Broaching is an important machining process that involves the use of a saw-like tool known as a broach. It is used to remove materials. Two main types of broaching that exist are; linear and rotary. Linear broaching is applied to a broaching machine or what is also referred to as a broach.
Conversely, rotary broaching entails the use of a broach pressed to the workpiece to cut it in axisymmetric shape. A rotary broach is very efficient. Broaching is used where precision is required. That is the reason it is vital in aerospace broaching.
Rotary Broaching for the Precision of Aerospace Segments
When there is a dire need for mass production of components broaching is essential so that the entire process can be a success. When making aerospace segments, rotary broaching tools are used. This type of broaching allows for special tolerance, sizes, gauges, and forms.
The aerospace industry requires custom made shapes such as square, hexagon, and polygon. Through broaching its possible to come up with various parts that the aerospace requires.
Benefits of Rotary Broaching in Aerospace Engineering
- Aerospace broaching, using the rotary method is quick and accurate. This makes it possible to make aerospace segments effortlessly.
- There are no secondary operations required. This ensures that the aerospace equipment is efficient and durable.
- It doesn’t require a lot of adjustments.
- Works on any Mill, Lathe, or VMC.
- The quality of the finished segment is great.
- There is a reduction in machine time, meaning greater profits for the manufacturing company.
The Process of Rotary Broaching for Aerospace Segments
Preparing the part
- First, it is necessary to pre-drill a pilot hole. A pilot hole needs to be larger compared to the diameter of the form. It should also be deep compared to the form you are broaching. There is a different approach for a blind hole too. The depth of the form should be drilled deeper to allow room for chip accumulation. This can be found at the bottom of the blind hole.
- Secondly, add a chamfer in the pilot hole. The chamfer needs to be larger than the major diameter for the form you are broaching. This is a process that General Broach Company knows how to do correctly.
When rotary broaching an external form, the following steps are followed:
- Turn the bar slightly below the diameter of the form
- Add lead-in chamfer at the rear of the broaching area
- For dimensions, 0.625 inches undercut should be added at the periphery of the form.
Technical Aspects of Rotary Aerospace Broaching
A rotary broach tool holder is used for the process to be successful. It requires one degree offset from the shank’s centerline. This process allows the broach to penetrate the targeted part at a certain angle. Only one portion of the form should be cut at a time. The broach is fed into the full form and cut in one pass. To prevent crashing into the workpiece, the rotary broach bit has a back taper.
As the broach cuts the forms material, the chips are separated. The chips can be left at the bottom or taken out using the same drill. When broaching external forms, there should be some relief provided towards the form’s end to ensure the chips fall off as the broach gets to the desired depth.
Materials Where Rotary Broaching Can Be Performed
Ideal materials for rotary broaching include mild steel, brass, and aluminum. Nonetheless, due to developments in powdered metal steel, including PM T-15 and PM M-4, rotary broaching is successful in titanium 300 and 400 series. The same is true for Inconel and stainless steel. Other materials that rotary broaching can be applied include 4140, 416, 1144, 17-4, bronze, nickel, copper, acrylic, and cast iron.
Some materials require coating using TiCN, TiN, and Alcrona Pro for rotary broaching to be made possible. However, Alcrona Pro is the coating that rotary broaching applications work best.
Forms Applicable Rotary Broaching
In aerospace engineering, various shapes are required for various segments. These include serration, square, rectangular, hexagon, Torx-style, keyways, Splines, double and single D, Rosan, J500, 12-point double hex, and Double Square.
Speeds and Feeds in Rotary Aerospace Broaching
Naturally, in aerospace engineering, mass production of parts is necessary. As such, it is clear that the speeds and feeds in rotary broaching is a necessary consideration. The speeds and feeds vary, relying on some factors. These include material, form, pre-drill diameters, among others. Most rotary broaching applications run at 500-700RPM feed rate for 0.001 to 0.003 inches per revolution.
However, it is necessary to use 50-100RPM before reaching the required depth. After a depth of 0.20 inches, the RPM can be increased after clearing the chamfer area. After this, the RPM can be increased accordingly. Substantially, this prevents the rotary broach from skipping around, causing unsightly marks. The process also prevents the risk of fracturing or chipping the rotary broach and diminishing the tool life.
As discussed above, rotary broaching is used in various industries. In the aerospace industry, it is essential in providing quality segments and forms using the required precision. Durability is vital for aerospace parts as some of these parts are used in satellites and space stations that are in space for a long duration. For other machines used for exploration of planets such as the Mars Rover, it is clear that it has to withstand some tough terrain and different elements in space.
Therefore, the strength and durability of the parts are essential. Using rotary broaching, both mass productions are manageable, and the manufacture of small components is possible. Most aerospace engineers use rotary broaching to make aerospace expeditions manageable and provide segments for aerospace engineering that cater to space environments.
Aerospace broaching is a complex procedure that should only be done by professional companies like General Broach. Our company has years of experience and clearly understands what should be done and how to maneuver each process.