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Broaches

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Broaches are divided into two groups: the internal broaches for making spline holes used to process automobile reducers and machine tools, and the surface broaches for processing the surface of specially shaped parts used to process the turbine blade grooves of power generator and jet engine and various kinds of industrial machine.
We design and produce many kinds of original broaches based on our long experience and know-how, and have already delivered them to many customers.

Nanodynamic Broach

Feature

  • Super-hard coated to maximize the tool life (twice as long as that when TiN coated).
  • Flaking of machined work piece surface is reduced (roughness of tooth surface of broach has significantly been improved (Ra 0.03μm).

Surface roughness

Nanodynamic
Dynamic
Surface roughness Ra
Internal Broach

Internal Broach

Performance

Flaking work piece is reduced and the tool life became twice as long as that when Tin coated.
Broach type: Φ25x1500L MAC-A
Teeth for wear measurement : #31 finish teeth

Constant Cutting Force Broach

Feature

  • Stable machining with constant cutting force of the roughing teeth
  • Lowering the cutting force setting will give less impact to the existing machine and allow the use of a lower rank compact machine.
  • Increasing the cutting force setting will maximize the performance of existing machine leading to shorter tool length and less machining time.

Example

Work piece: DP24/48, PA30°, NT30, cutting length 23.5 mm, C45
Broach: Involute spline broach, Φ33 x L900, SKH51

Burr-free Broach

Feature

  • The original designed of cutting teeth can minimize occurrence of burr.
  • The original super-hard material with excellent grinding performance can ensure prolonged cutting edge sharpness.

Example

Work piece: m2.0, PA20°, NT30, cutting length 18.1 mm, 18CrMo4
Broach: Involute spline broach, Φ65 x L1350

Work piece machined with conventional broach

Work piece machined with burr-free broach

Fir Tree Broach

Feature

Using technologies and know-how developed through the long year experience of supporting our aircraft and turbine manufacturing departments, we can provide high-precision and high-quality products.

  • High precision can be obtained with the original optimized design based on our rich experience and advanced technologies.
  • Long tool life achieved by adopting high-alloy powder high-speed steel for difficult-to-machine materials
  • High reliability ensured by the dedicated line equipped with the advanced NC gear grinding machine and sharpening machine
Fir Tree Broach

Fir Tree Broach

Application example

Layout and tooth size of fir tree broach

Layout and tooth size of fir tree broach

Layout and tooth size of dovetail broach

Layout and tooth size of dovetail broach

Groove machined with fir tree broach

Groove machined with fir tree broach

Groove machined with dovetail broach

Groove machined with dovetail broach

Processing by broach

■Processing by internal broach

The internal broach can make up the specific shape of work piece internal surface efficiently and with high precision.
Normally the internal broach is inserted into a pilot hole which is made on the work piece before machining.
Various kinds of hole can be created by selecting the optimum cutting edge shape and cutting method (for example, round hole, square hole, polygon hole and various kinds of spline hole and tapered hole).

Processing by internal broach
Processing by internal broach

Examples of machining result

(1) Round broach
Round broach

(2) Spline broach
Spline broach

(3) Serration broach
Serration broach

(4) Polygonal broach
Polygonal broach

(5) Special shape broach
Special shape broach

(5) Special shape broach
Special shape broach

Examples of machining result

■Processing by surface broach

The surface broach can make up the specific shape of work piece outer surface efficiently and with high precision.
Roughing and finishing can be conducted at the same time, which means significantly higher productivity than milling, plaining and grinding.
It can machine many kinds of shape (for example, plane surface, contour surface, various kinds of groove, concave-convex surface, gear, turbine blade root, and turbine disk groove) and their outline can be either simple such as keyway or complex such as fir tree shape.

Processing by surface broach
Processing by surface broach

Examples of machining result



Examples of machining result



Cutting method

Cutting method

Note: The stripe of concentric circle indicates the order of machining process.

Types of Broaches with Round Teeth

Types of Broaches with Round Teeth

The numbers such as (1) and (2) indicate the order of machining process.

Hardness of Work piece

Hardness of work piece suitable for broaching is generally HB200 to 230 (HRC14 to 21).
Also up to HB300 (HRC32) is used popularly. Too soft steel may cause adhesion on the side of tooth or the land resulting in low quality of finishing surface with tear or flake. Harder work piece than HB300 may shorten the life of broach.

Cutting Speed

The cutting speed has an influence in both the accuracy of broaching and the tool life. Use the recommended values for each material shown below as the guide to determine the cutting speed.

Recommended cutting speed by materials

Recommended cutting speed by materials

How to Resharpen Broach Teeth

■Timing of resharpening

Resharpen the teeth normally when the symptoms as below occurred in the broach, work piece and broaching machine.
In practical ways, use the number of machined work pieces as a standard when the symptoms appear.

Broach
  • Whitish land due to wearing appears on the cutting edge.
  • Abnormal wear, chipping or crack occurs on the cutting edge.
  • Chips are pressed and adhere to the gullet.
Machined work piece
  • Machined size is smaller than normal (the thickness gauge does not get in).
  • Machined surface is more rough than normal.
  • Abnormally high heat is generated when machining ends.
Broaching machine
  • Cutting force is abnormally high.

■Cautions for resharpening

Tool
  • Remove adhesion from the cutting face.
  • Correct if the tool is warped.
  • Securely fix the tool to the sharpening machine.
    (If the crack of edge cannot be removed by resharpening, contact us.)
Grinding wheel
  • Use a sharp CBN grinding wheel.
  • To increase grinding efficiency, use a grinding wheel with as large diameter as possible.
  • Regularly dress the grinding wheel.
Grinding condition
  • Grinding amount: Grind the same amount for each tooth to remove worn part.
  • Grinding rate: 1,800 to 2,000 m/min
    (In case of internal broach, work piece rotating rate:around 30 m/min)
Others
  • For internal broach, be careful to prevent interference between the tool and the grinding wheel (see how to determine the grinding wheel angle for resharpening internal broach teeth shown in the right).
  • Use well-maintained sharpening machine.
  • Make sure that the grinding fluid is not deteriorated and feed an appropriate amount.

■Grinding wheel angle for resharpening internal broach teeth

In contrast to the case of surface broach, internal broach may not be resharpened correctly if the diameter and setting angle of grinding wheel are not appropriate, as the grinding wheel and the tool may interfere with each other.
See the relation with broach shape (outer diameter and rake angle) as below for reference.

Grinding wheel angle for resharpening internal broach teeth

Explanation of the diagram : If you resharpen the broach of diameter d=30 with the grinding wheel of diameter D=50 and the cutting edge hook angle is α=15°, the appropriate setting angle of grinding wheel is β=41°.

Diagram of setting angle of grinding wheel for resharpening intemal broach teeth

■Points to be checked after resharpening

  • Ensure that the wear and crack of the cutting edge are completely removed.
  • No grinding burn.
  • Ensure the roughness of finishing surface is at 3.2s or less.
  • No remarkable unevenness in gullet that may prevent chip removal (see right).
  • Ensure degaussing was conducted.
■Products Page

contact

Business contact: Strategic Sales Operation Department
Phone: +81-77-552-9760

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