About Us
Tuyue is headquartered in Room 1-1402, Mingzhu Plaza, Economic and Technological Development Zone, Jiaxing, Zhejiang Province, China. Jiaxing is part of the Yangtze River Delta Economic Zone, one of the most dynamic and economically active regions in China. Strategically positioned between Shanghai and Hangzhou, the city sits within a major transportation corridor.
The surrounding infrastructure includes well-developed ports, railways, highways, and air transport networks, enabling efficient connections to both domestic and international markets.
Benefiting from Jiaxing’s strong manufacturing foundation and advanced logistics system, we are able to provide global customers with fast response times, stable delivery performance, and efficient supply chain support. This strategic location is one of Tuyue’s key advantages in serving international clients worldwide.
The factory covers a total area of approximately 16,000 square meters.
It is equipped with well-organized production workshops, warehousing areas, and quality inspection facilities, supporting a fully integrated manufacturing process from raw material processing to finished product shipment. The spacious facility not only ensures stable production capacity but also provides a solid foundation for large-scale orders and customized manufacturing.
With a modern production layout and efficient internal logistics management, we are able to maintain high product quality while achieving efficient production, on-time delivery, and flexible production scheduling. This enables us to meet the diverse procurement needs of global customers across various application scenarios.
We have more than 20 years of manufacturing and supply experience in the fastener industry. In the early stages, our company focused on the research, development, and production of self-drilling screws, building extensive expertise in manufacturing processes and quality control.
Since 2007, we have been distributing a full range of hardware fastener products in Ningbo, China, serving both domestic and international markets.
To better meet the growing export demands of global customers and provide specialized international trade services, Zhejiang Jiaxing Tuyue Import & Export Co., Ltd. was officially established in Jiaxing, Zhejiang Province, in 2020. The company is dedicated to the export of fastener products worldwide.
We are a professional fastener manufacturer, not a trading distributor. Quality control is the core priority of our team. From order confirmation and engineering review to production and final shipment, every stage is strictly monitored to ensure that our products meet customer technical requirements and international quality standards.
Before mass production begins, we exchange physical samples and confirm technical drawings to eliminate potential errors at the source. During production, we can provide production videos and on-site photos upon request, ensuring transparent manufacturing management.
After production is completed, we carry out in-process inspections and final inspections to ensure that every batch passes quality verification before shipment.
Through a systematic quality management process, we are committed to delivering stable, reliable, and fully traceable qualified fastener products to global customers.
Our average annual shipment volume is approximately 800 standard containers. This stable annual shipping scale reflects our mature production system, sufficient capacity allocation, and efficient supply chain management.
With our in-house production lines and standardized manufacturing processes, we are able to support large-volume orders as well as multi-category production simultaneously, while ensuring consistent product quality and on-time delivery. For long-term partners or project-based orders, we can provide flexible capacity planning and delivery schedules according to specific requirements. Even during peak seasons, we maintain stable supply capabilities to meet the continuous global demand for fastener products.
Details are as follows:
Standard Fasteners: The minimum order quantity is 300–500 kg per size. This applies to standard specifications that use existing molds and are suitable for mass production (such as common DIN or ISO bolts and nuts).
Non-Standard Customized Fasteners: The minimum order quantity is 1,000 kg per size. This applies to customized products that require new molds based on customer drawings, process adjustments, or special materials.
The final MOQ depends on factors such as product specifications, material, process complexity, and packaging requirements. To receive the most accurate quotation and proposal, we recommend that you:
Prepare detailed information: Provide product drawings, specification standards, material requirements, surface treatment, and other relevant details.
Contact our sales team directly: Our team will evaluate your specific requirements and provide a precise MOQ, pricing, and production lead time based on your actual needs.
Product and Design
Stainless steel bolts are prone to galling (cold welding) during installation, which is an inherent characteristic of stainless steel materials. Although stainless steel forms a protective oxide layer on its surface for corrosion resistance, this layer may be damaged or removed during tightening as contact pressure and relative sliding between threads increase.
When the oxide film breaks down, microscopic surface asperities on the exposed metal begin to shear and adhere to each other, leading to a progressive process of “adhesion–tearing–galling.” In severe cases, the threads may completely seize. Continued tightening can result in bolt fracture or thread stripping.
Once galling occurs, friction increases significantly, and the applied torque can no longer be effectively converted into the required bolt preload. This is also the main reason why, in practice, the bolt may feel increasingly tight while the desired preload is not achieved.
Reduce installation speed: Lower tightening speed helps minimize frictional heat and reduces the risk of galling.
Apply lubrication to internal and external threads: Use anti-seize lubricants containing molybdenum disulfide or extreme-pressure wax. For food-grade or medical applications, compliant lubricants must be selected.
