Machining is the process by which material is precisely removed by mechanical means in a controlled manner by machine tools. Companies that perform machining are called machine shops.
Machining can be segmented into three process categories:
Cutting – the material is removed with single- or multi-point tools, sometimes designed of engineered for a specific predetermined part or result; examples include milling, turning and drilling (known as the 3 main machining processes)
Abrasive – the material is removed with an abrasive material such as a grinding wheel/tool, extrusion material or water (waterjet cutting)
Energy – materials are removed with electrical, chemical or other sources of energy; examples include electrical discharge machining (EDM), electro-chemical machining (ECM), laser cutting and plasma arc cutting
Machining can also be broken into two operational categories: manual machining and CNC machining.
Manual machining refers to the process by which a machinist sets up tooling and work holding, and then manually operates machine tools such as milling machines, lathes, drills or saws to perform various machining operations to make parts. Manual machining is the means by which all machining was once performed; today, it is usually only suitable for small lot runs with minimally complex geometry and other projects associated with prototype development.
Computer Numerical Controlled (CNC) machining refers to the machinist using CNC controlled equipment to perform the machining operations. Types of machine tools that can be CNC-enabled are called machining centers, turning centers, Wire EDM (Electrical Discharge Machining), and multi-spindle and Swiss-style screw machines – virtually any machine tool can be built or fitted with computer numeric controls. The vast majority of machine shops today utilize CNC machining technology to improve accuracy and efficiency. The CNC machines are programmed by converting part geometry in Cartesian coordinates (X,Y, Z) and formatting those coordinates into a programming language such that the CNC controller can interpret them move the axes of the machine tool to automatically remove the required material from the work piece to form the finished machined component. CNC machining produces parts in a very consistent manner and is ideal for large quantity part runs and parts with complex geometry.
Machine shops automate the programming of CNC machines by utilizing CAD\CAM (Computer Aided Design \ Computer Aided Manufacturing) systems. The part geometry is transferred from the CAD system to the CAM system where the machinist can apply and visualize various machining strategies in a virtual on-screen environment. These strategies are applied to eliminate waste, select more efficient tool paths, improve surface finish, and other process improvements. Once the machinist is satisfied with a particular machining strategy, the CAD\CAM system will output the CNC code, commonly referred to as g-code, post-processed and ready to load into the controller of the machine tool that will be used to actually perform the machining operations.
Machining is used in all industries and applications, including aerospace, medical, energy, military/defense, and transportation/agriculture for heavy equipment manufacturing.
For more on machining applications and processes:
5 Axis Machining
Emergency / Onsite
Machining of Castings
Micro Machining (Miniature Machining)