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Thorough explanation of screw manufacturing processes: The process from raw materials to finished products

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  • September 11th, 2025
Thorough explanation of screw manufacturing processes: The process from raw materials to finished products
From everyday items to automobiles, aircraft, and buildings, screws are indispensable components across all industries. Though they may seem like small parts, their role is significant—they affect product safety and durability. Screw manufacturing involves multiple processes and advanced technologies, making it a complex and highly important operation. The quality of a screw largely depends on the materials selected. Common materials include steel, stainless steel, and brass. Steel is strong and widely used for general applications. Stainless steel offers excellent corrosion resistance and is ideal for humid or outdoor environments. Brass is highly workable and often used for decorative purposes. Choosing the appropriate material based on environment, required strength, and durability allows screws to perform optimally and ensures long-term safety. Screw manufacturing begins with material selection and proceeds through various stages—heading, thread rolling, heat treatment, and surface treatment. Each stage plays a crucial role in determining the final quality of the screw. The heading process forms the head of the screw. First, wire is cut to the necessary length, then a press called a header machine applies pressure via a die to shape the head. There are two types: cold heading (performed at room temperature and suitable for mass production) and hot heading (using heated material to enable more complex shapes). Header machines perform automated sequences including cutting, forming, and ejecting. The die is a critical tool that defines the screw’s head shape and requires high precision. Key quality control points in this process include temperature and pressure regulation. Poor temperature control may lead to cracking or deformation. Insufficient pressure can result in irregular head shapes. Skilled technicians carefully operate machinery to maintain strict quality management. Thread rolling creates the threads on the screw blanks formed in the heading process. Using tools called thread rolling dies, threads are formed by pressing the blanks while rotating them. Compared to cutting, thread rolling results in stronger threads and higher production efficiency. Common machines include flat-die and cylindrical-die rolling machines. Flat-die machines press the blank between two flat dies using a reciprocating motion. Cylindrical-die machines use rotating round dies for continuous thread formation. Important quality control points include pressure and speed settings. Excessive pressure can crush threads or crack the material; insufficient pressure may produce incomplete threads. High speed may reduce thread accuracy. Optimal settings are used to maintain stable quality. Heat treatment enhances the strength and toughness of screws. Common techniques include quenching ...

【Must-Read for Beginners】Screw Selection Guide for Manufacturing by Application

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  • September 05th, 2025
【Must-Read for Beginners】Screw Selection Guide for Manufacturing by Application
In the manufacturing industry, screws are crucial components that affect product quality and durability. With a wide variety of types and standards, appropriate selection can be said to be a fundamental element in product development. However, selecting screws requires specialized knowledge, which can be difficult for beginners. This guide covers everything from the basics to advanced applications of screws, supporting the selection of optimal screws for various purposes. Through this article, readers will gain comprehensive knowledge about screws and improve the accuracy of screw selection in product development. Screws come in a wide variety of types depending on their shape and application. Appropriate screw selection is essential for ensuring product performance and safety. Below, we explain representative screw types and their respective features and applications. These are relatively small in diameter and often used in combination with nuts or female threads. They are suitable for fixing relatively small parts in precision equipment and furniture. Head shapes are also diverse, including flat head, round head, and truss head, allowing for selection according to application. Characterized by their hexagonal heads, bolts are used in combination with nuts and are widely employed for fixing relatively large parts and structures in machinery and building structures. They can withstand high tightening torque, making them suitable for locations requiring strong connections. Tapping screws can be screwed directly into material without a pilot hole, and were developed to improve work efficiency. They are effective for relatively soft materials such as wood and thin metal sheets. Since the threads cut into the material as they advance, they provide a firm fixation. Wood screws are designed specifically for wood, with pointed tips and threads shaped to bite easily into wood. They are utilized in various woodworking situations, such as furniture assembly and DIY woodworking. SEMS screws, which have a washer integrated, eliminate the need to prepare a washer separately, contributing to improved work efficiency. Additionally, since the washer cannot detach, they also have the effect of preventing parts from being lost. Many screws specialized for specific applications also exist. For example, trapezoidal screws and ball screws are used in mechanisms that convert rotational motion into linear motion. These screws are selected when precise positioning or the transmission of large forces is required. The choice of screw material is very important depending on the usage environment and required performance. Below, we explain representative screw materials and their respective characteristics and ...

