Starting with raw materials and milling, turning, or drilling down to the right shape has long been the known and preferred method for machine shop production. Over the years, process evolution has given subtractive manufacturing a diverse range of tools, devices, and methods for creating a wide array of parts and products. Beginning in the 1980’s, 3D printing reversed this process, building materials from the bottom up through a combination of CAD software and laser technology, first constructing simple objects like hammers and screwdrivers and now building complex, delicate items such as dental implants or aerospace components. Where they have been traditionally separate processes, many manufacturers are combining the advantages of each process in different ways to optimize production.
Combined by Tools
You have to add to subtract. More than a mathematical principle, a German manufacturing took this idea into its machine shop to produce subtractive tools through an additive process. In producing drills with through-coolant capabilities, the smallest drill size was limited by subtractive machining processes. Milling down a drill smaller than 13 mm created instability that subtractive machining couldn’t compensate for. However, building up the small drills through laser melting of a metal powder base created drills with more efficient coolant channels and sizes as small as 8 mm. These small drills will go on to precisely machine other tools and components through subtractive manufacturing.
Combined by Process
While additive manufacturing can produce a smaller, more precise product, or a more complex piece through computer-aided design, milling and turning can typically produce more simple parts faster. For complicated pieces required in large amounts, the combined advantages of both processes can produce more parts with exact specificities in a smaller time frame. Okuma America Corp. incorporates a combined system of their own subtractive machines with RPM Innovations’ additive devices to create a streamlined production line, giving additive machines the jobs that would be impractical for milling machines, and using subtractive manufacturing for quick, high-production jobs.
Combined by Production Stage
When it comes to design, prototyping or customization, CAD programs allow engineers to make small corrections and changes with a few clicks, and see what their product would look like in small batches made through 3D printing. If the design doesn’t work, a different small batch can be constructed without retooling machines or changing production processes. For items that are ready for production in large volumes, machining creates a fast, cost-effective, efficient system for pumping out thousands of units. For simple products that require little or no customization, traditional machines and processes can get the job done fast and easy. Together the processes create a market-ready product optimized for manufacturing and design.