Machinists use a rotary cutter during the milling process to remove excess material from a workpiece. The cutting tool usually remains perpendicular to the part. It often include a number of cutting points which shear away unwanted material.
Today, milling has become the most common form of machining. This process allows machinists to create many different types of features on a workpiece. In its most basic form, milling requires just a few essential components: a workpiece, and a milling machine equipped with a fixture and a milling cutting blade (or blades).
Manual Operation vs CNC Machining
Before the invention of computers, manufacturers relied exclusively on manually operated milling machines. Today, hobbyists in home shops sometimes still use manual milling technology. Yet automated CNC mills usually offer many production advantages.
For example, compare the technology of a jewelry maker milling a metal ring band manually compared with a manufacturing plant using CNC machining to generate multiple identical metal ring bands per hour. A craftsman producing a single ring with the assistance of a manual mill must physically direct the cutting tool to help shape the finished product. By contrast, during CNC machine milling, a computer software program helps automate machining processes. It may allow a manufacturer to turn out several identical ring bands within a short period of time by permitting simultaneous uniform cutting along pre-designated angles.
The acronym CNC stands for "computer numerical control". Automation permits the process of milling to occur more rapidly and more uniformly within fabrication environments.
A CNC milling machine relies upon a computer processing unit to direct the movements of the milling cutter blade along coordinates within a numerical grid system. Many of these machines utilize a vertical grid (although CNC mills using horizontal grids also exist).
A modern CNC mill usually consists of a fixture, a sophisticated controller unit and interface technology, one (or more) milling cutter tools, a motorized drive system, a cooling system and an electrical system to handle inputs and outputs. Typically, a software program will direct the machine's movements. A CNC mill allows an operator to cut along arcs more easily.
CNC Milling Devices
Modern CNC milling devices fall into groups based upon the capabilities of the milling machines. Today, companies engaged in manufacturing may rely upon very advanced computer numerical control milling machines to generate large quantities of uniform metal components.
Typically, manufacturers classify these machines based upon the number of axes available to the rotary cutting tool. Machines today usually offer between 3 and 5 axes at a minimum:
3-axis CNC Machining
The machine offers X and Y horizontal movements, plus a Z axis allowing up and down movement.
4-axis CNC Machining
Some modern CNC milling machines also furnish a W axis to permit easier diagonal movements of the cutting tool over a vertical plane, in addition to standard 3 axis CNC X, Y, and Z movement.
5-axis CNC Machining
A machine offering a variety of cutting angles, and therefore typically requiring CAM ("computer aided mapping") programming capabilities. A program translates computer assisted drafting designs into 3-D models. These sophisticated machining tools use a standard 4 axis CNC format (X,Y,Z, and W axes), plus the ability to cut at a variety of angles. A 5 axis CNC machine offers capabilities to form very complicated, intricate shapes from a multitude of angles. By swiveling the angles of cutting blades, the milling machine spindles permit the reproduction of complex shapes accurately.
Large Format CNC Mills
Large format machines can replicate much larger parts than other types of CNC mills. For instance, they may possess longer spindles capable of moving across an expanded grid. These milling machines permit manufacturers to produce larger components compared to other CNC mills. CNC large format machines offer numerous advantages for firms engaged in industrial parts manufacturing, for instance. They may permit the generation of metal parts in a greater range of sizes.
Benefits of CNC Mills
The benefits of a CNC mill sometimes vary. However, these machines typically offer greater throughput and accuracy than manual milling tools. By enabling a manufacturer to reproduce a part repeatably with a high degree of positional precision, a CNC mill helps ensure the duplicability of metal components. Machine manufacturers can rely on a software program to assist the automated cutting mill in reproducing the exact same workpiece dimensions every time. (Human error generally won't result in parts failing to meet desired design specifications unless a computer programming or other manufacturing mistake interferes with the correct execution of the milling software program.)
A CNC mill offers other potential advantages, also. For instance, a computerized program may enable a design team to better visualize the appearance of a final milled product before the construction of a prototype. In the past, machinists could not take advantage of this type of "virtual reality" preview.
Today, a CNC mill may work efficiently with a wide array of materials, including woods, metals and plastics. Well-designed CNC milling machines often rely upon user-friendly interfaces to reduce the learning curves involved in applying this technology within a production environment. Since computers may possess the capacity to store libraries of materials, some machines enable machinists to select from a number of stored design programs. When correctly operated, a CNC mill used in conjunction with excellent quality control measures can reproduce metal components rapidly and accurately, usually with a far greater degree of accuracy than conventional manual milling technology permits. In some fabrication environments, automated milling machines reduce manpower requirements, and thereby promote leaner, more efficient manufacturing!