Subtractive Manufacturing refers to removing excess raw materials through processing in the manufacturing process and finally obtaining the required shape and size. Those that meet this feature are called subtractive manufacturing. This is in contrast to the current additive manufacturing corresponding to 3D printing, which used to be called machining.
Examples: original carved characters, furniture, things made with milling machines and lathes, all things made with materials. This process has been doing subtraction during the manufacturing process, so there will be the concept of raw material utilization, which means that the reduction of materials will produce waste.
The material does not limit it, but it is limited by the processing method. Even a highly complex processing method cannot process honeycomb-shaped objects, hollow objects, etc. For the machining, the tool can not make it.
Machining is an essential part of the manufacturing process for many metal products. Machining refers to the process of removing material from the workpiece. The materials manufactured are not limited to metals, but materials such as wood, plastics, ceramics, and composites can also be done with CNC machines. Common CNC machining machines include milling machines, lathes, punching and cutting machines, etc.
A person who specializes in machining is called a machinist. The room, building, or company where the machining is done is called a machine shop.
In smart manufacturing applications, smart machines are no longer operated by machinists but automatically through IoT and smart factory brains. The machine shop is still there, except that the shop is filled with smart machines and automatic unmanned lines, and the role of people is to prepare materials, maintenance, and repair.
The machining methods for reducing material manufacturing are usually divided into five categories: drilling, turning, milling, grinding, and planning.
A specific drill (Drill), rotating clockwise, is used to drill a hole in the workpiece, the parameters of which include the hole diameter and depth. The drill is usually a twist drill, and in the clockwise drilling, helical fragments (helical) are discharged along the grooves of the drill bit. This is one of the most common machining methods, with various drill bit types to meet various drilling needs.
This is the most basic way of machining on a lathe, where the workpiece is fixed on a rotating fixture, the tool itself does not rotate, and the workpiece rotates at high speed. The distance between the tool and the workpiece (distance from the center of rotation, radius) can be controlled.
This is the most basic type of machining on a milling machine, using a high-speed rotating milling cutter that follows a predetermined travel path through the workpiece. The tool’s parameters include the tool’s diameter, the geometry of the tooltip, the material, etc. The milling parameters include the milling depth, width of milling, tool rotation speed, feed speed, etc. In milling, the workpiece can be fixed, and the tool moves. It is also possible to move the workpiece while the tool is not moving.
Grinding uses a rotating grinding wheel to perform the workpiece. Similar to what we do with sandpaper, but in this case, it is the high-speed wheel that grinds the workpiece, using a coolant to achieve a cool down to grind.
Figure 2-29 Subtractive material manufacturing sample
5. Planing (Chip Formation)
Planing is a processing method of a planer, which is similar to the principle of a woodworking planer. However, the tool itself does not move, but the workpiece itself moves as a whole to achieve the purpose of processing. The same as the actual carpenter’s planer, but the machine helps realize the reciprocating movement, thus realizing the planning process. Figure 2-29 Subtractive material manufacturing sample with milling done by skeletonizing cutter and drilling done by twist drill.By learning the processing methods of subtractive manufacturing, understanding the processes in implementing smart manufacturing, how to use smart machines to achieve specific processes, and how to achieve unmanned operations.