Subtractive manufacturing has long been a foundation of modern industrial production—but that doesn’t mean it’s old school. Tools, processes, and possibilities have been evolving to keep pace with the needs of manufacturers—and that pace is only accelerating thanks to recent advances.
The term subtractive manufacturing refers to any process in which material is cut, shaped, or finished to achieve a desired configuration and size. Whether you’re milling wood or carving stone, routing aluminum or cutting steel, even shaping plastics and composites—if you end up with less material than you started with, it’s subtractive.
Modern subtractive processes originated in the 1940s with the creation of numerical control (NC) machines. Engineers augmented existing machining tools with motors that moved the tool or part to follow instructions from punched rolls of paper tape. Beginning in the 1960s, computers became the controlling mechanism. Computer Numerical Control (CNC) machines revolutionized the industry and remain central to subtractive manufacturing today.
Whatever form of machining you’re talking about, CNC approaches bring us greater accuracy, less material waste, reduced labor costs, and improved safety. With CNC, machines can run 24/7, only needing to be shut down for routine maintenance or when problems occur.
Multi-axis machining enables you to shape your material from multiple directions either in sequence or at the same time. The earliest multi-axis milling machines were introduced in the 1800s and worked on three planes, meaning that the machine moved forward and backward, right and left, as well as up and down. Today, manufacturers have new options to boost efficiency and accuracy when creating components.
With 3+2 machining (sometimes referred to as positional 5-axis machining), you can translate the workpiece along the three axes, then rotate the tooling spindle on an additional two axes. The 5 axes don’t move at the same time—that’s why it’s called 3+2—but you can achieve many of the same benefits that full 5-axis machining offers.
With 5-axis machining, the X, Y, Z, A, and C axes can all move at the same time, and it’s something worth seeing in action.
3+2 machining often serves as a transitional step for companies when the cost of new 5-axis machines is prohibitive. Not every job requires 5-axis machining, but it does offer greater design freedom. With every kind of machining, there are limitations in terms of what shapes you can make. But when it comes to maximum productivity and accuracy, all 5 axes moving at the same time can’t be beaten. It also results in new processes and techniques being unlocked for manufacturers. Here’s an example of barrel finishing in Autodesk Powermill, a process that wasn’t possible with 3+2.
5-axis machining is a way to future-proof your machine shop and to make parts in new ways.
Subtractive manufacturing has been with us for a long time, and it’s not going anywhere. It’s still the best way to handle detail and finish work. Today, additive manufacturing offers new options for the forms we can make.
When we combine additive and subtractive techniques together on the same machine, we get hybrid manufacturing—the best of both worlds. Now you can create a new part from scratch with 3D printing, and then use CNC techniques to apply the finish.
You can also switch back and forth between methods—put down a layer of material with 3D printing, then use subtractive to machine it, then add another layer, and so on.
Companies can either buy additive manufacturing equipment to add to their CNC machines, or they can buy new machines that have both additive and subtractive capabilities.
The Future of Subtractive Manufacturing
A range of new technologies could transform the subtractive manufacturing landscape over the next 10 years.
For one thing, advances in the composition and configuration of the tools themselves are likely to change what’s possible. Manufacturers are already taking advantage of polycrystalline diamond (PCD) tooling, which is fabricated from sintered diamond particles. PCD tools are harder, more resistant to wear, and can run 10 times faster than standard carbide tools. They are also becoming available in smaller sizes and different configurations, making them applicable in a growing array of settings.
Another technology that will bring change to the industry is the Internet of Things (IoT). With IoT technology, different machines within the manufacturing space can collect data and communicate with each other in real-time with minimal human intervention. Manufacturing processes can be monitored and adjusted according to predetermined tolerances, enabling preventive and predictive maintenance, reducing machine crashes, and increasing tool life. Embedded IoT systems can also support worker training and augment the skills and abilities of operators. Errors can be tracked and data gathered, enabling you to improve operations over time. It’s a whole new approach to human/machine collaboration.
Finally, no discussion of the future of subtractive manufacturing would be complete without the mention of artificial intelligence (AI), which is driving change in every industry. Besides, what are you going to do with all that data from the IoT? AI can help you organize, analyze, then optimize data. It can even help you create digital twins of your manufacturing line—so you can simulate production before firing up the machines for real.
AI like this requires significant computing power, of course, but as processors become stronger and as additional power becomes increasingly available (and affordable) in the cloud, more becomes possible in subtractive manufacturing every year.