Tap control: choosing the right solution

Tapping consists of making a helical thread in a hole in order to install a screw.
This thread is the result of a combination of rotation and translation.
This operation can be performed in the die - a solution that Pronic has been offering for over 30 years.
 
 
This is achieved by converting the sliding movement of the press ram into a rotational movement.
This rotary motion is then transferred to the tap.
Finally, the helical motion is obtained by combining the rotational motion of the tap with a translational motion equal to the pitch of the tap.
 
This is what is called tap driving.

More information

The quality of the in-die tapping is directly linked to the way the tap is controlled.
 
Two solutions exist:
Spring compensation
How does it work? The tapping spindle is installed on the upper sole of the tool.
A spring or a cylinder presses on the back of the tap holder to force the tap into the hole to be tapped.
It is the tap, itself, that creates the helical motion of the thread as it enters the material.
 
 
What are the advantages?

• Simple and functional
• Works very well for small diameters and soft materials
• Low system cost (excluding tap cost)

What are the drawbacks?

• Installed in the tool and dedicated to the application.       
• Random tapping quality, especially at the entry thread level
• Tapping height limited by the installation kinematics.
• Faster tap wear due to slippage at the entrance of the hole to be tapped
• Wear of the spring that presses on the tap holder. This degrades the quality of the tapping.
• Reliability

 
2- Cartridge piloting
How does it work? The cartridge is a screw/nut system in which the tap is installed.
This cartridge is installed in a housing and gives the helical movement.
The pitch of the cartridge is identical to the one of the tap.
 
What are the advantages?         

• Better tapping quality
• Control of the tap movement during the whole tapping cycle
• Several kinematics solutions possible
• Possibility to check that the tap has gone through the part
• Possibility to tap blind holes
• Tapping of very hard materials without slippage at the entrance of the hole to be tapped
• Increased tap life
• Reliable system

What are the drawbacks?

• Higher cost

Both solutions are functional and can be used on a daily basis.
They allow tapping at high speeds > 120 spm/min
Which solution to choose?
The answer is primarily related to the characteristics of the hole to be tapped:
The cartridge control is necessary when :
 - the height of the thread is >= the diameter
 - the material to be tapped is high strength steel
 - the thread diameter >= M5
 
All our solutions are equipped with tap control cartridges to ensure the best press tapping experience.
 
Would you like to discover in-die tapping? Do you have a question? Do not hesitate to contact us.

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