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What Is CNC Machining?
CNC machining is a standard subtractive manufacturing process that relies on machines with computer numerical control instead of human input to produce parts. A CNC machine takes instructions from a computer, guiding the rotating tools’ movement to achieve the best results.
The CNC machining process begins with the creation of the CAD file format which the computer uses. A program translates the CAD file into either M-codes or G-codes, which contain instructions on how the CNC machines should work.
Other than the excellent accuracy of the CNC machining process, it allows greater repeatability. It also offers more impeccable results than traditional manufacturing methods because the machine mitigates error risks. CNC machines can produce multiple parts the same way throughout a production cycle, with each part having the same features as the last one.
Asides from faster cycle times and reduced risks of error, you can experience critical benefits of using the CNC precision machining, such as mass production, reduced costs, and low human input. CNC machines increase the technological possibilities for businesses, so the process is widely accepted by many.
Most CNC machines move along a 3-axis while others have a 4- or 5-axis machining. Here are typical examples of these machines:
- Mills
- Lathes
- Drills
- Grinders
- Plasma Cutters
- Routers
What Is 3D Printing?
3D printing is a widely embraced and flexible technology with extensive manufacturing benefits and industrial applications. Another term for 3D printing is additive manufacturing, a broad term for various techniques.
Additive manufacturing units create parts in layers allowing the perfect design flexibility and efficiency. More so, 3D printing helps to reduce production cycle times as it is a faster and ideal method for rapid prototyping services and cost-efficient for low-volume production.
Additionally, 3D printing offers different types of printing, enabling more flexibility in choosing the suitable material, method, cost, speed, surface finish, etc. Various industries commonly utilize different strategies to get the best from 3D printing.
Here are the typical 3D printing techniques across sectors:
- Material Jetting
- Powder Bed Fusion
- Binder Jetting
- Material Extrusion
- Direct Energy Deposition
- Vat Polymerization
- Sheet Lamination
Although, the general misconception is that 3D printing technology is limited to thermoplastics and related compounds. Thermoplastic resins are the most widely used material for 3D printing applications in various industries. However, the contemporary reality of 3D printing technology is that it is compatible with 3D printing metals, ceramics, bio-compounds, and other materials, influencing its versatility.
Rapid prototyping is one of the primary applications of 3D printing technology. Product designers and producers utilize this method to test the design liability using thermoplastics due to their cost-effectiveness and ability to cure quickly.
However, there are certain downsides to the 3D printing technology, which impacts its volume production due to the costs and time involved. Nevertheless, the technology continues to advance at a substantial high-speed potential for industrial applications. Support structures also ensure the printability of any parts using 3D printing.
Are CNC Machining and 3D Printing Similar?
Although 3D printing and CNC machining is naturally different methods with varying applications and approaches, they are both advanced technologies. A significant similarity between both processes is that both techniques begin with creating CAD files and follow a set of instructions from a computer. This CAD model is a reference for the G- or M-codes in CNC machines, while the 3D printers use it to make instant layers of a final product.
Is CNC Machining Better than 3D Printing?
Generally, anyone conversant with the manufacturing arena would understand that there is no one solution to all the production complexities in any sector. As a result, both 3D printing and CNC manufacturing are practical solutions to various manufacturing problems.
Meanwhile, placing one above the other is difficult or nearly impossible because each has its benefits and setbacks. Nevertheless, they can help you determine the ideal technique for your products. For instance, 3D printers offer great flexibility, allowing the creation of parts with highly complex geometries.
More importantly, each part made with the 3D printer maintains the same per unit cost, irrespective of the volume produced. On the other hand, CNC machining provides economies of scale, helping you to reduce the overall costs to a significant level.
However, there are several instances where these technologies can fetch the desired results. Still, it would help if you considered different factors such as budget, production time, and other technical variables. Below are some of the differences between CNC machining and 3D printing:
Quality
CNC machines offer tight tolerances, allowing products to be created with polished and smoother surfaces. The CNC machining materials are not vulnerable to several defects like layer lines, warping, or bending, as in the 3D printing process.
Although some 3D printers manage to offer a high degree of accuracy sometimes, they end up compromising quality most of the time. Both production techniques experience geometric limitations. CNC technology can create parts with very thin walls, which can be difficult or nearly impossible for 3D printing.
Waste
The amount of waste generated during operation is one of the notable differences between the CNC machining and the 3D printing process. CNC machining is a subtractive process that cuts away excess material from a block of raw material, producing more waste that is not recyclable.
On the other hand, 3D printers utilize the precise quantity of material needed to produce the required parts. In addition, 3D printers make little to no noise and don’t chatter/vibrate during operation.
Material Availability
Both techniques are highly compatible with various materials, such as plastics and metal alloys. However, 3D printers work best with plastic filaments. The typical thermoplastic resins in 3D printing include ABS, ULTEM, PLA, and Nylon. Various niche 3D printers enable the printing of components using materials like ceramics.
On the other hand, the commonly used CNC machining plastics include Polypropylene (PP), Nylon (PA66), PEEK, Acrylic (PMMA), and Polycarbonate (PC). Aluminum is the standard metal used for manufacturing prototypes across industries because it is highly recyclable and has excellent protective qualities. Other common examples of metal used in CNC machining include brass, titanium, stainless steel, zinc alloy, and magnesium alloy.
CNC Machining vs. 3D Printing: Helpful Tips and Considerations to Choosing the Best Technique
There are several critical decisions that product designers, manufacturers, and engineers consider before kick-starting production. Amongst these decisions is determining the best manufacturing technique for the product. So, examining the ideal equilibrium between accuracy, speed, and cost for a suitable performance and the highest profit is essential.
