What common problems are encountered when tapping ?
What general suggestions can be made for tapping applications ?
What are the top ten causes of tap breakage ?
The tap I am using fails on reversal. What causes this and what can I do to fix it ?
What can cause chips to clog the flutes while tapping ?
How can I prevent stripped or chipped threads in the taps that I am using ?
I have a problem with torn threads in the part that I am tapping. What can I do ?
The tap I am using binds/sticks while tapping. What causes this ?
Why does the tap I am using show excessive wear ?
What is causing a breakdown in the cutting face of my taps ?
The tap I am using is overheating. What gives ?
There is a very poor finish on the thread in the part that I am tapping.  Why does this happen ?
What can cause excessive frictional drag and an increased power requirement ?

What common problems are encountered when tapping ?
Problems encountered in tapping are often the fault of the tapping machine, tap holding devices and conditions of the hole to be tapped. The tapping machine should be checked for spindle, fixture and work alignment; for slipping belts, wear and power. The tap holding device should be checked as to correct type, for wear and alignment with the hole. The drill hole should be checked for diameter and trueness in round and axis to assure correct percentage of thread engagement. Blind holes must have sufficient chip room at bottom.
 

What general suggestions can be made for tapping applications ?
1. If holes are undersize or oversize check against the setup instructions. Check the tap for correct pitch diameter limit for desired class of thread, and the drill for correct size.

2. If the tap is producing rough threads it generally means that the tap is pushing or tearing the metal instead of cutting it. The tap may be dull, have galled threads or may be running at too slow a speed. If none of these applies, increasing the hook angle of the cutting face may help.

3. If the tap is loading (metal clinging to tap) or galling, check the lubrication. Here, too, the tap may be dull, or it may be producing too high a percentage of thread. Shift to a surface treated tap.

4. If tap breakage is encountered the tap may be cutting too high a percentage of thread, be insufficiently lubricated or have too little clearance for chips at the bottom of a blind hole. If none of these conditions exist, increase the speed, except in hard or tough materials. In these materials, lower the speed.
 

What are the top ten causes of tap breakage ?
1. Using the wrong type of tap.
2. The tap is dull.
3. The tap has been incorrectly ground.
4. The drilled hole is too small.
5. The drilled hole is too shallow.
6. There is misalignment between the tap and the hole.
7. Using the wrong machine.
8. Using an incorrect fixture or holding device.
9. The material you are tapping has become work hardened.
10. Not using enough lubricant, or using the wrong type of lubricant.
 

The tap I am using fails on reversal. What causes this and what can I do to fix it ?
Tap failure on reversal can be caused by a tap that is cutting too tightly. Use a different tap with an increased cutting face angle to correct this. Tap galling can also be the cause, in which case a tap with an increased face angle on the back of the land should be tried.  This type of failure can also happen when chips are being wedged between the flutes (see next item).
 

What can cause chips to clog the flutes while tapping ?
1. Using the wrong type of tap.
2. Using a tap with an insufficient chamfer.
3. The tap you are using has an incorrect cutting face angle for this application.
4. The tap has rough flutes.
5. The tap has flutes that have been improperly reground.
6. Not using enough lubricant, or using the wrong type of lubricant.
 

How can I prevent stripped or chipped threads in the taps that I am using ?
Stripped or chipped threads are often caused by misalignment of the tap with the workpiece. Careless handling of taps and using dull taps can also result in this problem. Be sure that you do not use a tap that is too hard, or has the wrong surface treatment to avoid this type of damage. Lastly, proper resharpening of the tap is imperative.
 

I have a problem with torn threads in the part that I am tapping. What can I do ?
This can happen when a tap with the incorrect cutting face angle (usually too small) is used. Try using a tap with a higher cutting face angle.  Also, the drilled hole may be too small for this application, or chips may be clogging the flutes (see above). Check the tap that you are using; it may have broken threads, or have been improperly resharpened. This can also occur when using the wrong type of lubrication, or not enough.
 

The tap I am using binds/sticks while tapping. What causes this ?
There are several possible causes; the drilled hole may be too small, the tap lands may be too wide or the tap may have an incorrect cutting face angle for this particular application. Additionally, there may be a lack of the proper type of lubricant. A surface treatment on the tap can often prevent binding/sticking from occurring.
 

Why does the tap I am using show excessive wear ?
The material you are tapping may be unusually abrasive or inclusions may be present.Try using a surface treated tap. Excessive wear can also be caused by misalignment.
 

What is causing a breakdown in the cutting face of my taps ?
This can occur when a tap with an incorrect cutting face angle is employed, or when the application requires a surface treated tap and you are not using one.
 

The tap I am using is overheating. What gives ?
You may be using a tap with excessive land width.  Also, there may be a lack of lubricant or you may be using the wrong type of lubricant. Using a dull tap can cause this as well, as can excessive flank contact. In the case of excessive flank contact, switching to a similar tap with pitch diameter relief is usually recommended. If none of these apply, check your tapping speed, as it may be too fast.
 

There is a very poor finish on the thread in the part that I am tapping.  Why does this happen ?
This is often an indication that you need a tap with increased pitch diameter relief. It may also be due to an incorrect cutting face angle which is usually too small. A poor finish can sometimes be caused by tapping a hole that is too small. This condition is also observed when using a tap which has an insufficient number of chamfered threads, or when using a tap that is dull. Finally, use of the wrong type of lubricant, or not enough lubricant can give a poor finish.
 

What can cause excessive frictional drag and an increased power requirement ?
1. Pitch diameter relief may be required.
2. The point size on the tap may be too large.
3. The tap might be dull.
4. The tap may have an incorrect cutting face angle.
5. You could be using the wrong tapping speed.
6. Lack of lubricant, or use of the wrong type of lubricant.
7. Incorrect or inadequate equipment.
8. Misalignment of the tap in the workpiece.