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  Low-Temperature Black Chromium Plating for Ball Screws: Process, Benefits, and Applications As ball screws are increasingly used in robotics, automation, medical devices, and semiconductor equipment, customers are placing higher demands on corrosion resistance, wear resistance, and product appearance. One surface treatment that has attracted growing attention is Low-Temperature Black Chromium Plating. Unlike conventional black oxide treatment, low-temperature black chromium plating provides excellent corrosion resistance and a durable black finish without affecting the mechanical properties of precision ball screws. What Is Low-Temperature Black Chromium Plating? Low-temperature black chromium plating is an electroplating process that deposits a thin layer of black chromium onto the metal surface at a relatively low temperature, typically between 20°C and 35°C. Because the process operates at a low temperature, it does not alter the heat-treated hardness or dimensional accuracy of precision ball screws, making it suitable for high-performance mechanical components. Typical Process Flow The manufacturing process generally includes the following steps: Surface polishing or grinding Degreasing and cleaning Acid activation Optional nickel undercoating (for improved adhesion) Low-temperature black chromium electroplating Rinsing with deionized water Sealing treatment Low-temperature drying (typically 60–80°C) This process produces a uniform black surface with excellent adhesion and long-term durability. Key Advantages 1. No Effect on Heat-Treated Hardness Most precision ball screws are hardened by induction hardening or through hardening to achieve a surface hardness of approximately HRC 58–62. Since black chromium plating is performed at only 20–35°C, it does not reduce hardness or affect the material's mechanical properties. 2. Minimal Dimensional Change The typical coating thickness is: 0.5–2 μm (standard) Up to 5 μm for special applications Such a thin coating has minimal influence on the dimensions of precision components. However, for high-accuracy grades such as C3 or C5 ball screws, coating thickness should still be considered during manufacturing. 3. Improved Corrosion Resistance Compared with conventional black oxide treatment, black chromium plating offers: Superior corrosion resistance Better color stability Improved resistance to fading With an appropriate sealing treatment, the coating can typically achieve 72–240 hours of salt spray resistance, while optimized processes may exceed 500 hours, depending on the coating system and test conditions. 4. Excellent Wear Resistance Black chromium coatings generally have a hardness of approximately HV 700–1000, providing significantly better wear resistance than traditional black oxide finishes. This makes the process suitable for exposed machine components that require both durability and an attractive appearance. Is Black Chromium Suitable for Ball Screws? The answer depends on which part of the ball screw is being coated. Recommended Areas Low-temperature black chromium plating is well suited for: Shaft ends Mounting journals External exposed surfaces Non-functional areas These areas benefit from improved corrosion resistance, wear resistance, and an attractive matte black appearance. Areas Not Recommended The following surfaces are generally not recommended for black chromium plating: Ball screw raceways Ball nut raceways Precision rolling contact surfaces Although the coating is extremely thin, it can still: Slightly alter raceway geometry Increase surface roughness Affect preload consistency Potentially reduce service life if coating wear or peeling occurs under rolling contact For these reasons, most high-precision ball screw manufacturers leave the raceways in their ground condition while applying surface treatments only to non-working areas. Comparison with Other Black Surface Treatments Process Temperature Typical Thickness Corrosion Resistance Wear Resistance Suitable for Precision Ball Screws Black Oxide 135–150°C <1 μm Fair Low General applications Low-Temperature Black Chromium 20–35°C 0.5–2 μm Excellent Excellent Yes (non-raceway areas) Black Nickel 40–60°C 2–10 μm Good Moderate Limited applications DLC (Diamond-Like Carbon) PVD/CVD 1–3 μm Excellent Outstanding High-end applications Applications in Robotics and Automation As humanoid robots, collaborative robots, and medical automation continue to evolve, manufacturers increasingly require components that combine: High precision Long service life Corrosion resistance Low reflectivity Premium appearance Low-temperature black chromium plating is an excellent solution for improving the durability and appearance of shaft ends and external surfaces without compromising the precision of the ball screw. Conclusion Low-temperature black chromium plating offers an ideal balance of appearance, corrosion resistance, and wear resistance for precision mechanical components. For high-precision ball screws, however, industry best practice is to apply the coating only to non-functional areas such as shaft ends and mounting sections, while keeping the raceways in their precision-ground condition. This approach ensures maximum accuracy, long service life, and reliable performance. At MINI Ball Screw, we provide customized surface treatment solutions based on your application requirements. Whether your project involves industrial automation, medical equipment, semiconductor machinery, or humanoid robotics, our engineering team can recommend the most suitable surface finishing process for your ball screw assembly.

