{
    "slug": "general-tolerances-iso-2768",
    "title": "ISO 2768 未注公差：f、m、c、v 与 H、K、L",
    "description": "未注尺寸不代表没有公差：本页给出 ISO 2768 中线性、角度与几何公差（f/m/c/v 和 H/K/L）的完整表格、等级选用规则与各国等效标准。",
    "lang": "zh",
    "tables": [
        {
            "caption": "ISO 2768-1 线性尺寸的极限偏差（± mm，不含倒角）",
            "columns": [
                "公称尺寸范围（mm）",
                "f（精密）",
                "m（中等）",
                "c（粗糙）",
                "v（很粗糙）"
            ],
            "rows": [
                {
                    "公称尺寸范围（mm）": "0.5 up to 3",
                    "f（精密）": "±0.05",
                    "m（中等）": "±0.1",
                    "c（粗糙）": "±0.2",
                    "v（很粗糙）": "—"
                },
                {
                    "公称尺寸范围（mm）": "over 3 up to 6",
                    "f（精密）": "±0.05",
                    "m（中等）": "±0.1",
                    "c（粗糙）": "±0.3",
                    "v（很粗糙）": "±0.5"
                },
                {
                    "公称尺寸范围（mm）": "over 6 up to 30",
                    "f（精密）": "±0.1",
                    "m（中等）": "±0.2",
                    "c（粗糙）": "±0.5",
                    "v（很粗糙）": "±1"
                },
                {
                    "公称尺寸范围（mm）": "over 30 up to 120",
                    "f（精密）": "±0.15",
                    "m（中等）": "±0.3",
                    "c（粗糙）": "±0.8",
                    "v（很粗糙）": "±1.5"
                },
                {
                    "公称尺寸范围（mm）": "over 120 up to 400",
                    "f（精密）": "±0.2",
                    "m（中等）": "±0.5",
                    "c（粗糙）": "±1.2",
                    "v（很粗糙）": "±2.5"
                },
                {
                    "公称尺寸范围（mm）": "over 400 up to 1000",
                    "f（精密）": "±0.3",
                    "m（中等）": "±0.8",
                    "c（粗糙）": "±2",
                    "v（很粗糙）": "±4"
                },
                {
                    "公称尺寸范围（mm）": "over 1000 up to 2000",
                    "f（精密）": "±0.5",
                    "m（中等）": "±1.2",
                    "c（粗糙）": "±3",
                    "v（很粗糙）": "±6"
                },
                {
                    "公称尺寸范围（mm）": "over 2000 up to 4000",
                    "f（精密）": "—",
                    "m（中等）": "±2",
                    "c（粗糙）": "±4",
                    "v（很粗糙）": "±8"
                }
            ]
        },
        {
            "caption": "图纸尺寸未标注公差时，按哪个公差执行？",
            "columns": [
                "步骤",
                "项目",
                "数值"
            ],
            "rows": [
                {
                    "步骤": "1",
                    "项目": "Dimension type",
                    "数值": "linear (Ø50 outer diameter) — ISO 2768-1 table"
                },
                {
                    "步骤": "2",
                    "项目": "Band",
                    "数值": "50 falls in over 30 up to 120"
                },
                {
                    "步骤": "3",
                    "项目": "m-grade deviation",
                    "数值": "±0.3 mm"
                },
                {
                    "步骤": "4",
                    "项目": "Acceptance range",
                    "数值": "49.700–50.300 mm (band 0.6)"
                },
                {
                    "步骤": "5",
                    "项目": "K-grade roundness",
                    "数值": "min(diameter tolerance 0.6, K run-out 0.2) = 0.2 mm; straightness of a 50 mm generator line (over 30–100) = 0.2 mm"
                },
                {
                    "步骤": "6",
                    "项目": "Verdict",
                    "数值": "Ø in 49.700–50.300 with run-out ≤ 0.2 mm against the datum axis = conforming"
                }
            ]
        },
        {
            "caption": "GB/T 1804 与 ISO 2768-1 的数值一样吗？",
            "columns": [
                "标准",
                "对应标准",
                "等级",
                "相对 ISO 2768 的数值",
                "名称／结构"
            ],
            "rows": [
                {
                    "标准": "ISO 2768-1:1989 / -2:1989",
                    "对应标准": "—",
                    "等级": "f m c v / H K L",
                    "相对 ISO 2768 的数值": "基准",
                    "名称／结构": "实际被引用的版本"
                },
                {
                    "标准": "DIN ISO 2768-1/-2:1991",
                    "对应标准": "direct adoption",
                    "等级": "f m c v / H K L",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "旧 DIN 7168 已被 DIN ISO 2768 取代"
                },
                {
