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What is CNC Machining?

CNC machining, which stands for “computer numerical control” machining, is where an engineer-programmed computer guides and commands the tool and machinery in a factory. While a CNC machine runs, a machinist pushes manufactured parts through the system by operating any manual buttons or levers. Though there is still manual labor associated with CNC machining, the computer software saves company resources by controlling complex machinery and reduces the necessary labor cost per manufactured part.

To start the operation of a CNC machine, an engineer must enter the designed program into the computer software. In turn, the deigned program will communicate the path the machine must take to develop the desired manufactured part.

Using numerical control, or G-code, the corresponding machine is given the desired functions such as accurate speed, feed rate, and coordination. The use of G-code allows the CNC machine to run mostly independently, including repetition of cycles, and reduces the need for manual attentiveness.

In CNC machining, movement is most often programmed across the X and Y axes. The G-code then dictates the movements of the tool which has been positioned and guided via stepper or servo motors. For any project that requires more than the minimal amount of force and speed, a closed-loop system will be used to ensure accurate speed, consistency, and precision required.

 

Types of CNC machine programming:

  • Open/Closed-Loop Machining Systems

    • Open-Loop/non-feedback system: The signal moves in a single direction between controller and motor, eliminating possibility for error feedback that strays from the exact specifications outlined in the G-code. This makes an open-loop system practical for less complex applications using stepper or servo motors.

    • Closed-Loop/feedback control system: The controller is able to receive feedback, which allows for error correction, and can regulate minor anomalies in process. A closed-loop system is best used to control speed, consistency, and accuracy used for applications like Tool Building for Plastic Injection Molding.

 

Types of CNC Machines:

  • CNC Mills

    • A CNC Mill, controlled by pre-programmed computer software, rotates with a cylindrical tool bit, also known as a milling cutter. The milling cutter, held by the spindle, varies in size and shape based on the requirements of each job. A CNC Mill is designed to move along the multiple axes which, in turn, allows the cutter to achieve a large range of angles. In a typical CNC Mill, there are 2-5 axes the cutter can travel along.

  • Lathes:

    • The Lathe is a versatile machine used for material removal by actions such as sanding, cutting, drilling, knurling, or deformation of tools. The Lathe spins on its axis where the material is then carved away to create the desired product shape.

  • Plasma Cutters:

    • Using an accelerated jet of hot plasma, a Plasma Cutter is able to cut through electrically conductive materials such as steel, stainless steel, aluminum, brass, copper, and more.

  • Electric Discharge Machines (EDM):

    • A Die Sinker EDM is used when creating complex cavity shapes, for example, plastic injection molds. First, a positive form is created from a graphite electrode to project he desired cavity shape. The graphite electrode is then submerged into the machine, causing sparks to eat away at the surface as the sparking gap (or the distance necessary to produce sparking) closes.

    • A Wire EDM uses a thin wire as an electrode to make dies from hardened steel. As the wire moves along a controlled path, the electrical discharge becomes eroded between the wire and the workpiece. Therefore, a spool of wire continuously threads wire through to maintain a fresh discharge.

    • A Hole Drilling EDM drills precise holes by spinning a high-speed electrode tube on an electrically conductive material.

  • Water Jet Cutters

    • A Water Jet Cutter can cut through a large range of materials using a high-pressure water jet. The jet can pump pure water or a mixture of water and an abrasive substance used to cut through harder materials such as metal. This type of CNC machine is compatible with materials that would sustain damage at high temperatures often associated with other CNC machines.

 

What is the process from inception to production?

  1. An individual or organization develops an idea for a manufactured part or complete product.

  2. A 2D or 3D CAD drawing is developed to allow for accurate and timely quoting.

  3. At receipt of a P.O., or purchase order, the provided CAD drawings are translated into G-code that communicates to the CNC machine.

  4. To ensure a well-crafted part, the operator will complete a trial run to test for any flaws in the coding.

  5. After any potential issues with the design are resolved, a complete 1st round or full order is completed, dependent on order specifications and desired quantity.