Key to Improving Productivity: High-Speed Fastening Screws and Their Implementation Cases

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  • August 28th, 2025
Key to Improving Productivity: High-Speed Fastening Screws and Their Implementation Cases
In the world of manufacturing, daily productivity improvement is a major challenge. Especially in high-mix, low-volume production or during emergency production increases, the single task of fastening a screw can directly impact the entire line’s lead time and is fraught with the risk of producing defective products. In this context, “high-speed fastening screws” are gaining attention. As long-tail keywords like “high-speed fastening screw implementation effects” and “high-speed fastening screw Vietnam” suggest, their implementation effects and case studies in the Vietnamese manufacturing industry are increasing. Compared to conventional bolt and nut fastening, they dramatically improve fastening speed while achieving uniform torque management. They are also expected to be effective as a countermeasure against fastening defects on the manufacturing floor. This article will first cover the basic knowledge and market background of high-speed fastening screws, then introduce representative technical principles such as friction type and preset type. We will also touch on how to strengthen quality assurance through current-controlled drivers and traceability functions via IoT fastening management and traceability linkage. Finally, let’s decipher the key points for productivity improvement through actual implementation case studies in the automotive industry, electronics assembly, and the Vietnamese manufacturing industry. The intended audience is everyone in manufacturing responsible for parts procurement, production management, and quality assurance, especially those engaged in low-volume, high-mix production lines in the Vietnamese manufacturing industry. We will provide hints for improving line operating rates, reducing costs, and stabilizing quality by incorporating high-speed fastening screws. High-speed fastening screws are a category of screws that, by employing integral molding or preset methods and工夫した締結具 (innovative fasteners), can complete assembly in a few to a dozen seconds per screw. Previously, bolts and nuts were handled separately, and workers tightened them manually, resulting in long tact times and concerns about quality risks due to torque variations. Against the backdrop of expanding high-mix, low-volume production and labor shortages, as the need for automation and labor-saving on production lines increases, high-speed fastening screws are gaining attention as a solution that balances torque management and workability. Furthermore, products capable of cloud-based management of fastening history through IoT integration have also appeared, accelerating the move to achieve both precision and visualization simultaneously. High-speed fastening screws are broadly classified into three types: “friction-type fastening,” “preset-type fastening,” and “Posi-Lock method.” Friction-type fastening is a mechanism that secures parts together by applying appropriate pressure to the screw threads, preventing vibration and loosening. Representative products include ...

Streamlining Screw Inventory Management: Tips for Securing the Necessary Quantity

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  • August 21st, 2025
Streamlining Screw Inventory Management: Tips for Securing the Necessary Quantity
Screws not only “connect” products but are also the lifeline that supports the entire production line. However, with a vast number of types and sizes, even a stockout of a screw costing just a few yen can halt the line, potentially leading to delivery delays and increased costs. This article explains how to strike a balance to manage such screw inventory “without stockouts and without holding excess.” The intended readers are those in charge of production control, material purchasing, and on-site supervision. We have covered concrete measures directly applicable to practice, such as reducing man-hours for inventory counting that is a daily headache on the manufacturing floor, automated ordering using IoT, and cost reduction through procurement in Vietnam. By the time you finish reading this article, you should have a systematic understanding of screw inventory management and a checklist that you can try on-site immediately. Now, let’s take the first step toward optimal inventory. What you can learn in this article Understand the risks and costs of screw inventory shortages and surpluses. Learn how to determine optimal inventory levels using KPIs like inventory turnover rate and stockout rate. Even if a single screw costs only a few yen, a stockout can bring the entire production line to a halt, leading to significant opportunity losses. For example, in automotive parts factories, it is not uncommon for line stoppage costs to amount to several hundred thousand yen per minute. There are also latent risks that are difficult to quantify in monetary terms, such as customer contract penalties and brand damage due to delivery delays. On the other hand, excess inventory also ties up capital unnecessarily and puts pressure on warehouse space and inventory counting man-hours. Screws tend to have a vast number of items due to differences in size and material, and if not properly managed by location, the risk of mix-ups and contamination defects increases. To suppress both “line stoppages due to stockouts” and “cost increases due to excess inventory,” quantitative KPI management is essential. Inventory Turnover Rate Inventory Turnover Rate = Annual Issue Quantity ÷ Average Inventory Quantity For general-purpose items with low unit prices like screws, a turnover rate of 6 to 12 times a year is a benchmark (median value of 20 companies that introduced GIS Ohta Vietnam, 2024 results). A turnover rate of 3 times or less can be considered a sign of excess inventory. Stockout Rate Stockout Rate ...