  Single Nut vs. Double Nut Ball Screws: Which One Should You Choose? Ball screws are widely used in CNC machines, industrial automation, robotics, medical equipment, and precision positioning systems. One of the most common questions engineers face is whether to choose a single nut or a double nut ball screw. While both designs convert rotary motion into precise linear motion with high efficiency, they differ significantly in terms of backlash, rigidity, positioning accuracy, and cost. What Is a Single Nut Ball Screw? A single nut ball screw consists of one ball nut circulating steel balls along the screw shaft. It is the most common and economical configuration. Advantages Compact and lightweight design Lower manufacturing cost High transmission efficiency (typically above 90%) Lower starting torque Reduced friction and heat generation Easy installation and maintenance Typical Applications Industrial automation Packaging machinery 3D printers Semiconductor handling equipment General-purpose linear motion systems For many standard applications, a high-quality single nut ball screw provides excellent accuracy and long service life. What Is a Double Nut Ball Screw? A double nut ball screw uses two separate nuts connected by a spacer or an adjustable preload mechanism. By applying preload between the two nuts, axial backlash can be minimized or nearly eliminated. Advantages Near-zero backlash Higher axial rigidity Improved positioning accuracy Excellent repeatability Better vibration resistance More stable performance under heavy loads Typical Applications CNC machining centers Precision grinding machines Industrial robots Medical equipment Semiconductor manufacturing High-speed, high-precision positioning systems Double nut ball screws are the preferred choice when maximum precision and stiffness are required. The Biggest Difference: Preload The most important distinction between the two designs is preload. A standard single nut typically has little or no preload, which means a small amount of axial clearance (backlash) may remain. A double nut, however, is designed to apply controlled preload between the two nuts. This preload removes backlash, increases rigidity, and significantly improves positioning performance. For applications requiring micron-level positioning accuracy, a preloaded double nut is often the ideal solution. Performance Comparison Feature Single Nut Double Nut Structure Simple More complex Cost Lower Higher Size Compact Larger Backlash Small or adjustable Nearly zero after preload Axial Rigidity Good Excellent Positioning Accuracy High Very High Repeatability Good Excellent Starting Torque Lower Higher Friction Lower Slightly higher Heat Generation Lower Slightly higher Maintenance Easy More complex Does a Double Nut Increase Load Capacity? This is a common misconception. A double nut does not automatically double the dynamic load capacity of a ball screw. The basic load rating is primarily determined by factors such as: Screw diameter Ball diameter Ball track geometry Ball circulation design Material and heat treatment The main benefit of a double nut is not a dramatic increase in load capacity, but rather improved rigidity, reduced backlash, and more uniform load distribution. These characteristics help maintain positioning accuracy and stability under demanding operating conditions. Which One Should You Choose? A single nut ball screw is the ideal choice if your application prioritizes: Lower cost Compact installation space High efficiency Moderate positioning accuracy A double nut ball screw is recommended when your application requires: Zero or near-zero backlash High rigidity Superior positioning accuracy Excellent repeatability Heavy-duty or high-precision operation Custom Ball Screw Solutions At MINI Ball Screw, we manufacture both single nut and double nut ball screws for a wide range of industries, including industrial automation, robotics, medical devices, semiconductor equipment, and precision machinery. Our engineering team can recommend the most suitable configuration based on your load requirements, speed, travel, positioning accuracy, and operating environment. Looking for the right ball screw solution? Contact us with your drawings or technical specifications, and we'll help you select the optimal design for your application.

  Brass vs. Bronze Nuts for Trapezoidal Lead Screws: Which Material Is Right for Your Application? When selecting a trapezoidal lead screw, engineers often focus on the screw itself while overlooking one of the most critical components—the lead screw nut. The choice between Brass and Bronze can significantly affect load capacity, wear resistance, service life, and overall system performance. So, which material is the better choice? Brass Nuts Brass is a copper-zinc alloy widely used in general mechanical applications due to its excellent machinability and cost-effectiveness. Advantages Lower material and machining costs Excellent machinability for efficient production Good corrosion resistance in normal environments Suitable for light- to medium-duty applications Typical Applications General industrial machinery Automation equipment Packaging machines Light-duty linear motion systems If cost is a primary concern and the application operates under moderate loads, a brass nut can be a practical and economical solution. Bronze Nuts Bronze is primarily a copper-tin alloy and has long been recognized as the preferred material for heavy-duty lead screw applications. Phosphor bronze and tin bronze are especially popular because of their outstanding mechanical properties. Advantages Excellent wear resistance Superior load-carrying capacity Outstanding anti-galling performance Lower friction during sliding motion Longer service life under continuous operation Better performance in harsh environments Typical Applications CNC machinery Industrial automation Lifting systems Medical equipment Heavy-duty mechanical transmission High-duty-cycle linear actuators Bronze nuts are especially recommended for applications requiring long service life and high reliability. Brass vs. Bronze Comparison Property Brass Bronze Cost Lower Higher Machinability Excellent Good Wear Resistance Good Excellent Load Capacity Medium High Anti-Galling Good Excellent Service Life Medium Long Heavy-Duty Applications Suitable Highly Recommended Which One Should You Choose? If your application requires a cost-effective solution for moderate loads, Brass is an excellent option. However, if your equipment operates under high loads, frequent cycles, or demanding environments, Bronze offers significantly better wear resistance, higher load capacity, and a much longer service life, making it the preferred choice for professional mechanical transmission systems. At MINI Ball Screw, we manufacture custom trapezoidal lead screws with a variety of nut materials, including Brass, Tin Bronze, Phosphor Bronze, Engineering Plastics (POM), and other customized materials to meet your specific application requirements. Whether you need prototypes or high-volume production, our engineering team can help you select the most suitable material based on your operating conditions, performance requirements, and budget. Need help choosing the right lead screw nut material? Contact us with your drawings or application details, and our engineers will recommend the optimal solution for your project.