                    "标准": "EN 22768-1 / BS EN 22768-1",
                    "对应标准": "adopts ISO 2768-1",
                    "等级": "f m c v",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "—"
                },
                {
                    "标准": "GB/T 1804-2000",
                    "对应标准": "eqv ISO 2768-1:1989",
                    "等级": "f / m / c / v — same letters with Chinese grade names",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "字母相同，中文标准中名称做了翻译"
                },
                {
                    "标准": "GB/T 1184-1996",
                    "对应标准": "eqv ISO 2768-2:1989 (untoleranced part)",
                    "等级": "H K L",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "还包含单独标注公差的表格（不在本页范围内）"
                },
                {
                    "标准": "JIS B 0405-1991",
                    "对应标准": "adopts ISO 2768-1:1989",
                    "等级": "f m c v",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "日本把两部分拆成两个标准号"
                },
                {
                    "标准": "JIS B 0419-1991",
                    "对应标准": "corresponds to ISO 2768-2:1989",
                    "等级": "H K L",
                    "相对 ISO 2768 的数值": "相同",
                    "名称／结构": "拆分是它与 ISO 唯一的结构差异"
                }
            ]
        },
        {
            "caption": "f、m、c 还是 v——CNC 加工默认用哪个等级？",
            "columns": [
                "尺寸档（mm）",
                "m（± mm）",
                "c（± mm）",
                "c / m"
            ],
            "rows": [
                {
                    "尺寸档（mm）": "0.5 up to 3",
                    "m（± mm）": "0.1",
                    "c（± mm）": "0.2",
                    "c / m": "2.0"
                },
                {
                    "尺寸档（mm）": "over 3 up to 6",
                    "m（± mm）": "0.1",
                    "c（± mm）": "0.3",
                    "c / m": "3.0"
                },
                {
                    "尺寸档（mm）": "over 6 up to 30",
                    "m（± mm）": "0.2",
                    "c（± mm）": "0.5",
                    "c / m": "2.5"
                },
                {
                    "尺寸档（mm）": "over 30 up to 120",
                    "m（± mm）": "0.3",
                    "c（± mm）": "0.8",
                    "c / m": "2.7"
                },
                {
                    "尺寸档（mm）": "over 120 up to 400",
                    "m（± mm）": "0.5",
                    "c（± mm）": "1.2",
                    "c / m": "2.4"
                },
                {
                    "尺寸档（mm）": "over 400 up to 1000",
                    "m（± mm）": "0.8",
                    "c（± mm）": "2",
                    "c / m": "2.5"
                },
                {
                    "尺寸档（mm）": "over 1000 up to 2000",
                    "m（± mm）": "1.2",
                    "c（± mm）": "3",
                    "c / m": "2.5"
                },
                {
                    "尺寸档（mm）": "over 2000 up to 4000",
                    "m（± mm）": "2",
                    "c（± mm）": "4",
                    "c / m": "2.0"
                }
            ]
        },
        {
            "caption": "50 mm 处 ISO 2768-c 比 -m 松多少？",
            "columns": [
                "步骤",
                "项目",
                "数值"
            ],
            "rows": [
                {
                    "步骤": "1",
                    "项目": "Dimension type",
                    "数值": "angle 30° untoleranced, grade c — key off the shorter side"
                },
                {
                    "步骤": "2",
                    "项目": "Sides",
                    "数值": "60 mm and 8 mm → shorter side 8 mm → up to 10 band"
                },
                {
                    "步骤": "3",
                    "项目": "c-grade angular deviation",
                    "数值": "±1°30′ → 28°30′–31°30′"
                },
                {
                    "步骤": "4",
                    "项目": "Linear offset of the short end",
                    "数值": "8 × tan 1.5° ≈ ±0.21 mm"
                },
                {
                    "步骤": "5",
                    "项目": "Same angle read on the 60 mm side",
                    "数值": "over 50–120 band → c = ±0°30′ — the shorter side governs, not the longer"
                },
                {
                    "步骤": "6",
                    "项目": "If the drawing were m grade",
                    "数值": "up to 10 band = ±1°, 0°30′ tighter than c"
                }
            ]
        },
        {