Use dissimilar material combinations: For example, pairing a stainless steel bolt with an aluminum bronze nut can reduce metal adhesion. However, potential galvanic corrosion risks should also be evaluated.
Through proper assembly procedures and appropriate material selection, most stainless steel bolt seizing issues can be effectively prevented.
Fine-thread fasteners offer significant advantages under certain conditions. First, for the same nominal diameter, fine threads have a larger effective stress area, so their tensile strength is generally higher than that of coarse threads. Additionally, due to the smaller thread lead angle, fine threads are less likely to loosen under vibration, and the torque required during tightening is more controllable.
Second, the smaller pitch allows for more precise axial adjustment, making fine threads ideal for applications requiring high-precision positioning or fine tuning. Moreover, fine threads achieve adequate engagement length more easily in hard materials or thin-walled components, and the required preload can usually be reached with lower tightening torque.
However, fine threads also have certain limitations. Because the threads are more closely spaced and have a larger contact area, they are more prone to galling (seizing). During assembly, they require a longer engagement length, and the threads are more easily damaged by contaminants, cross-threading, or improper handling. Therefore, fine-thread fasteners are generally less suitable for high-speed automated assembly.
In most standard assembly situations, there is essentially no difference between tightening the bolt head or the nut, provided that the contact diameters, contact types, and friction coefficients of both sides are similar. When these conditions are met, applying torque from either side will generally result in the same bolt preload.
However, when these conditions are not consistent, the side you tighten becomes very important. For example, if the nut has a flange while the bolt head does not, and the torque specification is based on tightening the nut, tightening the bolt head instead may lead to over-tightening. This occurs because approximately 50% of the applied torque is used to overcome friction at the contact surface. When the friction radius decreases, more torque is transmitted to the threads, significantly increasing the actual bolt tension. Conversely, if the torque is specified for tightening the bolt head but the nut is tightened instead, insufficient preload may result.
In some applications, nut expansion must also be considered. During tightening, the threads can wedge the nut radially outward, reducing the number of engaged threads and increasing the risk of stripping. This effect is more pronounced when tightening the nut because the rotation tends to amplify radial expansion. Therefore, in applications sensitive to thread stripping (though uncommon for most standard bolts and nuts), tightening the bolt head rather than the nut can sometimes be advantageous.
In general, it is not recommended to use low-carbon steel nuts with high-strength bolts. Standards for fasteners specify nut thickness and strength grades based on a fundamental principle: under extreme conditions, the bolt should fail in tension before the threads strip. This is because bolt fracture is typically obvious and can be detected in time, whereas thread stripping usually occurs gradually. Components may continue to operate in a “partially failed” state, which can lead to severe or even catastrophic consequences.
Therefore, in design and selection, thread stripping must be avoided as much as possible. This requires that the nut’s load-bearing capacity matches or slightly exceeds the bolt’s strength. Using low-carbon steel nuts with insufficient strength to pair with high-strength bolts significantly increases the risk of internal thread stripping, making it an unreliable design practice.
Grade 8.8 bolts should be paired with grade 8 nuts.
Grade 10.9 bolts should be paired with grade 10 nuts.
Grade 12.9 bolts should be paired with grade 12 nuts.
Bolt heads are usually marked with their strength grade (e.g., “8.8”) and manufacturer identification, and nuts should carry corresponding performance grade markings (e.g., “8,” “10,” “12”).
Not necessarily, and in many cases, it is not recommended. Practical experience and research indicate that flat washers should generally be avoided, especially when stacked with locking washers, as this combination can weaken the locking effect and even introduce new risks. In fact, many traditional locking washers have been shown to provide limited anti-loosening performance.
The traditional role of a washer is to distribute the compressive load from the bolt head or nut. However, with the widespread use of flange bolts and flange nuts, this function is increasingly handled directly by the flange surface, avoiding the uncertainties introduced by additional components. In many applications, calculating the compressive stress on the nut face can show that it may exceed the compressive strength of the connected material, potentially causing material creep and loss of preload. While hardened flat washers were traditionally used to mitigate this, flat washers can shift or rotate during tightening, disrupting the torque–tension relationship and reducing assembly consistency.
Research also shows that the primary cause of fastener loosening is not rotational “backing off,” but micro-slip in the joint caused by lateral loads. Furthermore, impact assembly tools can create large variations in preload, with a fastener coefficient of up to 2.5–4. Even if the assembly appears consistent, the actual preload may be significantly lower. When combined with washer rotation or displacement, this uncertainty further increases the risk.
Do not use washers unless there is a clear requirement.
Prefer flange fasteners to achieve more stable compressive and friction conditions.
