The performance enhancement of electric vehicle drive motors is inseparable from innovations in electrical silicon steel materials and coating technologies.
Baosteel’s pioneering Z-coating (self-adhesive) technology for non-oriented silicon steel, with its unique self-adhesive insulating coating, significantly simplifies the stacking method of motor iron cores, exerting a “hidden power” in reducing core losses, minimizing noise, and enhancing manufacturing efficiency.
This article is aimed at motor R&D engineers and provides an in-depth analysis of Baosteel’s Z-coating technology—from its underlying principles and materials to manufacturing processes, performance characteristics, industry comparisons, and application trends. It also compares the products and market situations of self-bonding coated silicon steel offered by companies such as South Korea’s POSCO and Japan’s Nippon Steel.

01Z Coating Self-Adhesive Technology: Principle and Adhesion Mechanism
The principle of self-adhesive insulating coatings: The Z coating is a specially formulated organic insulating coating whose core component is a thermosetting resin applied to the surface of silicon steel sheets. When the silicon steel sheets leave the factory, The Z coating exists in the form of a B-stage resin: It is produced by applying a water-based phenolic-modified epoxy resin adhesive and then drying it at low temperature, resulting in a dry, flexible, and reactive film. This coating has a thickness of approximately 4–6 μm and contains about 45%–48% water-based phenolic epoxy resin, along with an appropriate amount of curing agents and accelerators. After the silicon steel sheets are punched and sheared, they are subjected to hot pressing—applying a certain temperature (around 170–180℃) and pressure—during lamination assembly. In the B stage, the resin coating rapidly softens and melts, then undergoes crosslinking and curing (C stage), forming a three-dimensional network structure that firmly bonds the sheets together. Simply put, The Z-coating uses a thermally curable adhesive to secure adjacent silicon steel sheets via “surface bonding,” replacing traditional mechanical fastening methods. 。
Bonding Mechanism and Material Composition: Z-coatings typically use a modified epoxy resin system, in which the resin matrix remains partially unreacted (retaining activity) during drying and rapidly cures upon hot pressing. The formulation contains phenol-modified epoxy resin to enhance bonding strength; the curing agent provides latent activity, while the accelerator speeds up the curing rate. Solvents and water ensure excellent coating performance. After curing, a robust resin adhesive layer forms at the bonding interface, exhibiting excellent dielectric insulation and mechanical strength. According to the company’s standards, the Z-coating is free of heavy metals such as Cr and is environmentally friendly and chromium-free. After curing, the bonding strength between iron chips is remarkably high, with a T-peel strength reaching over 3 N per millimeter. It is worth noting that... Z-coated silicon steel must be used within 6 months of manufacture to ensure the coating’s activity and adhesion performance. (Manufacturer’s recommended shelf life).
Processing technology features: The steel plant has added a coating process to the continuous annealing line for silicon steel strips, applying a self-adhesive adhesive coating by roller onto both sides of the steel strip and then using segmented, gradient heating and drying to prevent excessive curing of the resin. An appropriate drying curve—such as low-to-moderate temperature pre-drying at 120–160℃ followed by rapid high-temperature drying at 170–180℃—can ensure that the coating is both dry and retains its “activity.” During punching, the dried film coating exhibits a certain lubricating and anti-friction effect, resulting in excellent stamping performance. In the lamination and bonding stage, either overall heating and hot pressing or localized heating within the mold can be employed to achieve an integrated process of in-mold punching, lamination, and bonding. With technological advancements, some fast-curing coatings have been developed, reducing the curing time from the traditional 1.5 hours to just a few minutes, thereby significantly speeding up the lamination and bonding cycle. Overall, Z-coating technology combines materials science (resin formulation) with manufacturing processes (punching/hot pressing), offering a brand-new approach to motor core assembly.

