PZ Recessed Countersunk Head Self-extruding Screw

The PZ recessed countersunk head self-extruding screw is a commonly used fastener in mechanical connections. The following is the relevant information about it:

Structural Characteristics of the PZ Recessed Countersunk Head Self-extruding Screw

Head: It is designed as a countersunk head, which is flat and has an inclined surface around it. After installation, it can be flush with or slightly lower than the surface of the connected part, reducing the impact on other components and having a high aesthetic degree. The PZ recess design on the head can provide better torque transmission compared with the cross recess. Moreover, when using a screwdriver to turn it, it is not easy to slip, making the installation and disassembly more reliable.

Screw Shank: Similar to other self-extruding screws, there is a section of thread with an arc-shaped triangular cross-section at the end of the thread. When screwing into the pre-drilled hole, the three vertices of the triangular cross-section will apply intermittent and periodic pressure to the side wall of the pre-drilled hole, causing the base material on the inner wall of the pre-drilled hole to be extruded and pushed into the thread flanks and the root of the thread along the thread lead, thus forming an internal thread.

Advantages of the PZ Recessed Countersunk Head Self-extruding Screw

Low Screw-in Torque: Compared with self-tapping screws, self-extruding screws form internal threads by extrusion during the screwing-in process, while ordinary self-tapping screws form internal threads by cutting. Therefore, the screw-in frictional resistance of the PZ recessed countersunk head self-extruding screw is much lower than that of ordinary self-tapping screws, and it can be assembled on a thicker section.

High Locking Performance: When the screw is screwed in, the triangular cross-section at the tail of the thread extrudes the metal to form an internal thread. According to the laws of the minimum resistance of metal plastic deformation and the invariance of volume, the extruded metal fills into the screw threads along the thread lead. The thread fit clearance of this assembly structure is small, and it can even achieve the effect of the metal "locking" the screw, which has a good anti-loosening performance.

Good Appearance Effect: The countersunk head design makes the surface flat and beautiful after installation, which is suitable for occasions with high requirements for surface flatness and aesthetics. At the same time, compared with other recess types, the PZ recess is more delicate in appearance.

Application Scenarios of the PZ Recessed Countersunk Head Self-extruding Screw

Electronic Devices: It is widely used in the assembly of the casings of electronic products such as computers, mobile phones, and tablets, and the fixing of internal circuit boards. Its low screw-in torque can avoid damaging fragile electronic components, and its high locking performance can ensure that the screws will not loosen due to vibrations during the use of the devices. Moreover, the countersunk head design helps to keep the casings of electronic products flat and beautiful.

Furniture Manufacturing: It is often used in the assembly of furniture such as tables, chairs, and cabinets to connect wood materials. After installation, the surface is flat, making the furniture look more delicate. At the same time, the good locking performance can ensure the structural stability of the furniture and enable it to withstand various stresses in daily use.

Automobile Manufacturing: It can be used for the connection of automobile bodies and internal components, seat installation and other parts. It can withstand the vibrations and various stresses during the driving process of the vehicle, ensuring the reliability and safety of the connection. The countersunk head design is also beneficial to the aesthetics of the vehicle interior and the consistency of the overall style.

Other Fields: It is also applied in some industries with high requirements for appearance, such as machinery manufacturing, instrument manufacturing, and the connection of some decorative components in building decoration, etc., which can meet the dual requirements of connection strength and appearance in these fields.

Selection Method of the PZ Recessed Countersunk Head Self-extruding Screw

Selection According to the Material: For materials such as non-alloy, low-alloy, aluminum and aluminum alloys, copper and copper alloys (with a copper content greater than 63%), and zinc and zinc alloys with a tensile strength σb ≤ 600 N/mm², PZ recessed countersunk head self-extruding screws of ordinary materials can usually be selected. For materials with poor plastic deformation ability or prone to work hardening, such as stainless steel, gray cast iron, and magnesium alloy, they can also be used under certain usage conditions, but a cautious evaluation is required. If there is a risk of corrosion in the usage environment, such as in a humid environment or when in contact with corrosive media, screws made of stainless steel should be selected.

Selection According to the Specification: Determine the appropriate diameter and length specifications according to the thickness of the connected part and the requirements for the connection strength. Generally, when the connected part is thicker or a greater connection strength is required, screws with a larger diameter and a longer length should be selected; conversely, screws with smaller specifications should be selected. At the same time, it is necessary to ensure that the length of the screw is sufficient to completely pass through the connected part and form an effective connection, but it should not be too long to avoid excessive exposure, which will affect the appearance or cause potential safety hazards.

Installation Key Points of the PZ Recessed Countersunk Head Self-extruding Screw

Pre-drilled Hole Processing: Before installation, a suitable pre-drilled hole needs to be processed according to the screw specification and the material of the connected part. The diameter of the pre-drilled hole needs to be precisely controlled. The diameter of the pre-drilled hole varies slightly for base materials of different materials and thicknesses to ensure the fitting effect between the screw and the pre-drilled hole.

Ensure the Surface is Clean: Clean the surface of the connected part thoroughly to remove impurities such as oil stains, dust, and rust, ensuring good contact between the screw and the surface and improving the reliability of the connection.

Screw in Vertically: Use a suitable screwdriver or electric tool to screw the screw vertically into the surface of the connected part, avoiding tilting or eccentricity, otherwise it may lead to thread damage or an insecure connection. If an electric tool is used, pay attention to controlling the rotation speed and torque to prevent damage to the screw or the connected part due to too high a rotation speed or too large a torque.

Control the Screw-in Depth: According to the thickness of the connected part and actual needs, control the screw-in depth of the screw well. Avoid screwing in too deeply, which may cause the screw to penetrate the connected part or damage the internal structure, and do not screw in too shallowly to avoid an insecure connection.