Determination of the Second Digit for Injection Molded and Die Cast Parts

(Used under permission of Dixon and Poli,
Engineering Design and Design for Manufacturing)

The following figure should be used in determining the second digit for both injection molded and die cast parts:

Figure 11.1 Classification System for Basic Tool Complexity
Basic Complexity L <= 250mm (1) 250mm < L <= 480mm (1) L > 480mm (1)
Number of external undercuts(2) Number of external undercuts(2) Number of external undercuts(2)
zero one two more than two zero one two more than two zero one more than one
Second Digit 0 1 2 3 4 5 6 7 8 9 10


  1. Here, L is defined as the longest dimension of the basic envelope enclosing the part.

  2. An external undercut is a hole or depression on the external surface of a part which is not parallel to the direction of mold closure. Projections on an external surface which do not have a planar or non-planar dividing surface passing through them are also considered external undercuts. The number of external undercuts is equal to the number of surfaces bearing unidirectional holes and/or depressions not in the direction of mold closure and/or projections that prevent a single dividing surface from passing through all of the projections. The following figure gives an illustration of parts with and without external undercuts and the determination of the number of external undercuts: