钻孔是重要的一环 PCB 轮廓加工技术，钻头的选择尤为关键。 焊接硬质合金钻头以钻尖与刀体的连接强度高着称，可加工表面粗糙度好、孔径公差小、位置精度高的孔。 When the locking screw is tightened, the crown drill can reach as high a feed as the welding bit.

Many people mistakenly believe that drilling must be done at low feed rates and low speeds. This used to be true, but today’s carbide bits are a different story. 事实上，选择合适的钻头可以显着提高生产率并降低全面的每孔成本。

There are four basic types of drill bits with carbide cutting edges available to the end user: solid carbide, indexable inserts, welded carbide drill tips, and exchangeable carbide drill tips. Each has its advantages in a particular application.

The first solid carbide bits are used in modern machining centers. 这些自定心钻头由细晶粒硬质合金制成，并涂有 TIAlN 以延长刀具寿命，由于其特殊设计的切削刃，这些自定心钻头可在大多数工件材料中提供出色的切屑控制和去除。 整体硬质合金钻头的自定心几何形状和精度确保无需任何进一步加工即可获得高质量的孔。

可转位刀片钻头的直径范围很广，深度从 2XD 到 5XD。 They can be used in both rotary applications and lathes. 这些钻头对大多数工件材料使用自定心几何角度，以减少切削力并提供良好的切屑控制。

The welded drill bit machined the holes with quite high surface finish, high dimensional accuracy and good position accuracy without further finishing. 通过冷却通孔，焊接钻头可用于加工中心、数控车床或其他具有足够稳定性和转速的机床。

The final bit form combines a steel cutter body with a removable solid carbide point called a crown. The drill provides the same precision as the welded bit while achieving higher productivity at a lower machining cost. This next generation bit with carbide crown provides precise dimensional increments and a self-centering geometric Angle that ensures high dimensional precision.

Carefully consider tolerances and machine tool stability

The factory should select the bit according to the specific tolerances on the machining. 小直径孔通常具有更严格的公差。 因此，钻头制造商通过指定标称孔径和公差上限对钻头进行分类。 Of all the drill forms, the solid carbide bit has the tightest tolerances. This makes them the best choice for drilling holes with extremely tight tolerances. The factory can drill with a 10mm diameter solid carbide bit with a tolerance from 0 to +0.03mm.

一方面，带有可更换硬质合金牙冠的焊接钻头或高位钻头可以钻孔到 0 到 +0.07mm 的公差。 These bits are often a good choice for drilling production processes.可转位刀片钻头是工业中的重型工作钻头。 虽然它们的前期成本通常低于其他钻头，但它们也具有最大的公差，范围从 0 到 +0.3 毫米，具体取决于直径与孔深的比率。 这意味着当孔的公差很高时，最终用户可以使用可转位刀片钻头，否则他们必须准备用镗刀完成孔。 除了孔公差，工厂在选择过程中还需要考虑机床的稳定性。 因为稳定性保证了刀具寿命和钻孔精度。 The factory shall verify the status of machine spindles, fixtures and accessories. 他们还应该考虑钻头的固有稳定性。 例如，整体硬质合金钻头提供最佳刚性，从而实现高精度。

On the other hand, indexable blade bits tend to deflect. 这些钻头配备了两个刀片——一个位于中心的内刀片和一个从内刀片向外延伸到边缘的刀片——最初只有一个刀片参与切割。 This creates an unstable condition that causes the bit body to deflect. And the greater the bit moonlength deviation. Therefore, when using 4XD and more indexable blade bits, the plant should consider reducing the feed for the first mm and then increasing the feed to normal. The welded bit and the convertible crown bit are designed as two symmetrical cutting edges that form a self-centering geometric Angle. This stable cutting design allows the bit to enter the workpiece at full speed. The only exception is when the bit is not perpendicular to the surface being machined. It is recommended to reduce feed by 30% to 50% during cut and cut.

The steel bit body allows for slight deflection, enabling it to be used successfully on lathes. The solid carbide bit with good rigidity may be easily broken, especially when the workpiece is not centered properly. 不要忽视切屑 许多工厂在切屑去除方面存在问题。 In fact, poor chip removal is the most common problem in drilling, especially when machining mild steel. And it doesn’t matter what drill bit you use. Factories often use external cooling to solve this problem, but only for hole depths less than 1XD and with reduced cutting parameters. 否则，他们必须使用正确的冷却剂来匹配孔径的流量和压力。 For machine tools that do not have spindle center cooling, the factory should use a coolant out to in device. 请记住，孔越深，清除切屑就越困难，需要的冷却压力也越大。 始终检查制造商推荐的最低冷却液流量水平。 At lower flow rates, reduced feed may be necessary. Examining life cycle cost productivity or cost per hole is one of the biggest trends affecting drilling today. 这意味着钻头制造商必须设法结合某些工艺并开发可适应高进给率和高速加工的钻头。

The latest bits with interchangeable solid carbide tips offer superior economy. Instead of replacing the entire bit body, the end user buys only a carbide head that costs the same as regrinding a welded or solid carbide bit. 这些牙冠易于更换且精确，允许工厂在单个钻头体上使用多个牙冠来钻几个不同尺寸的孔。 This modular drilling system reduces inventory costs for bits with diameters from 12mm to 20mm.

此外，当重新研磨焊接钻头或整体硬质合金钻头时，它消除了备用钻头的成本。 The factory should also take into account total tool life when reviewing cost per hole. Typically, a single carbide bit can be reground 7 to 10 times in a factory, while a welded bit can be reground 3 to 4 times. 另一方面，牙冠钻头有一个钢刀体，在加工钢时可以更换至少 20 到 30 个牙冠。

还有生产力的问题。 焊接或整体硬质合金钻头必须重新研磨； Therefore, factories tend to reduce speed to avoid sticky chips. 但是，可更换钻头不需要重新研磨，因此工厂可以以足够的进给和速度进行加工，而不必担心硬质合金切屑。