{"id":5757,"date":"2025-12-24T05:18:00","date_gmt":"2025-12-24T05:18:00","guid":{"rendered":"https:\/\/korea-transmission.com\/?p=5757"},"modified":"2025-12-24T05:18:19","modified_gmt":"2025-12-24T05:18:19","slug":"gb-t-9145-2003-thread-limit-dimensions","status":"publish","type":"post","link":"https:\/\/korea-transmission.com\/th\/%e0%b8%9a%e0%b8%a5%e0%b9%87%e0%b8%ad%e0%b8%81\/gb-t-9145-2003-thread-limit-dimensions\/","title":{"rendered":"GB\/T 9145-2003 Thread Limit Dimensions"},"content":{"rendered":"

[et_pb_section admin_label=”section”]
\n\t\t\t[et_pb_row admin_label=”row”]
\n\t\t\t\t[et_pb_column type=”4_4″][et_pb_text admin_label=”Text”]<\/p>\n

\n

Introduction to GB\/T 9145-2003 Standard<\/h2>\n

This standard specifies limit dimensions for general-purpose metric screw threads of medium accuracy in the preferred series, ensuring interchangeability and performance in mechanical assemblies. It covers coarse and fine pitch threads for internal and external applications, with tolerances applied before plating for thin coatings.<\/p>\n<\/div>\n

\n

Scope<\/h2>\n

GB\/T 9145-2003 defines the limit dimensions for metric screw threads with medium tolerance precision and preferred series, applicable to general engineering purposes. It ensures that thread profiles do not exceed the maximum material condition defined by basic profiles and tolerance positions. This is crucial for fasteners in industries requiring reliable mating without interference, especially post-plating.<\/p>\n

    \n
  • Applies to threads before thin coatings like electroplating.<\/li>\n
  • Post-plating, profiles must stay within H or h positions.<\/li>\n
  • Focuses on medium engagement lengths for balanced strength and manufacturability.<\/li>\n<\/ul>\n<\/div>\n
    \n

    General Limit Dimensions<\/h2>\n

    No point on the thread root profile shall exceed the maximum entity profile per basic form and tolerance. For plated threads, actual contours post-plating must not surpass H\/h positions. This prevents over-tightening or failure in assemblies. Note: Tolerances suit thin platings; heavier coatings require adjustments.<\/p>\n<\/div>\n

    \n

    Coarse Pitch Internal Threads<\/h2>\n

    For medium precision, engagement length is medium. Tolerance zones: 5H for d \u2264 1.4 mm; 6H for d > 1.4 mm. Limits for pitch diameter D2<\/sub> and minor diameter D1<\/sub> ensure proper fit with external threads.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Thread<\/th>\nEngagement Length<\/th>\nPitch Diameter D2<\/sub><\/th>\nMinor Diameter D1<\/sub><\/th>\n<\/tr>\n
    ><\/th>\n\u2264<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n<\/tr>\n<\/thead>\n
    M1<\/td>\n0.6<\/td>\n1.7<\/td>\n0.894<\/td>\n0.838<\/td>\n0.785<\/td>\n0.729<\/td>\n<\/tr>\n
    M1.2<\/td>\n0.6<\/td>\n1.7<\/td>\n1.094<\/td>\n1.038<\/td>\n0.985<\/td>\n0.929<\/td>\n<\/tr>\n
    M1.4<\/td>\n0.7<\/td>\n2<\/td>\n1.265<\/td>\n1.205<\/td>\n1.142<\/td>\n1.075<\/td>\n<\/tr>\n
    M1.6<\/td>\n0.8<\/td>\n2.6<\/td>\n1.458<\/td>\n1.373<\/td>\n1.321<\/td>\n1.221<\/td>\n<\/tr>\n
    M1.8<\/td>\n0.8<\/td>\n2.6<\/td>\n1.658<\/td>\n1.573<\/td>\n1.521<\/td>\n1.421<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e212<\/td>\n1<\/td>\n3<\/td>\n1.83<\/td>\n1.74<\/td>\n1.679<\/td>\n1.567<\/td>\n<\/tr>\n
    \u0e21.2.5<\/td>\n1.3<\/td>\n3.8<\/td>\n2.303<\/td>\n2.208<\/td>\n2.138<\/td>\n2.013<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e213<\/td>\n1.5<\/td>\n4.5<\/td>\n2.775<\/td>\n2.675<\/td>\n2.599<\/td>\n2.459<\/td>\n<\/tr>\n
    \u0e213.5<\/td>\n1.7<\/td>\n5<\/td>\n3.222<\/td>\n3.11<\/td>\n3.01<\/td>\n2.85<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e214<\/td>\n2<\/td>\n6<\/td>\n3.663<\/td>\n3.545<\/td>\n3.422<\/td>\n3.242<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e215<\/td>\n2.5<\/td>\n7.5<\/td>\n4.605<\/td>\n4.48<\/td>\n4.334<\/td>\n4.134<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e216<\/td>\n3<\/td>\n9<\/td>\n5.5<\/td>\n5.35<\/td>\n5.153<\/td>\n4.917<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e217<\/td>\n3<\/td>\n9<\/td>\n6.5<\/td>\n6.35<\/td>\n6.153<\/td>\n5.917<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e218<\/td>\n4<\/td>\n12<\/td>\n7.348<\/td>\n7.188<\/td>\n6.912<\/td>\n6.647<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2110<\/td>\n5<\/td>\n15<\/td>\n9.206<\/td>\n9.026<\/td>\n8.676<\/td>\n8.376<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2112<\/td>\n6<\/td>\n18<\/td>\n11.063<\/td>\n10.863<\/td>\n10.441<\/td>\n10.106<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2114<\/td>\n8<\/td>\n24<\/td>\n12.913<\/td>\n12.701<\/td>\n12.21<\/td>\n11.835<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2116<\/td>\n8<\/td>\n24<\/td>\n14.913<\/td>\n14.701<\/td>\n14.21<\/td>\n13.835<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2118<\/td>\n10<\/td>\n30<\/td>\n16.6<\/td>\n16.376<\/td>\n15.744<\/td>\n15.294<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2120<\/td>\n10<\/td>\n30<\/td>\n18.6<\/td>\n18.376<\/td>\n17.744<\/td>\n17.294<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2122<\/td>\n10<\/td>\n30<\/td>\n20.6<\/td>\n20.376<\/td>\n19.744<\/td>\n19.294<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2124<\/td>\n12<\/td>\n36<\/td>\n22.316<\/td>\n22.051<\/td>\n21.252<\/td>\n20.752<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2127<\/td>\n12<\/td>\n36<\/td>\n25.316<\/td>\n25.051<\/td>\n24.252<\/td>\n23.752<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2130<\/td>\n15<\/td>\n45<\/td>\n28.007<\/td>\n27.727<\/td>\n26.771<\/td>\n26.211<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2133<\/td>\n15<\/td>\n45<\/td>\n31.007<\/td>\n30.727<\/td>\n29.771<\/td>\n29.211<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2136<\/td>\n18<\/td>\n53<\/td>\n33.702<\/td>\n33.402<\/td>\n32.27<\/td>\n31.67<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2139<\/td>\n18<\/td>\n53<\/td>\n36.702<\/td>\n36.402<\/td>\n35.27<\/td>\n34.67<\/td>\n<\/tr>\n
    M42<\/td>\n21<\/td>\n63<\/td>\n39.392<\/td>\n39.077<\/td>\n37.799<\/td>\n37.129<\/td>\n<\/tr>\n
    M45<\/td>\n21<\/td>\n63<\/td>\n42.392<\/td>\n42.077<\/td>\n40.799<\/td>\n40.129<\/td>\n<\/tr>\n
    M48<\/td>\n24<\/td>\n71<\/td>\n45.087<\/td>\n44.752<\/td>\n43.297<\/td>\n42.587<\/td>\n<\/tr>\n
    M52<\/td>\n24<\/td>\n71<\/td>\n49.087<\/td>\n48.752<\/td>\n46.681<\/td>\n45.971<\/td>\n<\/tr>\n
    M56<\/td>\n28<\/td>\n85<\/td>\n52.783<\/td>\n52.428<\/td>\n50.796<\/td>\n50.046<\/td>\n<\/tr>\n
    M60<\/td>\n28<\/td>\n85<\/td>\n56.783<\/td>\n56.428<\/td>\n54.796<\/td>\n54.046<\/td>\n<\/tr>\n
    M64<\/td>\n32<\/td>\n95<\/td>\n60.478<\/td>\n60.103<\/td>\n58.305<\/td>\n57.505<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    These dimensions provide guidance for nut manufacturing, ensuring compatibility with bolts under medium load conditions.<\/p>\n<\/div>\n

    \n

    Coarse Pitch External Threads<\/h2>\n

    Medium precision, medium engagement. Tolerance zones: 6h for d \u2264 1.4 mm; 6g for d > 1.4 mm. Limits for major diameter d and pitch diameter d2<\/sub>, with min root radius per GB\/T 197-2003.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Thread<\/th>\nEngagement Length<\/th>\nMajor Diameter d<\/th>\nPitch Diameter d2<\/sub><\/th>\nMin Root Radius\u0e40\u0e2d<\/sup><\/th>\n<\/tr>\n
    ><\/th>\n\u2264<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n<\/tr>\n<\/thead>\n
    M1<\/td>\n0.6<\/td>\n1.7<\/td>\n1<\/td>\n0.933<\/td>\n0.838<\/td>\n0.785<\/td>\n0.031<\/td>\n<\/tr>\n
    M1.2<\/td>\n0.6<\/td>\n1.7<\/td>\n1.2<\/td>\n1.133<\/td>\n1.038<\/td>\n0.985<\/td>\n0.031<\/td>\n<\/tr>\n
    M1.4<\/td>\n0.7<\/td>\n2<\/td>\n1.4<\/td>\n1.325<\/td>\n1.205<\/td>\n1.149<\/td>\n0.038<\/td>\n<\/tr>\n
    M1.6<\/td>\n0.8<\/td>\n2.6<\/td>\n1.581<\/td>\n1.496<\/td>\n1.354<\/td>\n1.291<\/td>\n0.044<\/td>\n<\/tr>\n
    M1.8<\/td>\n0.8<\/td>\n2.6<\/td>\n1.781<\/td>\n1.696<\/td>\n1.554<\/td>\n1.491<\/td>\n0.044<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e212<\/td>\n1<\/td>\n3<\/td>\n1.981<\/td>\n1.886<\/td>\n1.721<\/td>\n1.654<\/td>\n0.05<\/td>\n<\/tr>\n
    \u0e21.2.5<\/td>\n1.3<\/td>\n3.8<\/td>\n2.48<\/td>\n2.38<\/td>\n2.188<\/td>\n2.117<\/td>\n0.056<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e213<\/td>\n1.5<\/td>\n4.5<\/td>\n2.98<\/td>\n2.874<\/td>\n2.655<\/td>\n2.58<\/td>\n0.063<\/td>\n<\/tr>\n
    \u0e213.5<\/td>\n1.7<\/td>\n5<\/td>\n3.479<\/td>\n3.354<\/td>\n3.089<\/td>\n3.004<\/td>\n0.075<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e214<\/td>\n2<\/td>\n6<\/td>\n3.978<\/td>\n3.838<\/td>\n3.523<\/td>\n3.433<\/td>\n0.088<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e215<\/td>\n2.5<\/td>\n7.5<\/td>\n4.976<\/td>\n4.826<\/td>\n4.456<\/td>\n4.361<\/td>\n0.1<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e216<\/td>\n3<\/td>\n9<\/td>\n5.974<\/td>\n5.794<\/td>\n5.324<\/td>\n5.212<\/td>\n0.125<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e217<\/td>\n3<\/td>\n9<\/td>\n6.974<\/td>\n6.794<\/td>\n6.324<\/td>\n6.212<\/td>\n0.125<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e218<\/td>\n4<\/td>\n12<\/td>\n7.972<\/td>\n7.76<\/td>\n7.16<\/td>\n7.042<\/td>\n0.156<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2110<\/td>\n5<\/td>\n15<\/td>\n9.968<\/td>\n9.732<\/td>\n8.994<\/td>\n8.862<\/td>\n0.188<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2112<\/td>\n6<\/td>\n18<\/td>\n11.966<\/td>\n11.701<\/td>\n10.829<\/td>\n10.679<\/td>\n0.219<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2114<\/td>\n8<\/td>\n24<\/td>\n13.962<\/td>\n13.682<\/td>\n12.663<\/td>\n12.503<\/td>\n0.25<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2116<\/td>\n8<\/td>\n24<\/td>\n15.962<\/td>\n15.682<\/td>\n14.663<\/td>\n14.503<\/td>\n0.25<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2118<\/td>\n10<\/td>\n30<\/td>\n17.958<\/td>\n17.623<\/td>\n16.334<\/td>\n16.164<\/td>\n0.313<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2120<\/td>\n10<\/td>\n30<\/td>\n19.958<\/td>\n19.623<\/td>\n18.334<\/td>\n18.164<\/td>\n0.313<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2122<\/td>\n10<\/td>\n30<\/td>\n21.958<\/td>\n21.623<\/td>\n20.334<\/td>\n20.164<\/td>\n0.313<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2124<\/td>\n12<\/td>\n36<\/td>\n23.952<\/td>\n23.577<\/td>\n22.003<\/td>\n21.803<\/td>\n0.375<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2127<\/td>\n12<\/td>\n36<\/td>\n26.952<\/td>\n26.577<\/td>\n25.003<\/td>\n24.803<\/td>\n0.375<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2130<\/td>\n15<\/td>\n45<\/td>\n29.947<\/td>\n29.522<\/td>\n27.674<\/td>\n27.462<\/td>\n0.438<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2133<\/td>\n15<\/td>\n45<\/td>\n32.947<\/td>\n32.522<\/td>\n30.674<\/td>\n30.462<\/td>\n0.438<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2136<\/td>\n18<\/td>\n53<\/td>\n35.94<\/td>\n35.465<\/td>\n33.342<\/td>\n33.118<\/td>\n0.5<\/td>\n<\/tr>\n
    \u0e40\u0e2d\u0e47\u0e2139<\/td>\n18<\/td>\n53<\/td>\n38.94<\/td>\n38.465<\/td>\n36.342<\/td>\n36.118<\/td>\n0.5<\/td>\n<\/tr>\n
    M42<\/td>\n21<\/td>\n63<\/td>\n41.937<\/td>\n41.437<\/td>\n39.014<\/td>\n38.778<\/td>\n0.563<\/td>\n<\/tr>\n
    M45<\/td>\n21<\/td>\n63<\/td>\n44.937<\/td>\n44.437<\/td>\n42.014<\/td>\n41.778<\/td>\n0.563<\/td>\n<\/tr>\n
    M48<\/td>\n24<\/td>\n71<\/td>\n47.929<\/td>\n47.399<\/td>\n44.681<\/td>\n44.431<\/td>\n0.625<\/td>\n<\/tr>\n
    M52<\/td>\n24<\/td>\n71<\/td>\n51.929<\/td>\n51.399<\/td>\n48.681<\/td>\n48.431<\/td>\n0.625<\/td>\n<\/tr>\n
    M56<\/td>\n28<\/td>\n85<\/td>\n55.925<\/td>\n55.365<\/td>\n52.353<\/td>\n52.088<\/td>\n0.688<\/td>\n<\/tr>\n
    M60<\/td>\n28<\/td>\n85<\/td>\n59.925<\/td>\n59.365<\/td>\n56.353<\/td>\n56.088<\/td>\n0.688<\/td>\n<\/tr>\n
    M64<\/td>\n32<\/td>\n95<\/td>\n63.92<\/td>\n63.32<\/td>\n60.023<\/td>\n59.743<\/td>\n0.75<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    \u0e40\u0e2d<\/sup> See GB\/T 197-2003 Chapter 7 and Table 9 for root radius details. These ensure stress distribution and fatigue resistance.<\/p>\n<\/div>\n

