You’ve probably heard it before – and on more than one occasion.
My 3 axis CNC milling machine can do the same job as your 5 axis machine.
Hmm, perhaps. But it depends…
… there are advantages to using a 5 axis CNC machine for complex components. This post describes a head to head comparison for a specific precision engineering project and reveals how the performance advantages of 5 axis machines benefit YOU the customer.
Complex CNC machining
First, the job itself. This project required the machining of all six sides of a cube-shaped billet to manufacture pump baring housings. The Instagram images below show the work from all sides, you can scroll through to see all six.
Complex Component Features
Scrolling through the Instagram images above, you’ll notice that it’s an ideal job for a 5 axis machine. Although, a 3 axis machine is capable of manufacturing these components, some of the features were quite tricky:
- The bores had a fairly tight limit of 15 microns.
- The small radius of one feature required a little cutter yet long cut length!
- Lower down there is a barely perceptible angle of 1 degree (see image below) – we had a form cutter made to manage this.
3 axis CNC – operations described
To make this component requires 7 operations with a 3 axis machine, as follows:
- skim, machine step, profile and bore
- turn over, stepped block for support to hold. Machine to overall thickness with a step, pocket the slot, drill and tap holes, second slot
- turn over, bore
- turn again, profile slot and bore
- turn again, hole and counter bore slot, tap hole
- turn again, offset bore
- machine chamfer
Obviously, there is run and setting time for each operation. This is laid out in the table below:
|Operation||Run time||Setting time|
|1||25 mins||30 mins|
|2||15 mins||40 mins|
|3||4 mins||30 mins|
|4||5 mins||30 mins|
|5||5 mins||30 mins|
|6||8 mins||30 mins|
|7||3 mins||60 mins|
|Total||65 mins||250 mins|
Overall, the 3 axis machine would take 5 hours and 15 minutes to manufacture a single component.
5 axis CNC – operations described
It’s all so much easier with a 5 axis machine! Just two operations as follows:
- combines 3 axis operations 1 – 3 and 5 – 7: Partial profiling to allow handling of excess stock. Set in vice, set datum.
- for 3 axis operation 4: set in vice against stop, set datums.
And that’s it!
So, you’re probably thinking, with only two ops the 5 axis CNC option should be quicker. And, of course, it is!
|Operations||Run time||Setting time|
|1||30 mins||30 mins|
|2||5 mins||30 mins|
|Total||35 mins||60 mins|
Just an hour and 35 minutes in total. That’s a saving of three hours and 40 minutes per part! We have our winner.
Saving more than just time…
If the time saved on a single component is multiplied across a batch, 5 axis machining is significantly quicker. But you already know that – unless you’ve been under a rock since the 80s.
However, what you may not be aware of is the improved accuracy. With so much machined during the first operation the scope for misalignment is dramatically lowered because all features are relative to each other.
With the 3 axis machine, each time the part is turned over and set, there is scope for error.
Using 5 axis machines means accuracy is consistent because there’s only one operation for most of the machining. This saves time and reduces cost!
5 axis CNC machining means greater accuracy, shorter lead times and reduced cost! What’s not to like?
QED – Quality, Expertise and Delivery on time
So 5 axis beats 3 axis – not news, but a useful pointer on why a workshop with 5 axis machines is critical for complex projects.
But all machine shops are not made equal. You can’t forget QED – quality, expertise and delivery on time.
Those are the three pressing reasons your next project should be with Axis Precision Engineering! Because, although your current supplier may have 5 axis CNC milling machines, all too often inexperienced engineers use a 5 axis machine as if it only had 3! It’s sad but true.
And it means they will struggle with the complex work you send them.
Even with experienced engineers on board, if a workshop has failed to invest in the right software, they won’t be able to push their machines to the limit. That means complex components will be an issue for them.
Late deliveries and an inconsistent finish are a sign that your engineering supplier is beginning to fall short.