At HETAI, inspection is an essential part of our custom fastener manufacturing process. Because custom fasteners are manufactured according to specific customer drawings, samples, and technical requirements, inspection equipment must be selected according to the product’s dimensions, thread specifications, material, mechanical requirements, surface treatment, and application.

Different types of inspection equipment are used throughout production to ensure that custom bolts, screws, nuts, studs, pins, and other precision hardware meet the required specifications.

What equipment is used to inspect the dimensions of custom fasteners?

For dimensional inspection, HETAI commonly uses vernier calipers, micrometers, height gauges, and other precision measuring instruments. These tools can be used to check critical dimensions such as overall length, head diameter, shaft diameter, thickness, hole diameter, and other geometric features.

For components requiring tighter dimensional control, digital micrometers and high-precision measuring equipment can provide more accurate measurements. Depending on the manufacturing process and product requirements, HETAI can achieve approximately ±0.01 mm for suitable standard cold-forged fasteners, while CNC-machined custom fasteners may achieve approximately ±0.005 mm. Precision hardware components processed by grinding may reach approximately ±0.002 mm on suitable features and applications.

How are threads inspected?

Thread inspection is particularly important for custom fasteners because thread dimensions directly affect assembly and compatibility.

HETAI uses thread plug gauges, thread ring gauges, thread pitch gauges, and other thread inspection tools to check internal and external threads. These gauges can help verify whether the thread conforms to the specified diameter, pitch, tolerance, and functional requirements.

For special or non-standard threads, inspection methods may be selected according to the customer’s drawings and technical specifications.

What equipment is used for complex dimensions?

For precision components with multiple critical dimensions or complex geometries, CMMs (Coordinate Measuring Machines) and other advanced dimensional inspection equipment can be used. A CMM can measure multiple features and positions based on a defined coordinate system, making it useful for precision custom fasteners and machined hardware.

Optical measuring equipment may also be used for small or complex features that are difficult to measure accurately with conventional tools.

How are mechanical properties inspected?

Dimensional accuracy is only one part of fastener quality. Depending on the material and required grade, mechanical properties such as tensile strength, hardness, and other relevant characteristics may also need to be verified.

For applicable products, inspection may involve hardness testers, tensile testing machines, and other material-testing equipment. This is particularly important for high-strength fasteners such as grade 8.8, 10.9, and 12.9 products.

How are surface treatments inspected?

Surface treatment is also inspected according to customer requirements. Depending on the coating or finish, inspection may include checking surface appearance, coating thickness, corrosion resistance, and other specified properties.

For example, coating thickness can be measured using appropriate coating-thickness gauges, while corrosion resistance may be evaluated through the required testing method.

Inspection is based on the product requirements

At HETAI, we do not use the same inspection method for every custom fastener. The inspection plan is determined by the drawing, material, manufacturing process, dimensional tolerances, thread specifications, surface treatment, mechanical requirements, quantity, and final application.

Our goal is to ensure that every batch of custom fasteners is not only dimensionally accurate but also suitable for the customer’s actual assembly and operating requirements. From incoming material inspection and in-process inspection to final inspection before shipment, HETAI uses appropriate measuring and testing equipment to maintain consistent product quality.