Industrial Design
NAAMS. What it is and why it matters
- IARM Systems
- April 2022
- 8 min. read
When we talk about NAAMS, we refer to an American standard that defines a wide range of elements—machined parts, pneumatic components, alignment mechanisms, and more. These components form the essential building blocks of assembly systems in larger structures such as tooling, fixtures, or poka-yoke devices within the automotive industry.
Like any standard, its main goal is to optimize manufacturing processes while improving responsiveness when adjustments are required due to engineering changes in the part being assembled or tested.
In this article, we’ll explore some of the key components defined under the NAAMS standard and how they function within automotive tooling systems.
What does NAAMS mean?
NAAMS Global Standard Components for Assembly and Stamping is a U.S. standard jointly developed by major automakers—Chrysler, Ford, and General Motors—along with their suppliers. It defines the approved components used in the design and manufacturing of tooling and fixtures for metal parts in their vehicles.
This initiative began in 1992, but it wasn’t until 1995–1996 that the information became publicly available. Later, in 1997, the first official NAAMS website was launched to ensure the standard could be accessed by anyone involved in automotive manufacturing.
The primary purpose of this standard was to reduce production costs. At the time, frequent design updates to automotive parts required costly modifications to tooling. NAAMS introduced standardized adjustment methods that made it possible to reconfigure tools quickly and economically to fit new engineering data provided by the OEM.
NAAMS Shims.
To understand shims, we must first revisit a key concept: part alignment within a CAD model, also known as auto coordinates.
Auto coordinates define the reference system of a component within the tooling—based on the familiar X, Y, and Z axes.
Shims are thin precision plates used to make fine adjustments at controlled reference points called RPS (Reference Point Systems) or Datums, depending on the tool design. Because these points are critical, any adjustment must be highly accurate.
Even with precision machining, variations occur—both in the tooling and in the automotive components themselves when design changes are introduced. Shims help compensate for these variations, maintaining correct alignment with respect to the auto coordinate system.
Standard NAAMS shims are typically produced in sets totaling 5 mm in nominal thickness, though they can be configured differently depending on the application or client. They range from 2 mm down to 0.1 mm, with common adjustment increments of 0.25 mm, in line with automotive tolerances.
NAAMS L-block.
As the name suggests, L-blocks are machined components shaped like the letter “L.” They come in various sizes and configurations to meet space and strength requirements. According to NAAMS, these blocks are typically made from commercial iron (ASTM A-32) or stainless steel (grades 303 or 304), depending on their mechanical or environmental conditions.
Each L-block usually includes two dowel holes (to prevent rotation) and one bolt hole—threaded or through-hole depending on the configuration. Each block controls two axes of adjustment, meaning that two L-blocks are required per Datum or RPS point to achieve full adjustment across the three axes (X, Y, Z).
L-blocks share standardized dimensions with shims, allowing them to be stacked together precisely. This design enables fast, repeatable adjustments between machined components and ensures consistency across all assembly elements.
NAAMS Pins.
Locator pins, as the name implies, help position a part accurately and consistently during assembly or inspection. They may also function as poka-yoke devices, ensuring that each component can only be placed in the correct orientation.
These pins are installed at reference holes on the part and may be fixed or retractable, depending on the tool’s function. Under the NAAMS standard, they are typically made from carburized steel (SAE 8620), hardened to 58–62 HRC at a depth of 0.5–0.7 mm. This provides a tough, durable surface while maintaining a ductile core to resist fracture.
A distinctive feature of NAAMS locator pins is a machined flat face located 10 mm from the center, allowing compatibility with standard pin holders and L-block assemblies defined within the same standard.
NAAMS Risers.
Clamp arms, whether pneumatic or electric, are designed to secure parts in position within a fixture. Manufacturers of these devices have also adopted NAAMS specifications, producing standardized lines that comply with defined dimensions for mounting points, bolts, and action axes.
Con el objetivo de recorrer estás largas distancias y que no exista variación se construyen este tipo de conjuntos soldados los cuales son bastante robustos. En su mayoría son hechos de fierro comercial (ASTM A-36) y cuentan con una placa base y un cartabón que dan rigidez al resto de los elementos del conjunto.
NAAMS Clamp Arms.
These consistent dimensions allow clamp arms to integrate seamlessly with other NAAMS components such as shims, L-blocks, and pins—ensuring compatibility across tooling systems.
Conclusions.
The NAAMS standard was created to reduce costs and simplify adjustments resulting from engineering changes in automotive components. Even after more than 30 years, it remains a fundamental reference in the automotive industry for efficient, adaptable, and precise tooling design.
While other standards exist—such as German WV specifications, which can offer even faster adjustment times—they are typically more expensive and less widely adopted.
NAAMS, however, has proven its long-term value and reliability. If you’re looking to deepen your expertise in automotive tooling design, we recommend visiting the official site:
https://www.naamsstandards.org/