What are the latest fastening technology? Automation and AI to change manufacturing industry

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  • August 14th, 2025
What are the latest fastening technology? Automation and AI to change manufacturing industry
Screw fastening is a critical final process that influences the reliability and safety of a product. However, in recent years, conventional manual-based operations are reaching their limits due to the aging of skilled workers, labor shortages, shorter design cycles, and increasing demands for traceability. The number of industrial robots in operation worldwide is on the rise, reaching approximately 4.28 million units in 2023. The Asian region, in particular, accounts for 70% of the total, making the automation and advancement of fastening processes an essential requirement. This article provides a detailed explanation for personnel in production technology, quality control, and procurement on the fundamentals of screw fastening automation, torque management, JIS/ISO standards, the latest trends in AI/IoT, and case studies of implementation and their effects in the Vietnamese manufacturing industry. The objectives of automation are “stable quality,” “throughput improvement,” and “reduction of skill dependency.” The process consists of the following three stages: Supply: Parts feeders and orientation control units ensure a stable supply, while optical and weight sensors prevent jamming and contamination. Fastening: Achieves proper torque and angle control, along with improved positioning accuracy. Precision is maintained through clutch control and image correction technology. Inspection: Automatically judges torque and appearance, creating a database to be utilized for process improvement. Typical problems such as cam-out (the driver slipping out of the screw head) and insufficient or excessive torque can be addressed through multi-stage fastening and setting conditions specific to the material. JIS B 0205 specifies the basic profile and dimensional system for metric screw threads, while ISO 16047 defines the test conditions for torque-clamp force. Utilizing these standards enables the standardization and comparative verification of fastening conditions, which directly leads to quality stabilization. For critical parts, ensuring traceability through the storage of fastening data and serial number management is indispensable. ABL Series: A specialized machine for micro screws, compatible with M0.4 to M6. It has a proven track record of zero defects through precision torque control. HM Series: A high-speed fastening robot for high-mix, low-volume production, compatible with speeds up to 6,000 rpm. It is characterized by its rapid condition switching capabilities. THL900-EN01: A high-torque compatible model applied to the fastening of large structural components. It reduces work time by 30%. AI analysis enables the early detection of signs of abnormalities, realizing predictive maintenance. IoT integration allows for remote monitoring and the storage of data for all points, which aids in preventing ...

Checklist to minimize screw-related problems at manufacturing sites

  • Column
  • August 07th, 2025
Checklist to minimize screw-related problems at manufacturing sites
In a manufacturing setting, screws are a critical component that determines the strength and reliability of a product. However, when problems such as loosening, falling out, or thread damage occur, they can lead to product defects, increased accident risks, and higher rework costs, significantly reducing production efficiency on-site. This article introduces a practical checklist to minimize such “screw troubles.” The intended audience includes site managers, assembly workers, and quality assurance personnel. We have organized the key points for fastening management compliant with JIS and ISO standards into a “checklist format” that can be immediately used in daily assembly and inspection tasks. We have specifically focused on the keywords “screws,” “troubles,” and “checklist,” comprehensively summarizing the check items for each stage. First, let’s understand the typical trouble cases that frequently occur on-site and their backgrounds, and then grasp the essential points in each phase from design and selection to procurement and storage, fastening work, and inspection and maintenance. Finally, we will also propose how to incorporate this into the PDCA cycle and a preventive flow utilizing the latest tools such as IoT torque wrenches. This will enable you to simultaneously achieve quality improvement, cost reduction, and worker safety in the manufacturing workplace. This is a phenomenon where screws gradually loosen due to vibration, impact, or thermal expansion/contraction, eventually falling out. Cause: Insufficient preload, not using lock washers or thread-locking adhesives. Standard Example: JIS B 1050 “Tools and techniques for screw fastening” This is a defect where the screw head or threads are crushed due to excessive torque or misalignment of the screwdriver. Cause: Inadequate torque management by workers, wear and tear of tools. Countermeasure: Selection of strength classes recommended in ISO 898-1 “Mechanical properties of fasteners”. This is a phenomenon where screws crack and break due to excessive load or repeated stress. Cause: Insufficient consideration of impact load, use of materials with poor fatigue strength. Countermeasure: Material selection based on fatigue test data, improving fatigue resistance through surface treatment. Due to insufficient positioning of the workpiece, screws are fastened at an angle, causing poor contact and stress concentration. Cause: Lack of jigs/positioning pins, incorrect assembly sequence. Countermeasure: Introduction of dedicated jigs, clarification in Standard Operating Procedures (SOP). This is a problem where the screw surface rusts due to humidity or corrosive gases, causing it to seize and become difficult to loosen. Cause: Insufficient anti-rust treatment, poor humidity control during long-term storage. ...