            "caption": "ISO 2768-mK 中的 K 控制什么？",
            "columns": [
                "公称长度（mm）",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "公称长度（mm）": "up to 10",
                    "H": "0.02",
                    "K": "0.05",
                    "L": "0.1"
                },
                {
                    "公称长度（mm）": "over 10 up to 30",
                    "H": "0.05",
                    "K": "0.1",
                    "L": "0.2"
                },
                {
                    "公称长度（mm）": "over 30 up to 100",
                    "H": "0.1",
                    "K": "0.2",
                    "L": "0.4"
                },
                {
                    "公称长度（mm）": "over 100 up to 300",
                    "H": "0.2",
                    "K": "0.4",
                    "L": "0.8"
                },
                {
                    "公称长度（mm）": "over 300 up to 1000",
                    "H": "0.3",
                    "K": "0.6",
                    "L": "1.2"
                },
                {
                    "公称长度（mm）": "over 1000 up to 3000",
                    "H": "0.4",
                    "K": "0.8",
                    "L": "1.6"
                }
            ]
        },
        {
            "caption": "K 级下未注垂直度是多少？",
            "columns": [
                "短边（mm）",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "短边（mm）": "up to 100",
                    "H": "0.2",
                    "K": "0.4",
                    "L": "0.6"
                },
                {
                    "短边（mm）": "over 100 up to 300",
                    "H": "0.3",
                    "K": "0.6",
                    "L": "1"
                },
                {
                    "短边（mm）": "over 300 up to 1000",
                    "H": "0.4",
                    "K": "0.8",
                    "L": "1.5"
                },
                {
                    "短边（mm）": "over 1000 up to 3000",
                    "H": "0.5",
                    "K": "1",
                    "L": "2"
                }
            ]
        },
        {
            "caption": "未注对称度是多少？",
            "columns": [
                "公称长度（mm）",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "公称长度（mm）": "up to 100",
                    "H": "0.5",
                    "K": "0.6",
                    "L": "0.6"
                },
                {
                    "公称长度（mm）": "over 100 up to 300",
                    "H": "0.5",
                    "K": "0.6",
                    "L": "1"
                },
                {
                    "公称长度（mm）": "over 300 up to 1000",
                    "H": "0.5",
                    "K": "0.8",
                    "L": "1.5"
                },
                {
                    "公称长度（mm）": "over 1000 up to 3000",
                    "H": "0.5",
                    "K": "1",
                    "L": "2"
                }
            ]
        },
        {
            "caption": "K 级下未注圆跳动是多少？",
            "columns": [
                "公差等级",
                "圆跳动（mm）",
                "状态"
            ],
            "rows": [
                {
                    "公差等级": "H",
                    "圆跳动（mm）": "0.1",
                    "状态": "三个可靠来源一致"
                },
                {
                    "公差等级": "K",
                    "圆跳动（mm）": "0.2",
                    "状态": "三个可靠来源一致"
                },
                {
                    "公差等级": "L",
                    "圆跳动（mm）": "0.5",
                    "状态": "三个可靠来源一致"
                },
                {
                    "公差等级": "K 0.1 / L 0.2 (circulating copy)",
                    "圆跳动（mm）": "—",
                    "状态": "已登记、未采用——无可靠来源"
                }
            ]
        },
        {
            "caption": "未注的圆度、平行度和同轴度怎么处理？",
            "columns": [
                "项目",
                "未注取值规则"
            ],
            "rows": [
                {
                    "项目": "Roundness",
                    "未注取值规则": "等于该要素的直径公差，且不超过径向圆跳动值（K：0.2）"
                },
                {
                    "项目": "Cylindricity",
                    "未注取值规则": "不作单独规定——由圆度、直线度和平行度控制"
                },
                {
                    "项目": "Parallelism",
                    "未注取值规则": "取尺寸公差与直线度/平面度值中的较大者"
                },
                {
                    "项目": "Coaxiality",
                    "未注取值规则": "不作规定；极限情况下等于径向圆跳动值"
                },
                {
                    "项目": "Total run-out",
