What are PMIs and what are they needed for?
PMIs are Product Manufacturing Information that are attached to the 3D model or assembly during the construction process and stored within the file.
PMIs include the following
- Surface information
- Geometric dimensions and tolerances
- Form and position tolerances
- Text notes
- Machining method (reaming, drilling, milling, etc.)
These dimensional and manufacturing tolerances, which are normally only available in a drawing, are specified as the PMIs of the 3D model and allow it to provide manufacturing-relevant information on which other processes such as CAM and CMM can be based in order to automate the manufacturing processes.
Why do you need tools like the PDTM?
Design usually works with nominal dimensions, taking tolerance specifications into account. In CAM programming, however, the middle dimensions on the tolerance center are often used for programming.
If the PMIs are attached directly to the 3D object in CAD, the manufacturing process can be optimized by using this information to further consistency and automation.