CNC Milling Machines are used to shape metal and other solid materials using specialised cutting tools programmed and managed by Computer Numerical Control (CNC) systems. The machining process creates a specific part or product with the help of CAD software, short for Computer-Aided Design.

Today, you won’t find many items that haven’t gone through CNC milling machines as most sectors rely on this specialised process. Some examples are cars, aeroplanes, machine parts, moulds for household machines, toys and even prosthetics. All of these are likely to have one or several CNC-machined components.

CNC Milling Machines And CAD/CAM Software

In the early days of machining, it was done manually or mechanically but over the years, the technology improved and has developed into Computer Numerically Controlled systems. Now, with the input of a human operator, these computer programmes control and drive the machining centre. It has also gone from 3 and 4-axis to 5-axis machining to produce far more intricate parts.

Although most CNC machine programmes use CAD/CAM software and an automated process, it still requires the skills and expertise of a human operator. They have a big role to play including the following:

• Clearly understand the specifications
• Set up the tooling accordingly
• Decide on the cutting conditions based on the materials in question
• Ensure that the finished product meets the specifications and criteria

Understanding CNC Milling Machines

CNC milling machines employ rotary tools to remove materials following instructions from the CAD file to create the specific part or component. The machine’s computer effectively controls the function and coordinates of the cutter and only requires minimal human involvement to complete the machining process.

Operators attach the workpiece to the table and install the cutting tools on the spindle before starting the CNC program. From there, they can start the CNC milling process with up to thousands of RPM. Once the machine is ready, operators may do any of the following, depending on the project specification:

• slowly feed the workpiece into the stationary rotating tool
• move the tool across the stationary workpiece
• move the tool and the workpiece in relation to one another in some cases

Types of CNC Milling Machines

CNC milling machines are often classified based on the number of axes on which they can operate or the spindle directions. Below is a breakdown of 5 different types:

Vertical Mill

As the name suggests, a vertical milling machine’s spindle axis is vertically oriented. Vertical milling is a method of cutting materials in which the cutting tools move while the workpiece remains stationary. Two common types of vertical mills are Turret mills and Bed mills, each operating a little differently.

With a Turret mill, the stationary spindle is supported by the mill’s table, which may be moved vertically or horizontally. The spindle on a Bed mill is positioned vertically, thus allowing for up and down movement. This tandem motion of the worktable and horizontal travel results in the machining operation.

Horizontal Mill

A horizontal mill functions similarly to a vertical one, except for the cutters which are positioned on a horizontal spindle. These mills have a larger cross-sectional area than vertical mills, allowing for quicker material removal rates, especially from grooves and slots.

3-Axis Mill

The workpieces are fixed in place on the 3-axis milling machines, while the cutting tools execute operations for CNC milling components of all sorts, sizes, and requirements.

4-Axis Mill

The structure is similar to the 4-axis milling machine to that of the 3-axis milling machine, with the exception of a turntable, which can do more operations.

5-Axis Mill

The 5-axis milling machines’ rotational axis is the Z, which means there are five directions in which the milling cutters may move, including the A and B axes along with the X, Y and Z linear axes. A 5-axis machine can complete more complex tasks without having to reset the piece or change the tooling. However, higher levels of precision machining, need higher levels of CAD/CAM programming and a more skilled operator.

Maintenance Of CNC Milling Machines

Maintenance is also an important aspect of operating CNC milling machines. Operators must understand how to identify and resolve potential problems that may arise during operation. If something isn’t functioning correctly or if components aren’t being generated as expected, the operator must know where to look and how to fix it.

A well-maintained machine is a productive one, and it’s the operators who first notice when something isn’t right. Faults or lack of efficiency caused by wear and tear can also be avoided if they are detected early on. As such, effective machine maintenance could even save money in the long term.

How To Avoid Overheating in a CNC Machine Shop

Overheating in a CNC machine shop can result in moisture condensing on electronic components which can lead to corrosion. Experts believe that if the temperature in a CNC machine shop is high and with moderate humidity, that there is still a lot of moisture around.

As such, CNC machine shops must control both heat and humidity levels to prevent damaging electronics. While this can be a real challenge, the easiest solutions include adequate air exchange, central air conditioning and dehumidifier systems. It may not always be possible to maintain optimum temperature and humidity, but the closer you get, the greater the odds of not damaging your electronic devices.

CNC Milling Machines At PRV Engineering

Over the years, PRV Engineering has expanded our facility and operations to meet increased demand from an ever-growing marketplace. Our state-of-the-art facility has more than 30 CNC machining centres with a wide-ranging capacity. All of our turning centres have a CAD/CAM link that enables us to quickly and efficiently programme the most complex of components.

As with turning, all our machining centres have True 3D-Modelling and an Engraving Facility. This gives us the ability to perform die sinking, pattern making and engraving of special purpose tooling and gauges. Contact us if you have any questions about PRV Engineering’s CNC milling machines or how we can help with your project. Remember to follow our weekly blog posts for all the latest developments in engineering, manufacturing and technology.