Practical problem solving: the 7 steps, Toyota's 8 steps and a worked example

What is practical problem solving?

Practical problem solving is a fixed sequence of steps that takes a problem from the first vague report ("scrap is too high") to a cause that has been proven and a fix that is written into the standard. The word practical means it is done where the work happens, with the people who do it, using facts gathered on the floor rather than opinions gathered in a meeting room.

Toyota teaches the method to its own staff as Toyota Business Practices, usually shortened to TBP, in eight steps. Jeffrey Liker describes TBP in Toyota Culture, written with Michael Hoseus (McGraw-Hill, 2008), and in The Toyota Way to Lean Leadership, written with Gary L. Convis (McGraw-Hill, 2012). An earlier seven-step version, drawn as a funnel from a large vague problem down to one point of cause, appears in Liker's The Toyota Way (McGraw-Hill, 2004). Most factory training today uses one of these two, with small changes in the step names.

Under the steps sits plan, do, check, act. Steps 1 to 5 are the plan, step 6 is the do, step 7 is the check and step 8 is the act. The eight steps exist because teams rush the plan: they see a problem, agree a fix in ten minutes, and then watch the same problem come back a month later. Each step has an output, and the next step should not start until the last one has produced it.

The 7 steps of problem solving, and which seven

A search for the seven steps of problem solving returns at least three different lists. Two of them are close cousins of Toyota's eight steps. The third, McKinsey's, comes from consulting and answers a different kind of question.

Laid next to the eight steps, the shop-floor sevens are the same method with one step folded in. The funnel in The Toyota Way merges clarifying and breaking down into its first three steps and has no separate target step. The training version usually drops the breakdown and the target, which is why teams using it often jump from a plant-wide number straight into brainstorming causes. If your problem is a defect, a breakdown or a missed output target, the eight steps are the safer choice, because the two steps the sevens leave out are the ones that stop the team guessing.

McKinsey's seven steps are worth knowing, but they solve a different kind of problem. They start from a question with no standard to compare against, break it into a tree of smaller questions, and end with a recommendation and a story to tell the people who decide. Use them for a make or buy decision or a new plant location. Use the eight steps when there is a gap between how the process should run and how it does.

Worked example, steps 5 to 8: from countermeasures to the next problem

Step 5, develop countermeasures

The team first puts in containment, which protects the next shift but fixes nothing: until the program is restored, the L2 operator runs the warm-up by hand and gauges every bore in the first hour. Then it weighs the real countermeasures. Two ideas were dropped. Retuning the tool offsets every morning treats the symptom and depends on the operator getting it right each day. Leaving L2 idling overnight would warm it, but at a cost in power and wear for nothing a 15-minute program does not already give.

Step 6, see countermeasures through

Each action goes on the cell's board with its owner and date, and the team leader reviews it at the daily huddle. The plant-wide program check slipped a week because a breakdown took the maintenance planner's time. The board showed it the day it slipped, and the area manager moved the date openly rather than letting it drift.

Step 7, evaluate both results and process

The process check matters as much as the number. The new start-up sheet shows the warm-up recorded on 19 of the 20 mornings. On the twentieth, a late start cut it to 6 minutes, and 5 of that morning's 40 bores were oversize; the other 9 of L2's 14 were spread across the four weeks. So the countermeasure works when it is followed, and the one miss came from production pressure, not from the program. The team leader and the supervisor agreed that a late start never shortens the warm-up, and the start-up standard now says so.

What the result is worth: 360 minus 198 = 162 fewer scrapped parts in four weeks. At 20 parts an hour, each scrapped part is 3 minutes of lathe time, so 162 x 3 = 486 minutes, or 8.1 hours of capacity back. Checked the other way: 8.1 hours x 60 = 486 minutes, and 486 / 3 = 162 parts.

Step 8, standardize and share

The control replacement procedure, the start-up check sheet and a one-point lesson at L2 now carry the change. The check of the other nine CNC machines found one more, a mill in cell 6, whose warm-up program had been cut to 5 minutes; it was restored the same day. Then the team looks at the new Pareto: cell 4 sits at 1.10% against the 1.0% standard, and thread damage, 78 of the 198 scrapped parts or 39.4%, is now the biggest piece. That becomes the next step 1.

Laid against the seven-step funnel in The Toyota Way, the same work fits: initial perception is the full scrap bin, clarify and locate the point of cause are steps 1 and 2 above, the 5 Whys is step 4, and countermeasure, evaluate and standardize match steps 5, 7 and 8. What the funnel does not ask for is the target in step 3, which is why the team above knew in week 10 that it had finished.

Practical problem solving vs 8D, A3, PDCA and DMAIC

The eight steps are often confused with 8D because both have eight parts. They come from different places and start from different triggers. 8D came out of Ford's team problem solving manual in the late 1980s and is built around a customer complaint. Practical problem solving comes from Toyota and is built around any gap against a standard or a goal, including ones no customer has seen.

A sensible rule for a plant: run the eight steps for your own recurring problems, switch to 8D when a customer asks for one (the analysis you already did on the floor feeds straight into D2 to D7), and escalate to DMAIC when two rounds of the eight steps have not found the cause. When a quality system needs a record that the cause was found and removed, the eight-step sheet is the evidence for a CAPA.

Templates and tools for the 8 steps

Start on paper or a whiteboard, because the first drafts change a lot. The free A3 problem solving template has room for every step on one sheet. For step 1, the is / is not template sharpens the problem statement. For step 2, the Pareto chart maker and the scrap rate calculator turn a list of defects into the picture the team works from. For step 4, the fishbone diagram maker lists the possible causes, and the root cause analysis guide explains which cause tool fits which problem.

In LeanSuite, Lean Studio has the A3, 5 Whys and fishbone boards, and a tag raised on the floor that keeps coming back can be escalated into a Kaizen or A3 project in one click, keeping the tag's history. Kaizen & Projects then tracks the project's actions through to results. For the wider list of lean methods and where each one fits, see lean tools.