NITTOSEIKO CO., LTD. Product Lineup

”CP-Grip(R)" is a coating to solve the contamination problem. This coating consists of microcapsules filled with a viscus liquid. During fastening, micro-capsules are broken and release the viscous liquid inside, and capture the metal chips. ■ Catch the chips generated during fastening → Prevents scattering and dropping of chips ■ Reduce friction with the mating material → Lower thread forming torque, enabling a wider torque range → Maintains stable proper fastening torque even with variations in pilot hole size → Prevents galling *For more information, please refer to the catalog. Feel free to contact us with any questions.

Self-tapping screws that reduce the disturbance of carbon fibers during screwing into CFRP, suppress strength degradation, and enable stable fastening. ■ Self-tapping fastening Achieves stable self-tapping even in CFRP Simplifies the manufacturing process ■ Weight reduction and cost reduction Eliminates the need for insert nuts and tapping Achieves product lightweighting and cost savings ■ Excellent versatility Usable not only for CFRP but also for CFRTP, as well as resins and metals *For more details, please download the PDF document or feel free to contact us.

Self-tapping screws that have undergone carburizing hardening are further subjected to high-frequency hardening only at the tip. This achieves stable, high-quality self-tapping for high-strength materials such as "High Tensile 150" and stainless steel plates. 【Features】 ■ The tip is hard, allowing for self-tapping in high-tensile materials. ■ The risk of delayed fracture is suppressed to a level equivalent to carburizing hardening. ■ Supports total cost reduction by eliminating the need for tapping processing. *For more details, please download the PDF document or feel free to contact us.

1. The tightening surface becomes flat, allowing for the layering of components. This will further miniaturize mechanical parts of AV equipment. 2. There is no need for measures to eliminate the protrusion of the head, such as counterboring or pressing. 3. It reduces discomfort in appearance and touch, making it suitable for use in product exteriors. *For more details, please download the PDF document or feel free to contact us.

Solve loosening concerns in self-tapping into plastic materials! "GIZATITE(R)" is a self-tapping screw for plastic designed to provide excellent anti-loosening performance by utilizing the deformation of the plastic during tapping process. By providing grooves to the thread, the deformed plastic flow into the grooves during self-tapping, creating resistance against reverse rotation and prevent loosening. Even under severe conditions such as expansion and contraction of the plastic due to temperature changes or reverse rotation caused by vibrations, the wedge effect of the plastic entering the grooves delivers outstanding anti-loosening performance. *For more details, please download the catalog or feel free to contact us.

The combination of the "New Generation Self-Tapping Screw Tap Tight® 2000" and the "Friction Coefficient Stabilizer Flix®" will change the future of self-tapping fastening! By merging the rice ball shape (triangle) with an innovative curved thread profile, we enhance mechanical properties, fastening performance, and workability. This screw elevates fastening performance to a new dimension. We also offer a different specification product that can self-tap into high-tensile materials (strength classification 10.9). 【Features】 ■ Achieves self-tapping with high-tension bolts (strength classification 10.9) ■ Exhibits high axial force equivalent to bolt fastening ■ Reduces variation in axial force, enabling reliable tightening ■ Total cost reduction through self-tapping *For more details, please download the PDF document or feel free to contact us.

"ALUMITITE(R)" prevents galling that can occur during self-tapping into soft metals such as ADC. 【Features】 ■ Prevent of galling with the mating material ■ Lower fastening torque ■ High anti-loosening effect *For more information, please refer to the catalog. Feel free to contact us with any questions.

"AKROSE (Akurozu) HYBRID(R)" is a bonding technology that shapes materials using cold forging techniques, then strengthens the bonding between those materials through pressing, and further enhances the adhesion at the atomic level through diffusion bonding. It is suitable for dissimilar bonding of metals such as iron, stainless steel, aluminum, and copper, achieving high adhesion and bonding strength at the bonding interface. Since specialized equipment or jigs are not required during heat treatment, manufacturing costs can be reduced, making it suitable for mass production. 【Features】 ■ Enables product creation that leverages the characteristics of the materials used, such as strength and conductivity ■ Contributes to lightweight, high-functionality, and cost reduction of products ■ No pre-treatment required even for materials that are difficult to bond through diffusion, such as aluminum *For more details, please download the PDF document or feel free to contact us.

