Learning The Difference Between Internal And External Broaching

Broaching is a process which is capable of producing precision equipment and precision parts. There are two basic types of broaching used by manufacturers today, those being internal broaching and external broaching. This discussion will examine both procedures so that the difference between internal and external broaching will be apparent.

If your company is in need of one of these two broaching processes, the information contained below should help you decide which would be the most appropriate procedure for you to use.

About Internal Broaching

Internal broaching is most often used when it’s necessary to cut a precise hole or a unique type of shape from some kind of soft metal. The basic steps involved in internal broaching are as follows: 1) choose a soft metal like aluminum, bronze, or brass, 2) – decide which kind of broaching service will be used, for instance, vertical broaching or rotary, 3) – place the metal piece securely on the machine or on the assembly line, 4) – install the specific broaching tool which will be used for this application, 5) – apply whatever cutting fluid will be used for this procedure, and 6) – carry out the internal broaching process.

Types of Internal Broaching

Having chosen internal broaching as your procedure of choice, you’ll still have to make a decision about which type of broaching to use in order to achieve the precise specifications needed. The two most common types of internal broaching are rotary and vertical broaching. Rotary broaching involves the usage of a rotating broach tool which will be used to create the design you have in mind.

It’s most commonly used when you need to create an asymmetrical hole in one pass. Depending on the specific kind of design involved, a broach manufacturer might use a lathe or a screw machine. Rotary is used most frequently when a component is of a harder material which requires a lathe, as opposed to a typical broaching machine.

Vertical broaching is used more frequently in pulldown applications or in push applications. These machines are very space-efficient and provide a number of different cut lengths or strokes so as to create the desired end result. This kind of broaching machine style is used quite frequently to create deep slots and other external usages.

Each of these broaching types are used so as to minimize any time which is spent in the creation of specific components. Every piece which gets created must pass certain quality standards, while also being produced according to a fairly tight timeline. In some cases, it will be necessary to make multiple broaching passes, and in other cases, the machine will be able to create the necessary parts using a single precise movement.

About External Broaching

The first step in any external broaching process calls for a broaching manufacturer to use a fully customized broach tool in order to make a precise cut. Broaching tools must rely on a number of cutting teeth so that unique shapes and regular holes can be created in the piece parts being worked on. External broaching is a highly refined process and it must be customized to the specific part being created. In effect, this produces a repeatable and reliable process that can easily be applied to high-volume production.

In contrast to internal broaching, external broaching relies on a cutting tool which has drafted-outward sides. This allows a precision-cut to be created on the external side of apart and is commonly used to create gears, bolts, and other components, all of which call for a very exact shape from the broaching tool.

After you have set up an external broaching machine, a huge number of identical parts can easily be created, and in fact, this is one of the reasons external broaching is used on a given application. Keep in mind that the precision of the parts is only as good as the precision of the broaching tool, so before you can actually create any really outstanding parts, it will be necessary to develop a precise broaching tool capable of high-speed performance.

Types of External Broaching

External broaching is generally accomplished through rotary or horizontal broaching processes. A rotary will make use of a tool holder and a broaching tool and is similar to a lathe in that it’s a spinning tool that uses regular cuts so as to produce an outer profile that matches the required specifications. Whether a contoured finish or straight edges are desired, a rotary broach is perfectly capable of handling your needs. This particular type of machine makes use of a 1° misalignment so as to lower the contact between the cutting surface and the part itself.

This allows you to power through harder materials than most broaching services are capable of. Horizontal broaching is a more traditional broaching machine that pulls the broach directly through any part so that an internal or external cut can be applied. Although horizontal machines are also often used for internal broaching, they can be retooled so as to accomplish external broaching as well. Horizontal broaching machines were more common in the past, but have now been largely replaced by more space-efficient vertical broaching machines.

Uses for External Broaching

As previously stated, external broaching is commonly used when it’s necessary to produce large quantities of components that require great precision. Some of the industries which make extensive use of external broaching are aerospace, firearms, medical, heavy equipment, automotive, and industrial manufacturing. While external broaching is best used on softer metals such as stainless steel and aluminum, some broaching machines are outfitted so as to work with plastic and carbon fiber as well.

External broaching can be a highly affordable solution for a number of different industries, especially those which are interested in the fabrication of their own components. This can save you a ton of money because you won’t need to have your precise components shipped to you from across the country or from some other location around the globe. If you can set up your external broaching process in-house and achieve reliable results, you will undoubtedly achieve significant savings over the cost of having them manufactured elsewhere and shipped from a remote location.