Advantages of the 02Z Coating in Motor Core Manufacturing
Applying the Z-coating to the stator and rotor core laminations of electric motors brings multiple advantages:
1. Eliminate stress loss and reduce iron loss: Traditional riveting and welding can introduce localized mechanical stress or thermal effects into silicon steel sheets, thereby degrading magnetic performance and increasing iron losses. In contrast, the self-bonding coating achieves integral adhesion between sheets, eliminating both the compressive stress from rivets and the thermal stress from solder joints. As a result, silicon steel sheets experience virtually no stress-induced deformation, and their electromagnetic properties remain undamaged. Moreover, the Z-coating itself boasts excellent insulating properties, effectively preventing interlayer short circuits and reducing iron losses. According to research by POSCO, After replacing welding with self-adhesive bonding, the total core loss was reduced by approximately 5%. 。
2. Enhance core strength and stability: The self-adhesive glue forms a large-area bond between the laminations, providing high bonding strength and significantly enhancing the overall rigidity of the iron core. In contrast to mechanical fastening, which only provides localized fixation, adhesive bonding allows for uniform distribution of operational stresses, resulting in improved structural stability of the iron core. During high-speed rotation, the laminations are less likely to loosen or shift, thereby meeting the reliability requirements of high-speed, high-power-density motors. 3. Reduce vibration and noise: The inter-laminar adhesive layer exhibits damping properties, effectively suppressing the micro-vibrations between laminations caused by magnetostriction. At the same time, since there is no longer any need for riveting or welding with punch pins to secure the laminations, the core no longer experiences loosening or impact, thereby avoiding the resonance noise commonly associated with mechanical connections. According to reports, After adopting self-adhesive bonding technology, the noise from the drive motor can be reduced by approximately 5 decibels. For new-energy vehicles, this noise-reduction effect is particularly valuable and helps enhance the overall NVH performance of the vehicle. 4. Simplify the process flow and improve efficiency: With the Z coating, the core lamination process can eliminate the need for riveting and welding, instead opting for a single-step hot-pressing molding process. In particular, In the in-mold bonding process, punching and stacking can be performed simultaneously and automatically, simplifying the entire process into a single step and accelerating the production cycle. This not only reduces labor and equipment investment but also minimizes the accumulation of errors between processes, thereby improving the consistency of core dimensions. 5. Optimize the core design and insulation treatment: Self-adhesive bonding offers new design freedom for core structures. Since there’s no need to design riveting holes or welding locations, the utilization rate of silicon steel sheets is improved, and the local magnetic flux distribution becomes more uniform. After the adhesive has cured, the core becomes dense and waterproof; thus, in certain applications, subsequent varnish impregnation can be eliminated, simplifying the insulation process and avoiding potential coil contamination that might occur during varnish curing. 6. Environmental Protection and Maintainability: The Z-coating features a chromium-free, environmentally friendly formulation that complies with environmental regulations such as RoHS and REACH. The bonded iron core contains no residual welding slag, and its surface remains clean and tidy. During dismantling and disposal, heating alone is sufficient to separate the adhesive layer, making material recycling particularly convenient—unlike mechanical connections, which can damage the structure of the silicon steel sheets. Thanks to these advantages, Z-coating technology offers an effective solution to the key challenges in motor manufacturing, including losses, noise, and complex manufacturing processes. In today’s pursuit of high-efficiency, quiet motors—especially in the field of electric vehicle drive motors—self-adhesive coatings are rapidly gaining popularity.

03 Baosteel Z-Coating Products and Key Performance Parameters
As a pioneer in this technology, Baosteel has launched a series of non-oriented electrical steel grades with Z-coating, covering various thicknesses and performance levels. The following table lists several representative Baosteel Z-coated silicon steel grades along with their key parameters (typical values):
Note: Insulation class refers to the heat resistance of the coating. Class F is rated for approximately 155°C, while Class H is rated for approximately 180°C.
In the table, B35A230-Z is Baosteel’s classic high-grade non-oriented silicon steel (nominal thickness 0.35 mm, iron loss 2.30 W/kg). After being coated with a Z coating, it can be used in high-efficiency small and medium-sized motors. B50A800-Z belongs to the standard grade (0.5 mm thick, iron loss approximately 8.00 W/kg) and is suitable for general industrial motors, corresponding to the former national standard grade 50W800. It is worth noting that in recent years, Baosteel has globally launched, for the first time, an ultra-thin, high-strength non-oriented silicon steel—B10AHV900M-Z—with a thickness of only 0.10 mm. Its iron loss under conditions of 1.0 T/400 Hz does not exceed 9 W/kg (typically 8.5). This means that it maintains extremely low losses even at high frequencies, setting a new performance benchmark for non-oriented silicon steel. This grade boasts both an ultra-high alloy content and an exceptionally thin thickness, and features a Z-coating to ensure reliable lamination bonding. It is— New-energy vehicle drive motors and humanoid robot motors The cutting-edge material.
