Broaching is a machining process that involves removing material using a specialised tool called a broach. The broach can cut grooves, slots, or other intricate shapes because it has a sequence of cutting teeth that gradually get sharper. A final product with high precision and surface finish is produced by pushing or pulling the broach through the workpiece during the broaching process.
The method of removing metal from a workpiece by cutting a defined route which involves pushing or dragging a broach is called the broaching process. This involves moving the multi-cutting tool while keeping the workpiece static or moving the workpiece while keeping the instrument static.
There may be some relative rotation between the tool and the workpiece. The broaching tool can be used internally via the workpiece's focus point or externally across the workpiece's outer layer.
Did you know? Broaching is one of the fastest metal removal processes, capable of removing material quickly. Compared to other machining techniques, broaching effectively produces complex shapes and profiles in less time.
What Is Broaching?
Broaching is a metalworking technique that removes material from a workpiece consistently, continuously, and precisely using a sharp, hardened, grooved tool. The broaching process involves employing a tool with elevated teeth of varying sizes that accurately cut away a set quantity of material with every swipe over the piece being worked on.
Broaching occurs when the multi-cutting tool rotates while the workpiece remains stationary or when the workpiece moves while the tool remains stationary. In rare circumstances, the tool and workpiece may rotate relative to one another.
Broaching can be done internally through the centre of the workpiece or externally over the workpiece's surface.
Types of Broaching
Broaching machining is employed when precise cutting, particularly for unusual forms, is required. Often machined surfaces include spherical and non-circular gaps, spirals, keyways, and flat surfaces.
The type of tool used on a broaching machine is a toothed tool called a broach.
Broaching is classified into two types:
1. Linear: In linear broaching, the broach is run linearly against the workpiece surface to accomplish the cut, and this is a more prevalent procedure.
Linear broaches are used in a broaching machine, which is often abbreviated as a broach.
2. Rotational: Rotational broaching involves rotating and pressing the broach into the workpiece to cut an axisymmetric form. A rotary broach is a tool used on a lathe or screw machine.
Both techniques cut in a single pass of the broach, making them highly efficient.
Modes of Broaching
Broaching process is done in the following modes.
- Internal Broaching: Internal broaching is used chiefly to increase the size of holes. This procedure typically employs a pull-type broaching tool, although, for lighter work pieces, a push-type broach may be employed.
- External Broaching: This is mainly used for flattening a surface, cutting key channels, slots, and grooves outside an item, such as a shaft, etc. This method is also used in gear fabrication.
- Pull Type Broaching: A pull broach is a broach that is exposed to tensile tension during machining, and the type of broaching operation performed by a pull broach is known as pull broaching. This procedure avoids dislocation and cracking.
This type of broach has a high production rate. Pull broaches are typically constructed in a single piece and used for internal broaching. The number of teeth in the tool is more, and it has many applications.
- Push Type Broaching: A push-type broach is frequently exposed to compressed force during machining. These are shorter than pull-type broaches and are usually used for exterior broaching.
The number of teeth is less, and the chances of tool failure are higher. As it has limited applications, the production rate reduces.
- Ordinary Cut Broaching: Ordinary cut broaching employs ordinary broach, with teeth progressively increasing in height from tooth to tooth over the length of the broach.
- Progressive Cut Broaching: Teeth in progressive cut broaching grow in width rather than height along the length of the broach.
- Solid, Section, and Modular Broaching: Solid broaches are single-piece tools used primarily for interior broaching. Sectional broaches are created by connecting different sections of the broach.
Module broaches are created by combining many modules into a single item. It is employed in external broaching.
A broaching machine draws or pushes through the workpiece surfaces to get a polished flat or curved surface. This can be used on internal and external surfaces.
The tool of the broaching machine is drawn or pushed through the surface to get the process done. The broaching operation is very straightforward.
It is used to provide linear motion to the tool and to keep the workpiece immobile. The broaching tool can be moved vertically or horizontally.
Hence there are two types of machines: vertical machines and horizontal machines.
Horizontal machines are typically used for internal machining, while vertical machines are used for exterior and surface machining.
Broaching is a high-speed manufacturing method used to create unique, precise components. Broaching machines come in a variety of shapes and sizes. However, they always employ tools for removing a certain quantity of material from an unfinished product or manufactured component.
The procedure can produce a circular hole, an uneven external form, a keyway, or many irregular shapes depending on the broach employed.
