New England Broach Company
199 Long Plain Road
P.O. Box 45
Whately, MA 01093
Tel: (413) 665-7064
  (800) 680-7727
Fax: (413) 665-8457
newenglandbroach@aol.com
 
COMMON BROACHING PROBLEMS:
Broaching Problems Possible Causes Corrective Action
Workpiece Stuck On Broach 1. Insufficient machine capacity. 1. Check broaching machine to see if it is delivering rated power.
  2. Dull cutting edges. 2. Check broach design, perhaps back-off clearance is insufficient or step per tooth is too great.
3. Clogged tooth gullets. 3. Sharpen broach if required. Check tooth design.
4. Failure of power during cutting stroke. 4. Each tooth gullet should be cleared of chips between passes.
5. Misalignment of the broach puller with workpiece. 5. Check alignment of fixture for holding workpiece with centerline of broach puller.
6. Hole in workpiece not square with face which contacts fixture. 6. Be sure that the hole in the workpiece is square with the face that contacts the fixture.
Galling Or Pickup 1. Too low or variations in hardness of workpiece. 1. For the broaching of steel, best results are obtained at a Rockwell 14 to 30 R.C.
  2. Insufficient flow or wrong type of coolant. 2. All major oil companies have qualified cutting oil consultants.
3. Poor broach design. 3. Inspect the broach closely and sharpen if necessary.
Broach Breakage Check 1 to 6 in "Workpiece Stuck on Broach"
7. Interrupt cutting stroke.
7. Stroke of machine should be adjusted so that broach never leaves guides.
Chatter 1. Too few teeth in contact with workpiece simultaneously. 1 Check pitch of broach with "Pitch formula."
  2. Excessive hardness of workpiece. 2. It is sometimes possible to eliminate chatter by changing the rate of travel, coolant, face
Broaching Drifting In Cut 1. Poor sharpening. 1. Check broach carefully and resharpen if necessary.
  2. Broach not properly supported especially in a horizontal machine. 2. If internal broaching on a horizontal machine rear support may be required.
3. Variations in hardness workpiece. 3. In broaching steel, best results are obtained at a Rockwell hardness of 14 to 30 RC
4. Not enough broach teeth in action simultaneously. 4. Check pitch of teeth using "Pitch formula."
5. Body diameter too small.  
Scores On Broached Surface 1. Poorly ground chipbreakers. 1. Change design of chipbreakers on last few roughing teeth or semi-finish teeth.
  2. Metal pickup. 2. Remove any pickup. Check tooth profile design.
3. Burrs left on cutting edges from sharpening. 3. Grinding burrs must be removed after sharpening.
Rings In The Broached Holes Or On The Surface Of The Workpiece 1. Uniform pitch of teeth may cause surging. 1. Sometimes the use of staggered pitches eliminates this condition.
  2. Back-off clearance may be excessive. 2. Sheer cutting teeth on surface broaches help prevent surging.
3. Burrs left on cutting edges after sharpening. 3. After sharpening burrs must be removed from cutting edges.