CNC Machining in Space Exploration
Complex Machined Shapes for Space Components
Providing machined components for the space market is usually accomplished by using CNC machine tools. Demand in these markets continues to require tighter tolerance ranges and better finish callouts. In the past, the CNC equipment used to produce these parts were two-axis (lathes) and three-axis (milling). Many of the more complex shapes were produced using a combination of these machines, which required multiple setups. With every setup you introduce a greater possibility for error.
Now with advances in control, servo, and tooling technology, we can produce the most complex geometries on a single machine with 5-axis simultaneous machining capabilities. Five-axis machines minimize the number of setups, greatly reducing tolerance stack up and producing higher tolerance, more consistent parts.
Defining 5-Axis Machining
Traditional CNC machines move in two linear axes (X and Z) for lathes and three linear axes (X, Y, and Z) for machining center. The term “5-axis” refers to the number of directions in which the cutting tool can move. On a 5-axis machine, the cutting tool moves across the X, Y, and Z linear axes as well as rotates on the A and B axes to approach the workpiece from any direction.
The ability to precisely machine a workpiece without having to move it from fixture-to-fixture has distinct advantages over conventional three-axis machining. The most obvious benefits of 5-axis CNC machining are as follows:
Improved Tool Life
Improved tool life and cycle time are a result of being able to program the tool and/or table which enables the machine to maintain optimum cutting position and constant chip load.
The major (and most well-known) advantage of 5-axis machining is the ability to machine complex shapes, while minimizing the number of chucking or fixturing positions. The additional movement creates machining angles and arcs for the cutting tool and for chip relief that were only previously possible with a multitude of special fixtures or additional setups.
Five-axis machines can machine nearly every visible surface, excluding the bottom or clamping area. This ability significantly reduces the need for multiple setups or special fixtures. Depending on the workpiece, in some instances, you can reduce the number of setups to one.
Tolerance stack up (imprecision) is one of the results and challenges every time you have to move the part for re-chuck of fixture. Once a part comes out of the machine, precise alignment is lost. By using the same zero or home location, feature-to-feature accuracy is improved.
3+2 Axis Machining
There are parts that can only be successfully machined using full 5-axis simultaneous movement, but not all parts require the simultaneous 5-axis movement. Some parts require five axes, but not simultaneously. You can have machines with three + two axes.
In three + two machining, the fourth and fifth axes are used to locate the workpiece (or cutting tool, depending on the type of machine) in a fixed position. In these scenarios, there is no need for all five axes to move simultaneously.
The same tool paths can be achieved in a three-axis machine, but only after loading and unloading between multiple setups, fixtures, or machines. The 5-axis machine increases uptime, decreases human error, and eliminates the need for special fixtures. For parts with features or holes on multiple faces or angles, three + two machining is the clear choice.
Better Surface Finish
Using the rotating fourth and fifth axes, the part can be orientated to bring it closer to the cutting tool. If the part can get closer to the cutting tool, then the cutting tool can be shorter. A shorter cutting tool is less susceptible to vibration at higher cutting speeds, which directly impacts surface finish.
As technology advances, so do the markets’ expectations for higher quality products, at competitive pricing. To meet this challenge, Intrex has made significant investments in full 5-axis and three + two axis equipment. We also have made significant investments in systems software to oversee and control our entire manufacturing process.
We would welcome an opportunity to speak to you about addressing your supply chain needs. Contact Intrex today.