  Precision in Motion: The Strategic Role of Ball Screws in the Optical Communication Industry Introduction As the global demand for high-speed data transmission escalates with the rise of 5G, AI, and hyperscale data centers, the optical communication industry is shifting toward unprecedented levels of integration. Technologies such as Silicon Photonics (SiPh) and 800G/1.6T optical modules require assembly and alignment accuracies at the sub-micron or even nanometer level. At the heart of the equipment making this possible is the precision ball screw, a critical component that provides the high-fidelity linear motion necessary for optical excellence. Key Applications in Optical Communication 1. Automated Optical Alignment and Packaging The most critical phase in optical manufacturing is the alignment of lasers (LD), photodetectors (PD), or Fiber Arrays (FA) with optical waveguides. The Role: Ball screws drive multi-axis alignment stages (often 6-DOF systems) to achieve perfect light coupling between the chip and the fiber. Requirement: This requires Ground Ball Screws (C3 grade or higher) to ensure the nanometer-level resolution and repeatability needed to minimize coupling loss. 2. Silicon Photonics Wafer Testing Before dicing, silicon photonics wafers must undergo rigorous testing where optical fiber probes must be positioned precisely over grating couplers. The Role: Precision ball screws drive the X-Y-Z motion of the probe stations. Advantage: Unlike standard lead screws, ball screws offer minimal friction and high response rates, ensuring consistent accuracy during high-volume automated testing. 3. Micro-Positioning in Optical Components Large-scale mechanical optical switches and Variable Optical Attenuators (VOA) occasionally utilize mechanical displacement to alter light paths or adjust signal strength. The Role: Miniature ball screws (often with diameters as small as $\emptyset 3mm$ to $\emptyset 6mm$) are used to adjust the physical position of internal mirrors or prisms. Trend: As devices shrink, the demand for high-precision, small-form-factor screws continues to grow. 4. Optical Fiber Drawing Towers In the upstream production of optical fiber, a massive fiber preform must be fed at a highly constant speed into a high-temperature furnace. The Role: A heavy-duty yet precise ball screw manages the Feeding System. Impact: The smoothness of the screw’s movement directly dictates the consistency of the fiber diameter; any vibration can result in geometric flaws that render the fiber useless. Technical Requirements for the Industry To serve the optical communication sector effectively, ball screws must meet specific, stringent criteria: Miniaturization: With optical modules becoming increasingly compact, there is a specialized market for micro-precision ball screws that can deliver high performance in confined spaces. Cleanroom Compatibility: Assembly often occurs in ISO-rated cleanrooms. Ball screws must utilize low-outgassing, vacuum-compatible, or dust-free lubricants to prevent the contamination of sensitive optical surfaces. Ultra-Smooth Travel: Since even microscopic vibrations can cause power fluctuations during alignment, the ball screw must exhibit minimal torque variation and high running smoothness. Conclusion While the optical communication industry is defined by the transmission of light, its physical infrastructure relies heavily on the mechanical precision of ball screws. From the initial drawing of the fiber to the final packaging of a high-speed transceiver, precision motion control remains the "silent enabler" of modern high-speed connectivity. For manufacturers capable of providing customized, high-precision, and miniaturized motion solutions, the optical industry represents a high-growth frontier.

Ball Screw Low Temperature Black Chrome Plating - Technical Data Sheet 1. Basic Information This technical data sheet specifies the standard parameters, performance indicators, application scope and related notes of low temperature black chrome plating process for ball screw. It is applicable to the production, inspection and selection of precision mechanical components, optical parts and other ball screw products requiring black chrome plating protection and decoration. Plating Type: Low Temperature Electrolytic Black Chrome Plating (Cr + Cr₂O₃ composite coating) Applicable Industry: Precision Manufacturing, Optical Engineering, Automotive, Aerospace, Medical Devices, Electronic Components   2. Basic Process Parameters Item Specification Unit Plating Type Low Temperature Electrolytic Black Chrome Plating (Cr + Cr₂O₃ composite coating) — Operating Temperature -10 ~ +25 (Typically controlled at 0 ± 5) °C Plating Bath System Trivalent Chromium (Preferred) / Hexavalent Chromium — Bath pH 2.0 ~ 3.5 — Cathode Current Density 15 ~ 50 A/dm² Plating Time 3 ~ 15 (depending on required thickness) min Anode Material Lead‑tin Alloy / Graphite / Special Inert Anode —   3. Coating Properties Item Standard Value Test Method Coating Thickness 1.0 ~ 3.0 (Typical: 1.5 ~ 2.0) μm Microhardness 300 ~ 600 HV Adhesion Grade 1, no peeling, no blistering ASTM D3359 Cross‑cut Test Appearance & Gloss Uniform matte black / semi‑matte black; Gloss < 15 GU Visual inspection, gloss meter Surface Roughness Ra 0.2 ~ 0.8 (depending on substrate finish) μm Heat Resistance Stable ≤ 300 °C without discoloration; short‑term heat resistance up to 480 °C Thermal cycling test   4. Corrosion & Wear Resistance Item Performance Test Condition Neutral Salt Spray (NSS) > 200 hrs without red rust; > 400 hrs with sealing treatment ASTM B117 Wear Resistance Excellent, better than black oxide and conventional nickel plating Dry sliding / Taber abrasion test Chemical Resistance Good resistance to weak acids, alkalis, oils and solvents; limited resistance to strong oxidizing acids Immersion test   5. Dimensional & Thermal Characteristics Item Performance Thermal Deformation Negligible, no annealing or thermal expansion (low temperature process ensures no thermal damage to workpieces) Dimensional Accuracy Ultra‑thin uniform coating, minimal influence on workpiece dimensions, suitable for parts with micron‑level tolerance   6. Applicable Base Materials & Main Applications 6.1 Applicable Base Materials Steel, stainless steel, aluminum alloy, copper alloy, and other common metal substrates. 6.2 Main Applications • Precision transmission components: ball screws, linear guides, spline shafts (corrosion protection + precision retention) • Optical and semiconductor parts: light‑shielding components, precision instrument parts (light absorption + cleanliness) • Automotive and aerospace parts: interior components, sensors, instruments (matte black appearance + durability) • Medical devices: precision casings, surgical instruments (corrosion resistance + biocompatibility) • High-end hardware: bathroom accessories, watches, precision hardware components (texture + wear resistance)   7. Advantages • Low temperature operation avoids thermal deformation, annealing and softening of workpieces, ensuring the dimensional precision of high-precision components. • Ultra-thin and uniform coating, with minimal impact on the original dimensions of workpieces, suitable for parts with strict tolerance requirements. • Excellent corrosion resistance and wear resistance, far superior to conventional black oxide and ordinary nickel plating processes. • Uniform matte black appearance, good light absorption performance, suitable for optical and precision equipment requiring low reflectivity. • Wide applicability, compatible with various common metal substrates, meeting the needs of different industrial fields.  

Amid the tide of modern technology, humanoid robots, as the perfect integration of artificial intelligence and mechanical engineering, are gradually stepping into our lives.   They not only play a vital role in fields such as industrial production lines, medical assistance, and disaster rescue, but also demonstrate boundless potential in industries like entertainment and education.   Behind all of this, there lies a component that seems unremarkable yet is of crucial importance — ball screws and bearings. I. Joint Transmission: The Key to Flexibility   Ball screws are closely connected to the "joints" of humanoid robots and serve as one of the core components enabling their flexible movement. Imagine this: without ball screws, every movement of the robot would become stiff and imprecise. It is precisely the presence of ball screws that allows the rotation of the motor to be accurately converted into linear motion, thereby realizing the smooth bending and extension of the robot's joints. Whether it is simulating human walking steps or performing complex gesture movements, ball screws play an indispensable role.  

Tesla’s Optimus Gen-2 robot uses 14 Swiss GSA inverted planetary roller screws—8 in the upper limbs and 6 in the lower limbs. Kepler’s K2 “Bumblebee” humanoid robot also adopts 12 self-developed planetary roller screw actuators paired with rotary actuators. It can last up to 8 hours on a single charge and lift 30 kg of weight with ease. Thanks to its proprietary core technology, the base version costs only $30,000.  In China, Unitree’s humanoid robots R1 and G1 use high-precision planetary roller screws in their leg actuators. UBTech’s Walker X and Zhiyuan robots also incorporate planetary roller screws, supplied by Yuhua Precision, a subsidiary of Best. Rumors suggest that the Unitree robot showcased at the Spring Festival Gala used planetary roller screws provided by Changsheng Bearings. Planetary roller screws operate through line contact rolling friction, avoiding significant material wear. Their lifespan is 10 times that of ball screws. They also possess a degree of self-locking, sharing part of the load and reducing the actuator’s power consumption. That is their mystery.

As a crucial mechanical transmission element, a roller screw enables the conversion between linear and rotational motion through rolling contact between rollers, the screw shaft, and the nut. The principle of a planetary roller screw is similar to that of a planetary reducer. From a high-speed power source like a motor or engine to the working end of the device, there must be a process of deceleration and torque amplification—this is what the transmission mechanism achieves. Small rollers revolve and rotate around the main screw, just like planetary bodies orbiting in space. Planetary Roller Screws are widely used in industrial automation, CNC machine tools, aerospace, and automotive manufacturing.  In the upstream supply chain, screw shafts are typically made from alloy structural steel, while nuts and rollers are made from high-carbon chromium bearing steel. Key components include the screw shaft and the nut. Internationally, planetary roller screws mainly use alloy structural steel, with nuts and rollers made of fully hardened 100Cr6 bearing steel, costing over 5,000 RMB per ton. In China, martensitic stainless steel and austenitic stainless steel are the main materials, with prices exceeding 10,000 RMB per ton. Key features of planetary roller screws include high transmission efficiency, precise positioning, strong load capacity, and long service life, making them indispensable in modern mechanical transmissions.