Broaching, like drilling, moulding, and grinding, is a highly specialised, accurate production operation. Each broaching machine is built to produce a single hole with optimal precision, speed, and accuracy.
Broaching operation is a highly effective machining method in this regard, primarily when delicate metals and plastic elements are used.
However, there are some situations where a broaching machine may be inefficient. Particularly hard metals may need frequent tool conditioning; each specialised cut necessitates a new tool.
This might be a problem if your organisation does not have the means to refurbish and construct old broach tools. Fortunately, a certified broaching business can help you with all of your customising and maintenance needs.
The metal removal process in broaching is similar to shaping except that it employs a set of progressive teeth that may remove more material in a single pass. Broaching operations are best described by the term “precision machinery”.
The shaping process necessitates a number of strokes to cut the desired width of the workpiece. Each stroke eliminates a small layer of metal.
This method takes longer, which is inefficient. This constraint is removed by the broaching method, which employs a sequence of cutting edges on a rod or bar-type cutter.
Principle of Cutting
The cutting principle incorporates a relationship between force, tension, and surface. The pressure exerted is greater when the area for a given amount of force is small.
Because of this, a sharp cutting tool may remove metal from the subject.
Broaching employs the use of a multi-point piercing device with a succession of continuous cutting edges. The broaching tool has a high level of durability, is hard, has rapid cutting speed, and is resistant to wear.
It is produced from exceptionally strong tooling materials such as high-speed stainless steel, cemented carbide, etc. This tool is a broaching machine attachment.
Broach design is characterised by construction, configuration, metal material, and cutting-edge geometry. The broach design has multiple progressive edges working in a push or pull motion on the workpiece surface.
The material is removed from the narrow end of the taper to the broad end. This results in a completed product and some reduction in the stress on each tooth.
The height of each tooth of a broach is customised as per the requirement of the cut or groove for a particular machine or workpiece.
Advantages of the Broaching Process
As the production rate is high when using a broaching process, the manufacturing machine prefers this process for the following advantages.
- A broaching operation delivers excellent precision in just a single phase or pass of the workpiece. A single pass can achieve multiple effects, like cutting and finishing.
- A broaching method achieves excellent surface quality and reduces the need for surface polishing operations.
- It can drill intricate holes inside the workpiece. The internal keyways can be cut using the high precision of the broaching machine.
- A broach is highly resilient and does not degrade. It also has high dimensional accuracy and tolerance.
- The temperature during the process remains constant, reducing error due to thermal stress.
- Highly trained operators are not required, as a semi-skilled operator can operate a broaching machine.
- Lubricant applications are simple and quick.
- It is a cost-effective method of mass-producing machined components.
Disadvantages of the Broaching Process
Broaching has a few drawbacks.
- The broaching tool, broach, has a high initial cost. Has high initial customisation costs. It can be costly and expensive for small-scale production as one broach is used for just one operation. It is viable for mass production only.
- Designing, sharpening or restoration costs for a broach tool is challenging and time-consuming. However, this is a one-time effort.
- Fixtures and workpieces must be sufficiently sturdy to resist cutting forces.
- It is only effective for eliminating small trace levels of metals and is not advisable for heavy work.
Applications of the Broaching Operations
Broaching is an essential manufacturing method that produces excellent surface polish and dimensional precision products. Broaching applications include:
1. Broaching is used in the automobile industry for manufacturing or carving gears or gear teeth into machines.
2. It is also used to make keyways for pulleys and conveyors.
3. In machine work, it is used to carve grooves in casting and forging processes.
4. Various agricultural machinery pieces are made using broaching in the agricultural tools industry.
5. It punches complex structures and carves intricate forms into workpieces.
6. Broaching is a common and highly successful practice in some major industries.
The following are some industries where this technique is employed.
- Industrial manufacturing
- Agriculture industry
- Oil and Gas
- Heavy equipment manufacturing
- Fasteners and gears
- Aerospace component manufacturers
In conclusion, broaching is a machining method that removes material using a specialised tool called a broach. It generates a variety of shapes and features from various materials.
A broaching machine provides benefits such as precision and efficiency but has downsides such as expensive setup costs and restricted adaptability. Broaching is a valuable method but must be cautiously used for specialised tasks.
Follow Khatabook for the latest updates, news blogs, and articles on micro, small and medium enterprises (MSMEs), business tips, income tax, GST, salary, and accounting.