Baosteel’s Z-coated products generally feature high magnetic flux density (B50 typically ranging from 1.65 to 1.75 teslas) and low iron losses. Different models are tailored for various frequency and power levels: thicker sheets (0.50–0.65 mm) are suitable for power-frequency motors, thinner sheets (0.20–0.35 mm) are designed for medium- and high-speed motors, while ultra-thin sheets (≤0.15 mm) are specifically optimized for high-speed, high-frequency applications such as high-speed electric spindles and motors for new-energy vehicles. The adhesion strength of the Z coating can be adjusted by varying the coating thickness and formulation; typically, the peel strength exceeds 3 N/mm, and higher performance levels can be negotiated under special requirements. In addition, Baosteel has also developed high-temperature-resistant versions of the coating (with a heat resistance rating of Class H) to meet the demands of environments with elevated stator temperatures.
Overall, Baosteel’s Z-coating series of electrical steel achieves an optimized combination across multiple dimensions—including iron loss, magnetic induction, strength, and thickness—providing material solutions tailored to a wide range of motor designs, from low-speed, high-efficiency applications to high-speed, extreme-performance requirements. This enables Chinese domestic motor manufacturers to obtain world-class bonded silicon steel materials without relying on imports.

04 POSCO Self-Adhesive Coated Silicon Steel Products and Technologies
POSCO of South Korea also boasts leading technology in the field of self-adhesive coatings for non-oriented silicon steel. POSCO’s related products are sometimes referred to as “self-adhesive electrical steel” or Hi-M Core (high-efficiency motor core material), among other names. The coating categories developed by POSCO correspond roughly to Baosteel’s Z-coating; for example, the internal POSCO designations SM and SH represent two distinct types of self-adhesive coatings.
1. SM Coating (Standard Motor) High-adhesion self-adhesive coating designed to enhance motor efficiency. The SM coating offers high bonding strength and is suitable for processes where no further annealing is required after conventional stamping. The coating itself firmly bonds and secures the iron core. Thus, the welding or mechanical fastening steps are skipped.
2. SH Coating (Stress-relief Anneal) Self-adhesive coating suitable for stress-relief annealing (SRA). This coating can withstand a single low-temperature annealing treatment following the stamping of silicon steel sheets, allowing for maximum stress relief before bonding and further enhancing efficiency. SH is suitable for motor manufacturing processes that pursue extreme performance.
POSCO’s self-adhesive coated silicon steel shares a similar principle with Baosteel’s Z-coating: both involve pre-applying an organic adhesive layer onto the surface of silicon steel sheets, which are then thermally pressed and bonded during lamination. The key difference lies in the fact that POSCO was among the first to commercialize this technology for its high-grade silicon steel series, the Hyper NO line. As early as 2017, POSCO announced that its Hyper NO high-grade silicon steel utilized a self-adhesive bonding process, replacing traditional welding to enhance the cohesion of the iron core. Measured results show that, compared to conventional materials that do not employ this technology, Hyper NO exhibits approximately a 5% reduction in iron loss and a roughly 5 dB decrease in motor noise. This improvement is attributable to two main factors: First, Posco has achieved an ultra-thin thickness of around 0.15 mm by optimizing the rolling process, significantly reducing eddy-current losses. Second, the self-adhesive coating eliminates welding stresses and inter-laminar vibrations, thereby lowering additional losses and noise.
Typical POSCO non-oriented silicon steel grades, such as the 35PNV and 50PNM series, are available with either insulating or self-adhesive coating options. For example, POSCO’s 35PNS250 (0.35 mm) exhibits an iron loss of approximately 2.25 W/kg and a magnetic flux density B50 of about 1.66 T—performance that is comparable to Baosteel’s B35A230. If the same series is coated with an SM self-adhesive layer, the laminated core no longer needs to be riveted or welded for fixation, resulting in higher overall motor efficiency. POSCO has also developed a specialized material called PNM-Core, which emphasizes wear resistance and low remanence, making it ideal for small, high-speed relay magnetic circuits and other applications requiring self-adhesive bonding.
