At HETAI, quality inspection is an essential part of our custom fastener manufacturing process. We use a combination of dimensional inspection, thread inspection, material verification, mechanical testing, and surface quality checks to ensure that custom fasteners meet customer drawings, technical specifications, and application requirements.

The inspection methods depend on the product’s design, material, manufacturing process, required tolerances, and intended application.

1. Dimensional Inspection

Dimensional inspection verifies that each custom fastener matches the dimensions specified in the engineering drawing. Our inspection may include checking:

• Overall length and diameter
• Head dimensions and shape
• Thread diameter and pitch
• Shoulder, groove, slot, and chamfer dimensions
• Critical tolerances and geometric features

Common measuring instruments include digital calipers, micrometers, height gauges, optical measuring equipment, and coordinate measuring machines (CMM). Appropriate instruments are selected according to the required measurement accuracy and part geometry.

2. Thread Inspection

Thread accuracy is critical to proper assembly and reliable fastening. HETAI checks external and internal threads to verify that they meet the specified thread standards and dimensions.

Inspection tools may include:

• Thread ring gauges for external threads
• Thread plug gauges for internal threads
• Thread pitch gauges
• Optical measuring instruments for special thread profiles

We can inspect metric, inch, and customized threads according to the customer’s requirements.

3. Material Verification

The material used in a custom fastener directly affects its strength, hardness, corrosion resistance, and service life. HETAI verifies material specifications according to the purchase requirements and applicable standards.

Depending on the project, material verification may involve checking material certificates, supplier documentation, material identification, and chemical composition through appropriate testing methods.

Common materials include carbon steel, alloy steel, stainless steel, brass, aluminum, and other engineering materials.

4. Mechanical Property Testing

For fasteners that require specific mechanical performance, we conduct or arrange appropriate tests based on the product specifications and applicable standards.

These tests may include:

• Hardness testing
• Tensile strength testing
• Yield strength testing
• Proof load testing
• Other mechanical tests required by the drawing or relevant standard

For example, when manufacturing high-strength fasteners such as property classes 8.8, 10.9, or 12.9, the relevant mechanical requirements must be verified according to the applicable standard and product specifications.

5. Surface Treatment and Appearance Inspection

Surface treatment can influence corrosion resistance, appearance, and service performance. Depending on the selected finish, inspection may include checking coating thickness, surface uniformity, color consistency, and visible defects.

For projects with specific corrosion-resistance requirements, suitable corrosion tests, such as salt spray testing, may also be arranged according to the agreed specification.

6. Final Inspection Before Delivery

Before shipment, finished custom fasteners undergo final inspection according to the agreed quality requirements. This may include dimensional sampling, thread checks, appearance inspection, quantity verification, and packaging checks.

For critical components or projects with special quality requirements, HETAI can establish a more detailed inspection plan based on the customer’s drawings and acceptance criteria.

How Does HETAI Ensure Custom Fastener Quality?

As a custom fasteners manufacturer with over twenty years of experience, At HETAI, quality control is not limited to the final inspection stage. It is considered throughout the manufacturing process, from reviewing customer drawings and selecting materials to production monitoring and final product inspection.

To help us establish the right inspection plan, customers can provide 2D drawings, 3D CAD models, material specifications, required tolerances, applicable standards, and any special testing requirements.

HETAI has manufactured custom fasteners and precision hardware components since 2001. We work with customers to ensure that every product is inspected according to its design, technical requirements, and intended application.