    \n

    Fine Pitch Internal Threads<\/h2>\n

    Medium precision, medium engagement, 6H tolerance zone. Fine pitches offer better vibration resistance and adjustment precision.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Thread<\/th>\nEngagement Length<\/th>\nPitch Diameter D2<\/sub><\/th>\nMinor Diameter D1<\/sub><\/th>\n<\/tr>\n
    ><\/th>\n\u2264<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n<\/tr>\n<\/thead>\n
    M8\u00d71<\/td>\n3<\/td>\n9<\/td>\n7.5<\/td>\n7.35<\/td>\n7.153<\/td>\n6.917<\/td>\n<\/tr>\n
    M10\u00d71<\/td>\n4<\/td>\n12<\/td>\n9.5<\/td>\n9.35<\/td>\n9.153<\/td>\n8.917<\/td>\n<\/tr>\n
    M10\u00d71.25<\/td>\n4<\/td>\n12<\/td>\n9.348<\/td>\n9.188<\/td>\n8.912<\/td>\n8.647<\/td>\n<\/tr>\n
    M12\u00d71.25<\/td>\n4.5<\/td>\n13<\/td>\n11.368<\/td>\n11.188<\/td>\n10.912<\/td>\n10.647<\/td>\n<\/tr>\n
    M12\u00d71.5<\/td>\n4.5<\/td>\n13<\/td>\n11.216<\/td>\n11.026<\/td>\n10.676<\/td>\n10.376<\/td>\n<\/tr>\n
    M14\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n13.216<\/td>\n13.026<\/td>\n12.676<\/td>\n12.376<\/td>\n<\/tr>\n
    M16\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n15.216<\/td>\n15.026<\/td>\n14.676<\/td>\n14.376<\/td>\n<\/tr>\n
    M18\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n17.216<\/td>\n17.026<\/td>\n16.676<\/td>\n16.376<\/td>\n<\/tr>\n
    M18\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n16.913<\/td>\n16.701<\/td>\n16.21<\/td>\n15.835<\/td>\n<\/tr>\n
    M20\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n19.216<\/td>\n19.026<\/td>\n18.676<\/td>\n18.376<\/td>\n<\/tr>\n
    M20\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n18.913<\/td>\n18.701<\/td>\n18.21<\/td>\n17.835<\/td>\n<\/tr>\n
    M22\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n21.216<\/td>\n21.026<\/td>\n20.676<\/td>\n20.376<\/td>\n<\/tr>\n
    M22\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n20.913<\/td>\n20.701<\/td>\n20.21<\/td>\n19.835<\/td>\n<\/tr>\n
    M24\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n22.925<\/td>\n22.701<\/td>\n22.21<\/td>\n21.835<\/td>\n<\/tr>\n
    M27\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n25.925<\/td>\n25.701<\/td>\n25.21<\/td>\n24.835<\/td>\n<\/tr>\n
    M30\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n28.925<\/td>\n28.701<\/td>\n28.21<\/td>\n27.835<\/td>\n<\/tr>\n
    M33\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n31.925<\/td>\n31.701<\/td>\n31.21<\/td>\n30.835<\/td>\n<\/tr>\n
    M36\u00d73<\/td>\n12<\/td>\n36<\/td>\n34.316<\/td>\n34.051<\/td>\n33.252<\/td>\n32.752<\/td>\n<\/tr>\n
    M39\u00d73<\/td>\n12<\/td>\n36<\/td>\n37.316<\/td>\n37.051<\/td>\n36.252<\/td>\n35.752<\/td>\n<\/tr>\n
    M42\u00d73<\/td>\n12<\/td>\n36<\/td>\n40.316<\/td>\n40.051<\/td>\n39.252<\/td>\n38.752<\/td>\n<\/tr>\n
    M45\u00d73<\/td>\n12<\/td>\n36<\/td>\n43.316<\/td>\n43.051<\/td>\n42.252<\/td>\n41.752<\/td>\n<\/tr>\n
    M48\u00d73<\/td>\n15<\/td>\n45<\/td>\n46.331<\/td>\n46.051<\/td>\n45.252<\/td>\n44.752<\/td>\n<\/tr>\n
    M52\u00d74<\/td>\n19<\/td>\n56<\/td>\n49.717<\/td>\n49.402<\/td>\n48.27<\/td>\n47.67<\/td>\n<\/tr>\n
    M56\u00d74<\/td>\n19<\/td>\n56<\/td>\n53.717<\/td>\n53.402<\/td>\n52.27<\/td>\n51.67<\/td>\n<\/tr>\n
    M60\u00d74<\/td>\n19<\/td>\n56<\/td>\n57.717<\/td>\n57.402<\/td>\n56.27<\/td>\n55.67<\/td>\n<\/tr>\n
    M64\u00d74<\/td>\n19<\/td>\n56<\/td>\n61.717<\/td>\n61.402<\/td>\n60.27<\/td>\n59.67<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    These values support finer load distribution in high-vibration environments.<\/p>\n<\/div>\n

