Solutions for general requirements for screws and nuts fasteners for electrical equipment (distribution boxes)

Solutions for general requirements for screws and nuts fasteners for electrical equipment (distribution boxes)

The screws usually used on the distribution box are galvanized screws, stainless steel screws, copper screws, and so on. Galvanized screws are iron screws with a galvanized surface to increase their corrosion resistance and durability. Stainless steel screws are mainly composed of precious metals such as chromium and nickel, which have high resistance to rust and corrosion and long service life. Copper screws, on the other hand, have the advantages of good electrical conductivity and strong oxidation resistance and are mainly used in electrical equipment. Grounding terminals, insulation screws on the distribution cabinet special grounding terminals, with connecting panels and boxes, play a role in grounding, Equipotential connection. Sheet metal parts fixed screw type. Screws used for fixing sheet metal parts usually have the following types:

1. Common threaded nails, i.e., ordinary screws, which are a common type of fixing because they are easy to find and have good availability, and are widely used in a variety of electronic equipment, machinery, and the automotive industry.

2. Self-tapping screws:  These can be fixed by penetrating directly into sheet metal parts as they have self-applied threads.

3. Expansion bolts: a locking mechanism that expands when pressurized and holds the part tightly in place, are a reliable fastening method often used in construction and mechanical equipment.

Sheet metal parts fixing screw specification selection: screw specification selection should be based on the thickness and material of the fixing material. Usually, the diameter of the screw is proportional to the thickness of the fixed material, and the length should be greater than or equal to the thickness of the fixed material. In addition, the material of the screws should be matched with the material of the sheet metal parts to ensure the angle and robustness.

4. To ensure that the special explosion-proof type distribution box or to prevent touching the exposed electrically charged parts of the fasteners, it is necessary to allow only the use of tools (such as screwdrivers, wrenches, etc.) to loosen or remove them.

5. If the material of the fastener screws and nuts is suitable for the housing material, the fastener screws and nuts for the housing containing light metal can be made of light metal or non-metallic materials.

6. Only if the shape of the threads is suitable for the material of the housing is it possible to tap screw holes in the housing for the installation of a cover that may be opened in the course of work.

Requirements of special fasteners: the pitch of thread, tolerance fit, bolt (nail) head, or nut should meet the requirements of relevant standards.

1. The pitch of the thread should be in line with the requirements of large-pitch metric threads, from the provisions of the standard thread series preferred, the nominal diameter range of 1mm ~ 64mm; thread tolerance should be in line with the 6g / 6H (the number indicates the tolerance level, the higher the precision of the value is smaller; the letter indicates that the position of the tolerance band, the external threads with a lower-case letter, the internal threads with a capital letter).

2. Standard parts by the standard requirements

3. Hexagonal bolts should meet the requirements of DIN933 or DIN931.

4. Hexagon socket head cap screws should meet the requirements of DIN912.

5. Hexagon socket set screws should be by DIN913 & ISO4026 (Hexagon Socket Set Screws With Dog Point), ISO40274 & DIN914 (Hexagon Socket Set Screws With Cone Point), ISO4027 & DIN915 (Hexagon Socket Set Screws With Dog Point), ISO40274&DIN914 (Hexagon Socket Set Screws With Cone Point), ISO4027&DIN915 (Hexagon Socket Set Screws With Dog Point) or ISO4029&DIN916 (Hexagon Socket Set Screws With Dog Point).

Alloy Steel Cup-Point Set Screws： Made from alloy steel, these set screws have a thin edge that digs into hard surfaces for a secure hold. The length listed is the overall length.

Black-oxide alloy steel set screws resist corrosion in dry environments.

Zinc-plated alloy steel set screws resist corrosion in wet environments.

Alloy Steel Extended-Tip Set Screws： Also known as half dog-point set screws, these set screws have a protruding tip that locks within a mating hole or slot to keep parts aligned. The length listed is the overall length. Black-oxide alloy steel set screws resist corrosion in dry environments.

Metric Alloy Steel Cone-Point Set Screws： Made from alloy steel, these set screws have a pointed tip that wedges into the contact surface for a secure hold on soft materials such as brass. The length listed is the overall length. Zinc-plated alloy steel screws resist corrosion in wet environments.

When using other bolts (nail) head or nut fasteners, explosion-proof equipment should be marked "X" in the product instruction manual for these fasteners in detail, explaining that only the same fasteners can be replaced.

