A broaching machine is a machine tool that employs a broach to process workpiece holes, planes, and shaping surfaces. Broaching can provide great dimensional precision and surface roughness while also providing high productivity and suitability for mass manufacturing.In this article, we will introduce the features, differences, and applications of these different types of broaching machines one by one.
What is Broaching?
Broaching is a machining operation that removes material using a toothed tool known as a broach. There are two major forms of broaching: linear and rotary. The most typical procedure is linear broaching, which involves running the broach against the surface of the workpiece to generate the cut.
Linear broaches are used in a broaching machine, also known as broach. Rotary broaching involves rotating and pressing the broach into the workpiece to create an axisymmetric form. A rotary broach is used in lathes and screw machines. Both techniques complete the cut in a single pass of the broach, making them extremely efficient.
Broaching is used for precise machining, particularly on strange forms. Machined surfaces include circular and non-circular holes, splines, keyways, and flat surfaces. Typical workpieces include small to medium-sized castings, forgings, screw machine components, and stampings. Even though broaches can be costly, they are typically preferred over alternative methods when utilized for large-scale manufacturing runs.
Basic Components of Broaching
- Broaches: The broach is a long, thin instrument with numerous teeth that is used as the major component in the broaching process. It is intended to gradually carve the required form into the workpiece.
- Workpiece: The material that goes through the broaching procedure. It may be manufactured from a variety of metals, including steel, aluminum, and brass.
- Broaching Machine: The machinery that performs the broaching procedure. The broaching machine secures the workpiece and helps the broach’s travel through the material.
- Fixture: A device that holds the workpiece in place during the broaching procedure. Fixtures provide stability and precision during the cutting process.
- Cutting Fluid: Cutting fluid is frequently used during broaching to minimize friction, disperse heat, and increase overall process efficiency.
What is the Broaching Process?
Setup and fixturing
Before the actual broaching procedure, careful preparation is required. A fixture on the broaching machine holds the workpiece securely in place. Proper alignment is required to ensure precision in the finished product.
Broach Selection
Choosing the proper brooch is an important choice. Broaches exist in a variety of forms and sizes, and choosing the right one is dependent on the required characteristics and the material of the workpiece.
Broaching Operations
The broach is carefully guided through the workpiece, removing material with each pass. The operation is frequently finished in a single stroke, which makes it extremely efficient. The cutting operation might be linear or rotary, depending on the type of broaching equipment and broach utilized.
Inspection
Following the broaching process, the workpiece is thoroughly inspected to ensure that all necessary requirements and tolerances are satisfied. Any required modifications can be made at this point.
Advantages of Broaching
- Very high output rate compared to milling, planing, and boring.
- The product has excellent dimensions and form correctness, as well as a smooth surface finish.
- Roughing and finishing in one stroke with the same cutter.
- Only one cutting action is required, making design, construction, operation, and control easier.
- Extremely appropriate and inexpensive for mass production.
- Expertise is not necessary.
- Beautifully polished face.
- Short cycle time, great precision.
- Broaching operations require little skill.
- Broaching can be used to finish both internal and exterior surfaces.
- This method allows for a tolerance of +-0.0075 mm and a surface polish of around 0.8 microns.
- Cutting fluid may be easily placed where it is most effective since a broach draws the fluid into the cut.
Disadvantages of Broaching
- A broach is a tool with many cutting edges used for cutting. The process of preparing cutting edges is expensive. The original cost of it is really expensive.
- Broaching has a size constraint for the workpiece. Broaching operations are not suitable for very big workpieces.
- Broaching is not feasible on surfaces that have impediments.
- The use of broaching is limited to finishing and precise sizing since it can only remove tiny amounts of material. It is not feasible to remove bigger stocks in a broaching operation.
- It is crucial to securely fasten the workpiece during broaching in order to preserve its precision and surface quality. Clamping devices need regular maintenance and incur expenses.
Broaching Materials
The selection of materials for broaching is determined by the characteristics of both the broach tool and the workpiece being machined. Broach tools, as cutting implements, are commonly crafted from durable and abrasion-resistant materials to endure the pressures exerted during the cutting procedure.