The "Colorless Tight (R)" features two types of screw threads with different nominal diameters aligned on the same axis (with a common pitch), allowing for self-tapping in the threaded sections of both the workpiece and the counterpart material. This action prevents loosening and play in the workpiece when axial force decreases or creep occurs. As a result, the measures against creep that were previously implemented using iron collars or insert nuts become unnecessary, leading to reductions in cost and labor, as well as a lightweight fastening structure. 【Features】 ■ Reduces loosening after axial force decrease and creep ■ Achieves lightweight products ■ Reduces fastening costs ■ Prevents misalignment as the screw itself ensures alignment, eliminating the need for positioning pins or similar tools ■ Allows for initial fastening through axial force *For more details, please refer to the PDF document or feel free to contact us.

Screw fastening refers to the process of fastening two or more components using screw parts. This document summarizes the surrounding knowledge of "screw fastening" in an easy-to-understand manner using illustrations. If you have any concerns regarding screws, please feel free to consult our company, which has world-class screw production capabilities. [Contents] ■ What is screw fastening ■ Examples of screw fastening ■ Problems caused by over-tightening Others *For more details, please refer to the PDF document or feel free to contact us.

This document explains various parts and names of screws, as well as their dimensions, using illustrations and photographs. If you have any issues related to screws, please feel free to consult with us, a company with world-class screw production capabilities. 【Contents (partial)】 ■ Parts of a screw ■ Names of screws ■ Commonly used names and dimensions * On this page, you can also download the document "Knowledge of Screws - About Screw Fastening." * For more details, please refer to the PDF document or feel free to contact us.

This document explains the differences between machine screws, tapping screws, and tap-tight screws. We will introduce the characteristics of each type of screw in detail. If you have any issues related to screws, please feel free to consult with us, a company with world-class screw production capabilities. 【Contents】 ■ Machine Screws ■ What are Tapping Screws? ■ What are Tap-Tight Screws? * You can also download the document "Knowledge of Screws - Commonly Used Head Shape Dimensions" from this page. * For more details, please refer to the PDF document or feel free to contact us.

The head of a screw has various functions such as workability, weight reduction, and resistance to loosening. In this document, we introduce commonly used head shapes and publish the dimension tables for the very important size 0 and JIS head shapes for quality control. If you have any concerns regarding screws, please feel free to consult with us, a company with world-class screw production capabilities. [Contents] ■ Dimensions of size 0 cross-recessed head shape ■ Dimensions of JIS head shape * On this page, you can also download the document "What is the difference between small screws, tapping screws, and tap-tight screws?" * For more details, please refer to the PDF document or feel free to contact us.

"Cold forging" is a processing technology that applies pressure to metal at room temperature to deform and shape it. Compared to cutting processes, it generates almost no material loss (metal waste) and maintains the strength of the material. Additionally, it allows for processing with high precision and reduced variation. 'AKROSE(R)' is a new method that utilizes the cold forging technology developed through the design and manufacturing of industrial fasteners (screws) to achieve strong dissimilar metal bonding. It addresses the challenges of conventional metal bonding technologies. 【Features】 ■ Achieves bonding of diverse materials ■ Achieves bonding of multiple materials ■ Achieves complex bonding shapes ■ Improves the adhesion of bonded products ■ Enhances the strength of the bonded joints ■ Reduces environmental impact *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce our "composite components (fasteners + α)" that we handle. Starting with the "O-ring waterproof screw," which features a groove for setting an O-ring at the bottom of the screw neck to enhance waterproof performance, we also offer products such as the "rubber valve shaft," which has rubber molded onto the head of a metal screw, and the "steel ball press-fit assembly," which incorporates steel balls. Please feel free to consult us when you need our services. 【Product Lineup (Partial)】 <Fasteners + Resin and Rubber Parts> ■Washer set screws ■Decorative screws ■Heat-resistant screws *For more details, please refer to the PDF document or feel free to contact us.

