Interpretation of how to look at the quality of the combination screw

The quality of a combination screw starts with the wire used in its construction. The screw wire is the first critical factor in determining the overall quality of the combined screw. If the wire is substandard, even the most advanced production equipment and skilled workers won’t be able to create high-quality combination screws.

Next, the appearance of the combination screw is an important indicator of its quality. A well-made combination screw should have a properly sized head, a flat washer that sits smoothly, and threads that pass the stop gauge test. These details must be carefully inspected. A good combination screw should meet either national standards or specific customer requirements in terms of size, finish, and performance.

Lastly, the plating color is another aspect to consider. While iron-based combination screws typically require plating, stainless steel ones are usually passivated to improve their corrosion resistance. Poorly controlled plating can lead to significant color variations, which may affect the aesthetics of the product.

Key Considerations When Installing High-Strength Bolts

1. Quality Matters to Pay Attention To

(1) Any surface rust, oil stains, burrs on the bolt hole walls, or welding protrusions should be thoroughly cleaned before installation.

(2) After treating the friction surface, it must meet the required coefficient of friction. High-strength bolts must be accompanied by matching nuts and washers.

(3) During installation, the treated friction surface must remain free from oil, dirt, or other contaminants.

(4) Keep the friction surface dry during installation and avoid using it in rainy conditions.

(5) Before installation, check and correct any deformation in the connected steel plates.

(6) Avoid hammering the bolt during installation to prevent thread damage.

(7) Regularly calibrate the electric wrench to ensure accurate torque and follow the correct tightening sequence.

2. Main Safety Technical Measures

(1) Use an adjustable wrench that matches the nut size. Never use a small wrench with an extension sleeve. For high-altitude work, use a dead wrench and secure it with a rope if necessary.

(2) When assembling connecting bolts on steel components, never insert your hands into the connection surface or the screw hole. When removing the horn plate, keep your fingers on both sides of the plate.

Overview of Locknut Characteristics and Application Range

A nut is a mechanical component used to fasten two parts together. It connects with a screw of the same thread size. For example, an M4-0.7 nut is only compatible with an M4-0.7 screw (where M4 refers to the inner diameter of about 4mm, and 0.7 indicates the pitch between threads). Similarly, American nuts like 1/4-20 match with 1/4-20 screws (with an inner diameter of approximately 0.25 inches and 20 threads per inch).

The DISC-LOCK locknut consists of two parts with staggered cam mechanisms. Its internal wedge design has a slope angle greater than the bolt’s nut angle, allowing it to tightly grip when vibration occurs. The convex parts of the locknut shift, creating tension that prevents loosening effectively.

Key Features: Easy to install; durable; no need for washers; easy to remove; reusable; made from medium carbon steel; compatible with high-strength bolts such as 8.8 and 10.9; tested under US military MIL-STD 1312 vibration tests; passed Junker and dynamic tests.

Applications: Automotive (cars, trucks, buses), compressors, construction machinery, wind power equipment, agricultural machinery, foundries, drilling tools, shipbuilding, military, mining equipment, oil rigs (onshore or offshore), public infrastructure, rail transit, transmission systems, metallurgical equipment, rock hammers.

Rivet Nut and Its Characteristics

A rivet nut, also known as a self-locking nut, is designed for use on thin sheets or sheet metal. It has a circular shape with embossing teeth and a guiding groove at one end. The principle involves pressing the embossing teeth into a pre-drilled hole in the sheet metal. The hole is slightly smaller than the rivet nut’s teeth, and pressure causes the nut to deform the surrounding material, locking it in place. Rivet nuts come in different types, such as S-type for fast-cut steel, CLS-type for stainless steel, SP-type for stainless steel, and CLA-type for copper and aluminum, each suited for different environments. They are commonly used in chassis cabinets and sheet metal applications, with sizes ranging from M2 to M12.

Difference Between Screws and Bolts

Screws and bolts serve different purposes. Screws are typically used to fasten fixed parts and are easy to install and remove. They generally have lower strength compared to bolts. Bolts, on the other hand, are stronger and are often used in load-bearing applications. In addition to fastening, they can withstand higher forces. A well-designed system allows bolts to handle tension or compression without being subjected to shear stress. Most screws are threaded into holes in a part, while bolts are usually tightened with a nut. Of course, exceptions exist, but they should be used with care and flexibility.