Driven by intelligent driving technology, the application and demand for ball screws in linear actuators within chassis systems are growing. The continuous progress of current intelligent driving technology places stricter requirements on vehicle chassis systems, especially in key application scenarios such as steer-by-wire, brake-by-wire, and active suspension. The market demand for linear actuators composed of motors, ball screws, and sensors is expected to grow significantly, specifically reflected in the following aspects: 1) Steer-by-wire: The current mainstream technology is EPS (Electric Power Steering), where R-EPS (Rack-mounted EPS) can use ball screws. When the motor position is closer to the steering gear, the efficiency of power assist transmission is significantly improved. R-EPS is known for its low noise, fast power assist response, and large power assist output. Although relatively costly, it is very suitable for medium, large, and extra-large vehicles. 2) Brake-by-wire: Ball screws are used in EMB (Electro-Mechanical Brake). The core difference between EMB and traditional braking systems is that it needs to convert the rotary motion of the motor into the linear motion of the brake pad, which can usually be achieved through various transmission methods such as ball screws, linkages, and electro-hydraulic combination. Ball Screws, especially planetary roller ball screws, with their excellent load capacity, large equivalent reduction ratio, high transmission efficiency, high transmission accuracy, excellent synchronization performance, and transmission reversibility, are expected to be widely used in EMB. 3) Active suspension: Ball screws are used as actuator components in active suspension systems. In this application, ball screws can convert bidirectional rotation into unidirectional rotation of the motor shaft and effectively increase the motor speed, thereby avoiding the high-frequency forward and reverse rotation issues of regenerative motors and thus improving energy recovery efficiency. Additionally, this mechanism has many advantages such as a wide damping force adjustment range, high structural reliability, high transmission efficiency, and low cost. The automotive ball screw market has broad prospects, expected to exceed 7 billion yuan by 2025. Based on the strong demand for ball screws from new energy vehicles, we calculate the automotive ball screw market with the following assumptions: 1) According to data released by the CPCA for 2023, passenger car annual sales reached 21.7 million units, of which new energy vehicle sales were 7.74 million units. The passenger car market will maintain a stable annual growth of 1%. 2) Only consider the application of ball screws in new energy vehicles, mainly using ball screws and planetary roller ball screws. 3) Regarding price, we assume the unit price of planetary roller screws is 1500 yuan, and the unit price of ball screws is 400 yuan, expecting these prices to decrease year by year. Overall, the automotive ball screw market shows strong growth potential. It is expected that by 2025, the total market size will exceed 7 billion yuan.

Ball Screw in Industrial Mother Machines (Machine Tools) Development of high-end machine tools accelerates; guide rails and ball screw play important roles in industrial automation equipment. With the continuous advancement of industrial automation, the machine tool industry has risen to the core of national development strategy. In recent years, China has successively introduced multiple relevant policies to accelerate the development of high-end CNC machine tools, and the localization process of high-end machine tools is expected to speed up. Guide rails and ball screws are widely used in industrial automation equipment such as CNC machine tools, milling machines, and lathes. Through the precise positioning and stability of guide rails and ball screws, high-precision machining and positioning of workpieces can be achieved. The application of guide rails and ball screws can not only adjust the height, position, and angle of the workpiece but also greatly improve work efficiency and production quality.  Ball screws are used in conjunction with guide rails and are key components for transmission and positioning in CNC machine tools. With the improvement in the performance of ball screws, servo motors, and control units, the reduction mechanism can be omitted from the feed system of CNC machine tools, directly connecting the servo motor with the ball screw. This improvement brings multiple advantages: on one hand, it simplifies the entire system structure, reduces error-prone links, and improves reliability; on the other hand, due to reduced moment of inertia, servo characteristics are also improved, resulting in faster response speed and higher positioning accuracy of the machine tool. Ball Screws and guide rails hold significant value in the machine tool industry and have huge market potential. Taking a common three-axis CNC machine tool as an example, its configuration includes three linear axes: X, Y, Z. Each linear axis usually requires a ball screw. Considering the unit price of high-precision domestic ball screws is about 1000 yuan per piece, the total value of ball screws in a high-precision three-axis CNC machine tool is about 3000 yuan. Considering the overall price of a three-axis CNC machine tool is usually in the range of several hundred thousand yuan, the cost of screws occupies a certain proportion of the total machine tool cost. Referring to the raw material procurement proportion data of Kede CNC and Neway CNC, transmission materials account for about 20%. According to MIR DATABANK data, the scale of China's metal cutting machine tool market was about 113.5 billion yuan in 2023. Affected by the industry cycle in the first three quarters of 2024, the domestic market size decreased by about 6% year-on-year. It is estimated to decrease by about 6.1% for the whole year of 2024, with the Chinese metal cutting machine tool market size expected to be about 100 billion yuan in 2024. Therefore, the estimated market size for screws and guide rails in China's machine tool field is about twenty billion yuan.