    \n

    Fine Pitch External Threads<\/h2>\n

    Medium precision, medium engagement, 6g tolerance zone. Provides stronger core sections for enhanced shear strength.<\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Thread<\/th>\nEngagement Length<\/th>\nMajor Diameter d<\/th>\nPitch Diameter d2<\/sub><\/th>\nMin Root Radius\u0e40\u0e2d<\/sup><\/th>\n<\/tr>\n
    ><\/th>\n\u2264<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e2a\u0e39\u0e07\u0e2a\u0e38\u0e14<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n\u0e19\u0e32\u0e17\u0e35<\/th>\n<\/tr>\n<\/thead>\n
    M8\u00d71<\/td>\n3<\/td>\n9<\/td>\n7.974<\/td>\n7.794<\/td>\n7.324<\/td>\n7.212<\/td>\n0.125<\/td>\n<\/tr>\n
    M10\u00d71<\/td>\n4<\/td>\n12<\/td>\n9.974<\/td>\n9.794<\/td>\n9.324<\/td>\n9.212<\/td>\n0.125<\/td>\n<\/tr>\n
    M10\u00d71.25<\/td>\n4<\/td>\n12<\/td>\n9.972<\/td>\n9.76<\/td>\n9.16<\/td>\n9.042<\/td>\n0.156<\/td>\n<\/tr>\n
    M12\u00d71.25<\/td>\n4.5<\/td>\n13<\/td>\n11.972<\/td>\n11.76<\/td>\n11.16<\/td>\n11.028<\/td>\n0.156<\/td>\n<\/tr>\n
    M12\u00d71.5<\/td>\n4.5<\/td>\n13<\/td>\n11.968<\/td>\n11.732<\/td>\n10.994<\/td>\n10.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M14\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n13.968<\/td>\n13.732<\/td>\n12.994<\/td>\n12.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M16\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n15.968<\/td>\n15.732<\/td>\n14.994<\/td>\n14.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M18\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n17.968<\/td>\n17.732<\/td>\n16.994<\/td>\n16.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M18\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n17.962<\/td>\n17.682<\/td>\n16.663<\/td>\n16.503<\/td>\n0.25<\/td>\n<\/tr>\n
    M20\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n19.968<\/td>\n19.732<\/td>\n18.994<\/td>\n18.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M20\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n19.962<\/td>\n19.682<\/td>\n18.663<\/td>\n18.503<\/td>\n0.25<\/td>\n<\/tr>\n
    M22\u00d71.5<\/td>\n5.6<\/td>\n16<\/td>\n21.968<\/td>\n21.732<\/td>\n20.994<\/td>\n20.854<\/td>\n0.188<\/td>\n<\/tr>\n
    M22\u00d72<\/td>\n5.6<\/td>\n16<\/td>\n21.962<\/td>\n21.682<\/td>\n20.663<\/td>\n20.503<\/td>\n0.25<\/td>\n<\/tr>\n
    M24\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n23.962<\/td>\n23.682<\/td>\n22.663<\/td>\n22.493<\/td>\n0.25<\/td>\n<\/tr>\n
    M27\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n26.962<\/td>\n26.682<\/td>\n25.663<\/td>\n25.493<\/td>\n0.25<\/td>\n<\/tr>\n
    M30\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n29.962<\/td>\n29.682<\/td>\n28.663<\/td>\n28.493<\/td>\n0.25<\/td>\n<\/tr>\n
    M33\u00d72<\/td>\n8.5<\/td>\n25<\/td>\n32.962<\/td>\n32.682<\/td>\n31.663<\/td>\n31.493<\/td>\n0.25<\/td>\n<\/tr>\n
    M36\u00d73<\/td>\n12<\/td>\n36<\/td>\n35.952<\/td>\n35.577<\/td>\n34.003<\/td>\n33.803<\/td>\n0.375<\/td>\n<\/tr>\n
    M39\u00d73<\/td>\n12<\/td>\n36<\/td>\n38.952<\/td>\n38.577<\/td>\n37.003<\/td>\n36.803<\/td>\n0.375<\/td>\n<\/tr>\n
    M42\u00d73<\/td>\n12<\/td>\n36<\/td>\n41.952<\/td>\n41.577<\/td>\n40.003<\/td>\n39.803<\/td>\n0.375<\/td>\n<\/tr>\n
    M45\u00d73<\/td>\n12<\/td>\n36<\/td>\n44.952<\/td>\n44.577<\/td>\n43.003<\/td>\n42.803<\/td>\n0.375<\/td>\n<\/tr>\n
    M48\u00d73<\/td>\n15<\/td>\n45<\/td>\n47.952<\/td>\n47.577<\/td>\n46.003<\/td>\n45.791<\/td>\n0.375<\/td>\n<\/tr>\n
    M52\u00d74<\/td>\n19<\/td>\n56<\/td>\n51.94<\/td>\n51.465<\/td>\n49.342<\/td>\n49.106<\/td>\n0.5<\/td>\n<\/tr>\n
    M56\u00d74<\/td>\n19<\/td>\n56<\/td>\n55.94<\/td>\n55.465<\/td>\n53.342<\/td>\n53.106<\/td>\n0.5<\/td>\n<\/tr>\n
    M60\u00d74<\/td>\n19<\/td>\n56<\/td>\n59.94<\/td>\n59.465<\/td>\n57.342<\/td>\n57.106<\/td>\n0.5<\/td>\n<\/tr>\n
    M64\u00d74<\/td>\n19<\/td>\n56<\/td>\n63.94<\/td>\n63.465<\/td>\n61.342<\/td>\n61.106<\/td>\n0.5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    \u0e40\u0e2d<\/sup> See GB\/T 197-2003 for root radius specifications, critical for avoiding stress concentrations.<\/p>\n<\/div>\n

    \n

    \u0e04\u0e33\u0e16\u0e32\u0e21\u0e17\u0e35\u0e48\u0e1e\u0e1a\u0e1a\u0e48\u0e2d\u0e22<\/h2>\n

    What tolerance zones apply to coarse internal threads?<\/h3>\n

    5H for diameters \u22641.4 mm; 6H for >1.4 mm, ensuring medium precision fit.<\/p>\n

    How does plating affect thread dimensions?<\/h3>\n

    Tolerances are pre-plating; post-plating profiles must not exceed H\/h positions for thin coatings to maintain assembly.<\/p>\n

    Why use fine pitch threads?<\/h3>\n

    They provide better vibration resistance and finer adjustments, with stronger cores per limits in tables 3 and 4.<\/p>\n

    What is medium engagement length?<\/h3>\n

    It balances thread strength and cost; use table values for specific ranges to avoid over- or under-engagement.<\/p>\n

    How to interpret root radius?<\/h3>\n

    Min values per GB\/T 197-2003 reduce stress; essential for fatigue-prone applications.<\/p>\n

    Are these limits for all materials?<\/h3>\n

    Yes, but adjust for special platings; consult standard for heavy coatings requiring oversized threads.<\/p>\n<\/div>\n

     [\/et_pb_text][\/et_pb_column]
    \n\t\t\t[\/et_pb_row]
    \n\t\t[\/et_pb_section]<\/p>","protected":false},"excerpt":{"rendered":"

    Introduction to GB\/T 9145-2003 Standard This standard specifies limit dimensions for general-purpose metric screw threads of medium accuracy in the preferred series, ensuring interchangeability and performance in mechanical assemblies. It covers coarse and fine pitch threads for internal and external applications, with tolerances applied before plating for thin coatings. Scope GB\/T 9145-2003 defines the limit […]<\/p>","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"

    \r\n

    Introduction to GB\/T 9145-2003 Standard<\/h2>\r\nThis standard specifies limit dimensions for general-purpose metric screw threads of medium accuracy in the preferred series, ensuring interchangeability and performance in mechanical assemblies. It covers coarse and fine pitch threads for internal and external applications, with tolerances applied before plating for thin coatings.\r\n\r\n<\/div>\r\n
    \r\n

    Scope<\/h2>\r\nGB\/T 9145-2003 defines the limit dimensions for metric screw threads with medium tolerance precision and preferred series, applicable to general engineering purposes. It ensures that thread profiles do not exceed the maximum material condition defined by basic profiles and tolerance positions. This is crucial for fasteners in industries requiring reliable mating without interference, especially post-plating.\r\n
      \r\n \t
    • Applies to threads before thin coatings like electroplating.<\/li>\r\n \t
    • Post-plating, profiles must stay within H or h positions.<\/li>\r\n \t
    • Focuses on medium engagement lengths for balanced strength and manufacturability.<\/li>\r\n<\/ul>\r\n<\/div>\r\n
      \r\n