                    "未注取值规则": "不作规定——由形状和位置公差控制"
                },
                {
                    "项目": "Angularity (inclination)",
                    "未注取值规则": "无单独数值——由角度公差和直线度/平面度值控制"
                }
            ]
        },
        {
            "caption": "30° 倒角未注公差是多少？",
            "columns": [
                "短边（mm）",
                "f",
                "m",
                "c",
                "v"
            ],
            "rows": [
                {
                    "短边（mm）": "up to 10",
                    "f": "±1°",
                    "m": "±1°",
                    "c": "±1°30′",
                    "v": "±3°"
                },
                {
                    "短边（mm）": "over 10 up to 50",
                    "f": "±0°30′",
                    "m": "±0°30′",
                    "c": "±1°",
                    "v": "±2°"
                },
                {
                    "短边（mm）": "over 50 up to 120",
                    "f": "±0°20′",
                    "m": "±0°20′",
                    "c": "±0°30′",
                    "v": "±1°"
                },
                {
                    "短边（mm）": "over 120 up to 400",
                    "f": "±0°10′",
                    "m": "±0°10′",
                    "c": "±0°15′",
                    "v": "±0°30′"
                },
                {
                    "短边（mm）": "over 400",
                    "f": "±0°5′",
                    "m": "±0°5′",
                    "c": "±0°10′",
                    "v": "±0°20′"
                }
            ]
        },
        {
            "caption": "未注半径和倒角高度按什么公差？",
            "columns": [
                "公称尺寸范围（mm）",
                "f",
                "m",
                "c",
                "v"
            ],
            "rows": [
                {
                    "公称尺寸范围（mm）": "0.5 up to 3",
                    "f": "±0.2",
                    "m": "±0.2",
                    "c": "±0.4",
                    "v": "±0.4"
                },
                {
                    "公称尺寸范围（mm）": "over 3 up to 6",
                    "f": "±0.5",
                    "m": "±0.5",
                    "c": "±1",
                    "v": "±1"
                },
                {
                    "公称尺寸范围（mm）": "over 6",
                    "f": "±1",
                    "m": "±1",
                    "c": "±2",
                    "v": "±2"
                }
            ]
        },
        {
            "caption": "超出一般公差的零件会自动判废吗？",
            "columns": [
                "标准状态",
                "现行状态",
                "说明"
            ],
            "rows": [
                {
                    "标准状态": "ISO 2768-1:1989",
                    "现行状态": "in force in practice",
                    "说明": "GB/T 1804、DIN ISO 2768 和 JIS B 0405/0419 都以它为依据；目前仍是各标准引用的版本"
                },
                {
                    "标准状态": "ISO 2768-2:1989",
                    "现行状态": "withdrawn (2021-02) — superseded by ISO 22081:2021",
                    "说明": "ISO 22081（GPS——一般几何规范）沿用相同的 H/K/L 未注数值；无论按哪一版，本页的几何公差表都成立"
                },
                {
                    "标准状态": "Integrated new ISO 2768 (linear + angular)",
                    "现行状态": "under publication",
                    "说明": "待整合版正式发布后，需重新核对本页表格"
                }
            ]
        },
        {
            "caption": "ISO 2768 会覆盖单独标注的公差吗？",
            "columns": [
                "层级",
                "规则"
            ],
            "rows": [
                {
                    "层级": "1 — individually indicated tolerances",
                    "规则": "ISO 286 配合带、GD&T 框格、明确标注的 ±：始终优先于一般公差带"
                },
                {
                    "层级": "2 — invoked general tolerance",
                    "规则": "ISO 2768 等级适用于所有未单独标注公差的尺寸"
                },
                {
                    "层级": "3 — good workmanship",
                    "规则": "验收由 ISO 8015 独立原则加过程能力决定；超出一般公差带不自动判废，但也不等于可以放行"
                }
            ]
        },
        {
            "caption": "ISO 2768 在图纸上怎么标注？",
            "columns": [
                "图纸标注",
                "引用内容"
            ],
            "rows": [
                {
                    "图纸标注": "ISO 2768-mK",
                    "引用内容": "线性与角度按 m，几何按 K——最常见的完整引用"
                },
                {
                    "图纸标注": "ISO 2768-m",
                    "引用内容": "仅尺寸；未引用几何等级"
                },
                {
                    "图纸标注": "ISO 2768-K",