Miniature Ball Screws Used in Dexterous Hands May Further Expand Screw Demand Tesla's third-generation dexterous hand replaced the worm gear scheme with a planetary ball screw. The transmission device of a dexterous hand can generally be divided into three stages: (1) First stage: Located on the motor side, mainly consisting of harmonic/planetary reducers and belts, serving to control precision and enhance torque. (2) Second stage: Mainly uses ball screws or bevel gears, responsible for action execution. (3) Third stage: Connects the driver and the joint end, mainly using tendon ropes or linkages. Ball Screws provide precise linear drive, possess the highest load capacity, and are suitable for scenarios like factories. Regarding reducers, Optimus Gen3 adopts planetary reducers (gearboxes) to improve transmission accuracy and enhance torque output capability. In the future, as integration demands increase, the usage of miniature ball screws and miniature reducers will significantly increase. Ball Screws Empower the Development of Humanoid Robots, Steady Progress in Ball Screw Projects by Domestic and International Companies Core evolution of ball screw precision transmission technology, significantly enhanced ball screw applications in the humanoid robot field. Before the advent of humanoid robot technology, ball screw devices mainly served as linear drive components in robotic arm systems, responsible for executing sorting operations, material handling, precision assembly, and component placement for electronic components. Their applications widely covered key areas such as the 3C industry, warehouse logistics management systems, and medical equipment. With the development of humanoid robots, ball screws have become an indispensable core component in building precision mechanical transmission systems due to their excellent performance. Especially in the joint construction and drive systems of humanoid robots, ball screws are extensively used in scenarios requiring extremely high precision and heavy load capacity, attracting widespread and high attention within the industry. China ball screw companies accelerate technological upgrades and capacity expansion, leading the new track in high-end manufacturing and robotics. In recent years, China ball screw companies have actively laid out ball/roller screw industries, gradually promoting technological upgrades and capacity expansion, entering fields like high-end manufacturing, robotics, and new energy vehicles. Among them: 1) some ball screw products have achieved partial mass production and are expected to become a new profit growth point. 2) Best Precision's high-precision ball/roller screw pair first set successfully rolled off the production line, with some products currently in the verification stage. 3) Some ball screw factories is steadily progressing in projects for automotive ball screws and humanoid robot planetary roller screws, with trial production lines already built. 4) Changsheng Bearing released a private placement plan in 2022, planning to invest 265 million yuan to expand self-lubricating bearing and ball screw capacity, including 30,000 sets of ball screws for the new screw track. 5) Hengli Hydraulic invested 1.5 billion yuan in 2021 to lay out linear drive projects, planning to achieve an annual production capacity of 104,000 planetary roller screw electric cylinders and 100,000 meters of ball screws, now entering the sample delivery and small batch supply stage. As the overall technical level of the industry improves, the competitiveness of domestic companies in the international market will further strengthen. Schaeffler supports Tesla Optimus, ball screw technological innovation leads a new chapter in smart manufacturing. As a trusted screw supplier for Tesla, Schaeffler plays an important role in the successful manufacturing of Optimus. Schaeffler continues to deepen technological innovation and industrial layout in new energy vehicles, robotics, and high-end manufacturing, focusing intensely on the R&D of ball screws, roller screws, and planetary roller screws. Its strategic layout aims to meet the market's urgent demand for high precision, high load capacity, and compact design. Currently, such high-performance transmission components are widely used in key areas such as steering assist systems and braking systems for new energy vehicles, as well as industrial robots and high-end machine tools. Schaeffler has successfully completed trial production and performance testing of some ball screw products, with the trial production line fully constructed. Simultaneously, samples of planetary roller screw products have entered a strict verification phase, laying the foundation for future large-scale mass production. Furthermore, Schaeffler enhances the R&D efficiency and application effectiveness of screw products by providing advanced online calculation tools and comprehensive digital solutions. These strategic initiatives fully demonstrate Schaeffler's technological advantages and systematic capabilities in the global screw market, providing strong momentum for the rapid development of smart manufacturing and the new energy sector.

Ball Screw is Core Component of Humanoid Robots, Screw Market Faces Ten-Billion Incremental Opportunity The industrialization process of humanoid robots is accelerating, with ball screws being a core component. A ball screw typically consists of a screw, a nut, and a reversal device. Ball Screw working principle involves converting the rotary motion of the screw into the linear motion of the nut, thereby driving precise displacement movement. The reversal device primarily serves to change direction during the motion process. In humanoid robots, a motor usually drives the ball screw to rotate, while the ball screw nut is connected to components requiring linear motion, thus driving these components to move along precise trajectories and distances Planetary roller ball screws at the joints and miniature ball screws in dexterous hands are two important types of screw components in humanoid robots. They play roles in precise transmission, transmitting and amplifying force, and providing feedback and position control. 1) Many actions of humanoid robots require extremely high precision ball screw, such as arm extension and finger grasping. In actions requiring greater force, planetary roller ball screws can amplify the force output by the motor through rational design to meet the power demands at the joints of humanoid robots. 2) Miniature ball screws can precisely control the opening and closing of fingers, enabling the grasping of objects of different shapes and sizes. When combined with sensors, screws can provide precise position feedback information to the control system of humanoid robots, enabling precise adjustments and improving motion stability and reliability. 1) Planetary Roller Ball Screws at Joints With the continuous promotion of humanoid robots, planetary roller ball screws are being applied more widely. Since Tesla released the humanoid robot Optimus, domestic and international industrial capital has accelerated its expansion into the humanoid robot field. For example, internationally, Samsung invested 59 billion KRW in local robot manufacturers, and Google launched RoboCat, a robot capable of self-improvement. Domestically, companies like Xiaomi, Fourier, Unitree, Zhiyuan, and Kepler have successively launched their humanoid robot products. As one of the core components of humanoid robots, ball screws are mainly used in linear joint parts to convert the rotary motion of the motor into linear motion. Particularly, planetary roller ball screws have advantages such as high load capacity, small size, fast response, low noise, and high precision, making them highly suitable for humanoid robot motion. The volume production of humanoid robots is expected to bring a ten-billion incremental space to the ball screw market. Based on Tesla Optimus parameters, one humanoid robot has 14 linear actuators. We make the following assumptions: 1) It is estimated that all joint parts of a humanoid robot will require planetary roller ball screws, totaling 14, potentially increasing to 16 later. 2) It is estimated that the long-term sales of humanoid robots can reach 1 million units. 3) Assuming the unit price of planetary roller ball screws decreases to 1000 yuan in the long term as the localization process accelerates. Overall, the volume production of humanoid robots will bring a ten-billion increment to the screw market.

