The Mechanical Engineer’s Guide to 5-Axis Machining
What started as a high-end machining technique focused on machining complex shapes has now transitioned to a nearly industry-standard technology to optimize the CNC Milling industry. Five-axis machining has practically reinvented how we think about milling parts.
Machining with 5-axis cutters allows users to cut costs on machining time, achieve higher precision on complex parts, and improve the overall production process. It can even change how parts are designed. Many mechanical engineers have changed their design criteria around this new tool, while those that haven't may still be stuck in the past.
5-Axis machining and modern manufacturing
The greatest change brought to the CNC and machining industry in recent history has been computerization and numerical control. With these capabilities came the transformation of the job of machinists and how engineers design for manufacturability. Computer-controlled machining brought greater capability and greater precision, but following this innovation, the limitations in machining were more mechanical.
The need for greater mechanical precision and the capability to mill more complex shapes gave birth to the 5-axis machine, and it was this quest for an improved capability that lead to its rise. As you likely realize, 5-axis machining was originally used only for expensive, high-tolerance parts, but all that has changed.
Due to the reducution in the need to change out fixtures, greater precision, the use of CAD to create precise, flowing parts, and the reduction in price, 5-axis machining is slowly becoming the standard for all milling manufacturing. In some cases, 5-axis machining is even cheaper than using a traditional 3-axis machine.
In terms of operation, 5-axis machines gain two rotational axis over traditional 3-axis machines. This allows for fewer fixture changes during machining and greater precision in complex parts. It also allows for numerically controlled machines to create the flowing and generative designs created using modern CAD tools. Due to the time savings from fewer fixture changes and a more “hands-off” approach for the machinist, it is also often cheaper for shops to use 5-axis production.
The manufacturing world is changing to adapt to the need to produce an innovative computerized design.
These changes have led to the development of both 3D printing and 5-axis machines. Mechanical engineers often only deal with designs, and may rarely cross over directly to machining and manufacturing. 3D printers brought prototyping manufacturing to the engineers' desktop, but 5-axis machines seem to only benefit machinists, right? This is somewhat true except for one major aspect - design for manufacturability.
Rethinking the design for manufacturability workflow
Workflows and the way parts are designed are wholly rooted in the understanding of how a part is going to be manufactured, or at least it should be manufactured. While this methodology is good, engineering mindset can often lag behind improvements in the manufacturing industry. It’s hard to adjust ingrained ideas about mechanical design, after all.
Engineers have to realize now, however, that with the widespread adoption of 5-axis machines, the way we think about manufacturability needs to change. According to a survey from the Modern Machine Shop, conducted in late 2015, 38% of the top machine shops already used 5-axis machines, and nearly all shops had at least 4-axis capabilities. Top shop owners also recognized that even simple parts could be manufactured better on 5-axis machines, according to the American Machinist.
Studies of recent growth trends in the manufacturing industry have proven the significant rise of 5-axis machining in recent years. Looking back, many questioned why switching from manual machines to CNC machines was a good idea, and were subsequently left in the dust. Engineers need to recognize that 5-axis is becoming an industry standard and adjust their design considerations accordingly.
With all of this said, 5-axis isn’t the cure-all for modern manufacturing in its present state. It is simply a catalyst driving the ability to innovate further. The goal of rethinking DFM methodologies is to allow engineers to innovate further in the design process and not be held back by past ideas no longer relevant to the industry.
After rethinking machining workflow, and understanding that 5-axis machining is a realizable production technique for producing even simple parts, we can start taking advantage of the improvements that this technique brings—of which there are many.
The proof is in the axis
The added rotational axis brought to bear in 5-axis machining brings benefits far beyond increasing part tolerances. 5-Axis.org recently ran a business analysis in regards to the machining of a standard 3-axis part against the same part on a 5-axis machine. On a standard 3-axis machine, the part required 5 hours and 30 minutes of setup time and nearly 20 minutes of machining time.
Moving the operation to a 5-axis machine, machinists were able to create the same part with only 1 and a half hours of setup and 13.5 minutes of machining. With a standard $80/hr rate for a machine shop, that saves the engineer or company $320 per part. Extrapolating further to the production of 100 parts a week, that’s $32,000 in savings each week, simply by using a 5-axis machine. Many shops recognize this and are making the switch, even if the machines are slightly more expensive.
The proof really is in the additional axis. The added flexibility brought about by not having to build as many custom fixtures or make changes in the middle of an operation brings benefits to every person in the production cycle.
Beyond cost, 5-axis machining also allows engineers to design more complex parts. Modern CAD allows the creation of complex and flowing parts that may be perfect for particular applications, but are hard to create in actuality. 3D-printing promises to take us in that direction eventually, but right now, it remains sparingly useful for widespread part production.
In contrast, 5-axis machining is a more practical and immediate approach to dealing with the manufacturability of complex designs. By actually being able to realize complex designs, engineers can create a product that performs better—maybe even with fewer components. This is a manufacturing technology available right now and which will only grow in future use.
Through 5-axis machining, engineers can design and create shapes with greater complexities of parts than ever before, at higher speeds and lower costs.
Moving forward with design
Innovation is at the heart of engineering, and at the heart of the future of making things. Futuristic designs in the engineering space are starting to look realistic. The capabilities of manufacturing are rapidly advancing, and production costs are being brought down. Even without an understanding that 5-axis is only going to grow in manufacturing utilization, engineers will need to rethink how we design today, keeping this new tool in mind.
It might have snuck up fast, or maybe some engineers saw it coming, but now is the time to adopt 5-axis machining into engineering design for manufacturability methodology. Innovation won’t wait.