In terms of market adaptation, POSCO, through its subsidiary Mobility Solution, directly supplies finished self-adhesive laminated core products to automotive OEMs. This integrated approach—combining materials and components—has enabled POSCO’s self-adhesive electrical steel to secure a prominent position in the global supply chain for new-energy vehicles. For instance, motor manufacturers from Hyundai Motor and General Motors have both begun sourcing high-grade silicon steel from POSCO and adopting its adhesive assembly technology. According to official POSCO information, its self-adhesive technology is not only suitable for manufacturing complex or small-sized cores; its key selling point lies in “eliminating riveting or welding processes and achieving highly efficient assembly.” Moreover, POSCO is investing in the construction of motor silicon steel processing centers overseas—in regions such as Europe and the Americas—signaling that its self-adhesive coated silicon steel products are poised to gain wider access to international markets. Overall, POSCO’s self-adhesive silicon steel boasts technical parameters (such as iron loss and magnetic induction) that are comparable to those of Baosteel, with certain advantages in specific thin-gauge specifications. In terms of market application, POSCO has leveraged its global presence to enter the supply chains of multinational automakers earlier than others—a strategy that domestic manufacturers would do well to emulate.

05新日铁自粘涂层硅钢的产品与特色
相较宝钢和浦项的积极推广，日本的新日铁住金（Nippon Steel）在无取向硅钢自粘涂层方面的公开信息较少。“自粘结涂层”并非新日铁产品宣传的重点，但这并不意味着其没有相关技术储备。日本厂商长期以来更注重硅钢材料本身的极限性能提升，如降低厚度、提高合金纯度和强度等，对叠片连接方式则多采用传统工艺（机械扣合、焊接并辅以浸漆等）。据报道，日企曾通过应力涂层和退火工艺来降低冲片应力影响，从材料层面保障电磁性能。然而，随着高速电机和静音需求兴起，日本钢厂也开始关注自粘结方案。例如新日铁可能提供定制的粘接涂层硅钢供部分客户试用，只是未形成独立商品品牌。
技术水平方面，日本无取向硅钢在薄规格和高磁感上保持领先。新日铁和JFE都能量产0.20mm及以下超薄硅钢（JFE的10JNEX系列更将取向硅钢做到0.10mm）。在新能源汽车驱动电机用钢上，日本侧重高强度牌号开发，以满足高速转子对屈服强度的要求 。一些高强NO钢牌号的屈服强度甚至超过700 MPa 。对于自粘接涂层，日本可能采用更耐高温的胶系，以适应叠片焊接后的应力消除热处理（类似POSCO的SH涂层概念）。然而，由于日本电机行业对可靠性和验证周期要求极高，在未完全验证前，此类自粘技术大规模应用仍较谨慎。
产品型号方面，新日铁官方尚未公开专门的自粘涂层牌号名称。可以推测其高牌号无取向硅钢（如NS EDGE系列）如果客户有需求，也可加涂自粘层。但与宝钢“Z”或浦项“SM/SH”不同，新日铁没有特定字母标识的自粘产品在市面上知名。这可能因为日本电机制造商目前多采用机械压装+浸渍工艺达到类似效果，即通过把冲片紧配合装入定子框架并整体浸绝缘漆固化，获得一定的降噪和加固效果。相比之下，直接采用硅钢自粘胶技术在日本市场尚未成为主流。因此新日铁在此领域的特色更多体现为材料本体性能突出（如低损耗高磁感、超薄高强），而在涂层粘接工艺上保持观望跟随态度。但不容忽视的是，日本厂商在绝缘涂层技术上积累深厚（很早就开发出高张力涂层、无机涂层等用于硅钢性能提升 ），这些经验也完全可以移植到自粘涂层配方的研发。一旦市场需求明确，新日铁和JFE有能力推出性能不俗的自粘涂层硅钢产品。总体而言，目前新日铁在自粘涂层无取向硅钢方面并无公开的拳头产品，技术水平应与宝钢浦项相差不大但市场化程度略逊，特色上可能更强调材料强度和可靠性以匹配日本电机制造的工艺习惯。

06三家企业产品对比：优势劣势、市场反馈与产业链协同
将宝钢、浦项、新日铁三家在自粘胶硅钢领域的产品横向比较，可以看出各自侧重和挑战：
