Flow, while an incredibly important concept, alone doesn't create a Lean value stream. The ability to regulate flow in real time between unit operations and processors along the chain also is crucial. Lean practitioners usually describe this system of regulation as pull. Directing the customer production signal to one point in the value stream (sometimes called the pacemaker process) provides a number of advantages: simplified information flow and proper inventory control while reliably serving customers in a safe and environmentally sound manner.
Between continuous chemical operations, the application of pull usually is straightforward and handled by process control systems (e.g., level control devices that balance inventories between adjacent steps). Invariably, every value stream has some operations that can't or shouldn't be combined in a continuous flow — due to physical distances, adjacent processes with highly disparate cycle times or a variety of other factors. Tanks, warehouses and other types of storage systems often signal non-continuous processes within the chemical value stream. Pull systems vary in their specific form but all aim to regulate the production of each value-stream activity so that every step produces exactly what is required for the next downstream step at just the right time.
Designing and building toward versatile and flexible systems that perfectly flow value toward the customer without interruption, overproduction and added cost/pain is the pinnacle of operational excellence. This is the fourth step to becoming Lean.
FOCUSING ON WHAT YOU CAN DO NOW
Successful organizations constantly seek to improve and innovate. However, the need to fight today's fires can make that tough. It's essential to find the right balance between short-term performance commitments and continual improvement. Doing this well requires new behaviors and new styles of engagement for everyone from the production operator to senior management.
One way to succeed is through the kaizen (literally, continuous improvement) process. It's important to understand that just because something can be improved doesn't mean it should be improved (at least not immediately). Here are five practical ways to put the kaizen process to work:
1. Stay anchored to the priorities and insights made clear by value-stream mapping and analysis.
2. Use appropriate tools such as modeling and discrete event simulation  to accurately quantify the impact of potential changes on the value stream.
3. Once the best changes are known, implement them fast and be ready to accept an 80% solution for 20% of the effort.
4. Highlight results to gain support for the next kaizen and be willing to fine-tune the value stream over time.
5. Lastly, make sure that the solution sticks — leverage Six Sigma to develop an appropriate control plan.
Striving for perfection at what really matters, engaging the organization in the evergreen kaizen process and achieving quick wins that lead to visible impact on the value stream truly define what it means to be Lean. This is the fifth and final step to becoming Lean.
ADAM RUSSELL is a group leader and Six Sigma master black belt for Eastman Chemical Company, Kingsport, Tenn. Email him at email@example.com.
1. Pratt, D., "A Marriage Made in Heaven" p. 25, Chemical Processing (May 2005).
2. Cope, D., "Consider Discrete Event Simulation," p. 27, Chemical Processing (Oct. 2010).