"Gear parts made by forging and rolling processes" can reduce material costs as they do not produce chips like cutting and grinding processes. Forging allows for a smooth finish with a surface roughness of Rz3.2. In terms of durability, surface hardness is increased by 20%, meeting the strength requirements for components such as motor drive parts. Additionally, it is possible to minimize dimensional variations within the lot. 【Features】 - Cost reduction through improved productivity - Significant reduction in processing time - Assurance of dimensional accuracy and quality improvement brought by forging - Selection from a variety of sizes and materials - Ability to choose suitable materials based on application and shape *For more details, please refer to the PDF document or feel free to contact us.

"Special cold-formed parts" are components processed by applying pressure to metal at room temperature, resulting in deformation and shaping. It is possible to manufacture stepped, large-headed, middle-necked, eccentric, and irregularly shaped shaft parts, among others. By using molds made of materials such as carbide for the forming process, products with uniform precision can be mass-produced. Additionally, because the fiber flow is continuous, high strength can be achieved. [Features] - Increased strength and uniform dimensional accuracy - Contribution to sustainability through resource conservation - Enhanced functionality of parts and overall cost reduction in assembly - Provision of suitable functions for fastening conditions, including anti-loosening and contamination measures *For more details, please refer to the PDF document or feel free to contact us.

The "Driver Bit" is a high-quality and durable bit that combines our unique precision processing technology and fastening technology. It is made from special steel that has been heat-treated to enhance durability. Additionally, it has excellent bite, significantly improving screw tightening operations. There is a wide variety of types available, including No. 0 bits and bits specifically for automatic screw tightening machines. With a lineup that excels in precision, durability, and cost performance, we respond to your trust. 【Features】 ■ Combines our unique precision processing technology and fastening technology ■ Excellent quality and durability ■ Provides excellent bite and significantly improves screw tightening operations ■ A wide variety of types available, including No. 0 bits and bits specifically for automatic screw tightening machines ■ Also manufactures bits for precision instruments *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce the anti-loosening screw 'Apslock(R)' handled by Nitto Seiko. By interfering a special screw thread shape with the relatively stable (less variable) flank surface among the components of the female thread, it exhibits a stable anti-loosening effect that is less affected by the accuracy of the female thread. This product achieves cost reduction by eliminating the application of adhesive. Please feel free to contact us when you need it. 【Features】 ■ Firmly grips the female thread ■ Cost reduction achieved by eliminating adhesive application → approximately 30% reduction compared to our previous products ■ Less affected by the shape of the inner diameter ■ Improved anti-loosening performance due to the pre-torque generated by interference ■ Long-lasting return torque *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce the 'G Pin' handled by Nitto Seiko Co., Ltd. This is a press-fit pin with three V-shaped grooves formed in parallel and at equal intervals along the vertical direction on the outer circumference of the pin. It exhibits a strong self-retaining force, providing high resistance to vibration and effective prevention of pull-out. The main applications include areas where it is necessary to prevent pin pull-out due to vibration and impact, and areas where it is desired to reduce reaming of mounting holes, such as in automobiles, home appliances, AV equipment, and office automation equipment. [Features] - A press-fit pin with three V-shaped grooves formed in parallel and at equal intervals on the outer circumference of the pin - High pull-out prevention effect due to strong self-retaining force, providing resistance to vibration - Suitable for areas where pin pull-out due to vibration and impact needs to be prevented - Suitable for areas where reaming of mounting holes needs to be reduced - Applicable in automobiles, home appliances, AV equipment, office automation equipment, etc. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce the 'S Pin' handled by Nitto Seiko Co., Ltd. It is a strong elastic spring pin made by coiling a thin plate with spring properties in a spiral shape, with both ends tapered for easy press-fitting. The entire outer circumference of the pin has strong elasticity, making it excellent in impact resistance and vibration resistance. The main applications are in areas where it is necessary to prevent the pin from coming loose due to vibration or impact, and where it is desired to reduce reaming of mounting holes, such as in automobiles, home appliances, AV equipment, and office automation equipment. 【Features】 ■ A strong elastic spring pin made by coiling a thin plate with spring properties in a spiral shape, with both ends tapered for easy press-fitting. ■ The entire outer circumference of the pin has strong elasticity, providing excellent impact resistance and vibration resistance. ■ Suitable for areas where reaming of mounting holes needs to be reduced. ■ Used in automobiles, home appliances, AV equipment, office automation equipment, etc. *For more details, please refer to the PDF document or feel free to contact us.

