NX Routing Part Library and Stock Setup: Common Pitfalls

Practitioners on the Eng-Tips "Siemens: UG/NX" forum have repeatedly flagged NX Mechanical Routing's part/stock library setup as one of the harder administrative tasks in NX — one long-time poster summed it up bluntly: routing is "NX's red headed step child that keeps getting ignored," reflecting ongoing frustration that library tooling and stock management have received less polish than mainstream modeling/assembly features. (Source: Routing mechanical, using family members as stock)

Two competing approaches to stock, and their tradeoffs

NX offers two ways to represent "stock" (raw pipe/tube/conduit segments before qualified parts are placed on them):

1. Part families as stock — parameterized family members driven by a spreadsheet-style part family table.
2. Routing part library (.ptb-based) stock — stock definitions stored in .ptb (part table binary/attribute) files organized into searchable library folders.

Key pitfall: .ptb files are independent of part families. If your part family table gets a new stock size/variant added, that change does not propagate automatically into the .ptb file — an administrator must manually update the .ptb with the new stock attributes, or newly-added family stock sizes simply won't show up correctly through the routing library UI. Users called this out as a source of drift between the "source of truth" part family and what routing actually offers designers. (Source: Routing mechanical, using family members as stock)

Why bother with the library approach anyway: the payoff is attribute-based search. With stock organized into the routing part library, a designer can right-click and search library folders by attributes — size, material, schedule, etc. — the same way they would search a part family table, without needing to already know the exact part number. This is a real productivity win for large stock catalogs, but it comes at the cost of the dual-maintenance problem above. (Source: Routing Parts Library - Siemens: UG/NX)

Getting custom stock into the library (the "ss2ptb" workflow)

Multiple threads describe essentially the same multi-step process for adding a new custom stock type to mechanical routing, and multiple forum participants independently confirmed it is tedious to get right the first time:

1. Create a parameterized model of the stock cross-section/geometry.
2. Edit the necessary data in NX Part Families (attributes, expressions, size table).
3. Export/save the part family data as an Excel file, then re-save it as a .txt file in the expected format.
4. Save the associated part with a .prt extension in the correct library location.
5. Run the ss2ptb.exe conversion utility to generate the actual .ptb file NX routing reads at runtime.

One poster summarized the overall experience plainly: "the library was quite a pain to get set up." (Source: Adding custom stock to the mechanical routing)

Practical takeaways for anyone standing up a routing library

• Decide at a corporate/CAD-admin policy level, not per-project, whether stock will be legacy swept-feature stock or converted to component-based stock via "Convert to stock as components" — mixing approaches across a library causes downstream confusion for designers switching between projects. (Source: NX Routing Mechanical Notes – Part 1)
• If you maintain stock as part families, put a process in place (checklist or script) to re-run the .ptb export whenever the family table changes — otherwise the library and the family silently diverge.
• Budget real setup time up front. This is consistently described as one of the more painful one-time investments in adopting NX Routing, not a quick checkbox.
• Consider whether the maintenance burden of attribute-searchable library folders is worth it for your catalog size; for a small, stable stock catalog, plain part families may be simpler to keep in sync even though search-by-attribute is lost.