Evolving from the numerical control (NC) machining process which utilized punched tape cards, CNC machiningis a manufacturing process which utilizes computerized controls to operate and manipulate machine and cutting tools to shape stock material—e.g., metal, plastic, wood, foam, composite, etc.—into custom parts and designs. While the CNC machining process offers various capabilities and operations, the fundamental principles of the process remain largely the same throughout all of them. The basic CNC machining process includes the following stages:
Designs for CNC machined parts are restricted by the capabilities (or inabilities) of the CNC machine and tooling. For example, most custom CNC machine parts tooling is cylindrical therefore the part geometries possible via the CNC machining process are limited as the tooling creates curved corner sections. Additionally, the properties of the material being machined, tooling design, and workholding capabilities of the machine further restrict the design possibilities, such as the minimum part thicknesses, maximum part size, and inclusion and complexity of internal cavities and features.
CNC Metal Spinning
Close cousins to lathes, CNC spinning lathe machines involve a lathe set with a blank (a metal sheet or tube) that rotates at high speeds while a metal spinning roller shapes the workpiece into a desired shape. As a “cold” process, CNC metal spinning forms pre-formed metal—the friction of the spinning lathe contacting the roller creates the force necessary to shape the part.
How Does a Swiss Machine Work?
Swiss machining, also known as swiss screw machining, uses a specialized type of lathe that allows the workpiece to move back and forth as well as rotate, to enable closer tolerances and better stability while cutting. Workpieces are cut right next to the bushing holding them instead of farther away. This allows for less stress on the part being made. Swiss machining is best for small parts in large quantities, like watch screws, as well as for applications with critical straightness or concentricity tolerances. You can find out more about this topic in our guide on how swiss screw machines work.
How Does a 5 Axis CNC Machine Work?
5 axis CNC machining describes a numerically-controlled computerized manufacturing system that adds to the traditional machine tool’s 3-axis linear motions (X, Y, Z) two rotational axes to provide the machine tool access to five out of six part sides in a single operation. By adding a tilting, rotating work holding fixture (or trunnion) to the work table, the mill becomes what is called a 3+2, or an indexed or positional, machine, enabling the milling cutter to approach five out of six sides of a prismatic workpiece at 90° without an operator having to reset the workpiece.
It is not quite a 5-axis mill, however, because the fourth and fifth axes do not move during machining operations. Adding servomotors to the additional axes, plus the computerized control for them – the CNC part –would make it one. Such a machine- which is capable of full simultaneous contouring- is sometimes called a “continuous” or “simultaneous” 5-axis CNC mill. The two additional axes can also be incorporated at the machining head, or split – one axis on the table and one on the head.
CNC Lathe Operator Training
To handle a CNC lathe, a machinist should have completed a set amount of coursework and earned appropriate certification from an accredited industrial training organization. CNC turning machining training programs will usually involve multiple classes or sessions, offering a gradual instruction process broken up into several steps. The importance of adhering to safety protocols is reinforced throughout the training process.
Beginning CNC lathe classes might not include hands-on experience, but they may include familiarizing students with the command codes, translating CAD files, tool selection, cutting sequences, and other areas. A beginner CNC lathe course may include:
Lubrication and scheduling lathe maintenance
Translating instructions into a machine-readable format and loading them into the lathe
Establishing criteria for tool selection
Installing tools and parts for handling the material
Producing sample parts, like die-casting parts
Later CNC lathe training typically involves actual lathe operation, as well as machine adjustments, program editing, and the development of new command syntax. This type of lathe machine training can include courses on:
Figuring out where edits are needed from comparing sample parts to their specifications
CNC programming edits
Creating multiple cycles of test components to refine the results of edits
Regulating coolant flow, cleaning the lathe, and repair and replacement of tools
CNC Machining Equipment and Components
As indicated above, there is a wide range of machining operations available. Depending on the machining operation being performed, the CNC machining process employs a variety of software applications, machines, and machine tools to produce the desired shape or design.
CAE: Computer-aided engineering (CAE) software are programs used by engineers during the pre-processing, analysis, and post-processing phases of the development process. CAE software is used as assistive support tools in engineering analysis applications, such as design, simulation, planning, manufacturing, diagnosis, and repair, to help with evaluating and modifying product design. Types of CAE software available include finite element analysis (FEA), computational fluid dynamics (CFD), and multibody dynamics (MDB) software.
Some software applications have combined all of the aspects of CAD, CAM, and CAE software. This integrated program, typically referred to as CAD/CAM/CAE software, allows a single software program to manage the entire fabrication process from design to analysis to production.
What is a CNC Machine? Types of CNC Machines and custom CNC precision machining parts