1. 产品性能与技术在核心磁性能上（铁损、磁感强度），三家高牌号产品差距很小，都达到国际领先水准。例如宝钢B35A230-Z与POSCO 35PNS250铁损均约2.3 W/kg级  ，磁感约1.66～1.70 T；超薄产品方面，宝钢0.1mm牌号率先突破损耗瓶颈 ，而POSCO和日企也有0.15mm左右产品储备 。粘接涂层性能上，宝钢和浦项均已实现量产供应，粘接强度满足大部分定子装配需求（剥离强度3–5 N/mm）。宝钢Z涂层胜在本土化快速迭代，比如通过优化配方提高胶接强度/厚度比，达到同等膜厚强度提高50%的效果 。浦项SM/SH涂层则在工艺适应性上有优势，如SH可配合退火以实现极低损耗 。新日铁相关产品虽未明确推出，但其材料强度和涂层耐热性能值得期待。总体看，宝钢/浦项在“有胶”细分赛道领先半步，新日铁在“无胶”高性能基材上仍保持传统强项。
2. 制造工艺与协同宝钢Z涂层贴合了国内电机厂工艺升级需要，其涂层固化温度与常规绝缘漆固化相近（约180℃），国内厂家引入成本较低。浦项依托自身叠片制造装备，提供从材料到铁芯的综合解决方案，更适合规模化、自动化程度高的客户 。日本由于电机产业链保守，钢厂和电机厂在这方面协同不足，自粘技术推进缓慢。产业链协同难点主要在于：下游习惯的改变——厂家需要增加模具加热装置或单独热压工序；存储运输——自粘涂层卷料须防潮、防过期，这要求钢厂和用户的供应链高度配合（宝钢建议6个月内用完即是例证）。宝钢通过与国内龙头电机企业联合开发试用，逐步打消了这些顾虑，建立起材料-工艺协同的范例。浦项则凭借全球技术支持帮助客户改造工艺。相比之下，新日铁要推广该技术可能面临更大的客户改变意愿障碍。
3. Market Response Based on market feedback, motor products using self-adhesive silicon steel have generally received positive reviews. The application of Baosteel’s Z-coated products in drive motors for new-energy vehicles has demonstrated significant improvements in both core noise and loss performance. Vehicle manufacturers (such as BYD and GAC Aion) have leveraged these advancements in noise control as a key selling point for their models. In particular, during high-speed operation competitions, the unique advantages of self-adhesive cores—high strength and low noise—have attracted considerable attention. Meanwhile, POSCO’s products have established a strong reputation in overseas home appliance and industrial motor markets; several manufacturers of high-efficiency air-conditioner compressors and elevator motors have specifically designated POSCO’s self-adhesive silicon steel to enhance their energy efficiency ratings. The market has also offered some suggestions for improvement—for instance, early reports from certain manufacturers indicated that the adhesive layer in bonded cores might age and crack after prolonged exposure to high temperatures. In response, Baosteel has upgraded its heat-resistant resin system, and the bonding reliability has now successfully passed rigorous testing (equivalent to thermal cycling throughout the motor’s entire service life). Overall, the market welcomes new materials that strike a balance between performance and environmental friendliness; however, it also calls for sufficient verification periods. Japanese customers tend to be more conservative and require long-term operational data to support their decisions. In this regard, Baosteel and POSCO still need to continue building up their track records in large-scale projects to gain broader recognition.