The choice of workpiece material might greatly differ based on the specific industry and application. The following are often utilized materials in the process of broaching:
- Steel Alloys: Broaching is a frequently employed technique on a range of steel alloys, such as carbon steel, alloy steel, and tool steel. These materials are commonly found in sectors such as automotive and aerospace.
- Aluminum: Aluminum and its alloys are often utilized, especially in industries that need lightweight components, such as aerospace and automotive.
- Brass and Bronze: Brass and bronze are utilized in situations where it is crucial to have resistance against corrosion and good electrical conductivity, such as in electronic components.
- Stainless Steel: Stainless steel is renowned for its exceptional resistance to corrosion and is frequently utilized, particularly in situations where hygiene and durability are of utmost importance, such as in medical equipment.
- Cast Iron: Broaching may also be used on cast iron, a material widely employed in several sectors due to its exceptional castability and machinability.
Broaching Methods
Broaching provides items with very smooth surfaces and dimensional correctness. A broaching tool has rough, semi-finish, and finish cutting teeth that can complete the machining of a rough surface in a single stroke.
A broach is a single-point cutting instrument with many points that cuts similarly to a flat-ended sharp tool like a chisel. In rare circumstances, the broach teeth can be placed diagonally to complete shearing cuts, resulting in a sliding or skewing distortion.
Linear Broaching
Of the numerous broach cutting methods, linear broaching is the most prevalent. The tool goes linearly over the workpiece surface, creating cuts as it approaches the end of the workpiece. The diagram is an example of linear broaching.
Pull Broaching
Pull broaching involves holding the workpiece in place while the broach is drawn through. The broaches used in this technique are lengthy and require a particular head. The stress caused by tugging strengthens the broach. The procedure is often used for interior or internal broaching, although it may also be utilized for surface broaching. Pull broaches have a large number of teeth and provide a longer cut.
Pull broaching can be done vertically, horizontally, or through the workpiece. Pull broaching is used to flatten automobile cylinder blocks and heads.
Push Broaching
A push broaching tool is shorter so that it can withstand the compressive pressures exerted when it passes through the workpiece. It has fewer teeth, which can bend or break under compressive stresses. Push broaching generates shorter cuts, resulting in smaller pieces.
Surface broaching is a popular use for push broaching equipment. When used for this purpose, they are known as surface broaching tools.
Continuous Broaching
Continuous broaching involves keeping the broach fixed in the broaching machine while the workpiece is moved continually. The motion of the workpiece might be either linear, horizontal, or rotational. This method is commonly employed for the purpose of broaching a substantial quantity of comparable workpieces simultaneously.
Spline Broaching
Spline broaching, also known as round broaching, produces round, plain, or irregular splines and spiral tooth shapes. It may be used to make shafts, gears, and other mechanical components that mesh together. Spline broaching is the most frequent type of broaching, which involves using a broach to create a sequence of ridges or teeth around the perimeter of a pre-cut hole. Spline broaching is an effective way to create serrated, straight, and involute splines.
Blind Broaching
Blind broaching is the broaching procedure in which the tool does not entirely travel through the component, resulting in a blind cavity. Blind broaching is performed on pieces that are not supposed to have a passthrough. Keyways can be built to be blind broached when the tool comes to a halt in the midst of the bore.
Internal Broaching
Internal broaching removes material from the interior or internal surface of a workpiece, also known as hole broaching. Before commencing the internal broaching process, a starter hole is drilled into the workpiece, known as blank preparing. Internal broaching is used to expand, broaden, and resize holes.
The internal broaching tool contains teeth that gradually get bigger to produce an excellent finish on the workpiece. Internal broaching is done with automated devices, such as a CNC machine, which can create holes in the workpiece rapidly and effectively. The internal broaching procedure can be done using either a push or a pull action. Internal broaches are categorized as round or spline.
External Broaching
External broaching, also known as surface broaching, removes material off the exterior of a workpiece. External broaching tools, like internal broaching tools, have teeth that gradually grow. External broaching employs a guided ram with a broach retaining device. The cutting power is supplied to the ram along the whole length of the broach.
External broaches are flat surfaces that shape surfaces. Flat surface broaching involves passing the tool over the workpiece to obtain the required surface. The form surface broaching method is intended to generate a variety of curves and shapes, including serrated, angular spline, gear forms, fir tree, compressor slots, and keyways.
