiative as Lean Six Sigma or Operational Excellence. Others simply incorporate the second methodology’s tool set into the first’s. Whatever the case, top executives must understand, endorse, support and communicate the value of the integration to head off turf wars. Lean Experts must be trained in Six Sigma; Black Belts must be trained in Lean. If both titles and roles are to be retained, then project administration becomes more complex. Sorting projects by type or maintaining separate project portfolios will be needed.

We have chosen to consider the larger, overarching methodology to be Six Sigma, with the improvement process using DMAIC/Lean and the creation process using Design for Six Sigma (DFSS). The Black Belt project leader then determines which process and tool set is to be used for the particular project.

Get engaged
Lean Six Sigma has a place both in discreet manufacturing and in the chemical industry, including all of its supporting transactional workflows and processes. A wise company is one that embraces both approaches equally; it is rewarded by the synergy that is created.

Douglas R. Pratt, P.E., formerly Director of Six Sigma Process Excellence for Dow Corning Corp., Midland, Mich., is now the company’s Six Sigma executive consultant. He has been with the firm for more than 30 years. E-mail him at

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