Today, let's talk about why ordinary ball screws cannot be used in the actuators of Tesla's hands and legs. There's no need to go over the principle of ball screws again. Let's talk about something new. Everyone knows the basic concept that a ball screw is a Goethe-type raceway, where the steel balls contact two points at a 45-degree angle. During movement, the steel balls rest on these two 45-degree points to move. Because the entire operation is point contact, it is very smooth. Can you understand this? If you can understand this, then you can understand that its efficiency is very high. What does high efficiency mean? If you use it as a force source and push this smooth screw, is it not effortless? It's like a cart with wheels. If you give it a very large force, won't the small cart be pushed 10 meters away in an instant, seemingly without any effort? Well, I'll tell you that its efficiency is 90%, which means that of the force you give it, only 10% is lost during operation. If you can understand efficiency, then you can understand that the efficiency of planetary ball screws is around 75%, which means you don't have to exert as much force.   Now, the problem arises. Although your small cart is smooth, if you load it with one ton of goods and push a heavy object, this heavy object will also push back against your force source (motor). You are sandwiched in the middle, bearing the force from both sides. One side bears the huge torque output from the motor, and the other side bears the pressure from the heavy object. At this point, as a point contact, you are in great pain because your steel balls are about to burst. Therefore, the lifespan of a ball screw is only one-tenth of that of a planetary roller screw. Yes, you heard it right. The lifespan of a planetary roller screw is ten times that of a ball screw. If you have no questions up to this point, congratulations, your comprehension is really good. So, what is a planetary roller screw? As the name suggests, a planet has to revolve around and rotate on its own axis to be called a planet. Therefore, during the operation of a planetary roller screw, there is no sliding friction between the screws, nor is it point friction. It is rolling line friction. That is, since it doesn't rub against the ground, it doesn't wear out, or the wear is very small. This is one of the sources of its long lifespan. Secondly, its rollers are a bit longer. Unlike ball screws, which are like eggs, they are like flat bars. When they bear a load, there are 6, 8, 9, or 11 flat bars, sharing the huge load with the main screw. Because it doesn't rub against the ground, its efficiency is not low either, but it's not as high as that of a ball screw. However, it's not too low either. The next point is the fatal core reason why ball screws cannot be used as actuators. That is, ball screws have no self-locking force at all. They can even be crushed by their own weight because they are too smooth. In contrast, planetary roller screws have a certain "self-locking force", which can buffer or be understood as having a certain counterforce, but they cannot completely self-lock.   So, what are the benefits? During operation, when you are pushing a heavy object, you know the principle of force is mutual. When you apply pressure to an object, the object exerts a counterforce on you. So, when a planetary roller screw is under load, the self-locking force of the planetary roller screw can share part of the load without transmitting it to the motor end, preventing motor stalling. Thus, the motor is effectively protected or does not reach its power peak. That is to say, you don't have to exert so much force. If the motor stalls for a long time, it will overheat and burn out. OK, so what does this have to do with humanoid robots? You know, on the legs and arms of robots, there are linear actuator joints, which are used to carry loads, just like human muscles. If you stand, where is your center of gravity? That's where the load is. Your linear actuator starts to work and bear the load. At this time, if it's a regular ball screw, the motor will consume a lot of power because it's not self-locking and all the load is returned to the motor. The motor has to work hard. If the load gets bigger and bigger, the motor can't handle it and it gets stuck. It starts to heat up. So the heavy-load characteristics and self-locking ability of planetary roller screws effectively help the motor reduce its workload, extend its service life, and save electricity! Isn't that great? Well, if you have any questions, leave a comment in the comment section.

The ball screw is an essential mechanical component that plays a crucial role in various industries. Miniature and super huge ball screws, despite their size differences, both have significant applications and technical challenges.   The miniature ball screws are often used in precision instruments and small-scale devices where space is limited but high accuracy and smooth movement are required. Their design and manufacturing demand meticulous attention to detail to ensure optimal performance. The materials used for miniature ball screws need to be of high quality to withstand the small loads and frequent operations.   On the other hand, super huge ball screws are employed in large-scale machinery and industrial equipment. These massive components have to handle immense loads and provide stable and reliable movement over long distances. The engineering and fabrication of super huge ball screws involve complex techniques and advanced manufacturing processes to guarantee their durability and functionality.   In conclusion, both miniature and super huge ball screws contribute to the advancement of technology and the improvement of mechanical systems, each in their own unique way and application scenarios.

The ball screw is a seemingly simple yet highly significant component in various mechanical systems. It interacts with the workpiece in a precise and purposeful manner to achieve the desired function.   When a screw is engaged with a workpiece, it creates a connection that holds things together firmly. The threads of the screw interlock with the corresponding features of the workpiece, providing stability and strength. This interaction is crucial in numerous applications, from the construction of buildings to the assembly of complex machinery.   The choice of screw type, size, and material depends on the specific requirements of the workpiece and the task at hand. A well-matched screw ensures optimal performance and durability. Moreover, the force applied during the screwing process also affects the final outcome.   In conclusion, the interaction between the screw and the workpiece is a fundamental aspect of mechanical engineering. It demonstrates the importance of precise design and careful implementation to achieve the desired functionality and reliability in any mechanical structure or device.