4. Price and Supply-Demand Trends High-grade non-oriented silicon steel itself is a high-value-added product. When combined with self-adhesive coating processing, its price tends to be slightly higher than that of conventional coated materials—typically by about 10% to 20%. In recent years, driven by the robust growth in both production and sales of new-energy vehicles, demand for this type of material has outstripped supply, causing prices to soar. However, major steelmakers have been ramping up production: Baowu Group has added new silicon steel production lines, and POSCO has increased its annual capacity from 160,000 tons to over 300,000 tons. As production capacity gradually expands and the supply-demand balance eases, prices are expected to become more rational. Meanwhile, the self-adhesive coating technology itself has seen cost reductions over the past few years as it has gained wider adoption—for instance, savings in overall manufacturing costs resulting from reduced riveting and welding processes can partially offset the rise in material unit prices. All links in the industrial chain are working hard to lower the cost of self-adhesive adhesive formulations and improve coating efficiency, thereby reducing the price barrier. Looking ahead, the cost-effectiveness of high-performance bonded silicon steel will continue to improve. Especially against the backdrop of increasingly stringent energy-efficiency regulations, the energy-saving benefits throughout the steel’s entire lifecycle will significantly offset its initial material costs.
In summary, Baosteel’s Z-coating, POSCO’s SM/SH coatings, and Nippon Steel’s potential self-adhesive products each have their own advantages: Baosteel boasts rapid local responsiveness and a comprehensive product lineup, enabling it to grow rapidly in emerging markets; POSCO benefits from mature technology and a strong international customer base, excelling in providing integrated solutions; and Nippon Steel, with its deep-rooted material expertise, enjoys high credibility in conservative markets. On the downside, Baosteel has relatively weaker overseas influence and started later; POSCO’s prices are slightly higher and its delivery times longer; and Nippon Steel’s pace of innovation has slowed down, causing it to miss out on certain early opportunities. To achieve effective collaboration across the industrial chain, steel mills and motor manufacturers must work together to overcome the challenges in the “last mile” of technology adoption—such as process upgrades and standard certifications. As all parties continue to refine their cooperation, self-adhesive coated silicon steel is poised to become one of the standard materials for high-efficiency motors in the future.

07 Current Application Status of Chinese Motor Manufacturers and Future Trends in Z-Coating Technology
Currently, Chinese domestic motor manufacturers are actively exploring the application of Z-coating technology to maintain their product competitiveness. New-energy vehicle manufacturers such as BYD, benefiting from high production volumes and in-house motor development, have taken the lead in adopting self-adhesive silicon steel from Baosteel and Shougang for stator laminations in drive motors, achieving results in reduced noise and improved peak efficiency. According to industry sources, For some of its high-end models, BYD employs a bonded laminated core technology for the motor stator, resulting in significantly lower electromagnetic noise levels in the high-speed range compared to competing products. Huawei’s electric-drive division has collaborated with Baosteel to develop a prototype “F Super Motor,” which utilizes Baosteel’s ultra-thin 0.10mm silicon steel material coated with a Z-layer. This motor boasts a remarkable rotational speed of up to 31,000 rpm and operates with exceptional smoothness. New automotive players such as GAC Aion and Geely have also shown strong interest in this technology and have begun to factor in the type of silicon steel coating when participating in bidding processes. Some traditional motor manufacturers—such as joint-venture suppliers like Volkswagen and Continental—have also started using self-adhesive core laminations in drive motors produced in China. Overall, domestic applications are transitioning from pilot verification to small-scale production stages. In particular, in segments such as new-energy passenger vehicles that demand high efficiency and quiet operation, as well as electrically controlled compressors, the penetration rate of self-adhesive technology is steadily increasing.
Future Trends Outlook: Looking ahead, Z-coating self-adhesive technology is expected to see wider adoption or further evolution in the following areas:
1. Higher speed, thinner design As motors evolve toward higher speeds and smaller sizes, ultra-thin silicon steel sheets with a thickness of 0.1 mm and bonding technologies will become standard features. Bonding technology ensures that over a hundred ultra-thin laminations can operate at high speeds without loosening. We will... We’re seeing high-speed motors with speeds of 60,000 rpm or even 100,000 rpm featuring self-adhesive iron cores. Made possible, meeting the demands of extreme applications such as flywheel energy storage and electric turbines.
2. Integration of Standardization and Process The industry is expected to develop manufacturing standards for bonded laminated core assemblies—including specifications for bonding strength testing and durability test methods—to ensure smooth large-scale application. Meanwhile, stamping dies integrated with processes such as heating and automatic stacking will become increasingly sophisticated, making in-mold bonding a standard procedure and further reducing both time and labor costs. The automated control of the bonding process—covering moisture, temperature, and pressure—will also become智能化 (intelligent), guaranteeing consistent quality across all core assemblies.
3. Collaborative Optimization of Materials and Processes Steel mills and motor manufacturers will strengthen collaborative development. For example, for specific motor models, they will customize coating thickness and curing curves to achieve the thinnest possible coating while maintaining sufficient bonding strength (thus improving the lamination factor). As demonstrated by Shougang’s recently released new coating, which reduces film thickness by 30% while maintaining the same level of strength. In the future, innovative approaches such as gradient bonding coatings—where the adhesive layer is locally reinforced in critical areas—may emerge, striking a balance between strength and performance.
4. Alternative Paths and Competing Technologies Although self-adhesive glue has prominent advantages, other approaches are also being pursued in parallel. First, improved mechanical connection: Shougang is developing new processes for dovetail lap joints and reverse interference fits, enabling high-precision interlocking without the use of adhesives, thereby reducing reliance on adhesive materials (currently still in the experimental stage). Second, laser welding + annealing: Some manufacturers are experimenting with precision laser welding of laminations and performing stress-relief heat treatment on the entire core to restore its loss performance. This approach places extremely high demands on equipment investment and process control, and it has not yet been widely adopted. Third, vacuum impregnation: The iron core, which has just been prepared and simply clamped, is placed into resin, vacuum-impregnated, and then cured to form a solid unit. This approach is similar to the bonding technique used for transformer cores—although...

The bonding strength is inferior to that of the Z-coating method, and resin may also seep into air gaps, affecting performance. However, as a transitional measure, some small and medium-sized enterprises still use this approach. Fourth, new material substitution: For example, nanocrystalline alloy sheets or iron-based amorphous strip laminations, thanks to their extremely low inherent losses, can meet efficiency requirements without the need for adhesives. However, these materials have poor mechanical properties and are difficult to process, so they are currently used more often in specialized applications—such as high-efficiency fan motors—rather than in mainstream automotive motors. Overall, in the field of mainstream drive motors, self-adhesive silicon steel remains the most practical and reliable solution in the short term; other approaches are unlikely to fully replace it and will instead only create localized competition.
5. Cost-friendly app In the future, Z-coating technology will also penetrate the mid- and low-end motor markets, particularly in the sectors of household appliances and small industrial motors. Once manufacturers have absorbed the costs associated with process upgrades, bonded iron cores will become increasingly attractive due to their noise-reduction and energy-saving benefits. For instance, if washing machine and electric-fan motors adopt bonded iron cores, they can operate more quietly and smoothly, giving these products a distinct market appeal. In price-sensitive segments, material suppliers may introduce simplified self-adhesive coatings—reducing coating thickness and eliminating certain expensive components—to lower costs and meet basic bonding requirements. This will further expand the application scope of self-adhesive technology.

08 Summary

As a groundbreaking innovation in the field of motor materials, Baosteel’s Z-coating self-adhesive technology for non-oriented silicon steel has already demonstrated tremendous potential in China’s and the global high-efficiency motor industry. Looking ahead, with the successful implementation and exemplary effects of more domestic motor manufacturers—such as BYD and Huawei—this technology is poised to accelerate its widespread adoption, driving a shift in motor design from the traditional “mechanical assembly” paradigm toward a “material bonding” paradigm. As performance requirements continue to rise, self-adhesive coated silicon steel, together with novel electromagnetic solutions, will play a pivotal role in meeting the demands of next-generation motors for high efficiency, low noise, and intelligent manufacturing. It is foreseeable that the broad application of Z-coating technology will become a new hallmark of China’s new energy and high-end equipment manufacturing sectors, while also encouraging international peers to step up their investments in this area, ultimately benefiting the entire motor industry’s upgrade. As engineering and technical professionals, we should remain vigilant about new advances in materials and processes, proactively plan our R&D and production capabilities, and seize the opportunities brought by this technological transformation.

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