Activity relationship chart

An activity relationship chart (ARC) is a tabular means of displaying the closeness rating among all pairs of activities or departments.¹ In an ARC there are six closeness ratings which may be assigned to each pair of departments, as well as nine reasons for those ratings (each is assigned by a reason code).

1. A: Absolutely necessary
2. E: Especially important
3. I: Important and core
4. O: Ordinary
5. U: Unimportant
6. X: Prohibited or Undesirable ²

1. Same table
2. Flow of material
3. Service
4. Convenience
5. Inventory control
6. Communication
7. Same personnel
8. Cleanliness
9. Flow of parts²

A rule of thumb is used to restrict the choice of rating letters:

• Very few A and X relationships (no more than five percent) should be assigned
• No more than 10 percent should be E
• No more than 15 percent should be I
• No more than 20 percent should be O
• About 50 percent of the relationships should be U

1. List all the departments within the facility, and draw a rectangle around each one.
2. Draw a rhombus between each department, until you fully construct the rhombus as a tree.
3. Divide each rhombus into two halves; the upper half will contain the rating letter, while the lower half will contain the rating-reason code.