Grinding: The ball screw and roller are mainly used in rolling or turning, and the nut needs to be ground in the finishing process, and the grinding process is more difficult. At present, overseas ball/planetary roller screws apply rolling or turning processes in low-precision fields (such as transmission) and grinding processes in high-precision fields (such as machine tools). In the field of humanoid robots, the lead screw and roller are mainly rolled or turned, while the nut is ground.   The bottleneck of the process is nut grinding. The humanoid robot uses the reverse planetary roller screw, which is characterized by the nut being longer than the screw, such as the turning will cause the shock knife, so the grinding is more suitable, but the grinding rod and the grinding wheel need to go deep inside the nut, need to do a small diameter, and the grinding wheel has a minimum speed of 20m/s, so the speed needs to reach 40,000-50,000 RPM, and it is very difficult to maintain processing stability at high speed. In addition, in the planetary roller screw, because the nut is longer, the thread line needs to be processed is longer, and the single nut needs to grind 5 thread lines (only one ball screw nut), the processing cycle is long, the production beat is low, the cost is high, and the production difficulty is more difficult than the ball screw.

The reverse planetary ball screw is suitable for compact scenarios, such as humanoid robots.   1) The reverse planetary roller screw has a longer nut and can achieve a greater load with less torque. The structure of the reverse planetary roller screw is similar to the standard type, but there is no inner tooth ring, both ends of the screw are processed with straight teeth meshing with the gears at both ends of the roller, the nut as an active part, the length is much larger than the standard type, and the advantage is that the higher rated load is achieved through the smaller lead, thus reducing the driving torque, suitable for compact situations.   2) The lead screw and motor can be integrated. The gear of the reverse planetary roller lead screw is designed between the roller and the lead screw to provide a smoother and more stable synchronous rotation motion, which is mainly used for small and medium loads, small strokes and high-speed applications. At the same time, the structure can realize the integrated design of motor and lead screw.

Tesla humanoid robot is expected to open the ball screw, planetary roller screw application space. According to the Tesla AI Day2022 information, the lower legs of the Tesla humanoid robot will use frameless motors and linear actuators with planetary roller screws. Under the assumption that Tesla's single humanoid robot needs 4 ball screws +10 planetary roller screws, the global population is about 8.2 billion people, and the robot penetration rate is 12 units / 10,000 people, it is estimated that the robot contribution to the application space of ball screws and planetary roller screws is expected to reach 7.475.6 billion yuan.

Ball Screw Processing method: According to Zheng Hong's "Research on Precision ball screw Machining Process Regulations", the common methods of grinding ball screw processing are: grinding wheel, hard turning, cyclone milling. (1) Grinding wheel: the highest precision, for precision requirements of high finishing, low production efficiency. According to the different cross-section shape of the grinding wheel, there are two kinds of grinding with single line grinding wheel and multi-line grinding wheel. Taking the grinding with single line grinding wheel as an example, the pitch accuracy can be reached to 5 ~ 6, the surface roughness is Ra1.25 ~ 0.1 micron, and the grinding wheel dressing is convenient. This method is suitable for grinding precision lead screw, thread gauge, worm, small batch thread workpiece and grinding precision hob. However, after the magnetic flaw detection of this process method, it will be found that there are cracks along the axis direction on the arc of the ball screw raceway, which can be solved by the process method of "small grinding amount multiple feed" or the technical method of "grinding - working raceway surface temperature stability - grinding". The grinding stress and grinding heat on the working raceway surface of the ball screw can be reduced to the maximum extent to avoid grinding cracks or burns. (2) Hard turning: It is used for roughing and finishing with low precision requirements and high production efficiency. Hard turning refers to the turning of hardened materials as a new technology and a new process of rough processing or final processing and finishing, avoiding the use of grinding processing technology. Hard turning usually adopts high speed and large cutting depth, and the metal cutting efficiency is more than 3 times that of grinding. During hard turning, a clamping can complete the processing of multiple surfaces of parts (such as the outer circle of the car, the hole in the car, the groove, etc.), while grinding requires multiple installations to complete, resulting in secondary installation errors; More than half of the heat generated by hard turning is taken away by the chips, and will not produce surface cracks and burns like grinding processing, so hard turning can make the workpiece obtain good processing accuracy and surface roughness, and can ensure the technical requirements of form and position tolerance (such as roundness, position accuracy). (3) Cyclone milling: for roughing and finishing with low precision requirements, the highest production efficiency. Ball screw work raceway roughing can also use cyclone milling, cyclone milling is a CNC lathe supporting the installation of high-speed milling thread power head, with a high-speed rotating cutter on the carbide forming tool, milling thread from the workpiece processing method, cyclone milling a knife forming, the use of compressed air chip cooling, and no need to process thread back slot, The stress concentration defect of the cutting groove is solved.

Ball Screw Heat treatment: According to Zheng Hong's "Research on Precision ball screw Machining process Regulations", GCr15 high-carbon chromium bearing steel is often used as ball screw material. Bearing steel has the advantages of high hardness, uniform organization, strong wear resistance and high contact fatigue strength after quenching and low temperature tempering, but bearing steel material is generally plastic, medium cutting performance, poor welding performance and temper brittleness. Therefore, the bearing steel material should be pre-heat treated before grinding the ball screw roughing, and the carbide in the GCr15 material should be spheroidized by spheroidizing annealing to obtain spheroidal or granular carbide organization uniformly distributed on the ferritic matrix, reducing the hardness of the material organization, improving the plastic function of the material, and improving the machining performance of the material metal cutting.