If washers must be used, ensure their hardness, dimensions, and fixation method are suitable for the application to prevent rotation or displacement during tightening.
Anti-loosening design should focus on achieving sufficient and consistent preload, rather than relying on traditional locking washers.
Metric and imperial fastener strength grades are not directly equivalent, but there are commonly accepted approximate comparisons within the industry. According to Section 3.4 of SAE J1199 (Mechanical and Material Requirements for Metric External Thread Steel Fasteners), metric fasteners use property classes to indicate strength. These can be approximately compared with common imperial grades as follows:
Property Class 4.6 ≈ SAE J429 Grade 1 / ASTM A307 Grade A
Property Class 5.8 ≈ SAE J429 Grade 2
Property Class 8.8 ≈ SAE J429 Grade 5 / ASTM A449
Property Class 9.8 ≈ Approximately 9% higher strength than SAE J429 Grade 5 / ASTM A449
Property Class 10.9 ≈ SAE J429 Grade 8 / ASTM A354 Grade BD
It is important to note that Property Class 12.9 does not have a direct and strictly equivalent imperial grade. In practice, it can only be compared based on mechanical performance parameters rather than treated as a standard-equivalent substitution.
The above correspondences are engineering approximations, not exact standard equivalencies.
Selection or substitution should always be based on specific standard requirements, including tensile strength, yield strength, elongation, and heat treatment condition.
For safety-critical or regulated applications, always verify the relevant SAE and ASTM standard clauses to avoid improper substitution.
In the past, bolts and screws were often distinguished by appearance: screws were typically fully threaded up to the head, while bolts usually had a partially unthreaded shank. However, in modern fastener standards and engineering practice, this distinction is no longer reliable and may even lead to confusion in product selection and communication.
According to the definition of the Industrial Fasteners Institute (IFI), the key difference between a bolt and a screw lies in how the fastener is intended to be used, rather than its shape:
Screw: Designed to be used with a threaded hole.
Bolt: Designed to be used with a nut.
In practice, many so-called “standard bolts” can be used either in a threaded hole or with a nut. However, IFI classifies a fastener as a bolt if its primary or typical application is to be used with a nut. Even if a short bolt is fully threaded up to the head, it is still considered a bolt as long as it is primarily intended for use with a nut.
By contrast, the term “screw” generally refers to product-type fasteners such as wood screws, lag screws, and various self-tapping screws. These fasteners typically form or cut their own mating threads during installation and do not rely on a separate nut.
It should be noted that the terminology and definitions established by IFI have been adopted by American Society of Mechanical Engineers (ASME) and American National Standards Institute (ANSI), and are widely used in modern engineering and standard systems.
Most standards and engineering guidelines recommend that the bolt should extend at least one full thread pitch beyond the nut to ensure full thread engagement and reliable preload. Some building codes require at least one visible thread beyond the nut; however, it is generally preferable to specify one full pitch, since the first thread may not be fully formed due to chamfering or manufacturing tolerances.
The design principle for nut thickness and thread length is that the bolt should fail in tension before the nut threads strip. This is because thread stripping is a progressive failure mode, and partially failed components may continue to be used, potentially leading to serious safety risks. Therefore, when selecting nuts and bolts, their strength grades should be properly matched to minimize the risk of thread stripping.
When installing threaded fasteners into sheet materials or low-strength blocks, the strength difference between the bolt and the base material can be significant. If the thread engagement length is calculated strictly according to the “bolt fails first” principle, the required engagement length may become impractically long. In addition, thread tolerances and pitch variations can further increase the difficulty of achieving proper engagement over extended thread lengths.
Stainless steel fasteners are widely used in industrial and construction applications due to their excellent overall performance. They are commonly applied in machinery manufacturing, construction engineering, automotive, electronics, food processing equipment, and marine environments.
First, outstanding corrosion resistance is the greatest advantage of stainless steel fasteners. Stainless steel contains chromium, which forms a dense passive oxide layer on the surface. This protective film effectively resists moisture, oxygen, chemicals, and salt spray corrosion, significantly extending the service life of the fastener. As a result, stainless steel fasteners are particularly suitable for outdoor, high-humidity, or corrosive environments.
Second, stainless steel fasteners provide a good balance of strength and toughness. When subjected to tensile, shear, and vibration loads, they maintain stable mechanical performance and are less prone to brittle fracture or failure.
In addition, stainless steel fasteners have lower maintenance requirements. Compared with carbon steel fasteners, they do not require additional coatings or frequent anti-corrosion treatments, which reduces maintenance and replacement costs. From a long-term perspective, stainless steel fasteners offer better overall cost-effectiveness. Although the initial purchase cost may be higher, their durability, reliability, and low maintenance requirements result in a lower total lifecycle cost.
