Broaches that have been properly designed and manufactured must take into account proper technique and broach maintenance so that the tool produced can be as effective and long-lasting as possible. When broach design has been properly made, it will be less subject to drifting, deflection, and possibly even breakage. At the same time, it will also provide much better efficiency while engaged in the cutting of any parts you require. Below are described some of the standard broaching procedures associated with producing the most popular kinds of broaches.

 

Broaching with Internal Hole Broaches 

No shims or bushings are required for internal whole broaches. It’s possible to produce square, round, hexagonal and other shapes in a single pass, and drilled bores which require a through-hole finish. All individual stock broaches will have preferred minimum cuts and maximum cuts which should be adhered to. The proper nesting and clamping of parts that are stacked are very important during this procedure, and the workpiece must be fixed in place with the baseplate and ram face.

All square and parallel surfaces on the ram face and the baseplate must be kept true. It’s very important to keep a rigid setup throughout the procedure, and a good deal of caution should be used when parts are stacked so that the integrity of the setup can be maintained. At the beginning of a particular cut, it must be ensured that the broach is properly centered beneath the ram.

Once the broach begins cutting, you should back off on the ram pressure, so that the broach can be centered, and this will provide better alignment. If the broach loses alignment once the cut has been started, you can just back off the ram pressure and realign the broach itself. This process will probably need to be repeated during successive cuts, in order to acquire a perfectly straight broach tool.

Here is a step-by-step guide to the procedure:

• Drill the pilot holes with a sharpened drill, so you have a true and clean-cut.
• Choose the right broach, making sure that the workpiece is equal to the broach’s pilot diameter.
• Insert the pilot into the part’s bore.
• Make sure that your ram speed is appropriate so that no edgewear accrues, and no chatter marks occur.
• Lubricate the components.
• Reduce ram pressure so the broach can be centered for better alignment, and reapply pressure to the broach as needed.
• Clean off the broach itself with a stiff brush, so that any chips from cutting are removed.

 

Broaching with Production Keyway Broaches

There are no shims or bushings required for broaching with keyway broaches. In this procedure, the shoulders and the back of the broach get ground down so as to fit the bore’s diameter, while also supporting itself during the keyway cutting in a single pass. As always, it’s important to adhere to the recommended guidelines for minimum cuts and maximum cuts.

It’s advisable to stack workpieces so as to establish the minimum cut length, and also to improve efficiency. It’s also very important to ensure that proper clamping and nesting of all stacked parts are done, and the workpiece must be solidly fixed in place, being square with the ram face and the baseplate. The parallel and square surfaces on the baseplate and the ram must always be kept true. The integrity of your setup should be maintained by stacking parts and ensuring a rigid setup at all times.

Make sure not to use a dull broach, because this can lead to a poor finish, and it might also increase the likelihood of breakage. When you begin your cut, make sure the broach is centered directly under the ram, because alignment is very important. Once the broach begins to cut, you can lower pressure on the ram so that the broach can center itself for better alignment. If it happens that the broach loses alignment after the cut has started, you can back off the ram pressure and allow the broach to align itself.

Here are the steps involved in this procedure:

• Choose the appropriate broach, then insert the pilot into the part’s bore.
• Lubricate all components.
• Relieve ram pressure so that the broach can center itself for better alignment, and if the broach does lose alignment after the cut begins, you should back off ram pressure and align the broach, then reapply pressure so that the broach can move through the work.
• Clean off the broach with a stiff brush, ensuring that all chips have been removed from the cutting section.
• Repeat the above steps for any subsequent parts which are intended to undergo the process.

Broaching with Single-pass Keyway Broaches

In order to broach one-pass keyway broaches, you will need the use of a bushing, the size, and style of which will be determined by the workpiece’s bore diameter. In a single pass, the broach will cut to full width and depth, although it will be necessary to ensure that the cut never goes beyond the length of the bushing. It’s important to use proper clamping and nesting of stacked parts, and the workpiece must be fixed in place solidly concerning the baseplate and the ramp face. Never use a dull broach for the cut, because this can increase the likelihood of breakage, and it can also lead to a poor finish. When beginning your cut, make sure the broach is directly under the ram, because correct alignment is vital.

Here are the steps involved in this procedure:

• Choose the correct bushing for the bore you are using, and insert it into the workpiece’s bore.
• Insert the broach for the keyway’s desired width into the slot for the bushing, and then check your alignment.
• Place the entire assembly in the press.
• Lubricate all components.
• Apply any necessary pressure to the broach, but if it loses alignment once the cut has started, you’ll need to back off the ram pressure and allow the broach to align itself.
• Clean off the broach with a stiff brush, ensuring that all cut chips have been removed from the cutting section.
• Repeat the steps above for any other parts going through the procedure.

 

Broaching with Individual Broaches or Keyway Sets

This procedure requires the use of both a shim and a bushing, and it’s possible that multiple shims may be needed. The size and style of these two components are determined by the workpiece’s bore diameter as well as the style of broach which is being used. Very small broaches are cut in one pass and don’t require a shim, but multiple pass keyway broaches will include shims to be used for the most part.

The shim is necessary to compensate for whatever thickness is removed from a cutting pass, and by adding it to the bottom of the bushing slot, the broach can be moved forwards toward its normal cutting depth. Any subsequent passes will necessitate the stacking of shims. As always, minimum and maximum cut length guidelines must be closely adhered to. It’s important to maintain the workpiece in a fixed position square with the ram face and the baseplate, and it’s also important to maintain proper alignment throughout the process.

Here are the individual steps involved in this procedure:

• Choose the appropriate bushing for the bore being used, and insert the bushing into the bore.
• Insert the broach into the bushing slot, and then check the alignment.
• Place the entire assembly in the press, ensuring that the broach is centered directly under the ram.
• Lubricate all components.
• Apply pressure to the broach, and back off that pressure if the broach happens to lose alignment.
• Clean off the broach with a stiff brush, so that all chips can be removed from the cutting section.
• Insert a shim and repeat the above steps for subsequent parts going through the process.