However, it would help to note that if a product is determined by one parameter at the expense of the other, the final result will be affected. As a result, the design phase often requires vast resources due to balancing all technical parameters and overall CNC machining costs.
Thus, there are other factors to consider when choosing between CNC machining and 3D printing asides from time, speed, and cost. We’ll discuss these factors below:
Ideal Material
One of the first considerations is deciding the ideal material for your CNC machining or 3D printing project. 3D printers are now compatible with materials ranging from thermoplastics to ceramics and metals. Nonetheless, this process has certain technological constraints regarding the product’s mechanical properties.
For example, 3D-printed metal parts lack adequate strength, and you may have to subject them to rigorous heat treatment before using them. However, this may result in a considerable increase in the overall cost, making the process incompatible with your business.
Meanwhile, CNC machining would be a better alternative because it can process metals quickly without needing heat treatment before the products are ready. However, there are several cases where 3D printing would be the best technology for processing materials for your products. Nevertheless, the specifics of your project would determine the ideal method between these two.
Preferred Production Volume
This is another crucial consideration that helps to decide the suitable manufacturing method for your project. Based on the generally embraced economies of scale concept, the more a manufacturer produces, the more cost-effective the production becomes.
Nowadays, CNC machining and 3D printing technology contribute significantly to the production volume of products in various sectors. CNC machines automatically fabricate CNC parts using minimal human labor while working around the clock.
3D printing is commonly used to create prototypes and sophisticated molds, allowing additional volume production with methods such as casting. However, most CNC machine shops choose CNC machining when volume production is a significant determinant due to the overhead costs and requires no additional processes.
Part Size/Geometry
The size or geometry of your part is another crucial consideration when deciding between CNC machining and 3D printing methods. Usually, CNC machines handle larger parts due to their size, while 3D printers have several related costs that make exceeding certain size ranges impossible.
As a result, the best solution, in this case, is to evaluate the specifics of the intended product. However, the general principle remains that CNC machining is the ideal choice between these two when handling larger parts.
Cutting Speed
CNC machines cut raw materials into preferred shapes faster than 3D printers. However, the overall production time does not depend solely on the cutting rates/speed. Parameters such as machines’ starting time and other pre-processing demands must be considered along with other factors such as the part’s size to decide the overall speed of the method.
The general rule of thumb remains that 3D printers are better for making smaller pieces because they start creating the parts instantly. However, CNC machining is the ideal process for larger components.
The Complexity of Design
Generally, different small or large parts have their respective design limitations. 3D printers excel in producing parts with complex designs because they develop components directly using the CAD model. There are no designs 3D printers can’t print, irrespective of the complexities.
CNC machining requires higher input from well-skilled technicians to prevent error risks in the cutting tool. Consequently, this makes creating many products with complex designs difficult or impossible to achieve.
In contrast, design complexities do not hinder the 3D printing process. It easily handles different requirements, such as hollow designs and impracticable features for other manufacturing processes.
Dimensional Accuracy Needed
Your manufacturing process choice influences the dimensional accuracy you require. Although CNC machines and 3D printers offer excellent dimensional accuracy and consistent results, the former relies on the operator’s initial input and G/M codes.
3D printers do not depend on the earlier stated factors like the CNC machines to provide consistent results. However, the differences between these technologies in dimensional accuracy are minor and insignificant for most applications. Hence, CNC machining and 3D printing methods stand toe-to-toe in this case.
Post-Processing Needs
CNC-machined parts are often fully ready for the market. Meanwhile, 3D printers work differently, as their typical applications involve assisting with mold creation or prototyping. Luckily, a rough surface finish is okay for both cases. However, in other applications requiring exceptional smoothness, you must use post-processing options to prepare the parts.
In addition, 3D-printed metal components often require heat treatment before being ready for use. The 3D printed parts usually have low fatigue strength and impact attributes due to the working principles of the 3D printing technique. This heat treatment ensures that the 3D-printed parts’ inner structure forms and performs well.
Eco-Friendliness of Machined Product
Both processes considered are compatible with a broad range of materials. The CNC machining method is free from hazardous materials, while 3D printing uses thermoplastics for prototypes. The thermoplastics used in 3D printing are otherwise recyclable and can be used for longer if used correctly.
As a result, both CNC machining and 3D printing are potential eco-friendly choices depending on the intended application and commitment to the environment.
Manufacturing Budget
Each of these processes has certain associated costs. Although 3D printers are suitable for making smaller one-off parts, volume production often requires continuous operations. Thus, CNC machining becomes the ideal option here.
For instance, the automotive application requires the best quality and technical factors. Likewise, it is customary to seek inexpensive solutions due to market competition and the fundamentals of business possibilities.
Additionally, it is essential to choose a faster process when considering the competition in the market. If you produce one or two parts while your competitors make ten or more in a similar time frame, your business eventually loses revenue regarding opportunity costs. It would help to know that whichever process you choose would require capital and operational costs.
Note that 3D printing is more cost-efficient for smaller parts. However, CNC machines can increase production requirements and reduce time cycles.
AT Machining: Your Reliable Partner for All Rapid Prototyping and Production Needs
AT-Machining is your one-stop-shop for all your manufacturing needs whenever you need professional expertise with the right experience in CNC machining services, 3D printing, injection molding, CNC milling, sheet metal fabrication, and several other manufacturing services. We offer reliable manufacturing services and consistent and accurate outcomes to various businesses. Our team of technicians ensures your products have high quality without having to speed more than your products require.
AT Machining offers an extensive list of manufacturing solutions and ensures the quality of products. Our unique and effective quality inspection system helps to maintain the required standards and provide the best. Don’t hesitate to submit your design and other details today; our innovative online platform offers instant quotes for all designs.