Key Points for Selecting Fastening Tools to Improve Efficiency on the Manufacturing Floor

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  • July 18th, 2025
Key Points for Selecting Fastening Tools to Improve Efficiency on the Manufacturing Floor
Securely and quickly fastening bolts and screws on the production floor is a crucial element that affects both product quality and line efficiency. Particularly at manufacturing bases in Vietnam, where high-mix, low-volume production and a shortage of skilled workers are advancing, the selection of appropriate fastening tools directly impacts yield and operating rates. This article will systematically explain the approach to tool selection and present a decision-making framework that can be immediately utilized in practice. Purpose of this article To systematically explain the “method for selecting fastening tools,” which is essential for increasing the operating rate of production lines, and to support on-site personnel in confidently choosing the optimal tools. Target Audience Engineers from Japanese companies working at or collaborating with factories in Vietnam who are in charge of production technology, maintenance, or equipment design, or local staff tasked with improving the fastening process. What you will gain after reading Decision-making criteria for selecting fastening tools based on bolt specifications, site conditions, and management accuracy. A checklist for comparing tools tailored to on-site conditions. Information on the support menu offered by Ohta Vietnam and the contact point for inquiries. If there is a large variation in torque values, rework such as re-tightening and quality inspection occurs, prolonging the cycle time. According to test data from the Tohnichi Torque Handbook, it takes an average of 9.6 seconds to tighten one M8 bolt with a manual torque wrench (direct reading type), whereas a fully automatic nutrunner can shorten this to 3.2 seconds, about one-third of the time. Furthermore, because powered tools have a constant rotation speed, the torque curve is stable, and there are reports of cases where the variation in tightening force (Cpk) improved from 0.6 to 1.4. In this way, tools with higher repeatability can significantly shorten work time, making them an essential condition for home appliance and motorcycle parts lines with short line tact times. A shortage of skilled mechanics has become chronic in ASEAN countries, including Vietnam, requiring the creation of systems that maintain quality while reducing the number of workers per line. Hydraulic torque wrenches and bolt tensioners allow even a single person to safely reproduce high torque through “reaction force assurance” and “simultaneous tightening,” realizing minimization of personnel and reduction of physical burden. In addition, preset-type torque wrenches and digital nutrunners are valued for their ability to provide OK/NG feedback with sound or light, allowing even new workers to become ...

Ohta’s Flexible Procurement Service Provides a Competitive Edge for Manufacturing Businesses

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  • July 16th, 2025
Ohta’s Flexible Procurement Service Provides a Competitive Edge for Manufacturing Businesses
The Vietnamese manufacturing industry has expanded rapidly in recent years, with an increase in new investments from companies, including foreign-affiliated ones. The entry of Japanese companies has been particularly active, with some data reporting that approximately 80% of these companies are in the manufacturing sector. Amidst this growth, procurement challenges have become apparent, such as “difficulty in predicting the quality and delivery times of local suppliers” and “inability to place bulk orders for high-mix, low-volume parts.” Source: JETRO “Excellent Vietnamese Supporting Industry Companies” Ohta Vietnam offers flexible procurement services to solve these practical challenges. By utilizing partner factories selected from JETRO’s list of excellent companies and our proprietary database, we provide one-stop support in Japanese, English, and Vietnamese, quality control compliant with ISO/JIS standards, and total cost optimization. For companies looking to diversify their procurement sources under a “China +1” strategy, we have established a system that allows them to safely and efficiently take the first step into procurement in Vietnam. This article will explain the latest trends in the procurement environment in Vietnam and how to utilize Ohta Vietnam’s services, with concrete examples for purchasing and materials managers in the manufacturing industry. The purpose of this article is to provide hints for updating your company’s procurement strategy after reading it. In recent years, Vietnam has been in the spotlight as the top candidate for the “China +1” strategy. As of 2024, the average manufacturing wage is equivalent to 304-340 USD per month, which is less than half of that in coastal China (hourly wage is 3 USD in Vietnam compared to 6.5 USD in China). Furthermore, tariff benefits can be enjoyed due to the effectuation of large-scale FTAs such as the CPTPP and RCEP. It is not uncommon for cases to see procurement cost reductions of up to 30% due to these factors. Against the backdrop of US-China friction and rising geopolitical risks, the demand for multinational diversification of parts supply chains is growing year by year. FDI into Vietnam in the first half of 2025 is at a record high of 11.7 billion USD, an 8.1% increase from the same period last year. Source: VietnamNet “Vietnamese workforce sees more money in their wallets for 2024”, Vietnam News “Foreign investment inflows rise to $21.5 billion in the first half of 2025” On the other hand, in high-value-added fields such as electronics and medical equipment, the ability to handle “high-mix, low-volume” and “short delivery ...

