Definition
Change point management (変化点管理, henkaten kanri) is the practice of identifying the specific points in a process where a condition has changed, or has deliberately been changed, and following those points until the result is confirmed. The change points are classified by the 4Ms. Man: a new or substitute operator, a shift change. Machine: a repaired, replaced, or modified piece of equipment, a tool change. Material: a new lot, a new supplier, a design change to a part. Method: a revised work sequence, a new standard. For each change the supervisor records what changed, what the risk is, who is responsible for watching the change, and when the changed condition will end, and then confirms the result.
The reason for the practice is stated the same way in Toyota's shop-floor materials and in its design-quality materials. Defects, safety incidents, and process instability most often originate at a change point. A process that was stable becomes unstable because something in it changed. Managing the change explicitly is how the abnormality is caught before it becomes a defect.
Japanese Origin
変化 (henka) means change. 点 (ten) means point. 管理 (kanri) means management or control. A 変化点 (henkaten) is the point in time and place at which a condition changes.
In product development Toyota's engineers use a paired term. 変更点 (henkōten) is a change made on purpose, a part, material, or specification the designer altered. 変化点 (henkaten) is a condition that changed as a result, or changed in the environment, without anyone altering it: a higher surrounding temperature, a different mating part, a new lubricant. Tatsuhiko Yoshimura's GD³ method directs design review to both, the things that were changed and the things that changed. Shop-floor change point management uses henkaten (変化点, change point) for every 4M change, planned or not.
How Change Point Management Works on the Shop Floor
Recording the change. At Toyota Motor Manufacturing Texas the FMDS board carries a Change Point Wing whose stated purpose is communication of 4M changes. Each entry answers four questions. What happened. What is the risk. Who is responsible. When will it end. The group leader posts the change, and the entry stays open until the changed condition has ended and the result has been confirmed.
What counts as a change point. Toyota's Global Production Center materials give a new operator, a tool change, a material lot switch, and a modified sequence as examples of a 4M element leaving its standard state. OJT Solutions, in its guidance for supervisors, adds the quieter cases: a procedure or force that differs slightly from operator to operator, an equipment setting that has drifted, and a material lot with different hardness. The OJT Solutions instruction to the supervisor is to keep a daily eye on whether the 4M conditions are stable and whether any change point has occurred.
Which changes are tracked. Change point management does not track every change in a workplace. Everything in a factory changes all the time, and a board that records everything records nothing useful. Toyota developed the practice to monitor specific items: the conditions altered by a problem-solving countermeasure, by a kaizen, or by a design or engineering change, where a new condition has been introduced on purpose and needs to be watched until the result is confirmed. Discovered changes in the 4Ms, such as a substitute operator or a new material lot, are added when the supervisor's daily check finds them. The list stays short and specific.
The board. The change point board (変化点管理板, henkaten kanri-ban) hangs beside the process layout and staffing chart and names a responsible manager. Each day has one row per M: person, equipment, method, material. Each row records the process, what specifically changed, the cautions to watch, the quality confirmation result, and the name of any substitute worker. When nothing changed in a category that day, the row says "no change." Writing "no change" is part of the discipline. The row is filled in every day, so a blank row is itself an abnormality.
Assessment under 3 Pillar Activity. Change point management is one of the scored items in the standardized work pillar of 3 Pillar Activity. Toyota's Global Production Center grades change point management in levels. At the bronze level the 4M management rules are defined and understood by the group, and defects that arose from change points are identified. At the gold level the rules are executed and logged as a history, the section manager (課長, kachō) and the foreman (工長, kōchō) review the history and follow up, and the line has recorded zero downstream or customer defects caused by change points for six consecutive months.
Position in the group leader's development. In the FMDS development path, change point management is introduced at the second stage, when the group leader moves from understanding the basics to using and teaching the tools. Change point management is paired there with focus activities and the FMDS dojo. The worked example in the FMDS guide shows fixtures returning to service after repair being tracked as change points until the result was confirmed.
Change Points in Design Review
Upstream of production, the same idea is the foundation of mizen-boushi and of Design Review Based on Failure Modes (DRBFM). Yoshimura's premise is that reliability problems arise when a proven design is changed. Good Design means minimizing change points and making every change visible. Good Discussion means a review focused on what changed and what could go wrong because of the change, rather than on the whole design. A change that falls within previously validated limits is a low-impact change point and does not require the full review.
Common Mistakes
Treating the log as the practice. Recording the change is the first step. The practice is following the process through the change and confirming the result. The gold-level standard is measured in defects, not in entries.
Tracking every change. A board that lists every fluctuation in the workplace buries the few changes that matter. The practice works when the tracked items are specific: the conditions a countermeasure, a kaizen, or a design change introduced, plus the discovered 4M changes the daily check turns up.
Starting before the process is stable. Change point management assumes a standard exists and is normally held, so that a change stands out against it. In an early lean program where standardized work is not yet followed and equipment is not yet reliable, everything is a change point and the practice cannot get traction. Basic stability and standardized work come first.
Leaving the responsibility with the operator. The entry names a responsible person, and at Toyota that is the supervisor. Change points are a management item, which is why they sit on the group leader's board and are scored against the group leader in 3 Pillar Activity.