That’s the question that starts the manufacturing process of every job.
Some parts are easy. The layout and methodizing process almost take care of themselves. Surfaces and features align simply on CNC 3 axis mill, Straight and parallel. Little planning needs to go into them.
Some parts look easy. Drawing them up in CAD takes little effort. But making them into real parts is a different level. Tolerance, hardness and surface finish requirements can combine to make a nightmare.
Take this part:
5 axis milling takes a part like this from “headache” to manageable.
Looks simple, right?
A CAD designer with but a few years under his belt can draw this part:
A CAD designer can easily write into the GDT data to require:
- alignment be within .005 for the intersection location of the two threaded bosses.
- The diameter at the base under the threads be within .0005”,
- the surface finish be better than a 63 finish.
- tight concentricity needs to be maintained,
- it has to be heat treated.
Drawing it up is fairly simple in a CAD system.
Being able to make this part requires years, if not decades of experience. It requires a solid understanding of both the capabilities and the limitations of the machines you have to work with. With that understanding, tool selection becomes critical. Tools too small won’t stand up, deflection becomes an issue, as does breakage. Tools too big apply more forces that could move fixtures; shifting of less that .001 will severely compromise tolerances. And machining the critical features in more than one operation was out of the question. Refixturing would become a nightmare.
Considering all this, it became obvious that there were few options on how to make this part: It had to be done in one 5 axis operation in a heat treated condition and all critical features needed to be finished out of the one operation.
So how do we make this part?
Answering this question and all the challenges that arose along the way would take a lot more than a blog post to cover. It requires
- an understanding of how metal and cutters interact. Both before and after heat treating
- interaction of all 5 axis, all at once, and how to align and adjust.
- Solid 5 axis programming capabilities
- A bit of thinking “outside the box”
Funny thing about thinking “outside the box”. Each time you do, that box gets bigger, with a new set of tools, both mental and physical.
As that box gets bigger, you can fit bigger problems into it.
Call it experience, or talent, or skill. It’s sure handy to have.