What sizes of broaches can I fit on the various broachers?

• The overall dimensions of broach + broach vary according to the type of broach and can be:

  

What sizes of broaches can I fit on the various broachers?

• Below are two diagrams depicting the relationship between broach sizes (horizontal axis) and broach patterns (vertical axis), both for HEXAGONAL / SQUARE broaches (fig.1), and TORX / TORX-PLUS broaches (fig.2).

How long does a broach last? What does the wear and tear on the broaches depend on?

• The service life of Brighetti tools is proportionate to the conditions of use, more or less correct, the characteristics of the material to be machined, and the amount of material removed according to the section to be performed.

  Tips to ensure longer broach life
  1) Use a machine tool that is rigid enough to withstand strong axial thrusts that can cause vibration and/or bending.
  2) Longer service life is achieved by checking, at regular times, the cutting edge of the tool and, if necessary, intervening with light front resharpening before the edges become excessively worn.
  Refinishing can be performed flat (zero rake angle).
  By resharpening the tool, the profile size is gradually reduced, about 0.01 for every tenth of a mm removed. In contrast, matrices for external profiles have a progressively increasing cutting section.
  Since it is necessary to keep the cutting axis concentric to the axis of the workpiece, it is necessary that the protrusion of the tool from the broaching table remain constantly by:
  – 45 mm for the G16L
  – 25 mm for G12 and G16
  – 18mm for the G8
  – 10 mm for the G5
  In case the regrind exceeds 1 mm it will be necessary to compensate with a ground washer to be mounted on the tool shank to restore that measurement.

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  TYPES OF SHARPENING ON REQUEST RELATIVE TO THE TYPE OF MATERIAL TO BE PROCESSED

  STANDARD SHARPENING “Brighetti Meccanica”
  Sharpening with flat surface and 2° rake angle.

CUP SHARPENING
On-demand sharpening for nonferrous materials and stainless steels with Rm less than 900N/mm2 with 2° rake angle.

FLAT SHARPENING PERPENDICULAR TO THE CUTTING EDGE
On-demand sharpening for cast iron and stainless steels with Rm greater than 900 N/mm2 with 2° rake angle.

What type of coating to adopt on broaches according to the type of material to be broached?

• Depending on the type of material being processed, coatings can be applied to the broaches to improve their durability in terms of the number of pieces produced, such asHDP RED (STAR 4), WONDER,INOX PLUS, and TIN.
  Below are some examples of materials to be machined with graphs showing the difference between the tool made from regular HSS versus the tool made from coated HSS.

What should we do in the case of machining square pits?

• In machining square quarries, it is good to remember that the amount of material to be removed is almost twice as much as in a hexagonal quarry, so the thrust to be exerted is greater. These processes normally require very stiff machines with considerable power.
  If it is possible, especially beyond the 20mm framework, some tricks should be used:
  1) the prehole should always be as large as possible
  2) when possible, request to chamfer the edges so as to remove the sharp edge that is the most fragile point of the tool (see “TYPES OF SHARPENING THAT PROTECT BROCKS FROM WEAR“)
  3) If the square section is requested with the full four floors, a UT-SQ to stow may be used.

  Of course, the same considerations apply to the execution of large hexagonal slots usually over 26 mm.

ON-DEMAND SHARPENING TYPES THAT PROTECT BROACHES FROM WEAR AND TEAR
To avoid or obviate possible edge breaking/chipping due to the strength of the material, broaches can be sharpened as shown in the following figures:

EDGES WITH RADIUS

square / hexagonal profile

Square broach with SPIGULAR SPIGULARS

EDGES WITH GROUND DIAMETER

square / hexagonal profile

Square broach with RECTIFIED SPIRITS

BEVELED EDGES
square / hexagonal profile

Square broach with blunted spikes

MACHINING SPECIAL PROFILES
1 – EVOLVING TEETHING (e.g. DIN 5480):

2 – MISSING TEETH:

What are the processing parameters to be followed depending on the type of broach steel, the profile to be made, and the type of material to be broached?

• Depending on the type of broach (hexagonal, square, torx or torx-plus), its size, the material from which they are made and the metal to be machined, feed rates vary according to the tables below.
  In choosing the feed rate and number of revolutions, the variations given by the: type of material to be machined, the characteristics of the machine tool, the grip of the part, and the rigidity of the machine itself will be crucial.
  The first step, to be carried out, strictly when the machine is stopped, will be to place the broach directly in contact with the material to be processed; this operation guarantees the best processing that will be obtained, since the broach and the material are synchronized; this synchronism, determines a better durability of both the broach and the broach.
  It is advisable to make a chamfer that covers the vertices of the profile to be executed, once the broach is laid down, zero and preload by 0.1mm and start machining with the parameters expressed by the table below.
  When the machining is finished, the broach exit will be performed with a fast feed, and fast-moving broach exit is strictly discouraged.

During processing, what thrust pressure is exerted between the broaches and the bar of material being processed?

• Estimation of the pressure that develops during broaching, according to the type of material to be broached, adopting the following processing parameters: no. of revolutions S 900, feed rate 0.06. The table below shows the estimated pressure that develops during broaching according to the type of broaching and adopting the following work parameters: no. of revolutions S 900, feed rate 0.06.

How can I intervene when the machine, during processing, goes into lockout or other similar problems occur?

• Here are some pointers for solving problems during machining: