How a CNC Milling Machine Operates
Once the 3D CAD design is ready, it gets translated by CAM software into G-code to direct the CNC milling machine to make the part. It’s these precise instructions that allow the machine to replicate the CAD model in the chosen material with high accuracy and efficiency.
The automated process also means that fewer machinists are needed to oversee the machine, which leads to lower production costs.
Spindle
Milling is a process that creates grooves, slots, holes, pockets and other impressions on materials. This can help to achieve a specific design for a product, part or component.
Once the blueprint for a desired shape is created using CAD software, it is then converted to a CNC program (or G-code). This acts as an instruction set for the machine to replicate in the chosen material.
The programmable tool is then attached to the spindle. The machine can then cut into the material with varying axes, speeds and feed rates. The tool is then removed from the spindle once the cutting operation is complete. The spindle is often lubricated with either Grease, Air-Oil or Hwacheon Oil-Jet to ensure optimal performance. The lubrication depends on the application and machining conditions.
Table
Unlike 3D printing, CNC milling removes material from the workpiece to shape it. This makes it ideal for creating precise, clean components. It is a preferred method for medical and military production, where smooth surfaces and consistent accuracy are necessary.
The machining process begins with the creation of the desired part design via CAD, which is then inputted into a computer-controlled machine that will operate on the different axes, such as X, Y and Z, to replicate the CAD design. A milling cutter then cuts into the chosen material, creating various impressions like holes, slots and threaded areas. These can then be used as the base for a variety of other fabrication techniques. Choosing machinable materials and optimizing design are essential to reduce machining time and cost.
Tool Holders
A CNC milling machine operates along a set of axes (X, Y, and Z) to create a variety of shapes, holes, and impressions. A key component to 
the precision process is the tool holder, which clamps onto the cutting tool to prevent damage to the spindle or workpiece.
These are made from hot rolled C1018, plenty strong but ductile enough to yield a bit if bashed. They have good concentricity less than.0008” and decent gauge lengths.
The material used depends on the type of machining being done. Ceramic materials are highly wear resistant but cost more than other options. Titanium is durable and machined well, but it is more expensive than other materials. It is also more susceptible to corrosion. TM Smith offers a range of standard and special tool holders to accommodate all types of manufacturing processes. Learn more about the different types and signs that a holder may need repair or replacement.
Arbors
Once the CAD model blueprint is ready, it’s converted into a CNC program. This serves as a set of instructions for the machine to replicate the shape of the intended product. The CAD program is subsequently imported into the milling machine, where specific fittings, spindles, tools, and vices are set up. This is the work that Xometry suppliers perform to prepare the machine to make your part.
A slab cutter, for instance, removes significant amounts of material in a single pass, leaving a rough surface texture. These types of cutters are commonly utilized in gang milling operations.
Despite the wide range of applications, a CNC milling machine comes with certain limitations that need to be considered before making a purchase. These limitations include initial investment cost, power consumption, and labor requirements.
Coolant
Coolant absorbs the heat that forms between your tool and workpiece, carrying it away to prevent thermal damage to both. It also lubricates the tool to reduce friction and improves surface finish quality.
Your CNC machine needs the right type and concentration of coolant based on your specific machining operation and materials being cut. Different mixes and concentrations provide a different balance of cooling and lubrication, with a leaner mix providing more cooling and a higher concentrate offering more lubrication.
The coolant flows through your machine’s pump, filtration, and delivery system to remove metal particles and debris from the mixture. The clean coolant is then recirculated back into the cutting area. This continuous loop helps eliminate waste and provides efficient, consistent cooling while ensuring your machine works correctly.