How do Auto Parts Screws meet the requirements of fastening force and reliability in different scenarios?

Auto Parts Screws need to meet diverse fastening force and reliability requirements in different application scenarios. This depends on factors such as the material, design, surface treatment, and installation method of the screw. The following are specific ways to meet the needs of different scenarios by optimizing these aspects:

Choose the right material
High-strength materials
For scenarios with high loads or dynamic stresses (such as engine cylinder head screws), use high-strength alloy steels (such as 40Cr, 45# steel) to provide higher tensile strength and fatigue strength.
In high-temperature environments (such as exhaust system connections), choose heat-resistant alloy steels or stainless steels to ensure that the screws can maintain performance under extreme temperatures.
Lightweight materials
In scenarios where lightweight is pursued (such as body structure connections), aluminum alloy or titanium alloy screws are used to reduce weight while ensuring sufficient strength.
Use composite material (such as carbon fiber reinforced plastic) screws to further reduce weight while improving corrosion resistance.
Corrosion-resistant materials
In humid or multi-chemical environments (such as chassis component connections), choose stainless steel or zinc/nickel-plated screws to enhance corrosion resistance.
Optimize screw design
Thread design
Choose the appropriate thread type (such as coarse or fine pitch) according to the load characteristics. Fine pitch threads are suitable for scenarios with high precision and high locking force requirements, while coarse pitch threads are more suitable for quick assembly.
Add self-locking functions (such as double-start threads or tapered threads) to prevent loosening due to vibration.
Head shape
Choose the appropriate head shape (such as hexagonal head, hexagon socket, cylindrical head, etc.) according to the installation space and tool compatibility. For example, hexagon socket screws are suitable for narrow spaces, while hexagon head screws are easy to operate manually.
Length and diameter
Accurately calculate the length and diameter of the screw to ensure that it can provide sufficient clamping force without exceeding the yield limit of the material.
Use short and thick screws for thin plate connections and long and thin screws for thick plate connections.
Surface treatment and coating

Anti-corrosion coating
Use electroplating zinc, Dacromet coating or phosphate coating to improve the corrosion resistance and wear resistance of the screw.
In extremely corrosive environments (such as marine environments), choose stainless steel screws or spray ceramic coating.
Friction coefficient control
Lower the friction coefficient through lubricating coatings (such as PTFE coatings), reduce torque fluctuations during tightening, and ensure uniform clamping force.
Use molybdenum disulfide coatings in high temperature environments to provide better lubrication.
Anti-loosening design
Add spring washers or nylon inserts to increase friction to prevent screws from loosening.
Use chemical anti-loosening agents (such as anaerobic adhesives) to form a strong bonding layer at the screw connection.
Installation process optimization
Precise torque control
Use a torque wrench or electric tightening tool to ensure that the tightening torque of the screw meets the design requirements and avoid over-tightening or over-loosening.
Achieve consistent clamping force and improve connection reliability by presetting torque values.
Preload management
Use a multi-stage tightening process in key areas (such as engine cylinder head screws) to gradually increase torque to reduce stress concentration.
Use a tensiometer to measure the actual elongation of the screw to ensure that the ideal preload is achieved.
Anti-vibration design
In scenarios with large vibrations (such as suspension systems), use designs with anti-vibration washers or stud nuts to enhance connection stability.

By selecting suitable materials, optimizing design, improving surface treatment and optimizing installation process, automotive parts screws can effectively meet the requirements of fastening force and reliability in different scenarios.