Short Neck Carriage Bolt

A short neck carriage bolt is a round-head fastener with a reduced square section directly beneath the head. It is used in assemblies where clearance beneath the bolt head is limited and a matching square hole is required to resist rotation during nut tightening.

Compared with a conventional carriage bolt, the shorter square neck is intended for applications involving thinner mating sections. Correct selection depends on the square neck height, plate thickness, hole geometry, bolt length, and required mechanical properties.

These fasteners are used in sheet metal assemblies, equipment frames, access panels, and other mechanical connections. They are available in metric and inch thread sizes, with material and surface finish options selected according to the application and applicable specifications.

Short Square Neck: The reduced square section accommodates assemblies with limited clearance beneath the bolt head. Neck dimensions must match the mating component.

Rounded Head Profile: The domed head provides a smooth external profile without the exposed edges of a conventional hexagonal bolt head.

Anti-Rotation Engagement: When the square neck fits a compatible square opening, it helps resist bolt rotation while the nut is tightened.

Material Options: Carbon steel and stainless steel options can be selected according to the required strength class, corrosion environment, and applicable fastener standard.

Surface Finish Choices: Available finishes may include zinc plating, hot-dip galvanizing, and other specified coating systems, depending on the material, dimensions, and manufacturing requirements.

Dimensional and Ordering Information
The thread diameter and bolt length are not sufficient to determine interchangeability. Buyers should specify the head diameter, head height, square neck width, square neck height, thread length, and required dimensional tolerances.
DIN 603, ISO 8678, and ASME B18.5 should be listed only when the actual product dimensions conform to the corresponding standard. Metric and inch thread systems should be specified separately, and material grades and surface finishes should match the selected fastener specification.

Square Neck Height and Plate Thickness

Check the neck height against the thickness and geometry of the mating component. The head should seat correctly, and the neck should engage the intended square opening without interfering with the assembly.

Hole Dimensions and Tolerances

The square opening must match the specified neck width and corner geometry. An oversized opening may permit unwanted movement, while an undersized opening may prevent installation.

Material and Property Class

Select carbon steel or stainless steel according to the required mechanical properties, corrosion conditions, and applicable fastener specification. Structural applications require engineering assessment of the complete joint rather than selection by property class alone.

Bolt Length and Thread Engagement

Determine the required length from the combined thickness of the connected components, washers, and nut engagement requirements. Confirm thread length and available clearance before ordering.

Surface Finish and Corrosion Requirements

Choose a coating based on exposure conditions, corrosion requirements, and compatibility with the base material. For high-strength fasteners, verify coating-related hydrogen embrittlement controls and any applicable process requirements.

For a quotation, provide the applicable standard or drawing, thread size, bolt length, square neck dimensions, material grade, surface finish, order quantity, and delivery destination. Drawings and annual demand estimates help determine the appropriate product configuration and supply requirements.

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