"P-Tight(R)" is a self-tapping screw for resin that can be screwed in half the time compared to standard single-thread screws. It is primarily used for fastening resin. The thread angle is 45°, which is sharp, reducing the burden on the resin. Additionally, the incomplete thread section below the head prevents boss breakage. 【Features】 ■ Less prone to resin cracking ■ No resin seizing ■ Fast screwing speed ■ High torque for thread destruction ■ Good performance with repeatable use *For more details, please refer to the PDF document or feel free to contact us.

Achieves higher anti-rotation performance by adding protrusions that extend from outer edge of the lobe towards the center. JOISTUD(R) series also reduce burrs and warping when clinching into sheet metals. 【Features】 ■ The mating material flows into the internal lode space, reducing burrs and warping. ■ Protrusions enhance the anti-rotation strength in the rotational direction. *For more information, please refer to the catalog. Feel free to contact us with any questions.

We would like to introduce our clinching stud bolt, 'JOISTUD(R)-SS'. By creating a height difference between the outer and inner parts of the anti-rotation protrusion and adding an angle difference to the slope, we reduce the load on the counterpart material during the insertion of the component, achieving a smaller head size while suppressing warping of the counterpart material. This solves our customers' challenges of space-saving and weight reduction. 【Features】 - Reduces the load on the counterpart material during component insertion - Achieves a smaller head size while suppressing warping of the counterpart material - Product specifications: φ6 - Applicable counterpart materials: steel, copper, aluminum, etc. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce our clinching stud bolt, 'JOISTUD(R)-WP'. Thanks to its unique structure, it allows for press-fitting work without crushing the O-ring embedded in the stepped section. When fastening the mounting components, the O-ring is compressed, achieving waterproofing at the interface between the mounting components and the counterpart material. 【Features】 ■ Waterproof standard: Equivalent to IPX7 ■ Allows for press-fitting work without crushing the O-ring embedded in the stepped section ■ Product specifications: φ6 ■ Applicable counterpart materials: Steel, copper, aluminum, etc. *For more details, please refer to the PDF document or feel free to contact us.

"JOISTUD(R)-S" is a clinching stud bolt designed for thin plates, aluminum, and copper that are prone to burrs, warping, and rotation issues. By allowing the mating material flow into the internal lobe area, burrs and warping are significantly reduced. 【Features】 ■ Reduces burrs to prevent contamination issues ■ Contributes to electrification & weight reduction by minimizing burrs and warping, and improving anti-rotation strength *For more information, please refer to the catalog. Feel free to contact us.

We would like to introduce our metal self-tapping screws, "S-Tight®." These are standard screws for self-tapping into metal materials, and after removing this product, it is possible to screw in small screws. Please feel free to contact us if you have any inquiries. 【Main Applications】 ■ Fastening to steel plates ■ Automotive, AV equipment, OA equipment, measuring instruments, etc. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce the self-tapping screws for resin and metal, 'B Tight(R)', handled by Nitto Seiko. The cross-section of the screw is shaped like a rice ball (triangle), which reduces resistance during screwing. Compared to regular tapping screws, work efficiency is significantly improved. Please feel free to contact us when you need assistance. 【Main Applications】 ■ Usable for all types of plastic resins ■ Areas troubled by resin cracking or screw spinning (screw stripping) ■ Can also be fastened to metal materials ■ Automotive, information communication, home appliances, AV equipment, OA equipment, etc. *For more details, please refer to the PDF document or feel free to contact us.

The "P Tight (R)-II" is a self-tapping screw for resin that prevents cracking and seizing of the resin. It consists of high peaks with a thread angle of 30° and low peaks with a thread angle of 60°. Due to its double-thread design, it can be screwed in half the time compared to a standard single-thread screw. As a screw suitable for general thermoplastic resins, it is mainly used for fastening resin components, with representative examples including screws for fastening cameras. 【Features】 ■ Difficult to cause resin cracking ■ Prevents resin seizing ■ Fast screwing speed and stable workability ■ Reusable ■ Prevents thread breakage *For more details, please refer to the PDF document or feel free to contact us.

