We know some broaching projects can be challenging, and want to let you know we will do our best to help you make your project a success.
For technical information about Polygon's new products, please visit our Rotary Broach Blog.
Please consider these reminders if you need support:
1. Rotary broaching requires a chamfer as large (or larger) than the major diameter. This helps the broach get started and minimizes skid marks.
*Please note: if you are having problems with skid marks, consider reducing the RPM to about 50-100 RPM for the first .005-.010" of contact with the work piece. After the broach is engaged, ramp up to full RPM.
2. Broaching depth may be limited to 1-2x the across flat or minor dimension. If the chips are too long, they may bind on each other in the hole and create resistance to the broaching tools.
*Please note: if you are having problems reaching full depth, anything you can do to reduce the pressure caused by chip accumulation will be helpful. In some cases, it may be possible to remove the broach, drill out the chips, and the re-align the broach to continue broaching.
3. Pre-drilled pilot holes must be larger than the across flat or minor dimension. Undersized pilot holes increase resistance due to large chip sizes. Check to see if your predrilled hole is at least 3% larger for hexagons, and 10% larger or more for squares.
4. Check to make sure the broach is on center with the hole.
5. Check to make sure the hole is deep enough for chips to flow into. If the hole is not deep enough, excessive force may damage the broaching tools, work piece, or machine.
*Please note: an undercut is ideal to allow chips to break free at the bottom of a blind hole. If not possible, consider drilling at least 50% more than the desired depth.
6. If the hole appears undersize, it may be due to a spiral condition. This twisting is caused by the backtaper and free turning spindle allowing the broach to drift if there is too much pressure. Try to reduce the amount of material removal or thrust required if possible. Also, try reversing spindle direction half-way through the hole. Reversing the spindle will reverse the direction of the spiraling and often correct the condition.
7. Finally, check the bearings in the rotary broach holder. If the bearings are not allowing the spindle to rotate smoothly, they may need to be replaced.
For further rotary broaching technical support please contact us at 239-628-4800 for assistance.