Product Overview
The Shoulder Nut is a specialized, one-piece fastener combining the functions of a standard hex nut and a precision-machined, unthreaded cylindrical shoulder (or collar). This integrated shoulder provides a precise bearing surface, acts as a spacer or stand-off, and ensures accurate axial location when assembled onto a shaft, rod, or stud. It is engineered for applications requiring exact component positioning, protection of threads from shear loads, and a secure anti-rotation mechanism.
Key Advantages
Precise Axial Positioning: The machined shoulder provides a consistent, reliable stop for mounted components, eliminating the need for separate spacers or shims.
Enhanced Load Distribution: The smooth, unthreaded shoulder offers an ideal bearing surface, distributing loads evenly and protecting delicate or fine-pitch threads from damage.
Anti-Rotation & Alignment: The shoulder can be designed with a close tolerance fit within a bore or against a flat, preventing the nut from rotating and ensuring proper component alignment.
Streamlined Assembly: Replaces multiple parts (nut + washer + spacer), simplifying the bill of materials (BOM) and accelerating assembly.
Thread Protection: Isolates the threaded portion from bending moments and radial forces, extending the service life of both the nut and the mating bolt.
Material Specifications & Grades
| Material Standard | Grade / Alloy | Typical Hardness | Characteristics |
|---|---|---|---|
| Acero al carbono | Grade 5 / 8.8 | HRC 22-32 (Heat Treated) | General purpose, cost-effective, suitable for high-strength applications. |
| Alloy Steel | Grade 12.9 / ASTM A574 | HRC 39-44 | Premium strength for the most demanding mechanical and structural loads. |
| Stainless Steel | ASTM A304 (A2) / 316 (A4) | – | Excellent corrosion resistance for harsh or hygienic environments. |
| Brass | C36000 | – | Good conductivity, corrosion resistance, and non-magnetic properties. |
| Aluminum | 6061-T6 | – | Lightweight, corrosion-resistant, and easily machinable. |
Product Series & Technical Specifications
Standard Series: Available in both metric and imperial sizes. The shoulder diameter, length, and thread are precisely controlled to tight tolerances.
Drive Types: Typically feature a Hex (across flats) or Flanged Hex profile for wrench tightening.
Thread Standards: Internal threads are precision-cut or tapped to ISO (Metric) or UNC/UNF (Imperial) standards.
Shoulder Features: Can be supplied plain, knurled for hand-tightening applications, or with specific finishes (e.g., ground, anodized).
Common Sizes: Shoulder Diameters: From 6mm to 50mm (or equivalent). Thread Sizes: Commonly M3 to M24, #4-40 to 1″.
Available Surface Finishes
| Finish Type | Specification / Process | Primary Benefit |
|---|---|---|
| Zinc Plated (Blue/Yellow/Trivalent) | ASTM B633 | Economical corrosion protection for steel components. |
| Electroless Nickel Plating (ENP) | MIL-DTL-32119 | Uniform, hard coating offering excellent corrosion and wear resistance. |
| Hot-Dip Galvanized | ASTM A153 | Heavy-duty protection for outdoor or corrosive environments. |
| Black Oxide | MIL-DTL-13924 | Provides mild corrosion resistance, reduces glare, and improves appearance. |
| Passivation (Stainless Steel) | ASTM A967 | Maximizes the inherent corrosion resistance of stainless steel. |
| Anodizing (Aluminum) | MIL-A-8625 | Provides durable corrosion protection and optional color coding. |
| Chrome Plating (Decorative) | – | Hard, bright finish for wear resistance and aesthetics. |
Typical Applications
Automated Machinery: For precise positioning of gears, bearings, sensors, and actuators on shafts.
Automotive & Transportation: In throttle linkages, suspension components, and transmission assemblies.
Printing & Textile Machinery: For mounting rollers and cylinders with exact axial location.
Aerospace & Defense: In control mechanisms and instrumentation where reliability and precision are critical.
Medical & Food Equipment: As adjustable stops or mounting points in hygienic designs (using stainless steel).
Quality Assurance
Our shoulder nuts are manufactured under a certified ISO 9001:2015 quality management system. Critical dimensions—including shoulder diameter and concentricity, length, and thread fit—are rigorously inspected using coordinate measuring machines (CMM) and optical comparators. Material and heat-treatment certifications are maintained for full traceability.
Manufacturing Expertise
Produced by Hebei Wohe Fastener Manufacturing Co., our shoulder nuts are machined from certified bar stock on CNC lathes and milling centers. This process ensures the high precision and fine surface finish required for the shoulder’s bearing function. Our expertise in precision machining and secondary operations allows us to meet the exacting specifications of OEMs in the automation, transportation, and specialty machinery sectors worldwide.
Availability: Standard configurations can be supplied from stock or semi-finished inventory.
Customization: We specialize in custom shoulder diameters, lengths, thread specifications, and special features (e.g., grooves, holes, unique markings).
MOQ: Prototype and small-batch production is supported. Production MOQs are negotiable based on complexity.
Lead Time: Standard items: 15-20 days. Custom-engineered parts: 25-35 days based on drawing review.
Note: For optimal performance, the mating component’s bore should be machined to a tolerance that provides the desired fit (sliding, press, etc.) with the shoulder. Always specify the required shoulder fit and thread engagement length when ordering. Specifications subject to change without notice.
