Point kaizen refers to small, isolated improvements that are easy to implement quickly. The impact of point kaizens are typically small but they can have a large impact. Point kaizen are in contrast to line kaizen, plane kaizen, cube kaizen, etc.
There is no limit to how small a point kaizen can be. That is why it is “zero dimensions”. This is good in that most point kaizen are immediate and remove safety hazards, make the workplace cleaner, etc. However one of the criticisms of point kaizens as the only type of continuous improvement effort is that it is hard to see the bottom line impact, or that the positive effects of point kaizen in one area can wipe out the benefits of a point kaizen in anotter area.
An example of a point kaizen would be organizing (5S) a tool cabinet in a machine shop.
A line kaizen would be layout change to create better flow, which may make the tool cabinet totally unnecessary, as the tools could be attached directly to the machine at point of use.
A plane kaizen would be to deploy these layout improvements horizontally (yokoten) to other lines, and this may change the design of the original flow line now that the entire shop is being moved and door-to-door flow can being considered.
A cube kaizen would be to make improvements “up and down” from the plane, or upstream and downstream by including the suppliers and customers (such as configuration engineering, heat treat, assembly, shipping, etc.). This might change how the parts are designed or how orders are released, further changing the layout of the factory (plane).
The idea is that as you go from point to line to plane to cube you are expanding your kaizen efforts enterprise-wide. This expands your thinking from one small area to the entire value stream. Just as in geometry, each type of kaizen adds another dimension (line = 1 dimension, plane = 2 dimensions, cube = 3 dimensions). Moving to each higher dimension brings you closer to the customer, and also to systemic root causes.
Some call cube kaizen “3D kaizen” but this is confusing with 3D as in “dirty, dangerous, difficult” rather than 3D as in “3 dimensions”.
There is a common misunderstanding of the definition of kaizen being a series of small, incremental, common sense improvements rather than more broadly any type of improvement that follows certain principles. If you only make small, incremental improvements this is only point kaizen, and that is not ok.
So when is it OK to do point kaizen?
1. When the alternative is no kaizen
2. When the point improvement does not worsen safety, quality, delivery or cost for upstream or downstream processes (i.e. when you avoid local optimization)
3. When it is part of a series of connected point improvements (a weaker version of line kaizen)
4. When the point improvement promotes a behavior change such as a “go see” style of management
5. When the points of improvement are along continuous process (as opposed to discrete processes) and therefore by definition can have an impact similar to a line kaizen
I would rather have people do point kaizen than not do kaizen at all. However it is too easy for people to learn a Lean tool and focus too much on implementing the tool for its sake rather than trying to understand the geometry of kaizen and how to use the tool to go from point to line to plane to cube.