Family Tables and Patterns

Family Tables

Certain types of mechanical components and subassemblies -- especially industry standard parts (bolts, screws, washers..) and supplier catalog parts (mold bases, ejector pins...) -- come in sets of fixed sizes. The various part variants are often represented as a hierarchy of:

part family
- part subfamily...
  - part family table
    - rows (variants) within the table (i.e. the "part")

Two key benefits accrue... a) instead of each user developing a new solid model for the component from scratch, he/she can simply access the available 3D catalog, saving modeling time, and b) reuse of available standard parts is encouraged, as opposed to costly custom part design/manufacture.

For example, below we select the Hasco catalog and the Z515 part family:

families

We are then presented with the part table, with each row in the table having different values for controlling part parameters. The user then selects a given row of the table (here row 2) and the 3D part is entered into our CAD/CAM system.

family table

Let's return to our mold base design task. Instead of modeling the mold block with variable dimensions, we'll select a catalog component from a family table.

insert table part

The family table can then be stored along with the feature on the "node" of the part history tree.

Later in the iterative design process, if something changes lower in the part's history tree (e.g. a new version of the "parent" mouse rear portion), then the table can be automatically re-searched to find a row in the table that best fits the design intent (e.g. the mold block should remain at least 20mm wider and 30mm taller than the parent part).

In a real production mold tooling example, table-driven parts may be used for dozens of mold base components. If the family table functionality of the CAD/CAM systems works well and reliably, this can be a major productivity and effectiveness gain.

Patterns

It is often the case in design of finished products and manufacturing tools that certain features within a part or parts within an assembly are arrayed in in rectangular or circular "patterns". In the case of mold making this is seen in the use of multi-impression tools, which in our simple example would be represented by the mold core and cavity for the mouse being replicated in a 3 x 2 array.

patterned mold core and cavity
Mold core and cavity in 3x2 pattern

Part history tree for patterned mold core,
associative to single mold core (parent)