Why Choose CNC Milling?

5 Axis milling machine cutting large angle for automotive part.

CNC milling, with its roots dating back to the mid-20th century, has evolved into a cornerstone of modern manufacturing. It relies on computer-guided precision to cut components from raw materials, enabling the creation of everything from intricate aerospace parts to custom firearm assemblies. The diversity of CNC milling machines ensures that there’s a machine tailored for almost any application, providing the industry with a versatile and adaptable tool for various projects. In this blog, we’ll discuss CNC milling, its numerous types and their applications, the benefits of choosing CNC milling for your project, ultimately arming you with the knowledge to optimize your manufacturing projects.

CNC mill cutting a small part with intricate angles, G-Code overlay has been added to image


CNC (Computer Numerical Control) milling is a sophisticated machining process that relies on computer programs, typically G-Code, to precisely control milling machines. These programs control critical parameters such as cutting speeds, feed rates, and tool paths, ensuring every operation is executed accurately. The versatility of CNC milling is unmatched, enabling the machining of almost any material, from metals and plastics to composites and exotic materials. Moreover, CNC milling machines can operate on different axes, allowing for intricate and complex geometries that would be challenging to achieve using traditional machining methods. The introduction of 3rd, 4th, or 5th axis milling machines has expanded CNC milling’s capabilities, making it ideal for industries like aerospace, medical, firearms, prototyping, and defense, where multifaceted components are standard.

When it comes to precision, CNC milling has set new standards, with tolerances as tight as 0.0005 inches now being the standard in world-class machine shops. This level of precision not only reduces the need for extensive post-processing but also elevates the overall quality of the end product. Reduced post-processing and improved quality are only two advantages of CNC milling. It also offers enhanced efficiency, as these machines can operate continuously with minimal human intervention, resulting in reduced production time and labor costs. The repeatability and consistency of CNC milling make it an invaluable tool for mass production, where identical designs must be replicated across multiple workpieces. As CNC milling continues to evolve, it has become a cornerstone of modern manufacturing, influencing various industries and allowing precision that was once deemed impossible to produce.

3rd axis milling machine at a stand still, preparing to continue milling the workpiece.


The benefits of CNC milling are not limited to precision and complexity. The efficiency brought to the table by CNC mills is a game changer. As mentioned before, the need for labor-intensive handwork, & post-processing is drastically decreased when using a proper milling machine. Additionally, CNC mills excel in significantly reducing the time it takes to produce parts. They succeed in minimizing material scrap, & operating unattended for extended amounts of time. CNC mills were designed with efficiency in mind, the automated tool changing system is another component that will help drive productivity and cost-effectiveness across numerous industries. Rapid prototyping and design iteration are simplified thanks to the efficiency benefits, meaning that prototypes and testing can easily be completed before committing to mass production. Successful rapid prototyping allows for parts to be refined and optimized, meaning that mass production will be completed precisely, and timely. Ultimately resulting in successful production schedules, and optimized resource utilization. Not only are you able to machine more intricate parts, while holding tighter tolerances, CNC milling allows you to do all of it at a faster rate.


Arguably the greatest benefit unlocked by CNC milling is the unparalleled complexity. 3D features that would challenge the limits of traditional methods, not only become feasible with CNC mills, but highly repeatable as well. 5th axis milling provides the ability to machine at multiple angles & orientations, without the need for repositioning the part, this is a valuable, time saving capability for intricate, multi faceted parts. 4th and 5th axis milling has become essential for milling parts with multiple angles and complex geometries. However, not all parts require 5th axis milling, in fact, 3rd axis milling is suitable for most basic parts. The number of necessary axes depends on the job, and is a direct correlation of the mills’ capability to machine multi sided parts. In industries such as aerospace, medical, firearms, defense, & OEM, tight tolerances and complex geometries have become the norm, meaning CNC milling isn’t going anywhere. The technologies’ capacity to create intricate and custom designs, while maintaining consistency and accuracy, has expanded the possibilities for innovation and product development. Ultimately enabling manufacturers to craft parts with intricate curves, and compound angles, that may have been seen as impossible in recent years.

Introduction to CNC Machining

A lathe taking advantage of live tooling, to cut a part using a live center
A lathe taking advantage of live tooling, to cut a part using a live center

In a manufacturing dependent world, CNC machining stands as a powerful and indispensable technology. CNC, or Computer Numerical Control, revolutionized the way we produce parts and components, requiring accuracy and efficiency unachievable using other techniques. At its core, CNC machining is an automated process that uses computer-controlled machines to precisely cut materials like metal, plastic, and more. In this blog post, we’ll dive into the basics of CNC machining and explore how it has transformed the world of manufacturing.

A standard CNC controller found on a variety of different CNC facilities
A standard CNC controller found on a variety of different CNC facilities

CNC machining almost completely (and in some cases, entirely) eliminates the need for manual operation, relying instead on computer programs, automation, and coded instructions to guide the tools. This allows for the creation of intricate and complex shapes that would be nearly impossible to achieve with traditional methods. The heart of a CNC system is its computer controller, which uses G-Code to interpret a design’s digital blueprint and translate it into precise movements of the cutting tools. This level of automation not only ensures consistent quality, but also drastically reduces human error, making CNC machining a staple of the modern manufacturing world.

Marzilli Machine uses a variety of 3D CAM software, with the most prominent being Mastercam. CAM, or Computer Aided Manufacturing, software serves as a bridge between the design and the production stages. CAM takes digital designs usually made with CAD, or Computer Aided Design, software and turns it into G-Code. This is mostly done with something called toolpaths. A toolpath refers to the precise movements made by a CNC machine’s cutting tool. Taken into account are the specific cutting paths, speeds, feeds, and the actions required by the tool. In the modern world of manufacturing, CAM can generate most toolpaths automatically, however this should always be checked for accuracy. Thankfully, CAM software knows this feature won’t always be 100% accurate. Many CAM programs offer simulation tools that enable users to preview the machining process.

Close up of CNC milling machine, cutting a fiberglass part
Close up of CNC milling machine, cutting a fiberglass part

The applications of CNC machining are seemingly endless. From the aerospace and weapon industries, to medical device manufacturing and prototyping, CNC machines are the go-to choice for producing high-precision parts. Whether you’re crafting a prototype for a groundbreaking invention or producing components for a mass-market product, CNC machining offers the precision and repeatability needed to meet the most demanding specifications.

CNC Mills: CNC mills are ideal for machining complex three-dimensional shapes and contours, making them suitable for tasks like sculpting, pocketing, and drilling holes at various angles. In a CNC mill, the cutting tool can approach the workpiece from various angles and directions, offering greater flexibility in tool orientation. This benefit grows greater when using a mill equipped with 5-Axis capabilities, which we will be covering in depth in a future blog post!

CNC Lathes: CNC lathes are best suited for rotational parts like shafts, bolts, and pins, as they excel in turning and facing operations. CNC lathes typically work with a fixed tool orientation perpendicular to the rotating workpiece. Meaning that they are commonly employed for producing cylindrical components, however thanks to live tooling, they are not limited to them. We will cover live tooling in depth in a future blog!

Quality Control: Quality Control, or QC, is a vital part of the production phase. QC checks are performed before production, known as First Article Inspection, or FAI. Parts continue to be inspected during production in the form of In Process Checks, or IPCs. This ensures dimensional accuracy throughout the production process. After production is complete, random samples are chosen and inspected. This is commonly known as the final inspection. We will fully dive into the benefits of QC in a future blog post.

Stay tuned for next Monday, where we will be discussing CNC Milling in depth. As well as how it could affect your company or project instantaneously!