The Proper Use of “Custom Screws” and “Standard Products”: The Key to Optimizing Cost Performance

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  • July 10th, 2025
The Proper Use of “Custom Screws” and “Standard Products”: The Key to Optimizing Cost Performance
In the world of manufacturing, a single screw, just a few millimeters in size, can have a significant impact on the overall quality, cost, and even the delivery time of a product. A screw is not merely a fastening component; it is a “linchpin of machinery” that is involved in all processes of design, procurement, production, and maintenance. Especially in recent years, with the diversification of products, shorter delivery times, and the advancement of overseas procurement, the optimal use of “standard screws” and “custom screws” has become more important than ever. Standard screws offer low cost and stable supply, but they also carry the risk of significantly compromising performance if they do not match the product or structure. On the other hand, custom screws can be optimized for required performance, but cost and lead time often become issues. This article provides practical judgment criteria and optimization perspectives that designers, procurement managers, and manufacturing engineers can implement on-site to address this “screw selection dilemma.” We will organize the differences between custom and standard screws, their manufacturing processes, and cost-performance considerations, and provide a practical explanation that includes a perspective rooted in the field, particularly in procurement and manufacturing in Vietnam. We hope that this article will provide you with practical hints on how reviewing your screw selection can achieve both improved product reliability and cost reduction. Screws, often used inside products, are not visually prominent. However, in reality, they are a crucial element that influences the assembly precision, performance, and safety of a product. It is not uncommon for the choice of a single screw to significantly alter performance aspects such as durability and vibration resistance. The selection of a screw is not simply a task of applying a standard; it affects the overall cost structure, delivery time management, and quality assurance of the product. For example, choosing an unnecessarily high-performance custom screw can lead to over-engineering, while a standard product that fails to meet the required performance can lead to product trouble. Judgment at the design stage is particularly important for screw selection. By quickly identifying “whether a standard product can be used” or “which parts should be custom-made,” it is possible to prevent rework and cost increases in later processes. This is an area where collaboration between design and procurement is required. For purchasing departments and maintenance sites, screw selection is a critical issue related to operational costs and ...

Prevent Fastening Failures in Manufacturing! Summary of Case Studies and Countermeasures

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  • July 03rd, 2025
Prevent Fastening Failures in Manufacturing! Summary of Case Studies and Countermeasures
In manufacturing sites, fastening with screws and bolts is a crucial process that supports the reliability of all machinery and equipment. However, if proper tightening is not performed, “fastening failures” such as loosening or breakage can occur, leading to quality defects and serious accidents. Such failures often arise from mistakes in the design phase, problems with tools or the working environment, or external factors like material properties, corrosion, or temperature, requiring constant attention on site. This article will clarify the basic mechanisms and main causes of fastening failures, while also providing easy-to-understand examples of actual troubles and their countermeasures. In manufacturing sites, fastening failures involving screws and bolts are frequently reported, and many of them lead to serious consequences such as the detachment of structural components or machine stoppage. Below are some representative issues along with their summaries. Case of Nut Detachment Due to Creep of Resin Parts In a certain device, a nut securing a resin part detached during operation. The cause was the creep of the resin due to axial force during fastening, and further deformation progressing due to external forces during use. As a result, the tightening force of the nut was lost, and the machine stopped. Fatigue Fracture of Rail Fixing Bolt (Poor Heat Treatment, Insufficient Torque) An SCM435 bolt used for rail fixing in railway vehicles experienced fatigue fracture due to repeated loads. The cause was coarse metal microstructure due to poor heat treatment, in addition to improper management of the tightening torque. Ultimately, fatigue fracture was confirmed through fracture surface observation. Defect Outflow Due to Misaligned Tightening and Double Tightening of Small Screws In the assembly process of electronic devices requiring minute torque tightening, misaligned tightening and double tightening that could not be visually confirmed occurred. The outflow of defective products was a challenge, but by introducing an error detection device that can precisely manage torque and angle, the outflow was completely prevented. Trouble and Undetected Issues Due to Appearance Defects (Burrs, Cracks) On a mass production line, burrs generated during the rolling process and minute cracks caused by forging were overlooked during inspection, leading to insufficient strength and fastening failures after assembly. This case highlighted the limitations of manual inspection. A common lesson learned from these cases is the importance of a three-pronged approach “design, process, and inspection” to ensure fastening reliability. Importance of Strength Confirmation and Material Selection at the Design Stage ...
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