The difference between imported screws and domestic screws.
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style="font-size:16px;">In the fastener system of the manufacturing industry, although screws are basic components, they directly determine the stability and service life of equipment and structures. With the transformation of China's manufacturing industry towards high-endization, the choice between imported screws and domestic screws has become the focus of many enterprises. There are significant differences between the two in terms of quality standards, technical processes, working condition adaptability, and cost control. It is not the case that "imported products are necessarily superior" nor that "domestic products are all inferior". Accurately understanding these differences is the key to scientific selection for enterprises. From high-end equipment manufacturing to people's livelihood engineering construction, the two types of screws have their own suitable scenarios and jointly support the high-quality development of the industry.
Differences in quality standards and quality control systems are one of the core distinctions between imported and domestic screws. Imported screws generally adhere to strict international standards and comprehensive quality control processes, such as American Standard ASTM, European Standard EN, and International Standard ISO. Some high-end products also meet industry-specific certifications, such as API certification in the petroleum field and NORSOK certification in the marine field. During the production process, imported screws usually go through multiple self-inspection and mutual inspection procedures. Even the raw material selection includes composition analysis, mechanical performance testing and other links, resulting in extremely high consistency in the dimensional tolerance and mechanical performance of finished products. Taking high-precision mechanical screws as an example, the dimensional tolerance of imported products can be controlled within ±0.01mm, and the rejection rate is less than 0.5%.
In contrast, the standard system of domestic screws presents a "stratified" characteristic. High-end products produced by leading enterprises have been able to benchmark international standards, and some products have passed certifications such as ASME and ISO, with increasingly improved quality control processes. However, restricted by production equipment and cost pressures, a large number of small and medium-sized manufacturers still produce in accordance with the minimum national standards, with simplified quality control links. This leads to large fluctuations in product dimensions and unstable mechanical performance, and the rejection rate of some low-end products even exceeds 5%. This stratified situation results in a pattern of "coexistence of advantages and disadvantages" for domestic screws in the market.
Differences in technical processes and working condition adaptability are particularly obvious in extreme environments. Imported screws have profound accumulation in material research and development, coating technology and other aspects, and are more adept at coping with extreme working conditions such as high temperature, low temperature, and strong corrosion. For example, imported low-temperature resistant screws used in LNG pipelines are made of molybdenum-chromium modified alloy steel through deep cold treatment, which can maintain good toughness in an extremely cold environment of -162℃ without fracture risk. Imported anti-corrosion screws adopting triple composite coating technology have a salt spray test life of more than 1500 hours, which can adapt to strong corrosion scenarios such as coastal and deep-sea areas. In addition, imported screws have significant advantages in core performances such as fatigue resistance and wear resistance. For instance, imported screws used in high-end automobile engines have a fatigue life of more than 1 million times, far exceeding that of ordinary domestic screws.
In recent years, domestic screws have made rapid progress in technical processes. By introducing advanced equipment and increasing R&D investment, leading enterprises have realized the substitution of some high-end products for imported ones. For example, in fields such as wind power and bridges, high-end domestic screws adopt independently developed modified alloy steel materials, and their fatigue resistance has approached the level of imported products. In terms of coating technology, the salt spray test life of some products can also reach 1200 hours. However, in the segmented fields of extreme working conditions, such as ultra-high temperature (above 500℃), ultra-low temperature (below -100℃) or strong corrosion (hydrogen sulfide, strong acid environment) scenarios, the adaptability of domestic screws still has a gap. The research and development of core materials and high-end coating technology still need to be broken through.
Differences in cost and delivery cycle are important practical factors affecting enterprises' selection. Due to factors such as tariffs, transportation, and brand premium, the cost of imported screws is usually 30%-100% higher than that of domestic screws, and the price of some non-standard customized products is even 2-3 times that of similar domestic products. In addition, the delivery cycle of imported screws is relatively long: conventional products require 15-30 days, and non-standard customized products may take as long as 45-60 days. Moreover, affected by fluctuations in the global supply chain and adjustments in tariff policies, there is a risk of delivery delays.
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JIALI FASTENER