      General Limit Dimensions<\/h2>\r\nNo point on the thread root profile shall exceed the maximum entity profile per basic form and tolerance. For plated threads, actual contours post-plating must not surpass H\/h positions. This prevents over-tightening or failure in assemblies. Note: Tolerances suit thin platings; heavier coatings require adjustments.\r\n\r\n<\/div>\r\n
      \r\n

      Coarse Pitch Internal Threads<\/h2>\r\nFor medium precision, engagement length is medium. Tolerance zones: 5H for d \u2264 1.4 mm; 6H for d > 1.4 mm. Limits for pitch diameter D2<\/sub> and minor diameter D1<\/sub> ensure proper fit with external threads.\r\n
      \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      Thread<\/th>\r\nEngagement Length<\/th>\r\nPitch Diameter D2<\/sub><\/th>\r\nMinor Diameter D1<\/sub><\/th>\r\n<\/tr>\r\n
      ><\/th>\r\n\u2264<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
      M1<\/td>\r\n0.6<\/td>\r\n1.7<\/td>\r\n0.894<\/td>\r\n0.838<\/td>\r\n0.785<\/td>\r\n0.729<\/td>\r\n<\/tr>\r\n
      M1.2<\/td>\r\n0.6<\/td>\r\n1.7<\/td>\r\n1.094<\/td>\r\n1.038<\/td>\r\n0.985<\/td>\r\n0.929<\/td>\r\n<\/tr>\r\n
      M1.4<\/td>\r\n0.7<\/td>\r\n2<\/td>\r\n1.265<\/td>\r\n1.205<\/td>\r\n1.142<\/td>\r\n1.075<\/td>\r\n<\/tr>\r\n
      M1.6<\/td>\r\n0.8<\/td>\r\n2.6<\/td>\r\n1.458<\/td>\r\n1.373<\/td>\r\n1.321<\/td>\r\n1.221<\/td>\r\n<\/tr>\r\n
      M1.8<\/td>\r\n0.8<\/td>\r\n2.6<\/td>\r\n1.658<\/td>\r\n1.573<\/td>\r\n1.521<\/td>\r\n1.421<\/td>\r\n<\/tr>\r\n
      M2<\/td>\r\n1<\/td>\r\n3<\/td>\r\n1.83<\/td>\r\n1.74<\/td>\r\n1.679<\/td>\r\n1.567<\/td>\r\n<\/tr>\r\n
      M2.5<\/td>\r\n1.3<\/td>\r\n3.8<\/td>\r\n2.303<\/td>\r\n2.208<\/td>\r\n2.138<\/td>\r\n2.013<\/td>\r\n<\/tr>\r\n
      M3<\/td>\r\n1.5<\/td>\r\n4.5<\/td>\r\n2.775<\/td>\r\n2.675<\/td>\r\n2.599<\/td>\r\n2.459<\/td>\r\n<\/tr>\r\n
      M3.5<\/td>\r\n1.7<\/td>\r\n5<\/td>\r\n3.222<\/td>\r\n3.11<\/td>\r\n3.01<\/td>\r\n2.85<\/td>\r\n<\/tr>\r\n
      M4<\/td>\r\n2<\/td>\r\n6<\/td>\r\n3.663<\/td>\r\n3.545<\/td>\r\n3.422<\/td>\r\n3.242<\/td>\r\n<\/tr>\r\n
      M5<\/td>\r\n2.5<\/td>\r\n7.5<\/td>\r\n4.605<\/td>\r\n4.48<\/td>\r\n4.334<\/td>\r\n4.134<\/td>\r\n<\/tr>\r\n
      M6<\/td>\r\n3<\/td>\r\n9<\/td>\r\n5.5<\/td>\r\n5.35<\/td>\r\n5.153<\/td>\r\n4.917<\/td>\r\n<\/tr>\r\n
      M7<\/td>\r\n3<\/td>\r\n9<\/td>\r\n6.5<\/td>\r\n6.35<\/td>\r\n6.153<\/td>\r\n5.917<\/td>\r\n<\/tr>\r\n
      M8<\/td>\r\n4<\/td>\r\n12<\/td>\r\n7.348<\/td>\r\n7.188<\/td>\r\n6.912<\/td>\r\n6.647<\/td>\r\n<\/tr>\r\n
      M10<\/td>\r\n5<\/td>\r\n15<\/td>\r\n9.206<\/td>\r\n9.026<\/td>\r\n8.676<\/td>\r\n8.376<\/td>\r\n<\/tr>\r\n
      M12<\/td>\r\n6<\/td>\r\n18<\/td>\r\n11.063<\/td>\r\n10.863<\/td>\r\n10.441<\/td>\r\n10.106<\/td>\r\n<\/tr>\r\n
      M14<\/td>\r\n8<\/td>\r\n24<\/td>\r\n12.913<\/td>\r\n12.701<\/td>\r\n12.21<\/td>\r\n11.835<\/td>\r\n<\/tr>\r\n
      M16<\/td>\r\n8<\/td>\r\n24<\/td>\r\n14.913<\/td>\r\n14.701<\/td>\r\n14.21<\/td>\r\n13.835<\/td>\r\n<\/tr>\r\n
      M18<\/td>\r\n10<\/td>\r\n30<\/td>\r\n16.6<\/td>\r\n16.376<\/td>\r\n15.744<\/td>\r\n15.294<\/td>\r\n<\/tr>\r\n
      M20<\/td>\r\n10<\/td>\r\n30<\/td>\r\n18.6<\/td>\r\n18.376<\/td>\r\n17.744<\/td>\r\n17.294<\/td>\r\n<\/tr>\r\n
      M22<\/td>\r\n10<\/td>\r\n30<\/td>\r\n20.6<\/td>\r\n20.376<\/td>\r\n19.744<\/td>\r\n19.294<\/td>\r\n<\/tr>\r\n
      M24<\/td>\r\n12<\/td>\r\n36<\/td>\r\n22.316<\/td>\r\n22.051<\/td>\r\n21.252<\/td>\r\n20.752<\/td>\r\n<\/tr>\r\n
      M27<\/td>\r\n12<\/td>\r\n36<\/td>\r\n25.316<\/td>\r\n25.051<\/td>\r\n24.252<\/td>\r\n23.752<\/td>\r\n<\/tr>\r\n
      M30<\/td>\r\n15<\/td>\r\n45<\/td>\r\n28.007<\/td>\r\n27.727<\/td>\r\n26.771<\/td>\r\n26.211<\/td>\r\n<\/tr>\r\n
      M33<\/td>\r\n15<\/td>\r\n45<\/td>\r\n31.007<\/td>\r\n30.727<\/td>\r\n29.771<\/td>\r\n29.211<\/td>\r\n<\/tr>\r\n
      M36<\/td>\r\n18<\/td>\r\n53<\/td>\r\n33.702<\/td>\r\n33.402<\/td>\r\n32.27<\/td>\r\n31.67<\/td>\r\n<\/tr>\r\n
      M39<\/td>\r\n18<\/td>\r\n53<\/td>\r\n36.702<\/td>\r\n36.402<\/td>\r\n35.27<\/td>\r\n34.67<\/td>\r\n<\/tr>\r\n
      M42<\/td>\r\n21<\/td>\r\n63<\/td>\r\n39.392<\/td>\r\n39.077<\/td>\r\n37.799<\/td>\r\n37.129<\/td>\r\n<\/tr>\r\n
      M45<\/td>\r\n21<\/td>\r\n63<\/td>\r\n42.392<\/td>\r\n42.077<\/td>\r\n40.799<\/td>\r\n40.129<\/td>\r\n<\/tr>\r\n
      M48<\/td>\r\n24<\/td>\r\n71<\/td>\r\n45.087<\/td>\r\n44.752<\/td>\r\n43.297<\/td>\r\n42.587<\/td>\r\n<\/tr>\r\n
      M52<\/td>\r\n24<\/td>\r\n71<\/td>\r\n49.087<\/td>\r\n48.752<\/td>\r\n46.681<\/td>\r\n45.971<\/td>\r\n<\/tr>\r\n
      M56<\/td>\r\n28<\/td>\r\n85<\/td>\r\n52.783<\/td>\r\n52.428<\/td>\r\n50.796<\/td>\r\n50.046<\/td>\r\n<\/tr>\r\n
      M60<\/td>\r\n28<\/td>\r\n85<\/td>\r\n56.783<\/td>\r\n56.428<\/td>\r\n54.796<\/td>\r\n54.046<\/td>\r\n<\/tr>\r\n
      M64<\/td>\r\n32<\/td>\r\n95<\/td>\r\n60.478<\/td>\r\n60.103<\/td>\r\n58.305<\/td>\r\n57.505<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\nThese dimensions provide guidance for nut manufacturing, ensuring compatibility with bolts under medium load conditions.\r\n\r\n<\/div>\r\n
      \r\n

