CNC Milling – Process, Machines & Operations

It seems like if you want to get a part manufactured today, you’re going to run into 3D printing and CNC.  It’s as if the entire world of manufacturing has gone to those two technologies.  Really, though, that’s not the case.  3D printing is a different beast; it’s almost always plastic-based; it’s slow, and generally better suited for simple prototypes, mold positives, or models.  That doesn’t mean you’re limited to CNC if you need something more.

Nearly a Century of the CNC Machining Process

CNC stands for “Computer Numerical Control”.  It came about in the 1950’s, though the Computer aspect came along later.  A lot of the even older mills and lathes are still out there, in everyday use, producing outstanding work.  They were built to last, and they are perfectly happy cutting with modern bits and tools with great accuracy.  They rely on the skills of the operator.  CNC milling relies on operator skills as well, but it’s a somewhat different set of skills.

CNC milling generally starts with a CAD (Computer Aided Design) drawing on a computer.  This lays out the shape of the part with all the dimensions, angles and details like thread pitches.  When you’re sure your drawing accurately depicts the part you want, it gets converted into a CAM (Computer Aided Manufacturing) file.  This is what’s used by modern CNC machines.  With the CAM file loaded into the machine, you set up the raw material, make sure the machine has the correct bits and tools, and turn it loose.  If everything’s right, you’ll wind up with a faithfully reproduced part.

Yes, that’s a pretty severe oversimplification, but in broad strokes, that’s the idea.  Complex parts may require starting from a casting.  They may require special hold-down tabs to allow the part to be secured in different positions during CNC milling.  They may require retooling or intermediate steps to verify dimensions along the way.  There are a lot of possible complications, but if the CNC machining process is the only way to create the part, that’s exactly what you do.

There’s also the question of just how complex your CNC milling needs are.  The simplest machines run three axis, just like their non-CNC predecessors.  In this day of highly complex parts, you can also find 5-axis, 7-axis, and even 9-axis CNC mills.

Simpler Can be Better

A great many parts don’t rise to that level of complexity.  Parts that can be efficiently formed from raw stock rather than a casting are less likely to require the capabilities of CNC milling.  Parts which don’t require complex curves on multiple axes and parts with lower tolerances are often easily produced on simpler mills, lathes, and press brakes.  Or you may find your parts can be produced using 3 or 5-axis CNC milling rather than something bigger. The beauty of that is lower cost.  The creation of CAD/CAM files, the setup of the CNC machines, and the higher operating costs translate to higher parts costs for you.  If you can minimize those costs or avoid them altogether and get your parts produced on manual or smaller CNC machines, your production costs will be considerably lower.

A professional CNC machine shop like MacFab will help you determine what kind of machining you should be shopping for.  They can tell you precisely what kind of manual or CNC machining process can produce your parts efficiently.  Rather then being swept up in technology, companies which need parts produced today have a greater variety of options than ever before, and MacFab is proud to be here to help them figure it out.