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What is CNC Machining?

what is cnc machining

Many people ask the question “what is CNC machining”? CNC stands for Computer Numerical Control.  This is a type of machining which subtracts material from the raw stock.  In other words, parts are created by removing the material from the workpiece.  This is done using a myriad of cutting tools.

This is different from other manufacturing processes such as injection molding, 3D printing or casting.  CNC machining uses digital manufacturing technology, producing highly accurate parts from a CAD (Computer Aided Design) file.  CNC machining is very competitive on price because of this high accuracy and high levels of automation.  This makes it ideal for on-off custom parts, prototyping or mid-level production.

There is almost no limitation to the materials which can be CNC machined. With the most common examples being metals and plastics such as ABS, Delrin, and nylon.

The process

The process of CNC machining is:

  1. An engineer designs the part using CAD software
  2. This CAD file is then turned into a CNC program (G-code) and then sets up the machine
  3. The CNC system then carries out the machining, creating the finished part

A brief history of CNC

  • 700B.C. – The oldest machined part (a bowl) was discovered in Italy and it was produced using a lathe.
  • By the 18th century, attempts were made to automate the machining process.  The machines were mechanical and used steam power to work.
  • MIT (Massachusetts Insitute of Technology) made a programmable machine in the late 1940s.  Punch cards were used to program the process.
  • True computer programming was added to the process, hence Computer Numerical Control
  • Today, Wisconsin Metal Tech has machines with multi-axis and multi-tooling capabilities.

Types of CNC Machines

CNC stands for Computer Numerical Control.  This is a type of machining which subtracts material from the raw stock.  In other words, parts are created by removing the material from the workpiece.  This is done using a myriad of cutting tools.

what is cnc milling

3-axis CNC machines

These are basic machines which allow movement of the cutting tool in 3-axis – X, Y and Z (Left, Right, Back and Forth, Up and Down).  It is one of the most widely used CNC techniques for producing mechanical parts.

CNC Milling

3-axis CNC milling machines are the most common type of CNC machining.  They are relatively easy to program and operate, meaning they are used by new-start companies or where costs have to be kept low.

  • The tools are attached to a spindle, this spindle is allowed to move along three linear axis – X, Y, Z.
  • The part to be worked is held stationary directly on the machine bed.
  • The block’s material is removed from the part using cutting tools or drills which rotate at high speed.

Quick production of simple parts

Highly accurate with tight tolerances

CNC Turning

CNC Lathes are widely used because they are able to produce parts at a high are of production.  They also allow the cost per unit to be lower than CNC milling.  CNC turning does have a disadvantage in that the lathes can only produce parts with a cylindrical profile.  The only way to overcome this is to CNC mill parts separately, but this does increase costs.

  • The workpiece is held on the spindle while it rotates at very high speeds.
  • A cutting tool or center drill traces the outer or inner perimeter of the part, forming the geometry.
  • The tool does not rotate and moves along polar directions (radially and lengthwise).

Best for high production runs

Lower cost per unit

5-axis CNC machines (Multi-axis)

Multi-axis machines or 5-axis CNC machining is available in 3 different types;

  1. 5-axis Indexed CNC Milling
  2. Continuous 5-axis CNC Milling
  3. Mill Turning Centers with Live Tooling

5-axis systems are basically milling lathe machines with added degrees of freedom of movement.  5-axis machines, for example, allow the bed and the tool head to rotate in addition to the other 3 linear axes of movement.  These machines are ideal for highly complex metal parts.

Indexed 5-axis CNC milling

Also known as 3+2 milling machines, as they have 2 additional degrees of freedom of movement.  The main benefit of this is the elimination of time-consuming manual positioning of the part.  This allows a far higher accuracy to complex parts than 3-axis machines.

  • The cutting tool can move along 3 linear axes
  • The bed and the tool head can rotate between operations

No need for manual repositioning

Higher accuracy of complex parts

Continuous 5-axis CNC milling

This type of CNC milling system is similar to Indexed 5-axis machines but all 5 axes can move at the same time.  This makes it possible to produce complex parts with the highest possible level of accuracy.  Continuous 5-axis CNC milling comes at a price as expensive machinery and very highly-trained, experienced machinists are needed.

  • The cutting tool is able to move in 3 linear and 2 rotational axes
  • All 5 axes can move at the same time

Complex parts at an accuracy not available elsewhere

Smooth surfaces with little machine marks

Mill-turning CNC centers

A Mill-turning CNC center is a CNC lathe machines equipped with CNC milling tools.  A variation of these is the Swiss-style lathe, which offers even higher precision.  These systems have the advantage of the high productivity of CNC turning and the flexibility of CNC milling.  This makes them ideal for producing parts such as camshafts at a cost lower than 5-axis CNC machining.

  • The part is attached to the spindle which can rotate at high speeds or be positioned at a precise angle
  • Both lathe and milling tools can be used to produce the part

The lowest cost of all 5-axis systems

Highly productive capabilities

Design freedom

In summary, CNC Machining is the ideal manufacturing process for simple or complex parts.  We work with all types of steel, aluminum, copper, brass, and various plastics.  Have a look at our capabilities and the services we offer here.  If you have some more questions or would like to start a partnership with a leading CNC machining company, get in touch with us.

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