Tapping is basically a threading operation in the hole.
This is done by using a tap (See figure). The tap is held in the Tapping machine (Or Drilling cum tapping or drilling machine) with help of collet/ chuc/ adaptor etc. attached to the spindle.
In case of machine tapping (as mentioned above), taps can be of two types
There is not much difference in appearance Cutting taps, as the name suggests, cut the treads in the hole, whereas Roll tap creates the threads by forming operation.
The process of generating threads in both cases is similar, in the sense that the tap advances by one pitch every rotation of the tap.
In other words, the feed in case of tap is always One pitch/ revolution of the tap.
Due to above, the tapping feed is quite high as compared to drilling.
The cutting / rolling (i.e. spindle speed) in case of tapping is hence kept comparatively much less than drilling. Various charts are available to select the cutting/ rolling speeds for various materials to be worked upon.
This is a skilled operation, the drill spindle has to be advance manually until the tap reaches and engages itself into the hole. The pressure on the handle has to be manipulated by the operator. Further the tap advances on its own by one pitch length every rotation. During this phase the operator should hold the handle only without exerting pressure. The operator has to reverse spindle as the tap reaches correct depth. The tap retract s on its own.
The methodology is same in this case also. However, the spindle reverses and retracts on its own. This is set with help of limit switch for the quill movement, which reverse the motor direction.
Note: These machines are generally not recommended for continuous production operation due to problems associated with motor over heating
These are specifically developed for tapping operation and these use a mechanism of Lead Screw OR Gear train to advance the tap by one pitch per rotation. These are quite fast/ accurate and suitable for continuous operation.
Auram Machines (I) Pvt. Ltd. can supply any of the above types in a wide range of capacity