What Kind Of Broach Do I Need?
Here are some broaching applications that may be appropriate for your needs:
- Automotive :The car business relies on speedy and precise mass production. A wide range of materials used in automobiles, including ferrous and nonferrous metals, are discussed. Furthermore, the appropriate types of plastic are broachable. Car and engine parts that require broaching include front and rear differentials, parking brakes, gearboxes, engine production components, and others. To produce the desired cuts, they will most likely need to employ round, square, standard keyway, and bespoke broaches.
- Military: The military-industrial complex is a major driver of innovative technologies in the modern world. They are in charge of advancements ranging from software to armament to land and air transportation vehicles. Because of the extensive use that these gadgets receive, their standards are stringent. To produce such components rapidly and cheaply, various types of broaches are used.
- Farming Tools and Implements: Farm tools must be able to tolerate high levels of strain, heavy use, and harsh circumstances. Broaching may be required for farm equipment such as cultivators, plows, rollers, slurry spreaders, reapers, various types of harvesters, balers, loaders, and mixers. Broaching is necessary for both large and tiny parts, and strict tolerances are frequently required to guarantee lifespan and minimal mechanical strain.
- Turbines: Turbines are an essential component in sectors such as aerospace, automotive, marine, and energy. Turbine broaching is a type of broaching in which specific broaches are employed, usually on horizontal broaching machines. Colonial Tools provides turbine broaches to meet any of your needs in this field.
Different Types Of Broaches
Broaches or broaching tools come in various shapes and types, each designed for specific applications and cutting requirements. Below are some common broaching tool shapes and types although custom broaches are widely used in the manufacturing industry.
Keyway Broaches
Almost all keyways in machine tools and parts are cut using a keyway broach, which is a small, flat bar with cutting teeth spaced along one surface. These broaches are capable of cutting both internal and exterior keyways. Internal keyways often require a slotted bushing or horn to fit the hole, with the keyway broach being pushed through the horn and guided by its slot.
- This broaching tool is used to cut keyways, which are slots that hold keys or other mating components.
- Available in a variety of sizes to accommodate varied keyhole diameters.
Square Broaches
- Designed to cut square holes or forms.
- Often used in applications that demand a perfect square form.
Hexagonal Broaches
- Used to carve hexagonal holes or forms.
- Bolts, nuts, and other hexagonal-shaped components are frequently manufactured using this material.
Round Broaches
The simplest sort of broach is a circular one. This is a circular bar that creates holes similar to those generated by a drill press. The distinction is that a broach cut is faster, cleaner, and allows for tighter tolerances. Round broaches may be used to quickly create precise holes and are ideal for high-volume mass manufacturing.
Splined Broaches
Spline broaches allow operators to cut a series of teeth or notches around the perimeter of a previously cut hole. This specific design is extremely important in the automobile sector, as splines are used extensively in driveshafts, gearboxes, and other components. The ridges along the spline’s perimeter provide an effective way of transmitting power from one area to another, as the component that fits within will have no wiggle space. Broaching guarantees that the high-tech components’ precision requirements are met.
- Used to cut splines, which are longitudinal ridges or teeth on a shaft.
- Important in the manufacture of gears and other components with spline connections.
Dovetail Broaches
- A cutting tool used to create dovetail-shaped grooves or slots.
- Commonly utilized in applications that need a sliding or locking mechanism.
Internal Broaches
- Finishing teeth are meant to cut interior details on a workpiece.
- Depending on the individual demand, it may be square, hexagonal, spherical, or other forms.
External Broaches
- Used to cut the exterior surfaces of a workpiece.
- Can generate exterior forms like flats, hexagons, and other geometries.
Surface Broaches
The slab broach is the most basic surface broach. It is a general-purpose instrument that cuts flat surfaces.
- Finishing teeth are meant to cut flat surfaces of a workpiece.
- Used to achieve a smooth and uniform surface finish.
Involute Gear Broaches
- Specifically developed to cut involute gears.
- Gear manufacture requires accurate tooth profiles to provide smooth gear engagement.
Serrated Broaches
- Used to cut serrations, which are a series of notches or teeth.
