{"id":5548,"date":"2026-07-10T10:00:33","date_gmt":"2026-07-10T01:00:33","guid":{"rendered":"https:\/\/ohtavn.com\/?post_type=media&p=5548"},"modified":"2026-07-08T16:26:11","modified_gmt":"2026-07-08T07:26:11","slug":"what-is-a-stud-bolt","status":"publish","type":"media","link":"https:\/\/ohtavn.com\/en\/media\/what-is-a-stud-bolt\/","title":{"rendered":"What is a stud bolt? \uff5cEasy explanation in 3 minutes"},"content":{"rendered":"
\n

Introduction<\/h3>\n<\/div>\n
\n

In manufacturing sites and plant designs, “Stud Bolts” are indispensable as unsung heroes. Unlike general hexagon bolts, this bolt has the unique shape of “having no head.” Why is it frequently used in flange connections for automotive engines and chemical plants?<\/p>\n<\/div>\n

\n

In conclusion, the biggest reasons for adopting stud bolts are “protection of the base material’s threads” and “ease of repeated disassembly and assembly”.\u00a0 They demonstrate their true value especially in locations requiring frequent maintenance or when fastening with base materials of relatively lower strength, such as aluminum die-cast.<\/p>\n<\/div>\n

\n

In this article, we will explain important points that procurement and technical personnel should know in 3 minutes, ranging from basic knowledge of stud bolts and how to read strength classes based on JIS standards, to procurement strategies in Vietnam which is a key card for cost reduction. We will also present hints to solve your company’s procurement challenges while incorporating the merits of local procurement provided by Ohta Vietnam.<\/p>\n<\/div>\n

\n

Basic Knowledge and Structure of Stud Bolts<\/h3>\n<\/div>\n
\n

Definition and Features of Stud Bolts<\/h4>\n<\/div>\n
\n

A Stud Bolt refers to a “rod-shaped bolt threaded at both ends and having no head”. Generally, it takes a structure where one side is embedded into the base material (engine block or equipment body) and a nut is attached to the other side for tightening.<\/p>\n<\/div>\n

\n

In JIS standards (Japanese Industrial Standards), it is classified as a “stud,” and broadly divided into the following types based on shape.<\/p>\n<\/div>\n

\n
    \n
  • Double end (Type with an implant side and a nut side)<\/strong>: It is divided into the side screwed into the base material (implant side) and the side where the nut is tightened (nut side).<\/li>\n
  • Full thread (All-thread type)<\/strong>: A type where the entire shaft is threaded, mainly used for flange connections, etc.<\/li>\n<\/ul>\n<\/div>\n
    \n

    Due to this shape, stud bolts also serve as “positioning guides.” When installing heavy flanges or covers, by planting the stud bolts first, parts can be temporarily placed by passing them through the bolts, significantly improving work efficiency.<\/p>\n<\/div>\n

    \n

    Differences and Merits Compared to General Bolts<\/h4>\n<\/div>\n
    \n

    When compared to hexagon bolts, stud bolts have clear engineering merits.<\/p>\n<\/div>\n

    \n
      \n
    1. Reduced damage to base material<\/strong>: Repeating attachment and detachment with hexagon bolts wears down the female threads of the base material (especially aluminum or cast iron), and in the worst case, the threads get crushed. With stud bolts, since the base material side remains fixed and only the nut side is operated, expensive component bodies are not damaged.<\/li>\n
    2. Securing strong axial force<\/strong>: Since it is tightened with nuts from both sides (or the implant side is firmly fixed), it is easy to stabilize axial force, and it has high reliability against loosening due to vibration.<\/li>\n
    3. Compact design<\/strong>: Since there is no hexagonal head, design freedom increases even in spaces where space is limited.<\/li>\n<\/ol>\n<\/div>\n
      \n

      Major Types, Standards, and Materials<\/h3>\n<\/div>\n
      \n

      Classification by Shape and Applications<\/h4>\n<\/div>\n
      \n

      There are various shapes of stud bolts to suit different applications.<\/p>\n<\/div>\n

      \n
        \n
      • Type 1 (Same diameter)<\/strong>: The thread diameter on the implant side and nut side is the same. This is the most common.<\/li>\n
      • Type 2 (Different diameter)<\/strong>: The thread diameter on the implant side is thicker than the nut side. It is used to increase the contact area to prevent pull-out when the base material is soft (such as aluminum).<\/li>\n
      • Chamfered end<\/strong>: The end face is flat.<\/li>\n
      • Round point, Flat point, Dog point<\/strong>: Types with processed end shapes to improve insertability.<\/li>\n<\/ul>\n<\/div>\n
        \n

        In the automotive industry, they are frequently used for fastening exhaust manifolds and cylinder heads, requiring durability in high-temperature and high-vibration environments.<\/p>\n<\/div>\n

        \n

        How to Read JIS Standards and Strength Classes<\/h4>\n<\/div>\n
        \n

        What determines bolt performance is the “strength class.” In the case of steel bolts, the grade is expressed numerically. For example, if there is a marking of “10.9”, it has the following meaning.<\/p>\n<\/div>\n

        \n
          \n
        • 10<\/strong>: Tensile strength is 1000 N\/mm\u00b2 (MPa)<\/strong>. (Left number \u00d7 100)<\/li>\n
        • 9<\/strong>: Yield point (or proof stress) is 90%<\/strong> of tensile strength. (Right number \u00f7 10)\n
            \n
          • Calculation formula: \u00b2<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n
            \n

            In other words, a “10.9” bolt indicates high performance where it breaks at 1000MPa and returns to its original state without permanent deformation up to 900MPa. Common strengths are “4.6” or “4.8”, but classes called High Tension Bolts (High Strength Bolts) such as “8.8”, “10.9”, and “12.9” are used for critical safety parts requiring high fastening force.<\/p>\n<\/div>\n

            \n

            Correct Selection and Tightening Management of Stud Bolts<\/h3>\n<\/div>\n
            \n

            Length Selection and Calculation Formula<\/h4>\n<\/div>\n
            \n

            Calculating the length (L) is important in selecting stud bolts. In the case of double ends, the following factors are generally considered.<\/p>\n<\/div>\n

            \n

            The overall length can be estimated using the following reference formula:<\/p>\n

            L = Thread Engagement Depth + Thickness of the Clamped Component + Nut Height + Thread Protrusion<\/strong><\/p>\n<\/div>\n

            \n
              \n
            • : Implant depth (Depends on base material. Approx. 1d for steel, 1.25d for cast iron, 1.5d to 2d for aluminum *d is nominal diameter)<\/li>\n
            • : Thickness of object to be fastened (Flange thickness, etc.)<\/li>\n
            • : Height of nut<\/li>\n
            • : Protrusion amount from nut (Usually 2 to 3 pitches)<\/li>\n<\/ul>\n<\/div>\n
              \n

              Failure to select the appropriate length leads to fastening failure due to bottoming out or insufficient strength due to insufficient thread engagement.<\/p>\n<\/div>\n

              \n

              Tightening Torque Management and Axial Force<\/h4>\n<\/div>\n
              \n

              The most common troubles in screw fastening are “loosening” and “breakage.” To prevent these, management of tightening torque (T)<\/strong>\u00a0to generate appropriate axial force (F)<\/strong>\u00a0is indispensable.<\/p>\n<\/div>\n

              \n

              The basic formula is as follows.<\/p>\n

              T = K \u00d7 d \u00d7 F<\/strong><\/p>\n<\/div>\n

              \n
                \n
              • : Tightening torque (N\u00b7m)<\/li>\n
              • : Torque coefficient (Varies by lubrication state. Usually 0.2, approx. 0.15 with lubricant)<\/li>\n
              • : Nominal diameter of screw (m)<\/li>\n
              • : Target axial force (N)<\/li>\n<\/ul>\n<\/div>\n
                \n

                For example, if you want to obtain a target axial force of 20,000N with an M10 bolt (d=0.01m), assuming a torque coefficient of 0.2,<\/p>\n<\/div>\n

                \n

                T = 0,2 \u00d7 0,01 \u00d7 20.000 = 40 N\u00b7m<\/p>\n<\/div>\n

                \n

                it becomes. At Ohta Vietnam, optimal product proposals based on such technical calculations are also possible.<\/p>\n<\/div>\n

                \n

                Stud Bolt Procurement in Vietnam and Ohta Vietnam’s Strengths<\/h3>\n<\/div>\n
                \n

                Current Status of Vietnamese Manufacturing and Cost Merits<\/h4>\n<\/div>\n
                \n

                The Vietnamese economy in 2024 is showing a strong recovery, with the real GDP growth rate reaching 7.1%<\/strong>. In the manufacturing industry, it is solidifying its position as the world’s factory as a top candidate for production transfer from China (China Plus One).<\/p>\n<\/div>\n

