The FlexSix Locknut Story

FlexSix Locknut: Precision Engineered. Proprietary Built. NASM25027 Compliant.

Two Locknut Market Problems: One Bold Solution

Market Problem One: Industrial Price Erosion

Aztech Locknut Company had built its reputation over decades supplying the industrial marketplace with dependable locking hardware. But by the late 1990’s, industrial locknuts were becoming a commodity, eroded by direct import pricing that left U.S. producers struggling to compete on cost.

Market Problem Two: Strains on Available Supply

Starting in 1903, SPS Technologies built the North American market for high-performance all-metal prevailing torque locknuts, establishing its all-metal locknut as the specification standard every major OEM and aerospace program desired. The defense industry codified that locknut’s performance as the basis for NASM25027, not merely defining the market but becoming it. By the late 1990s, that success strained supply. Lead times stretched, prices spiked, and industrial customers with SPS-specified assemblies found themselves short, with no qualified substitute.

The Bold Solution: Aztech Locknut Company Enters the Market

Aztech management committed to the FlexSix in 1999, a NASM25027-compliant all-metal prevailing torque locknut that customers could qualify alongside the incumbent SPS locknut, delivering supply security without compromising performance. Capital equipment OEMs, agricultural machinery builders, power generation assemblers, and heavy-duty transportation manufacturers all operate where engineering requirements and quality obligations drive procurement, not unit cost. Since 1999, Aztech has built the tooling, processes, quality systems, and application knowledge to serve these customers at the highest level. What began as a response to an SPS supply gap became the foundation of a durable, import-resistant business.

When the Machine Doesn’t Exist, We Build It

The engineering challenge on the table
Producing the FlexSix demands a precise sequence of manufacturing operations, each dependent on the last, executed with exacting consistency across millions of cycles. Owner Mark Kaindl challenged Aztech’s engineering team to define machines that could produce the FlexSix at the highest possible rate without compromising functional precision. The engineers rose to the challenge, then came the hard reality: the equipment they described did not exist. No catalog, no vendor, and no off-the-shelf solution combined the speed, precision, and process-specific geometry the FlexSix demanded.

Proprietary equipment, built from first principles
Aztech’s engineering and fabrication teams went to work. Each machine in the FlexSix production sequence was conceived around the specific demands of its operation, forces involved, tolerances required, cycle rates targeted, and tooling interfaces needed to maintain consistency as tooling wears. Proven mechanisms were adapted; where existing technology fell short, new solutions were engineered from scratch. The result was a suite of proprietary manufacturing machines, each purpose-built for its role in the FlexSix production sequence, with tooling designed in tandem so that geometry, seating, and registration are engineered as a matched system.

The central tension in high-volume precision manufacturing is the conflict between throughput and consistency. Aztech’s machines resolve that conflict, building repeatability into the machine’s own geometry and process controls so that dimensional consistency is a function of the equipment itself. Precision is not monitored into the FlexSix. It is built in. The knowledge embedded in these machines, engineering decisions, process parameters, tooling geometry, production refinements accumulated since 1999, and lives entirely within the company. When a customer specifies the Aztech FlexSix, they are buying the output of machines that exist nowhere else in the world.

Credentials, Compliance, and Complete Product Range

The credential foundation: AS9100 and ISO 17025
Proving performance is as essential as delivering it. AS9100, the internationally recognized quality management standard for aviation, space, and defense, means every Aztech process, from incoming material verification through final lot release, operates within a documented, audited, continuously improved framework. For customers whose quality obligations flow down through their supply chain, an AS9100-certified supplier is a requirement, not a preference. ISO 17025 laboratory accreditation validates that Aztech’s dimensional verification and prevailing torque testing are performed to internationally accredited standards, so when Aztech certifies a lot to NASM25027, the test data carries the weight of an accredited laboratory.

Full NASM25027 compliance across the complete product range
NASM25027 is the governing military and aerospace specification for prevailing torque, all-metal self-locking nuts, the standard the defense industry wrote around the original SPS locknut’s performance. In 2019, Aztech FlexSix manufacturing achieved full NASM25027 compliance, verified and documented by the AS9100 quality management system and the ISO 17025-accredited laboratory. The FlexSix product range covers materials from mild steel through 1200° stainless steel and sizes from #6 through 2”. Raw material is sourced from approved US domestic and qualified imported suppliers based on the specific requirements of each order, US-origin where contract flow-downs require it, qualified imported sources for the broader industrial market.  

The FlexSix: six points of engagement
The all-metal prevailing torque locknut derives its locking action entirely from the geometry of the nut itself, the deflected metal “beams” that grip the bolt thread mechanically. Where conventional designs rely on other types of thread interference, the Aztech FlexSix engages the fastener across six discrete, engineered contact segments. Each flexible segment carries a proportional share of the induced load, producing a locking action that is secure, uniform, and repeatable. Six segments. Six points of prevailing torque. One reliable outcome is FlexSix.

Aztech FlexSix Product & Program

All-Metal — No Inserts To Soften At Temperature	Mild Steel Through 1200° Stainless Steel
Six-Beam Locking Geometry For Uniform Friction	Quality Management: AS9100 Registered
Superior Prevailing Torque Endurance	Laboratory Accreditation: ISO 17025
Impact, Shock, And Vibration Resistance	US Domestic And Qualified Imported Material
NASM25027 Compliance	Proprietary Manufacturing Equipment
Product Sizes #6 Through 2”	American-Made Since 1999