Posts Tagged: Additive Manufacturing


Unique Advantages of Subtractive Manufacturing

Subtractive ManufacturingAdditive manufacturing, better known as 3D Printing, first started in the 1980s. Back then, it was a novelty concept reserved for advanced engineering research laboratories. In the 1990s, 3D printing made waves in the medical arena thanks to its ability to create custom medical devices. By the early 2000s, the open-source movement brought 3D printing into the homes of hobbyists and entrepreneurs During this time, people hailed it as the future of all manufacturing. It remains a promising technology, but subtractive manufacturing still offers many advantages over 3D printing.

Subtractive manufacturing techniques are those that remove material from a block to make a 3D part.

They are what we might call traditional manufacturing processes like milling, turning and even injection molding. Additive manufacturing processes, on the other hand, build up 3D parts by successively adding layers of material.

Although the cost for 3D printers continues to decrease, it’s still more expensive to 3D print many parts than it is to machine them. The printers themselves can be cost competitive, but the materials used in 3D printers are costly – especially if metals are involved.

Printing a part is a little bit like making pancakes – the first one usually gets tossed in the trash. This constitutes a waste of high-cost materials. Furthermore, 3D printers are more finicky and require frequent calibration and re-calibration when they’ve sat unused or when operators are swapping materials.

3D printed parts also require additional post-processing to achieve attractive surface finishes.

The additive component of the manufacturing process means pieces right out of a 3D printer have striations and stepped edges around radiuses. These surfaces require a subtractive manufacturing process to finish. Most subtractive manufacturing processes can produce finished surfaces.

Even if the striated surfaces of additive manufacturing is acceptable, 3D printer technology remains less reliable than subtractive manufacturing. High-reliability machines with good repeatability are expensive and require frequent maintenance while low-end devices typically cannot produce parts with consistent quality.

3D printing can be appealing for prototypes, but it is often limited to fit-and-feel prototypes. Because there are limited 3D printing materials available and the final mechanical properties are not always as good as those for machined parts, 3D-printed parts may not be robust or accurate enough for testing purposes. So, it sometimes makes sense to prototype with subtractive manufacturing processes and production materials instead.

Generally, subtractive manufacturing techniques are more familiar to designers.

Many designers even rely on certain functions that are common in CNC mills and lathes. For these folks, 3D printing can add cost for no discernible benefit. And with many machine shops capable of producing parts overnight using traditional techniques, the relative speed of 3D printing is rendered moot.

While additive manufacturing is attractive in some applications, good old milling, turning and molding are often better suited for the job at hand.


Additive Manufacturing: Better than Machining?

additive manufacturingAdditive manufacturing, the metal version of 3D printing with plastics, has been receiving a lot of attention lately. But how does additive manufacturing compare with traditional CNC machining?

Additive manufacturing works by building up multiple layers, each only a few thousandths of an inch thick, until the final product is completed. It is essentially the opposite of traditional machining, which starts with a block of material and then removes excess to result in the desired product.

There are some advantages to additive manufacturing. For example, this process can be a good choice for highly detailed parts or products. Additive manufacturing can also be useful when a high volume of design iteration is anticipated.

However, additive manufacturing is still a newer technology, and creating new metallics from scratch is a slower process, adding time to the production run versus CNC manufacturing.

CNC machining, by contrast, cuts away excess material from an original block rather than building up an object layer by layer. To compare the two technologies, CNC is most akin to a potter’s wheel, where a single lump of clay is refined through shaping and trimming to a final form. Additive manufacturing, however, takes small pieces of clay, slowly working them together to a finished product.

Despite the fact that it is the older technology, CNC machining has a number of advantages over additive manufacturing. To start, CNC is much faster than additive manufacturing. The difference is noticeable on a single cycle, but is significant when considering multiple objects. CNC can also be used with many different materials unlike additive manufacturing which, by contrast, is used mostly with plastics and some metals. CNC is most commonly associated with metals, but can also be used with plastics, wax, wood and more.

So which process is better? While both processes are computer controlled and are capable of producing high-quality products, the bottom line is that additive manufacturing does not yet compete with CNC for most applications.

In most cases – especially anything involving large-scale production – CNC remains the dominant choice for speed and efficiency.

However, for intricate detail and precision detailing, additive manufacture can offer some distinct advantages. At the end of the day, the question may not be which is better, but instead which is the best choice for a specific application, with products requiring both technologies in tandem to create a finished part or item.

CNC Masters has been helping hobbyists and business owners take their machining to the next level since 1990. Our CNC milling machines are designed to meet the needs of a variety of users, including those who need a mill with a small footprint. Contact us today at 626-962-9300 to find out how we can help you achieve your manufacturing goals.