Mil. Spec. High-Strength Steel Hex Head Screws: Choose these screws for their adherence to strict military standards for material and construction. Made from Grade 8 steel, they can be used in high-stress applications, such as valves, pumps, motors, and automotive suspension systems. They are at least 25% stronger than medium-strength steel screws. The zinc yellow-chromate plating resists corrosion in wet environments. The material meets ASTM A354BD and SAE J429 specifications for quality. Dimensions meet ASME B18.2.1 specifications. Grade 8 steel hex head screws are marked with six radial lines. Length is measured from under the head.

High-Strength Steel Hex Head Screws with Phillips Drive: When clearance for a wrench is limited, these screws have a Phillips drive so that you can install them with a screwdriver. With a tensile strength of 160,000 psi, they are stronger than Grade 8 screws and can be used in high-stress applications, such as valves, pumps, motors, and automotive suspension systems. The cadmium plating provides good corrosion resistance to salt water. Screws meet NAS (National Aerospace Standards) specifications for material and construction. Length is measured from under the head.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don't know the threads per inch. Fine threads are closely spaced to prevent loosening from vibration.

Medium-Strength Grade 5 Steel Square-Neck Carriage Bolts: Made from Grade 5 steel, these bolts are suitable for fastening most machinery and equipment. A square neck keeps them from turning when tightening a nut. A smooth, rounded head provides a finished look. Grade 5 steel bolts are marked with three radial lines. The material meets SAE J429 specifications for quality. Dimensions meet ASME B18.5 specifications. Length is measured from under the head.

Black-oxide steel screws are mildly corrosion-resistant in dry environments. Zinc-plated steel screws resist corrosion in wet environments. Zinc-flake-coated steel screws are 40 times as corrosion-resistant as zinc-plated screws and comparable to Magni-coated screws.

18-8 Stainless Steel Square-Neck Carriage Bolts: Made from 18-8 stainless steel, these bolts have good chemical resistance and may be mildly magnetic. They are a good choice for ACQ-treated (arsenic-free) lumber. A square neck keeps them from turning when tightening a nut. A smooth, rounded head provides a finished look. Length is measured from under the head. Dimensions meet ASME B18.5 or DIN 603 specifications. Some also meet ISO 8678. DIN 603 is functionally equivalent to ISO 8678, with slight differences in head diameter, height, and length tolerances.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don't know the pitch or threads per inch. Fine threads are closely spaced to prevent loosening from vibration.

 Please contact our team if you need high-quality steel hexagonal head screws with more detailed specifications and related information.

Email:adelajonly@gmail.com,www.juxinfasteners.com.

6. The thread tolerance of memorable fastener holes shall be by 6H and meet the following conditions.

a) The hole below the bolt's head should be no larger than the size requirements of the medium assembly of H13; that is, the gap should be no larger than the maximum clearance permitted by the medium assembly of H13 (for example, M6 bolts with the hole diameter should be no larger than Ф6.6).

b) Fine rod bolt head (or nut) below the hole should be tapped to ensure the bolt does not fall off. The screw hole size should ensure that the contact area with the connected parts is at least equal to the contact area of non-fine rod bolts in the light hole (Figure 3 in the "X" ring contact part). The fine rod fastening bolts and connected parts of the contact size X should not be less than the full threaded bolts (see Figure 2) contact size.

7. Hexagon socket set screw requirements: used to fasten the threaded cover of the hexagon socket set screw (such as anti-loosening purposes), the thread tolerance should be in line with the 6g / 6H, and the tightening after the screw hole can not be protruding from the screw. The selection of the appropriate screw material is an essential factor in ensuring the safety of using the distribution box. Suppose the screw material used is not suitable. In that case, it may lead to oxidization, corrosion, degradation of electrical properties, and other problems, thus affecting the operation of the entire power distribution system. For example, if ordinary iron screws are used to fix the cable, oxidation, and rusting may occur over time, resulting in the reduced contact area and increased resistance, which in turn leads to poor contact, line instability, and other problems, and in severe cases may even cause fire and other dangers. When choosing high-strength screws and nuts for distribution boxes, it is necessary to select the appropriate screw material according to the actual demand and the use environment. Be sure to pay attention to the specifications, size, and other parameters of the screws to ensure that they can securely hold the cables, sockets, and other equipment.