Precision CNC Machined Fasteners精密 CNC 紧固件

Almost every fastener in a catalogue is cold-headed: a wire is sheared and squeezed into shape in a couple of blows, at speeds measured in hundreds of parts per minute. That is unbeatable on price once you are buying millions, and it is why CNC fasteners exist in a narrower band — prototypes, low and mid volumes, materials that do not head cleanly, and geometries no header tool can form.

目录里几乎每一颗紧固件都是冷镦的：线材被剪切后经几次挤压成形，速度以每分钟数百件计。一旦年用量达到百万级，这个价格无可匹敌；正因如此，CNC 紧固件只存在于更窄的区间——打样、中小批量、冷镦成形性不好的材料，以及任何一种镦头模具都做不出来的几何形状。

We machine fasteners on turning centres and mill-turn platforms rather than heading them, which changes what is practical:

我们用车削中心与车铣复合机床加工紧固件，而不是冷镦，这改变了以下几件事的可行性：

• Tooling cost is near zero, so 20 pieces cost roughly what 2,000 do per part. A cold-headed equivalent needs a heading tool and a thread-rolling die before the first part exists.模具成本几乎为零，所以做 20 件的单件价格和做 2,000 件差不多。冷镦方案在第一件出来之前就要先投镦头模与滚丝模。
• Material freedom. 303 and 304 stainless, brass, aluminum 6061 and 7075, titanium and engineering plastics can all be machined from bar; several of them head poorly or not at all.材料自由。303 与 304 不锈钢、黄铜、铝 6061 与 7075、钛合金以及工程塑料都可以直接从棒料加工；其中有几种的冷镦成形性很差或根本无法冷镦。
• Geometry freedom. Shoulder screws, stepped standoffs, knurled nuts, captive panel fasteners and parts with cross-holes or side flats come off the machine finished.几何自由。台阶螺钉、阶梯定位柱、滚花螺母、面板固定紧固件，以及带横孔或侧扁面的零件，下机即为成品。
• Concentricity. Because the thread and the body are cut in one setup, we hold thread-to-body concentricity within 0.02 mm TIR as standard — something a transferred heading job rarely matches.同轴度。由于螺纹与本体在同一次装夹中加工，螺纹对本体同轴度标准可控制在 0.02 mm TIR 以内——这是需要转序的冷镦件通常做不到的。

The honest limit is unit cost at volume. Above roughly 50,000–100,000 pieces of a simple hex nut or spacer, cold heading plus thread rolling will beat machining on price, and we will say so at quote stage rather than quoting a part we should not be making.

坦白的边界是量产下的单件成本。简单的六角螺母或间隔柱一旦超过约 5 万–10 万件，冷镦加滚丝在价格上会胜过切削加工；我们会在报价阶段直接说明，而不是报一个本不该由我们做的零件。

Thread standard is the first thing to fix on a drawing, because it drives tooling and inspection. We cut metric threads from M2 to M36 and UNC/UNF imperial sizes, plus custom pitches to drawing, and default to tolerance class 6H for internal and 6g for external threads — the class that lets a standard gauge pass without play. Where a fastener runs in a vibrating assembly or a sealed bore, we will quote 5H/6H or 4h/6g on request; tighter classes cost more because they shorten tool life and force gauge inspection rather than sampling.

螺纹标准是图纸上第一个要定死的东西，因为它决定了刀具与检验方式。我们加工公制 M2 到 M36、英制 UNC/UNF，以及按图定制牙距；内螺纹默认 6H、外螺纹默认 6g——这个等级能保证标准量规通过且无松动。若紧固件用于振动装配或有密封要求的内孔，可按需求报 5H/6H 或 4h/6g；更紧的等级成本更高，因为刀具寿命会缩短，且必须用量规全检而不是抽检。

Beyond the thread itself, three dimensions decide whether a machined fastener fits on the line: thread-to-body concentricity, shoulder length and drive feature concentricity. We hold ±0.01 mm on critical diameters and 0.02 mm TIR on concentricity, and we verify threads with go/no-go gauges on first article and at a fixed sampling interval through the run — the same approach described in our first article inspection guide. Finishing is specified at the same time as the thread, because plating thickness changes the fit: nickel and zinc add roughly 5–15 µm per surface, which is enough to tighten a 6H/6g pair into a binding one if the drawing does not allow for it.

除螺纹本身之外，还有三个尺寸决定机加工紧固件能否顺利上线：螺纹对本体同轴度、台阶长度、以及驱动特征（内六角、一字槽等）的同轴度。关键直径我们控制在 ±0.01 mm，同轴度控制在 0.02 mm TIR；螺纹用通止规检验，首件全检、批量中按固定间隔抽检——与我们的首件检验指南所述方法一致。表面处理要与螺纹同时指定，因为镀层厚度会改变配合：镀镍与镀锌每面约增加 5–15 µm，如果图纸没有预留，足以让一副 6H/6g 配合变成咬死。