      Coarse Pitch External Threads<\/h2>\r\nMedium precision, medium engagement. Tolerance zones: 6h for d \u2264 1.4 mm; 6g for d > 1.4 mm. Limits for major diameter d and pitch diameter d2<\/sub>, with min root radius per GB\/T 197-2003.\r\n
      \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      Thread<\/th>\r\nEngagement Length<\/th>\r\nMajor Diameter d<\/th>\r\nPitch Diameter d2<\/sub><\/th>\r\nMin Root Radiusa<\/sup><\/th>\r\n<\/tr>\r\n
      ><\/th>\r\n\u2264<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmin<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
      M1<\/td>\r\n0.6<\/td>\r\n1.7<\/td>\r\n1<\/td>\r\n0.933<\/td>\r\n0.838<\/td>\r\n0.785<\/td>\r\n0.031<\/td>\r\n<\/tr>\r\n
      M1.2<\/td>\r\n0.6<\/td>\r\n1.7<\/td>\r\n1.2<\/td>\r\n1.133<\/td>\r\n1.038<\/td>\r\n0.985<\/td>\r\n0.031<\/td>\r\n<\/tr>\r\n
      M1.4<\/td>\r\n0.7<\/td>\r\n2<\/td>\r\n1.4<\/td>\r\n1.325<\/td>\r\n1.205<\/td>\r\n1.149<\/td>\r\n0.038<\/td>\r\n<\/tr>\r\n
      M1.6<\/td>\r\n0.8<\/td>\r\n2.6<\/td>\r\n1.581<\/td>\r\n1.496<\/td>\r\n1.354<\/td>\r\n1.291<\/td>\r\n0.044<\/td>\r\n<\/tr>\r\n
      M1.8<\/td>\r\n0.8<\/td>\r\n2.6<\/td>\r\n1.781<\/td>\r\n1.696<\/td>\r\n1.554<\/td>\r\n1.491<\/td>\r\n0.044<\/td>\r\n<\/tr>\r\n
      M2<\/td>\r\n1<\/td>\r\n3<\/td>\r\n1.981<\/td>\r\n1.886<\/td>\r\n1.721<\/td>\r\n1.654<\/td>\r\n0.05<\/td>\r\n<\/tr>\r\n
      M2.5<\/td>\r\n1.3<\/td>\r\n3.8<\/td>\r\n2.48<\/td>\r\n2.38<\/td>\r\n2.188<\/td>\r\n2.117<\/td>\r\n0.056<\/td>\r\n<\/tr>\r\n
      M3<\/td>\r\n1.5<\/td>\r\n4.5<\/td>\r\n2.98<\/td>\r\n2.874<\/td>\r\n2.655<\/td>\r\n2.58<\/td>\r\n0.063<\/td>\r\n<\/tr>\r\n
      M3.5<\/td>\r\n1.7<\/td>\r\n5<\/td>\r\n3.479<\/td>\r\n3.354<\/td>\r\n3.089<\/td>\r\n3.004<\/td>\r\n0.075<\/td>\r\n<\/tr>\r\n
      M4<\/td>\r\n2<\/td>\r\n6<\/td>\r\n3.978<\/td>\r\n3.838<\/td>\r\n3.523<\/td>\r\n3.433<\/td>\r\n0.088<\/td>\r\n<\/tr>\r\n
      M5<\/td>\r\n2.5<\/td>\r\n7.5<\/td>\r\n4.976<\/td>\r\n4.826<\/td>\r\n4.456<\/td>\r\n4.361<\/td>\r\n0.1<\/td>\r\n<\/tr>\r\n
      M6<\/td>\r\n3<\/td>\r\n9<\/td>\r\n5.974<\/td>\r\n5.794<\/td>\r\n5.324<\/td>\r\n5.212<\/td>\r\n0.125<\/td>\r\n<\/tr>\r\n
      M7<\/td>\r\n3<\/td>\r\n9<\/td>\r\n6.974<\/td>\r\n6.794<\/td>\r\n6.324<\/td>\r\n6.212<\/td>\r\n0.125<\/td>\r\n<\/tr>\r\n
      M8<\/td>\r\n4<\/td>\r\n12<\/td>\r\n7.972<\/td>\r\n7.76<\/td>\r\n7.16<\/td>\r\n7.042<\/td>\r\n0.156<\/td>\r\n<\/tr>\r\n
      M10<\/td>\r\n5<\/td>\r\n15<\/td>\r\n9.968<\/td>\r\n9.732<\/td>\r\n8.994<\/td>\r\n8.862<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M12<\/td>\r\n6<\/td>\r\n18<\/td>\r\n11.966<\/td>\r\n11.701<\/td>\r\n10.829<\/td>\r\n10.679<\/td>\r\n0.219<\/td>\r\n<\/tr>\r\n
      M14<\/td>\r\n8<\/td>\r\n24<\/td>\r\n13.962<\/td>\r\n13.682<\/td>\r\n12.663<\/td>\r\n12.503<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M16<\/td>\r\n8<\/td>\r\n24<\/td>\r\n15.962<\/td>\r\n15.682<\/td>\r\n14.663<\/td>\r\n14.503<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M18<\/td>\r\n10<\/td>\r\n30<\/td>\r\n17.958<\/td>\r\n17.623<\/td>\r\n16.334<\/td>\r\n16.164<\/td>\r\n0.313<\/td>\r\n<\/tr>\r\n
      M20<\/td>\r\n10<\/td>\r\n30<\/td>\r\n19.958<\/td>\r\n19.623<\/td>\r\n18.334<\/td>\r\n18.164<\/td>\r\n0.313<\/td>\r\n<\/tr>\r\n
      M22<\/td>\r\n10<\/td>\r\n30<\/td>\r\n21.958<\/td>\r\n21.623<\/td>\r\n20.334<\/td>\r\n20.164<\/td>\r\n0.313<\/td>\r\n<\/tr>\r\n
      M24<\/td>\r\n12<\/td>\r\n36<\/td>\r\n23.952<\/td>\r\n23.577<\/td>\r\n22.003<\/td>\r\n21.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M27<\/td>\r\n12<\/td>\r\n36<\/td>\r\n26.952<\/td>\r\n26.577<\/td>\r\n25.003<\/td>\r\n24.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M30<\/td>\r\n15<\/td>\r\n45<\/td>\r\n29.947<\/td>\r\n29.522<\/td>\r\n27.674<\/td>\r\n27.462<\/td>\r\n0.438<\/td>\r\n<\/tr>\r\n
      M33<\/td>\r\n15<\/td>\r\n45<\/td>\r\n32.947<\/td>\r\n32.522<\/td>\r\n30.674<\/td>\r\n30.462<\/td>\r\n0.438<\/td>\r\n<\/tr>\r\n
      M36<\/td>\r\n18<\/td>\r\n53<\/td>\r\n35.94<\/td>\r\n35.465<\/td>\r\n33.342<\/td>\r\n33.118<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n
      M39<\/td>\r\n18<\/td>\r\n53<\/td>\r\n38.94<\/td>\r\n38.465<\/td>\r\n36.342<\/td>\r\n36.118<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n
      M42<\/td>\r\n21<\/td>\r\n63<\/td>\r\n41.937<\/td>\r\n41.437<\/td>\r\n39.014<\/td>\r\n38.778<\/td>\r\n0.563<\/td>\r\n<\/tr>\r\n
      M45<\/td>\r\n21<\/td>\r\n63<\/td>\r\n44.937<\/td>\r\n44.437<\/td>\r\n42.014<\/td>\r\n41.778<\/td>\r\n0.563<\/td>\r\n<\/tr>\r\n
      M48<\/td>\r\n24<\/td>\r\n71<\/td>\r\n47.929<\/td>\r\n47.399<\/td>\r\n44.681<\/td>\r\n44.431<\/td>\r\n0.625<\/td>\r\n<\/tr>\r\n
      M52<\/td>\r\n24<\/td>\r\n71<\/td>\r\n51.929<\/td>\r\n51.399<\/td>\r\n48.681<\/td>\r\n48.431<\/td>\r\n0.625<\/td>\r\n<\/tr>\r\n
      M56<\/td>\r\n28<\/td>\r\n85<\/td>\r\n55.925<\/td>\r\n55.365<\/td>\r\n52.353<\/td>\r\n52.088<\/td>\r\n0.688<\/td>\r\n<\/tr>\r\n
      M60<\/td>\r\n28<\/td>\r\n85<\/td>\r\n59.925<\/td>\r\n59.365<\/td>\r\n56.353<\/td>\r\n56.088<\/td>\r\n0.688<\/td>\r\n<\/tr>\r\n
      M64<\/td>\r\n32<\/td>\r\n95<\/td>\r\n63.92<\/td>\r\n63.32<\/td>\r\n60.023<\/td>\r\n59.743<\/td>\r\n0.75<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\na<\/sup> See GB\/T 197-2003 Chapter 7 and Table 9 for root radius details. These ensure stress distribution and fatigue resistance.\r\n\r\n<\/div>\r\n
      \r\n