Nitto Seiko Co., Ltd. has developed a screw cross hole called "Share Cross(R)" that allows for the common use of driver bits with different sizes. To support more customers in their manufacturing processes, we, along with KM Seiko Co., Ltd., which specializes in construction screws, will begin full-scale sales from April 1, 2023. This product is adaptable to various fastening sites and will support the improvement of work efficiency in our customers' manufacturing processes. 【Product Features】 ■ Ensures sufficient drive strength - By providing a common torque transmission part, sufficient drive strength is ensured during the use of driver bits of different sizes. ■ Improved work efficiency - By sharing driver bits, tool changes at the work site become unnecessary, leading to improved work efficiency. *For more details, please refer to the PDF document or feel free to contact us.

■Flicks(R)009 → Generates high axial force and stabilizes it! 【Features】 1. Stabilization of friction coefficient... If the friction coefficient is stable, the generated axial force will be stable. 2. Low friction coefficient... Even with low torque during screw fastening, the generated axial force will be high. *For more details, please download the PDF document or feel free to contact us.

The "M Tight (R)" absorbs variations in pilot hole size due to its special thread angle and wide pitch, allowing for a broader acceptable range of pilot holes. It is a self-tapping screw for resin that excels in repeated use and is strong against loosening due to vibration and temperature changes. 【Features】 - Reduction of screw-in torque - Prevention of boss cracking - Compatible with various types of resin - Increased screw fastening holding power - High resistance to loosening from temperature changes and vibrations *For more details, please download the PDF document or feel free to contact us.

The "Cup Screw (R)" integrates a screw with a spring washer and flat washer, contributing to cost reduction. Additionally, by shaping the flange into a cup shape, it allows for high torque tightening and achieves a high anti-loosening effect, making it a special head screw. 【Features】 ■ Excellent anti-loosening performance ■ High maximum tightening torque ■ No washer needed, preventing damage to the joined materials ■ Does not loosen even with vibrations or temperature changes *For more details, please download the PDF document or feel free to contact us.

"PS Tight® II" is a precision self-tapping screw for thin resin plates. It demonstrates its effectiveness in fastening areas with a short engagement length (the length of the threaded portion), contributing to lightweight and compact designs. *For more details, please download the PDF document or feel free to contact us.*

For more details, please download the PDF document or feel free to contact us.

The "PC screw" is a self-tapping screw designed for soft thermoplastic resins that can withstand vibrations and temperature changes. It features sharp, high screw threads that provide strong fastening power and excellent resistance to loosening. 【Features】 ■ Can be screwed into soft thermoplastic resins ■ High holding power ■ High maximum tightening torque ■ Excellent resistance to loosening ■ Resistant to boss cracking and whitening *For more details, please download the PDF document or feel free to contact us.

"ASFA(R) WP" is a waterproof screw that can be fastened with high axial force. A flat washer under the head increases the contact area between the screw head and the mating parts. 【Features】 ■ Verified to prevent leakage for 30 minutes in a submerged test at a depth of 30 cm ■ Large contact area between the screw head and mating part helps prevent sinking even under high axial force ■ Eliminates the need for a counterbore on the fastened parts, contributing to overall cost reduction ■ Solves supply issues in the assembly process and supports to automation *For more information, please refer to the catalog. Feel free to contact us with any questions.

"Torx®" eliminates stress concentration due to the structure of the drive part, preventing damage to the product from drive hole deformation and cam-out (bit lifting during fastening). It efficiently transmits torque and ensures reliable fastening. 【Features】 ■ Maintains a high torque transmission rate ■ Allows for high torque fastening ■ Enables high torque transmission, saving space ■ No thrust required ■ Increased durability of the bit *For more details, please refer to the PDF document or feel free to contact us.

"Power Lock®" is a locking screw designed for fastening to a female thread with a rice ball shape (triangular) and a composite angle thread with 30-degree and 60-degree threads. When screwed in, the tip of the screw interferes with the female thread, enhancing the locking effect and demonstrating excellent vibration resistance and shock resistance. 【Features】 ■ Excellent anti-loosening performance ■ No need for adhesive fastening ■ No need for a seating surface to lock ■ Minimal contamination occurrence *For more details, please refer to the PDF document or feel free to contact us.