                    "引用内容": "仅几何；尺寸另行标注"
                },
                {
                    "图纸标注": "nothing stated",
                    "引用内容": "不存在一般公差——报价前须确认等级"
                }
            ]
        },
        {
            "caption": "JIS B 0405 与 ISO 2768-1 有对应缺口吗？",
            "columns": [
                "JIS 标准",
                "覆盖内容",
                "等级",
                "数值"
            ],
            "rows": [
                {
                    "JIS 标准": "JIS B 0405-1991",
                    "覆盖内容": "linear + angular (ISO 2768-1)",
                    "等级": "f m c v",
                    "数值": "identical"
                },
                {
                    "JIS 标准": "JIS B 0419-1991",
                    "覆盖内容": "geometry (ISO 2768-2)",
                    "等级": "H K L",
                    "数值": "identical"
                }
            ]
        },
        {
            "caption": "K 级下 200 mm 的未注平面度是多少？",
            "columns": [
                "冲突点",
                "采用值",
                "变体",
                "处理"
            ],
            "rows": [
                {
                    "冲突点": "v grade, 1000–2000 linear band",
                    "采用值": "±6",
                    "变体": "±5",
                    "处理": "三个来源对一个；±6 也符合 c×2 的递进规律——±5 已登记，未删除"
                },
                {
                    "冲突点": "straightness H, over 10–30",
                    "采用值": "0.05",
                    "变体": "0.06",
                    "处理": "三个来源一致；0.06 属于单页 OCR 转录错误"
                },
                {
                    "冲突点": "perpendicularity L, up to 100",
                    "采用值": "0.6",
                    "变体": "0.5",
                    "处理": "三个来源一致；0.5 那页存在与上面 ±5 相同的转录缺陷"
                },
                {
                    "冲突点": "run-out class values",
                    "采用值": "H 0.1 / K 0.2 / L 0.5",
                    "变体": "circulating K 0.1 / L 0.2",
                    "处理": "流传的变体背后没有可靠来源"
                }
            ]
        },
        {
            "caption": "钣金支架——按 m 还是 c 报价？",
            "columns": [
                "场景",
                "默认等级",
                "理由与例外"
            ],
            "rows": [
                {
                    "场景": "CNC turning/milling/drilling, structural parts",
                    "默认等级": "ISO 2768-mK",
                    "理由与例外": "行业标准默认：m 线性（0.5–2000 范围内 ±0.1 至 ±1.2）+ K 几何（圆跳动 0.2）"
                },
                {
                    "场景": "Fitting surfaces / bearing seats / seal faces",
                    "默认等级": "never general tolerance",
                    "理由与例外": "必须单独标注（ISO 286 或 GD&T）；m 档 ±0.3 面对 H7 +0.025/0 毫无意义"
                },
                {
                    "场景": "Sheet-metal bending / laser cutting (1–6 mm)",
                    "默认等级": "ISO 2768-c",
                    "理由与例外": "回弹与厚度波动；c 的 ±1.2 才是可报的公差带"
                },
                {
                    "场景": "Large welded frames",
                    "默认等级": "ISO 2768-v or ISO 13920",
                    "理由与例外": "焊接结构更适合 ISO 13920；v 是框架类惯例"
                },
                {
                    "场景": "Thin-walled, distortion-prone cut parts",
                    "默认等级": "usually c",
                    "理由与例外": "按 c 报价并写明——诚实报价胜过没人做得到的 m 档"
                },
                {
                    "场景": "Drawing with no tolerance statement at all",
                    "默认等级": "none — confirm",
                    "理由与例外": "ISO 2768 不会自动生效；按 mK 假设核价，写明该假设，并让客户确认等级"
                },
                {
                    "场景": "Plastic / 3D-printed parts",
                    "默认等级": "not this table",
                    "理由与例外": "收缩与工艺决定；ISO 2768 只覆盖金属切削和钣金"
                }
            ]
        },
        {
            "caption": "ISO 2768-1 覆盖的最小尺寸档是多少？",
            "columns": [
                "项目",
                "数值"
            ],
            "rows": [
                {
                    "项目": "Smallest linear band",
                    "数值": "0.5 up to 3 mm"
                },
                {
                    "项目": "f / m / c deviations there",
                    "数值": "±0.05 / ±0.1 / ±0.2"
                },
                {
                    "项目": "Below 0.5 mm",
                    "数值": "tolerance must be stated next to the dimension"
                },
                {
                    "项目": "Radii/chamfer heights, 0.5–3 mm",
                    "数值": "±0.2 (f = m), ±0.4 (c = v)"
                }
            ]
        }
    ]
}