Parts for aerospace applications are designed to maximize strength and minimize weight. That usually results in a lot of machining. Throw in the complex geometries, tight tolerances and exotic alloys specified in the drawings, and you can see why these parts are difficult to make.

Impro does a lot of precision machining of aerospace parts. Some go through familiar CNC processes like turning, milling and grinding, but 5-axis machining often provides the best manufacturing route. This blog explains why.

Basics of 5-Axis Machines

Conventional milling machines have three axes. Referred to as X, Y and Z, these are left-right, forward-backward and up-down motions. Their limitation is that to machine surfaces in anything other than orthogonal relationships (at 90°), the part has to be fixtured at an angle. This almost always means taking it off the machine bed and remounting it so the cutting tool can produce the surface or hole needed.

A 5-axis machine addresses this with two additional axes. These can be added either by mounting a rotary table on the machine bed, or by angling the spindle holding the cutting tool. The first is less expensive and provides a wider range of motion while the second allows simultaneous machining.

Simultaneous machining is when the spindle pivots while the tool is cutting. This allows production of complex contours. In contrast, the rotary table approach allows the machining of compound surfaces and holes, but only in a fixed position.

The Aerospace Part Challenge

Precision machining aerospace parts means addressing three challenges:

• Producing complex features: Pockets are needed for mass reduction, while complex contours minimize space needed in the aircraft and provide the necessary functionality.
• Maintaining tight geometric tolerances: Not just dimensions but also the relationships between features are tightly toleranced to achieve the required levels of performance.
• Minimizing cycle time: Many part designs call for extensive material removal, but the alloys used, such as 7000 series aluminum, titanium, and superalloys, are challenging to machine. High speeds are necessary to minimize costs.

How 5-Axis Machining Supports Aerospace Part Production

The major benefit is the ability to machine features on multiple faces and at angles other than 90° without removing and refixturing the part. This saves time and improves accuracy. It also reduces lead time because batches of parts aren’t queuing for a series of machining operations.

5-axis positioning can also reduce machining time, by allowing optimization of the milling cutter geometry to maximize the metal removal rate. This is especially beneficial when the volume of metal to be removed, combined with poor machinability, will result in long cycle times.

True 5-axis machining with simultaneous positioning also enables machining of parts that could not easily be produced any other way. This gives the design team more freedom to achieve mass and performance goals and so contributes to improved part design.

Challenges in 5-Axis Machining

Not all machine shops are up to the challenge of complex aerospace parts. Particular issues to deal with are:

• CNC programming
• Tool geometries
• Machine cost

The additional axes make CNC programming more complex than for conventional CNC machine tools. This is especially true when the programmer wants to adjust the cutting tool orientation to increase the material removal rate. The solution is to use one of the high-end Computer-Aided Manufacturing (CAM) software packages with 5-axis capabilities.

Cutting tools that can take advantage of 5-axis flexibility and handle the material challenges are more expensive than standard tools. Manufacturing engineers need to evaluate their costs and benefits while developing the CNC programs.

5-axis machining centers are very expensive. This is another reason why programming and tooling are important factors in achieving cost-effective production: the machines need to work hard to deliver an ROI.

Your Partner for Precision Machining Projects

Aerospace parts pose interesting machining challenges. They’re complex, made to tight tolerances and from hard-to-machine alloys.

5-axis CNC machining provides a cost-effective solution while at the same time meeting demanding geometric requirements. Impro has invested heavily in 5-axis machining centers to support customers in aerospace and other industries, and has the talent to fully exploit their capabilities. We’re also certified to AS 9100.

If you need a source for complex machined parts, we can help. Contact us to discuss your challenge.