Our complete range of fastener products includes rivets, metal washers and EPDM rubber washers, bolts, nuts, expansion anchors, and custom-made parts.
We also supply stamped components such as steel brackets, corner fittings, supports, and rigging hardware, as well as solar and photovoltaic mounting fasteners and a full range of stainless steel fasteners.
There are many types of screw heads to balance structural strength, assembly efficiency, and user safety across different applications. Different head shapes meet specific installation requirements:
Flat-head screws sit flush with the material surface, making them ideal for applications where appearance or limited space is a concern.
Round-head screws are versatile and suitable for most general-purpose connections.
Hex-head screws can withstand higher tightening torque, commonly used in load-bearing structures.
Socket or internal hex screws are ideal for tight spaces or designs where the screw head needs to be hidden.
In addition, different drive types (such as Phillips, Torx, or internal hex) offer various advantages in torque transmission, anti-stripping performance, and compatibility with automated assembly.
The diversity of screw head types has evolved to accommodate varying usage environments, material properties, and installation methods, ensuring reliable, efficient, and long-lasting connections.
Galvanization is a common electrochemical surface treatment process, also known as zinc plating. Its principle is to deposit a uniform and dense layer of zinc onto the surface of steel or iron products, creating a protective barrier between the metal and the external environment.
The zinc layer effectively slows down oxidation and corrosion of the steel while improving surface consistency and smoothness. Depending on the type of passivation treatment, galvanized surfaces typically appear in three colors: transparent (slightly bluish), yellow (with a golden pearlescent finish), or black, to meet different aesthetic and application requirements.
Due to its moderate corrosion resistance and low cost, galvanization is widely used in indoor environments and mild outdoor conditions. It provides a highly cost-effective protective solution for fasteners and metal components.
Separation or loosening of components is often related to thread galling or seizing. Galling typically occurs in metal fasteners, especially when the threads are cut rather than rolled, as cut threads tend to have a rougher surface and are more prone to galling. Additionally, oxidation on certain material surfaces can promote galling.
Galling occurs when microscopic surface particles break off during assembly and become trapped between mating parts, causing the components to stick or even seize completely, making disassembly very difficult.
To prevent this, fastener design should consider the risk of thread galling. This can be mitigated by selecting compatible materials, adjusting material hardness, or applying appropriate lubricants to the thread surfaces. These measures reduce friction and galling, ensuring reliable and long-term stability of the assembled components.
Preventing stainless steel corrosion relies on selecting appropriate materials, surface treatments, and processing techniques. For example, 303 stainless steel is easy to machine but has lower corrosion resistance than 302, 304, or 316 austenitic stainless steels. This is because chemical additives used during machining can promote corrosion, and 303 requires a specialized chemical solution for passivation.
To achieve optimal corrosion resistance, the part surface should be smooth, thoroughly cleaned, and passivated. Passivation typically involves immersing stainless steel parts in approximately 30% nitric acid solution to remove iron contaminants that could cause rust, forming a stable passive film and enhancing corrosion resistance.
For parts intended for marine or high-salt environments, selecting 304 or 316 stainless steel combined with proper surface treatment provides the best protection against corrosion.
A fastener coating is a chemical or physical treatment applied to the surface of a metal fastener to enhance its performance and extend its service life. Coatings can improve corrosion resistance, reduce friction, and enhance appearance. However, some coatings may pose toxicity concerns, so health and safety must be considered when selecting a coating.
Choosing the appropriate coating depends on the fastener’s specific function and operating environment. For applications where additional protection or performance enhancement is not required, coating can be omitted to save cost and processing time.
A fastener coating is a chemical or physical treatment applied to the surface of a metal fastener to improve its performance and extend its service life. Coatings can enhance corrosion resistance, improve lubrication, and enhance appearance. However, some coatings may be toxic, so health and safety should be considered when selecting a coating.
Choosing the appropriate coating depends on the fastener’s functional requirements and operating environment. For applications that do not require additional protection or performance enhancement, coating can be omitted to save cost and processing time.
Generally, they do not. Standard fasteners are not required to obtain UL certification or an ICC-ES report. Fasteners primarily follow standards such as ASTM (for construction applications), SAE (for automotive and mechanical applications), and ASME (for dimensional tolerances). For highway projects, AASHTO standards may also apply.
The ICC-ES mainly evaluates building products for compliance with building codes, but bolts and fasteners are already comprehensively covered by ASTM standards, so separate evaluation is not necessary. UL certification, provided by Underwriters Laboratories, is a voluntary safety testing service, and there is no legal requirement for ordinary fasteners to obtain UL certification. As long as bolts or fasteners comply with the applicable ASTM, SAE, or ASME standards, they meet the relevant code requirements.