"AKROSE(R)" is a technology that forms materials using our strength in cold forging technology, and then firmly joins multiple pieces of that material through press processing. Nitto Seiko has developed a metal coating technology that applies AKROSE(R). This technology can replace the surface film formation through conventional plating with the joining of dissimilar metal components. It reduces the environmental impact, processing time, and costs associated with plating treatment. Additionally, it offers various advantages such as high freedom in the shape and thickness of the coated metal, significant wear resistance, and a wide range of applicable materials. *The name "AKROSE(R)" combines "AKROS" (the best) and "CLOSE" (to adhere or seal). [Features] ■ Reduction of environmental impact, processing time, and costs associated with plating treatment ■ Increased freedom in shape and thickness ■ Improved wear resistance ■ Expansion of applicable materials *For more details, please refer to the PDF document or feel free to contact us.

"Tough Cross®" increases the driving surface by 20% compared to a standard #0 cross hole, reducing the load per unit area and preventing cross hole deformation when used with dedicated bits. Additionally, the durability of the bits is improved. 【Product Features】 ■ By expanding the driving surface, the load per unit area on the driving surface is reduced, preventing hole deformation and improving the durability of the bits. ■ The newly created driving surface θ section is positioned away from the screw axis, increasing the radius (driving center of gravity) where torque is applied, thereby reducing the load, preventing hole deformation, and improving the durability of the bits. ■ The two-stage shape adapts to lamix, and the neck reinforcement remains as it is, ensuring safety without compromising the safety factor while improving screwing performance. ■ The basic design is #0, allowing for loosening and tightening with #0 bits. ■ When combined with dedicated bits, it is effective in preventing paint peeling and plating from the head. *For more details, please refer to the PDF document or feel free to contact us.

"Torx Plus®" eliminates stress concentration due to the structural design of the drive part, preventing damage to products caused by drive hole deformation and cam-out (bit lifting during fastening) when tightening screws. It efficiently transmits torque, ensuring reliable fastening. Additionally, the auto-cross design allows for quick bit engagement during high-speed rotation on assembly lines. 【Product Features】 ■ Enables higher torque transmission ■ Reduces cam-out and thrust ■ Improves the minimum torque value of fastening tools (an average increase of 25% compared to Torx) ■ Extends the lifespan of fastening tools (an average of 2 times compared to Torx) ■ Enhances productivity and reliability ■ Torx Plus driver system Current Torx drivers can also be used for after-service of recesses. *For more details, please refer to the PDF document or feel free to contact us.

The "Ramimate(R)-J" is a screw that combines the special head screw "Ramimate(R)" which strongly supports thinness and lightweight design, with the special drive screw "Tough Cross(R)" that prevents reaming out. It prevents screw breakage, loosening, and head sinking, contributing to further thin and lightweight design. 【Product Features】 ■ Prevents screw breakage... Absorbs the force applied during fastening with a large screw head seating surface. Increases the maximum tightening torque (male screw breakage torque) to prevent screw breakage. ■ Prevents loosening... Increases friction between the screw head seating surface and the workpiece, preventing screw loosening. ■ Prevents head sinking... Increases the seating surface area to distribute the pressure applied to the workpiece surface. Safe for fastening to soft resins and thin plates. ■ Prevents reaming out... By increasing torque transmission compared to conventional products, it prevents reaming out. ■ Improves work efficiency... Increases the maximum tightening torque compared to conventional products and expands the torque range for optimal fastening. Makes torque management easier, especially improving workability in fastening with electric tools. *For more details, please download the PDF document or feel free to contact us.

"Strux(R)" is a self-clinching stud with a press-fit installation method that replaces traditional clinching studs and welded bolts. It achieves reliable fastening with high holding power and anti-rotation features. 【Product Features】 ■ Enables low-cost joining ■ No need for plating after assembly ■ Can be joined with materials that cannot be welded ■ Highly reliable connection ■ High holding power and anti-rotation capability *For more details, please refer to the PDF document or feel free to contact us.

The "Cup Bolt (TM)" integrates a screw with a spring washer and a flat washer, contributing to "weight reduction" and "cost reduction." By adopting a cup-shaped flange, it ensures reliable contact from the flange outer circumference, achieving a high anti-loosening effect. 【Features】 ■ Replacement of bolts with integrated washers for "weight reduction" & "cost reduction" ■ The cup shape provides an anti-loosening effect equal to or greater than that of a spring washer plus a flat washer *For more details, please download the PDF document or feel free to contact us.