- Serrated surfaces are commonly used in applications that need grasping or locking.
Taper Broaches
- Finishing teeth are meant to create tapered holes or forms.
- Useful in applications that need a progressive decrease in diameter.
Oval Broaches
- Used to cut oval or elliptical forms.
- Used in instances where a non-circular aperture is required.
These are only a few examples, and the variety of broach forms reflects the wide range of applications and machining requirements across industries. The preferred broach type is determined by parameters such as the desired feature, workpiece material, and unique production constraints.
Read More：Broaches Gudie
Type of Broaching machines
The broaching machine moves the broach or the workpiece through the broach, either by pushing or pulling. It also maintains the workpiece’s position to guarantee precision. This machine comes in a variety of forms, including:
Horizontal Broaching Machine
This broaching machine only performs pull-type operations. Pull-type procedures include pushing the broach first through the workpiece. When it emerges from the opposite side, a hook hooks through the pilot and pulls it all the way through. These machines take up more space because to their horizontal layout, but they have enough power to work on large things. They are suitable for round, spline, slot, or keyway broaching, as well as a variety of other interior shapes.
Nearly all horizontal Broaching machines come under the pull-type category, primarily internal or external broaching.
Learn More: What Is Horizontal Broaching?
Vertical Broaching Machine
These devices push or pull the broach vertically. They take up less floor space than horizontal broaching machines and are mostly utilized for surface broaching activities. Most operators prefer hydraulic power for their vertical broaching machines because it is less expensive. Vertical broaching machines are ideal for applications where the broach isn’t very lengthy or heavy.
Learn More: What Is Vertical Broaching?
Learn More: Difference Between Horizontal and Vertical Broaching Machine
Surface Broaching Machine
Whereas vertical and horizontal broaching machines are ideal for interior cuts, a surface broaching machine is designed for cuts along one edge of a component. For example, if a metal disk requires a notch cut out of its edge, it is set in place on a surface broaching machine. The broach glides along a vertical or horizontal guided track, and the teeth make the necessary cut in the disc’s side. The portion that pushes the broach is known as the ram.
Learn More: What Is A Surface Broaching Machine And How Does It Work?
Internal Broaching Machine
Internal broaching is the process of using a broach to shape the interior surface of a circular hole, slot, or groove. Internal broaching machines are not distinct, but they may be performed on any of the aforementioned types of machines. Internal broaching is a method that is employed to create internal gears. Internal broaching is also utilized for the purpose of refining the gun barrel bore.
During internal broaching, the workpiece is secured in a dedicated device known as a work holder, which is integrated into the broaching machine. The elevator is a component of the broaching machine that raises the broach above the work holding and subsequently lowers it through the workpiece. After passing through, the broaching machine’s puller, which can be described as a hook, securely seizes the pilot of the broach. Subsequently, the elevator disengages the upper part of the pilot, allowing the puller to smoothly draw the broach all the way through the workpiece. The workpiece is then extracted from the machine and the broach is passed entirely through it. Afterwards, the workpiece is extracted from the machine and the broach is elevated to re-establish contact with the elevator.
Learn More: What is Internal Broaching Machine?
External Broaching Machine
These devices are sometimes referred to as surface broaching machines. These machines are utilized to manipulate the outside surfaces of a workpiece. Contour broaching is another application where external broaching devices are utilized. Contour broaching is a process used to prepare surfaces that are concave, convex, or of any other shape, with very precise tolerances.
Rotary Broaching Machines
Rotary broaching, also known as wobbling broaching, differs from other broaching methods. It is a precise approach for creating polygonal forms inside or outside. Rotary broaching involves placing the cutting tool at a 1° angle to the workpiece’s midline, resulting in a chiseling or scalloping effect.
Rotary broaching can be done on a lathe or mill using a horizontal or vertical spindle machine, allowing the spindle to spin freely. Rotary broaching may be used to generate forms such as hexagons, squares, serrations, keyways, involute, spline, spur gear, digits, and letters.
Conclusion
BroachingMach is one of the best and largest broaching machine manufacturers in China, the largest manufacturer of broaching machines. As the process of broaching offers exceptional surface finishes and multi-dimensional accuracy.