      Fine Pitch Internal Threads<\/h2>\r\nMedium precision, medium engagement, 6H tolerance zone. Fine pitches offer better vibration resistance and adjustment precision.\r\n
      \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      Thread<\/th>\r\nEngagement Length<\/th>\r\nPitch Diameter D2<\/sub><\/th>\r\nMinor Diameter D1<\/sub><\/th>\r\n<\/tr>\r\n
      ><\/th>\r\n\u2264<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
      M8\u00d71<\/td>\r\n3<\/td>\r\n9<\/td>\r\n7.5<\/td>\r\n7.35<\/td>\r\n7.153<\/td>\r\n6.917<\/td>\r\n<\/tr>\r\n
      M10\u00d71<\/td>\r\n4<\/td>\r\n12<\/td>\r\n9.5<\/td>\r\n9.35<\/td>\r\n9.153<\/td>\r\n8.917<\/td>\r\n<\/tr>\r\n
      M10\u00d71.25<\/td>\r\n4<\/td>\r\n12<\/td>\r\n9.348<\/td>\r\n9.188<\/td>\r\n8.912<\/td>\r\n8.647<\/td>\r\n<\/tr>\r\n
      M12\u00d71.25<\/td>\r\n4.5<\/td>\r\n13<\/td>\r\n11.368<\/td>\r\n11.188<\/td>\r\n10.912<\/td>\r\n10.647<\/td>\r\n<\/tr>\r\n
      M12\u00d71.5<\/td>\r\n4.5<\/td>\r\n13<\/td>\r\n11.216<\/td>\r\n11.026<\/td>\r\n10.676<\/td>\r\n10.376<\/td>\r\n<\/tr>\r\n
      M14\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n13.216<\/td>\r\n13.026<\/td>\r\n12.676<\/td>\r\n12.376<\/td>\r\n<\/tr>\r\n
      M16\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n15.216<\/td>\r\n15.026<\/td>\r\n14.676<\/td>\r\n14.376<\/td>\r\n<\/tr>\r\n
      M18\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n17.216<\/td>\r\n17.026<\/td>\r\n16.676<\/td>\r\n16.376<\/td>\r\n<\/tr>\r\n
      M18\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n16.913<\/td>\r\n16.701<\/td>\r\n16.21<\/td>\r\n15.835<\/td>\r\n<\/tr>\r\n
      M20\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n19.216<\/td>\r\n19.026<\/td>\r\n18.676<\/td>\r\n18.376<\/td>\r\n<\/tr>\r\n
      M20\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n18.913<\/td>\r\n18.701<\/td>\r\n18.21<\/td>\r\n17.835<\/td>\r\n<\/tr>\r\n
      M22\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n21.216<\/td>\r\n21.026<\/td>\r\n20.676<\/td>\r\n20.376<\/td>\r\n<\/tr>\r\n
      M22\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n20.913<\/td>\r\n20.701<\/td>\r\n20.21<\/td>\r\n19.835<\/td>\r\n<\/tr>\r\n
      M24\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n22.925<\/td>\r\n22.701<\/td>\r\n22.21<\/td>\r\n21.835<\/td>\r\n<\/tr>\r\n
      M27\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n25.925<\/td>\r\n25.701<\/td>\r\n25.21<\/td>\r\n24.835<\/td>\r\n<\/tr>\r\n
      M30\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n28.925<\/td>\r\n28.701<\/td>\r\n28.21<\/td>\r\n27.835<\/td>\r\n<\/tr>\r\n
      M33\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n31.925<\/td>\r\n31.701<\/td>\r\n31.21<\/td>\r\n30.835<\/td>\r\n<\/tr>\r\n
      M36\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n34.316<\/td>\r\n34.051<\/td>\r\n33.252<\/td>\r\n32.752<\/td>\r\n<\/tr>\r\n
      M39\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n37.316<\/td>\r\n37.051<\/td>\r\n36.252<\/td>\r\n35.752<\/td>\r\n<\/tr>\r\n
      M42\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n40.316<\/td>\r\n40.051<\/td>\r\n39.252<\/td>\r\n38.752<\/td>\r\n<\/tr>\r\n
      M45\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n43.316<\/td>\r\n43.051<\/td>\r\n42.252<\/td>\r\n41.752<\/td>\r\n<\/tr>\r\n
      M48\u00d73<\/td>\r\n15<\/td>\r\n45<\/td>\r\n46.331<\/td>\r\n46.051<\/td>\r\n45.252<\/td>\r\n44.752<\/td>\r\n<\/tr>\r\n
      M52\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n49.717<\/td>\r\n49.402<\/td>\r\n48.27<\/td>\r\n47.67<\/td>\r\n<\/tr>\r\n
      M56\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n53.717<\/td>\r\n53.402<\/td>\r\n52.27<\/td>\r\n51.67<\/td>\r\n<\/tr>\r\n
      M60\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n57.717<\/td>\r\n57.402<\/td>\r\n56.27<\/td>\r\n55.67<\/td>\r\n<\/tr>\r\n
      M64\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n61.717<\/td>\r\n61.402<\/td>\r\n60.27<\/td>\r\n59.67<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\nThese values support finer load distribution in high-vibration environments.\r\n\r\n<\/div>\r\n
      \r\n

      Fine Pitch External Threads<\/h2>\r\nMedium precision, medium engagement, 6g tolerance zone. Provides stronger core sections for enhanced shear strength.\r\n
      \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      Thread<\/th>\r\nEngagement Length<\/th>\r\nMajor Diameter d<\/th>\r\nPitch Diameter d2<\/sub><\/th>\r\nMin Root Radiusa<\/sup><\/th>\r\n<\/tr>\r\n
      ><\/th>\r\n\u2264<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmax<\/th>\r\nmin<\/th>\r\nmin<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
      M8\u00d71<\/td>\r\n3<\/td>\r\n9<\/td>\r\n7.974<\/td>\r\n7.794<\/td>\r\n7.324<\/td>\r\n7.212<\/td>\r\n0.125<\/td>\r\n<\/tr>\r\n
      M10\u00d71<\/td>\r\n4<\/td>\r\n12<\/td>\r\n9.974<\/td>\r\n9.794<\/td>\r\n9.324<\/td>\r\n9.212<\/td>\r\n0.125<\/td>\r\n<\/tr>\r\n
      M10\u00d71.25<\/td>\r\n4<\/td>\r\n12<\/td>\r\n9.972<\/td>\r\n9.76<\/td>\r\n9.16<\/td>\r\n9.042<\/td>\r\n0.156<\/td>\r\n<\/tr>\r\n
      M12\u00d71.25<\/td>\r\n4.5<\/td>\r\n13<\/td>\r\n11.972<\/td>\r\n11.76<\/td>\r\n11.16<\/td>\r\n11.028<\/td>\r\n0.156<\/td>\r\n<\/tr>\r\n
      M12\u00d71.5<\/td>\r\n4.5<\/td>\r\n13<\/td>\r\n11.968<\/td>\r\n11.732<\/td>\r\n10.994<\/td>\r\n10.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M14\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n13.968<\/td>\r\n13.732<\/td>\r\n12.994<\/td>\r\n12.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M16\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n15.968<\/td>\r\n15.732<\/td>\r\n14.994<\/td>\r\n14.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M18\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n17.968<\/td>\r\n17.732<\/td>\r\n16.994<\/td>\r\n16.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M18\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n17.962<\/td>\r\n17.682<\/td>\r\n16.663<\/td>\r\n16.503<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M20\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n19.968<\/td>\r\n19.732<\/td>\r\n18.994<\/td>\r\n18.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M20\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n19.962<\/td>\r\n19.682<\/td>\r\n18.663<\/td>\r\n18.503<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M22\u00d71.5<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n21.968<\/td>\r\n21.732<\/td>\r\n20.994<\/td>\r\n20.854<\/td>\r\n0.188<\/td>\r\n<\/tr>\r\n
      M22\u00d72<\/td>\r\n5.6<\/td>\r\n16<\/td>\r\n21.962<\/td>\r\n21.682<\/td>\r\n20.663<\/td>\r\n20.503<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M24\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n23.962<\/td>\r\n23.682<\/td>\r\n22.663<\/td>\r\n22.493<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M27\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n26.962<\/td>\r\n26.682<\/td>\r\n25.663<\/td>\r\n25.493<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M30\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n29.962<\/td>\r\n29.682<\/td>\r\n28.663<\/td>\r\n28.493<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M33\u00d72<\/td>\r\n8.5<\/td>\r\n25<\/td>\r\n32.962<\/td>\r\n32.682<\/td>\r\n31.663<\/td>\r\n31.493<\/td>\r\n0.25<\/td>\r\n<\/tr>\r\n
      M36\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n35.952<\/td>\r\n35.577<\/td>\r\n34.003<\/td>\r\n33.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M39\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n38.952<\/td>\r\n38.577<\/td>\r\n37.003<\/td>\r\n36.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M42\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n41.952<\/td>\r\n41.577<\/td>\r\n40.003<\/td>\r\n39.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M45\u00d73<\/td>\r\n12<\/td>\r\n36<\/td>\r\n44.952<\/td>\r\n44.577<\/td>\r\n43.003<\/td>\r\n42.803<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M48\u00d73<\/td>\r\n15<\/td>\r\n45<\/td>\r\n47.952<\/td>\r\n47.577<\/td>\r\n46.003<\/td>\r\n45.791<\/td>\r\n0.375<\/td>\r\n<\/tr>\r\n
      M52\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n51.94<\/td>\r\n51.465<\/td>\r\n49.342<\/td>\r\n49.106<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n
      M56\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n55.94<\/td>\r\n55.465<\/td>\r\n53.342<\/td>\r\n53.106<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n
      M60\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n59.94<\/td>\r\n59.465<\/td>\r\n57.342<\/td>\r\n57.106<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n
      M64\u00d74<\/td>\r\n19<\/td>\r\n56<\/td>\r\n63.94<\/td>\r\n63.465<\/td>\r\n61.342<\/td>\r\n61.106<\/td>\r\n0.5<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\na<\/sup> See GB\/T 197-2003 for root radius specifications, critical for avoiding stress concentrations.\r\n\r\n<\/div>\r\n
      \r\n

      FAQ<\/h2>\r\n

      What tolerance zones apply to coarse internal threads?<\/h3>\r\n5H for diameters \u22641.4 mm; 6H for >1.4 mm, ensuring medium precision fit.\r\n

      How does plating affect thread dimensions?<\/h3>\r\nTolerances are pre-plating; post-plating profiles must not exceed H\/h positions for thin coatings to maintain assembly.\r\n

      Why use fine pitch threads?<\/h3>\r\nThey provide better vibration resistance and finer adjustments, with stronger cores per limits in tables 3 and 4.\r\n

      What is medium engagement length?<\/h3>\r\nIt balances thread strength and cost; use table values for specific ranges to avoid over- or under-engagement.\r\n

      How to interpret root radius?<\/h3>\r\nMin values per GB\/T 197-2003 reduce stress; essential for fatigue-prone applications.\r\n

      Are these limits for all materials?<\/h3>\r\nYes, but adjust for special platings; consult standard for heavy coatings requiring oversized threads.\r\n\r\n<\/div>\r\n ","_et_gb_content_width":"","footnotes":""},"categories":[220],"tags":[],"class_list":["post-5757","post","type-post","status-publish","format-standard","hentry","category-technical-documentation-and-references"],"_links":{"self":[{"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/posts\/5757","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/comments?post=5757"}],"version-history":[{"count":3,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/posts\/5757\/revisions"}],"predecessor-version":[{"id":5760,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/posts\/5757\/revisions\/5760"}],"wp:attachment":[{"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/media?parent=5757"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/categories?post=5757"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/korea-transmission.com\/th\/wp-json\/wp\/v2\/tags?post=5757"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}