Friday, June 29, 2007

Toyota Way Fieldbook (Part 3)

In a previous post, I discussed the "continuous improvement spiral" from The Toyota Way Fieldbook, and went into the first step, "stability." In this post, I'll go into the second step, "create flow."

Once processes are stabilized through implementation of the 6S's and elimination of big wastes and obstacles (machinery breakdowns, employee problems, poor quality, disorganization, shortages, etc.), we can look at creating flow.

What is flow? Flow is the ideal of how an order should move from process A to process B. Flow is trying to avoid having an order stored in a rack (inventory), stopped for rework (defects), or delayed because of any of the other 7 wastes.

Why is flow a positive thing? When work flows across processes, orders get to the customer quicker and at lower cost. This is the most tangible result. Another deeper and more valuable reason to have process flow is that it brings problems to the surface. When there is no buffer between processes, any little problem has the potential to shut down the process and eventually the entire production line. This is a great motivator to identify problems and solve them before they bite you in the butt. There's a reason why Toyota refers to TPS as the Thinking Production System; you have to use your head to keep the line rolling.

How do you create flow? First, make sure that you've properly stabilized the processes that are to be linked. If the cycle times of the processes can't make Takt time, then they aren't ready for flow. If they're truly ready, then go about linking the processes together. When doing this, the rule is to "flow where you can, pull where you must." Aligning processes side-by-side in a cellular flow is the ideal, but if that's currently not feasible, install a pull system.

What is a pull system? A pull system is just an agreement on how a downstream process is to notify an upstream process of when they need more of something. Upstream only produces when signaled by downstream. Many variants of pull systems exist: supermarket pull (stock parts, use kanban to signal for replenishment), sequenced pull (pull from a sequenced feeder), and FIFO sequenced flow (just like flow, but with a small buffer). The key is to constantly reduce the buffers and ultimately approach one-piece flow.

Once processes are connected via one-piece flow and pull systems, problems will be surfaced. These problems must be addressed and eliminated through the use of problem-solving skills. When these problems are removed, the processes will be left in a much better condition. The newly improved processes will be more reliable, more efficient, and much flexible. With the extreme variety that we have in our product offering, these are all necessities.

Sunday, June 24, 2007

Toyota Way Fieldbook (Part 2)

Previously, I described the "continuous improvement spiral" that I read about in The Toyota Way Fieldbook. The four steps involved with the spiral are: 1) stabilize, 2) create flow, 3) standardize, and 4) level incrementally. Now, I'll delve into the first step a little further.

Stabilizing a process means getting it ready for the rigors of flow. Instability can show up in many forms, including:

  • machinery breakdowns ("the foam-seal machine frequently breaks down")

  • employee problems ("we always have one guy out every day")

  • poor quality ("we've always got one guy on the back line working off gigs")

  • disorganization ("my air hose is usually over there, but somebody took it")

  • shortages ("we always run out of the right color of formica")

Unstable processes are not ready to be challenged by flow, so the initial focus has to be on stabilizing a process. So, how do we do this? According to the Fieldbook, the first step is to "stand in the circle" and observe the work. From this, you should be able to define the basic steps of the process, record the cycle time for each step, and draw a picture of the work area and the movement of manpower/material within it. This type of analysis puts you in a good position to identify "no-brainer" improvements. Once this initial low-hanging fruit is plucked, you can use workplace organization (basic stuff) and 5S (a little more advanced), and other tools to further eliminate waste. Once multiple operations/processes are stabilized, then you can connect them together to create flow. Flow should not be attempted before processes are stabilized, because the risk of failure would be great.

Are your processes ready for flow?

Toyota Way Fieldbook (Part 1)

I'm reading The Toyota Way Fieldbook. I'm through a few chapters now, and the most interesting concept that I've come across is the "continuous improvement spiral" discussed in chapter 3. Basically, it's a pattern of improvement (described below) that gets repeated over and over again, each time taking you deeper into the spiral (click here for an example of a spiral, have fun). The repeating pattern consists of 4 steps:

1) Stabilize = get the process ready for the intensity of flow by eliminating any process breakdowns (5S is one step towards achieving stability)

2) Create flow = move away from isolated processes to connected/interdependent processes (creating "pull" relationships is one step towards achieving flow)

3) Standardize = document the new process so that it can be improved upon by others, use visuals where possible (not intended to be a how-to-guide for installers)

4) Level incrementally = force the weak link in the process chain to break by "tightening the belt" (increasing production levels, reducing WIP buffers, adding more variety to the product mix, etc.)

Each time you perform step 4, instability will be created (processes will not be able to keep up due to hidden problems) and a new turn into the spiral will be needed. The result of this self-inflicted misery is a Lean process with a lot more capacity and reliability. In future posts, I'll discuss other aspects of the "Lean spiral."