                \n

                Particular attention should be paid to cost competitiveness. The minimum wage in Vietnam’s major cities (Hanoi\/Ho Chi Minh) is about 29,000 yen per month, which is still a large labor cost difference compared to Japanese manufacturing sites. Leveraging this cost merit, by performing bolt manufacturing and inspection tasks involving labor-intensive processes in Vietnam, a total cost reduction of about **15% to 30%** can be expected in some cases.<\/p>\n<\/div>\n

                \n

                Quality Control and Stable Supply<\/h4>\n<\/div>\n
                \n

                Although some voices say, “Overseas procurement brings anxiety about quality,” the current supply chain in Vietnam has become sophisticated due to the expansion of Japanese companies.<\/p>\n<\/div>\n

                \n

                Ohta Vietnam has established a management system of Japanese quality in this land of Vietnam.<\/p>\n<\/div>\n

                \n
                  \n
                • Thorough material certification (Mill Sheet)<\/strong>: Ensuring traceability of steel materials used.<\/li>\n
                • Precision inspection<\/strong>: Implementing a strict quality assurance process compliant with Japanese JIS standards, such as total inspection using screw gauges and introduction of image sorting machines.<\/li>\n
                • One-stop support<\/strong>: Consistently supporting from drawing creation of special-shaped stud bolts to prototyping, mass production, surface treatment, and export practice to Japan.<\/li>\n<\/ul>\n<\/div>\n
                  \n

                  Summary<\/h3>\n<\/div>\n
                  \n

                  Stud bolts are important fastening parts that influence the longevity and maintainability of machinery.
                  \nFor their selection, “understanding “Strength Class (10.9 etc.)” based on JIS standards and appropriate “Tightening Torque Calculation”are essential.
                  \nAlso, as cost competitiveness intensifies, procurement in Vietnam is a compelling option. With a vibrant market exceeding 7% growth rate and manufacturing costs cheaper than Japan, it is possible to stably procure high-quality parts.
                  \nOhta Vietnam<\/strong>\u00a0optimizes your company’s stud bolt procurement with reliable technical capabilities and networks in Vietnam. If you have challenges such as “no drawings,” “special standards,” or “want to lower costs,” please feel free to consult us. We will propose a concrete plan to update your procurement strategy.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

                  Introduction In manufacturing sites and plant designs, “Stud Bolts” are indispensable as unsung heroes. Unlike general hexagon bolts, this bolt has the unique shape of “having no head.” Why is it frequently used in flange connections for automotive engines and chemical plants? In conclusion, the biggest reasons for adopting stud bolts are “protection of the […]<\/p>\n","protected":false},"author":4,"featured_media":5546,"template":"","meta":{"_acf_changed":false,"_locale":"en_US","_original_post":"https:\/\/ohtavn.com\/?post_type=media&p=5545","footnotes":"","title":"What is a stud bolt? \uff5cEasy explanation in 3 minutes","_title":"field_639aec69b01cd","keywords":"Screws, bolts, fastening parts, professional tools, precision machining, parts sales","_keywords":"field_639aec76b01ce","description":"Explains the basics of stud bolts (shut bolts), JIS standards, strength classifications, and torque calculations in 3 minutes. Why is it used in cars and plants? We also introduce cost reduction through Vietnamese procurement and Ota Vietnam's quality control system. A must-read introductory guide for procurement and technology personnel in the manufacturing industry.","_description":"field_639aec87b01cf","h1":"What is a stud bolt? \uff5cEasy explanation in 3 minutes","_h1":"field_639aec90b01d0","main-title":"","_main-title":""},"media-cat":[23],"class_list":["post-5548","media","type-media","status-publish","has-post-thumbnail","hentry","media-cat-column","en-US"],"acf":[],"_links":{"self":[{"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/info-media\/5548","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/info-media"}],"about":[{"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/types\/media"}],"author":[{"embeddable":true,"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/users\/4"}],"version-history":[{"count":3,"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/info-media\/5548\/revisions"}],"predecessor-version":[{"id":6302,"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/info-media\/5548\/revisions\/6302"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/media\/5546"}],"wp:attachment":[{"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/media?parent=5548"}],"wp:term":[{"taxonomy":"media-cat","embeddable":true,"href":"https:\/\/ohtavn.com\/wp-json\/wp\/v2\/media-cat?post=5548"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}