Tormach Tooling System - Tapping Heads and Collets
Tapping is the most common way to thread holes, especially when it comes to small holes less than ½” in diameter. Tapping larger holes demands significant spindle power – these can often be just as effectively threaded with a thread milling process on smaller CNC machinery.
Effective CNC tapping requires synchronization of the spindle speed with feed rate. For a given spindle RPM, the corresponding feed rate is determined by the thread pitch of the tap. If not synchronized, the tap will not cut in a true helical path and result in damaged threads or a broken tap.
A tap will spin faster or slower as it engages more or less material. This is especially the case when the tap enters or exits the hole. The acceleration and deceleration of both the axes and spindle drive systems in CNC mills will also affect synchronization, especially when the tap reverses direction. For these reasons, a method is needed to allow the tap to adjust position as it threads. There are three tapping methods commonly used with CNC mills:
A) Auto Reversing Tapping Head. A Reversing Tapping Head uses an internal gear/clutch mechanism to provide axial float and also reverse rotation when the head withdraws. They are relatively complicated mechanically, but are easy to program.
B) Tension/Compression (or floating) Tapping Head. A Tension/Compression tapping head has a built-in spring mechanism that allows the tapping head to axially float. This allows for adjustment of the position of the tap as needed to maintain synchronization of feed and speed. Tapping speed is somewhat slower when compared to an auto reversing tapping head
C) Rigid Tapping. Rigid tapping uses specialized spindle control with positional feedback to accurately maintain coordination between spindle RPM and axial feed rate. Rigid tapping is typically found on production-grade vertical machining centers and dedicated hole making CNC machines. Rigid tapping is not possible on mills without sophisticated and specialized spindle control.
We offer both Auto Reversing and Tension/Compression Tapping Heads. Either method is compatible with a PCNC Mill.1 Rigid tapping is not recommended.
1 Tension/Compression Tapping is not compatible with PCNC 1100 Series 1, unless the sensorless vector spindle drive upgrade has been installed.
Tapping Heads
Auto Reversing Tapping Heads
Reversing Tapping Heads use a geared clutch to reverse tap rotation without the need for a change in spindle rotation.
Tension/Compression Tapping Heads
T/C tapping heads are robust and simple in operation, but require a change in spindle direction to retract the tap. These heads use interchangeable quick change collets to accomdate a range of practical tap sizes.
