Drilling and Tapping Services  

Tapping
The most popular method of cutting internal threads in  a part is by the use of a tap.  This process is called tapping and generally follows drilling a hole of a specified diameter. Typically taps can perform the threading task faster and more economically than other methods such as single point turning on a lathe.

The general types of hand taps include taper, plug and bottoming designs.  Tapers are commonly used for pipe threading, in that as you apply a plug for example, the tapered thread act to constrain the plug as it is turned/tightened within a pipe threaded opening.  Plug taps work best when applied to a through hole openings.  The entering end of the tap has a gradual increase in thread depth, to enable a gradual increase in stress on the tap as it plunges into the through hole opening.  Bottoming taps are generally applied to blind hole openings.  Blind holes differ in that metal fines caused by the threading process have no exit other than the entrance point of the tap.

Spiral point or gun tap – this tap is very similar to the hand tap except that the design of the flute at the point is different to make the tap stronger, to help with chip buildup and to speed the tapping process.  Spiral flute tap or helical-fluted tap – this tap comes in a wide variety of helix angles and does a great job at chip evacuation during the tapping process, however the strength of the tap versus a straight flute design is not a great.      

Taps are typically made from high-speed steels and other materials such as tungsten carbide. There are also special coatings that are applied for help with prolonged tool life. Tap threads are typically ground from these hard materials. The tapping process can be performed by hand with the help of a tapping handle or by machine such as lathes, mills, drill presses and tapping machines.

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