CNC Mill – How it Works & Advantages

If you’re a machinist or someone looking to open their parts manufacturing plant, then you may have already come across CNC milling. It is the machine that can automate the process and make your life a lot easier.

However, it might not be for everyone, you need to understand how the CNC mill works, and what its benefits are before deciding whether to buy one or not. That said, let’s dive right in:

So, What Does CNC Milling Do?

With the help of a CNC mill, you can transform a regular casting into a workable part that can be used in a larger product. These parts need to have greater tolerances, which the raw castings don’t have – they need to go through the machining process to have that tolerance. Here are the top three things done on CNC mills:

  • Creating Flat Surfaces: It puts a flat surface on the workpiece and creates a finished sealed surface without any risk of leakages.
  • Drilling Holes: As the name suggests, the casting is drilled holes into it and with tapping, threads are added – the most typical way to put together parts.
  • Boring Holes: If an existing hole needs to be enlarged, a stiff boring bar does the job using a single point tool for cutting that creates an accurate inner cavity in the workpiece With the help of boring, parts can be assembled very tightly.

A typical milling process usually includes the following steps:

  1. Creating parts designs in CAD
  2. Converting and formatting those CAD files into machine code
  3. Setting up the right machine with right axis options
  4. Letting the machine do its job and produce the parts
How Does CNC Mill Works?

The key factor in deciding how your mill is going to work or what the precision of the CNC mill will be for your project is its 3-5 axis milling options. Let’s discuss them below:

  • 2-Axis Machine: Although not very popular, it’s still used by many for building manual fixtures. It only moves on the X & Y axes and doesn’t repeat much.
  • 3-Axis Machine: Mostly leveraged for vertical milling, moves on all three axes – x, y & z.
  • 4- Axis Machine: This is the most commonly found machine in the CNC milling shop. It moves on the X, Y, & Z axes along with an additional B axis. This allows the table to rotate providing access around the workpiece.
  • 5-Axis Machine: This is the one with most angles as it offers x, y, & z along with additional B and A axes. These are specialty CNC milling machines and if you need the most precision in a CNC mill, 5-axis is your go-to machine.

The most commonly used ones are from 3-5 axis milling machines with the last one being the most accurate so it’s not recommended for high volume work.

Vertical & Horizontal CNC Mill – What’s the Difference?

There are two kinds of spindle orientations in the realm of CNC machines. The first one is vertical where the spindle axis, known as the z-axis leans vertically. In its c-column configuration, you will see the spindle move in the z-axis direction and the table holding workpiece will move in x and y axes in horizontal directions. The best part of using vertical CNC milling machines is they are the best fit for high-volume work where on-site milling is needed such as brackets and covers and their deadlines are closing with speed.

The horizontal CNC mills are opposite to what we discussed above. They have a horizontally oriented z-axis, which is usually paralleled to the machine’s length. The spindle moves on the vertical y-axis and when it goes horizontal, it moves along the x-axis.  The fixtures and pallets hold the workpiece in place and move in the z-axis while b-axis rotates. There are several benefits of horizontal machining such as the ability to access the machine from 4 sides, milling more complex parts, better evacuation of chips, and completing multiple tasks on a single fixture.

Advantages of Using CNC Mill:
  • There are various reasons why many machinists opt for CNC milling instead of the manual one, let’s have a look at them below:
  • The milling cutter is sort of a multi-touch took with each of its teeth participates intermittently in the work resulting in excellent cooling for the cutting tool, improved speed, higher durability, and better productivity.
  • It can almost take place of the planner because CNC mill has the ability to produce a broader range of products
  • If you need mass production and fast prototyping, CNC milling is perfect for you
  • You can produce thousands of milling parts in a very short time
  • With the high precision of the CNC mill, repeatability is very accurate. You can produce thousands of parts with the exact specifications
  • Numerical computer-based control that confirms the precision of final workpiece result
  • It is highly automated so that means you don’t need a large number of operators and labor to make it work, which reduces the cost
  • With 3-5 axis milling, you can create complex designs, specifications, geometries, and much more
  • CNC milling parts processing have great flexibility and adaptability
Some Caveats of CNC Milling:
  • The machine itself and the setup cost is more expensive than its manual counterparts
  • You need to have properly trained workers to operate the machine, small mistakes can result in big losses
  • Might not be very cost-efficient for small batches of products, but you will save a lot of money if producing a large number of the same products
Parting Words:

There is no doubt these automated machines have eliminated the need for hiring a big staff to take care of everything thing. Plus, the production time is reduced as CNC milling can be done faster than manual machine working.

However, it needs to have a design in CAD, which will be translated into the machine’s language, this can take a little bit of time. So if you are making mass batches of the same design, the CNC mill is perfect for you.