At Baosheng, CNC milling plays a vital role in our manufacturing process, blending the precision of traditional milling with advanced computer technology. This technique is essential for producing high-quality components, and we’re always ready to provide you with a quick, accurate quote for any milling project you have. Let’s dive deeper into this highly efficient process.
What is CNC Milling?
In simple terms, cnc milling is a subtractive manufacturing process that uses computer numerical control (CNC) to guide milling machines in removing material from a workpiece to create precise, custom-designed parts. The process involves a rotating cutting tool that moves along multiple axes to shape the material, which is typically metal, plastic, or wood. CNC milling can be done on both flat and complex surfaces, making it ideal for producing intricate components with tight tolerances. Its high level of automation allows for consistent precision and efficiency, especially in large-scale production or rapid prototyping.
When manufacturing parts of different complexity, different types of CNC milling machines are often used. For example, for simple parts, you may only need 3 axes, while some complex parts may require 5-axis or more CNC milling machines. However, in the actual processing, the most commonly used machines are 3-axis and 5-axis. Having said so much, let’s take a look at the demonstration of the CNC milling machine.
CNC milling involves using a variety of tools, ranging from standard end mills and drill bits to specialized face and profile milling tools, allowing for a wide range of shapes and designs to be created. Modern CNC mills are highly versatile, and with the right tools, they can manufacture almost any part or component.
The origins of CNC milling date back to 1952 when Richard Kegg, along with J.F. Reintjes and a team from MIT, introduced the first commercially available CNC milling machine. Since then, the technology has evolved significantly, incorporating greater complexity and automation.
In the milling process, cutting tools rotate to remove material from a workpiece, which is held in place during the operation. As the tool rotates and makes contact, material is gradually cut away following a pre-programmed path, including details like tool paths, depth of cut, and spindle speed.
CNC milling is widely used across industries such as automotive, aerospace, agriculture, construction, and electronics. It plays a crucial role in producing a vast array of parts, from engine components and fuel tank panels to medical devices like implants and surgical tools.
Steps in the CNC Milling Process
To get from the CAD model to the physical part (made by Baosheng or elsewhere!), several tasks must be completed, and we list these below for you.
1. Make your CAD Model
First things first, you have to create a 3D CAD model for the part you want to make, and include all the important information, like the part’s size, geometry, and shape of the part. Perhaps more important is making sure that your CNC milling machine is actually capable of cutting your CAD model. Parts should be designed with no (or minimal) undercuts. The size of the undercut that can be machined depends on the capabilities of the specific CNC machine. Undercuts are deep-set or sunken features in a part, and these can’t be cut with standard tools. CNC mills can technically make these cuts, but you’ll more than likely need specialized tools and/or multi-axis milling machines. Make sure to factor these into your budget because both tooling and manufacturing expenses could rack up costs.
2. Converting CAD to CNC
When the 3D CAD model is ready, the next step is creating a CNC program to control and instruct the CNC milling machine on how to make the part. Using CAM software, you can create precise instructions for the machine that tell it how to move the cutters and tools when it’s making the part. These programs are often written in G-code or M-code. The portions of the program written in G-code focus on the operating parameters of the tools, such as spindle speed, the direction of movement, and cut depth. These M-code instructions deal with random bits and bobs, like tool changes, turning the machine on and off, and other secondary functions. CAM software usually comes with a simulator that lets you know whether your CNC programs can successfully make the part you want it to.
3. Prepare the CNC milling machine
Once the CAD model and the CNC program are ready, the CNC milling machine is prepared to fabricate the designed part. The CNC program needs to be imported into the milling machine and then a pre-prepared blank with the pre-machining dimensions should be inserted into the part of the machine holding the workpiece. The specific fittings, spindles, tools, and vices are also set up in the machine. This is the work that Baosheng suppliers do to make your part.
4. Executing the Program
With the CAD model developed, the CNC program created, and the CNC milling machine prepared, the machining program can be executed. When a CNC program is in action, you’ll never really need to intervene. The CNC milling machine will follow the program line by line to make the piece as instructed, and once the full program has been executed, the part can move on to any subsequent steps.
Popular CNC Milling Methods
There are dozens of different milling forms that can fabricate parts. The first was plain milling—a process that cuts flat surfaces parallel to the tool’s rotation. Since it first burst onto the manufacturing scene, CNC machining has led to many other types of milling being developed. These include:
Face Milling: This cuts material to create a surface perpendicular to the rotating axis of the cutter.
Angular Milling: This method removes material from a flat surface of the workpiece at an angle.
Form Milling: This also cuts material, but this time to make irregular surfaces (i.e., curves).
Gang Milling: This method is able to ramp up the rate of production as it uses two cutters, sometimes more, to cut the material.
face milling diagram
A diagram of face milling, a common form of milling
Equipment Used in CNC Milling
To successfully carry out this process, a few different pieces of equipment that all work together are needed, and we list these below:
A worktable to hold the piece steady during machining
A saddle that’s under the worktable, for extra support and to keep the worktable’s movement parallel to the tool’s rotating axis
A knee that’s under the saddle to support the worktable and saddle. Its position can be adjusted vertically to accommodate different part thicknesses.
A spindle is used to hold the cutter and direct its translational and rotational movement.
An arbor is a shaft that tools are fixed to, and it’s assembled through the spindle.
A ram (an optional item) is usually used in vertical or angular milling machines to help support the spindle.
Cutting tools such as end mills.
The interface (at least a screen and keyboard) is how the operator communicates with the computer that’s controlling the CNC machine.
The Downsides of Using CNC Milling
NC milling can be used to create parts from a wide array of materials, including metals, plastics and elastomers, ceramics, and composites. Because of this, CNC milling is a highly versatile manufacturing process that can be used to fabricate seemingly any part — with limitations. One of these it’s high cost, even for the simplest machine. For more technologically advanced machines, you can expect a steeper investment.
The machine will also dictate the size of the part you can make, and the part’s shape and any details will depend on the equipment’s capabilities. Recessed details on the part’s surface, like undercuts, will need specialized tools, and sometimes multi-axis equipment, which is also pricey. Also, the success of the process depends on the abilities of the operator; if tools and programs aren’t set up correctly, you could end up with unusable parts and waste.
