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Lean Tools, Training, and Systems

Boundary Diagram

aka Block Diagram, Block Boundary Diagram

What is a Boundary Diagram?

A boundary diagram is a graphical illustration of the relationships between the subsystems, assemblies, subassemblies, and components within the object as well as the interfaces with the neighboring systems and environments.

FMEA template


Boundary diagrams are often a mandatory element of a Design FMEA (DFMEA), and should be stored in a folder alongside the related FMEA, along with the Interface Matrix, P-Diagram, and all other related documents.

A Block Boundary Diagram defines the scope of each DFMEA, breaks related DFMEAs into manageable levels.

Although boundary diagrams can be constructed to any level of detail, the most important criteria are to:

  1. Identify the major elements
  2. Illustrate how they interact with each other,
  3. Illustrate how they may interact with outside systems

In the early stages of creating a DFMEA,

your boundary diagram might consist of only a few blocks representing major functions and their interrelationships at the system level. Then, as the design matures, your boundary diagram will be fleshed out, and you might create additional ones to illustrate lower levels of subsystems, all the way down to the component level.

Training video
DFMEA Steps 2 and 3
and Boundary Diagram

For example...

A completed system FMEA boundary diagram has blocks representing the subsystems within its scope and its interfacing systems. Then, moving into the subsystem, another boundary diagram is developed showing components of the subsystem as the block elements. For large systems a third or fourth level boundary diagram may be necessary for smaller subsystems, components and their relationships to the lowest level.

Boundary Diagram template

There is no special boundary diagram template, because you can easily create your block boundary diagram using your Systems2win Flowchart template.

Boundary Diagram

Sample Boundary Diagram example from Ford Motor Company


testimonial quote


This Boundary Diagram template comes with many other useful DFSS tools