CNC Machining

Computer Numerical Control or CNC for short, is an automated process for controlling machine tools. In contrast to Manual Machining processes, CNC machines make use of computer systems, that are programmed at either a computer terminal or other user interface. The code is then sent to the machine which will automate the entire machining process using electric or fluid-powered motors and actuators to move the machine tools multiple axis of motion. This code is sent to the machine as a sequential program, meaning that each step of the process is rendered in sequence. A common form of CNC machine language is G-code. Often times this G-code is created as an output of CAD (computer-aided drafting) or CAM (computer-aided manufacturing) software tools, where solid models of the parts to be created are “drawn” and then transferred to the machine. 

CNC machining centers can cover a range of processes including; milling, turning (sometimes referred to as lathing), drilling, cutting, electrical discharge machining, grinding, 3D printing, and more. The most common types of equipment that fall under the CNC moniker are CNC Mills (Milling Machines) and CNC Lathes (Turning). These machine tool processes start with a raw material (typically metal, wood, plastic or other composites) and cut away material to a final desired shape through high speed relative motion between the “cutting tool” and the “work piece”. In this process small pieces or ‘chips’ of material are removed with a high frequency. Other technologies that are CNC controlled are typically referenced by their specific technology, eg- EDM (Electrical Discharge Machining). These machines can process a variety of different materials including; wood, plastics, metals, composites and ceramics. More about the specific manufacturing processes of machinery, along with our approach to this technology can be found on the CNC Machining Services page.

There are several benefits of CNC machines over traditional manual machinery. For one, because these machines are highly automated, it means that after the machine is programmed, it can run virtually unattended during operation. Adding additional automation for machine tending (part/material loading and unloading), can enable CNC machinery to run “lights out” or completely without human intervention. This is ideal for higher volume production batches. Once the program is created it can be stored and then recalled at the push of the button, making repeat production lots extremely efficient and cost effective. CNC’s boast great precision (accuracy and repeatability) performance as well, ensuring that you will achieve improved consistency throughout your batch. Additionally CNC equipment can create much more complex part geometry including contoured surfaces, and unique shapes.

Manual Machining

In contrast to CNC equipment, manual machining, as the name describes, requires much more manual intervention to operate the equipment. Instead of a programmer converting a blueprint or solid model of the desired part into machine code that will then be uploaded to a CNC, a machinist operating a manual machine, must instead convert the dimensional requirements of the part blueprint into hand operated motion on the machine tool to accomplish the same desired final outcome or finished part. This is done through a series of cranks and knobs used to control speed of a machining spindle and feed rate of the moving tables. Depending on the particular machine being used, the part or workpiece is either moved relative to a fixed spindle or cutting tool, or the spindle is moved relative to a fixed part. Machinists that operate manual machine tools, require significant training and education in order to understand how to operate the machine, how to read the print and specifics of different tooling types and material properties. 

Like CNC equipment, there are a variety of different processes that fall under manual machining. The most common are turning which is accomplished on a Lathe, milling which is accomplished on a Mill or Milling Machine, and drilling, which is accomplished on a Drill Press. More about the specific manufacturing processes of manual machinery, along with our approach to this technology can be found on the Manual Machining Services page. 

In general for higher volume production runs and repeat work a CNC may be a more ideal solution, in that the additional time required to ‘program’ the part can be amortized over the larger volume, and is outweighed by the efficiency gained through automation. On smaller runs or parts with less complexity, it is often advantageous to use manual equipment, as there is no programming time required. Technologies exist that can be paired with manual equipment to provide some of the same functionality of CNC control without all of the cost. For example, you can add G-code and contouring capability to some manual machines. Manual machines are generally limited in the complexity of parts they can produce, which is a significant advantage that CNC machinery has over them.

Electrical Discharge Machining (EDM)

Electrical Discharge Machining or EDM for short, is commonly referred to by a number of other names in industry including; spark machining, wire burning and die sinking to name a few. EDM is another subtractive manufacturing technology where material is removed from the work piece via a controlled series of rapidly occurring electric sparks. These electrical discharges pass from an electrode on the machine, through a dielectric (or non-electrically conductive) fluid (typically oil or deionized water) to the work piece, which functions as the second electrode in the system. As electricity passes from the tool electrode to the workpiece it starts to breakdown the material gradually removing it. This process is designed for electrically conductive materials most often metals. The tool electrode can be constructed into various forms to create unique shapes in the work material.

Electrical Discharge Machining is Computer Numerical Controlled (CNC) machining process, so like CNC Machining discussed above, EDM machines can achieve very tight control and consistency over the manufacturing process. They also require programming of the machine in advance of part creation. Generally speaking EDM machines can hold tighter tolerances and improved finish specifications over traditional machining technologies. EDM is also an ideal solution for metals with higher hardness properties, as the cutting rate is often un-affected by hardness of the work material. This means that raw materials can be machined fully-hard and therefore do not require post-processing heat treat to harden the part. This can improve cost and manufacturing lead time. EDM machines can also be used to cut very intricate surface contours which are more challenging for traditional machining technologies. 

There are three main types of Electrical Discharge Machining- Wire EDM, Sinker EDM and Hole-Drill EDM. Each has its own advantages and disadvantages in the manufacturing process and more information on each can be found on the Electrical Discharge Machining Services page.

Precision Grinding

Here we have used the term Precision Grinding to separate grinding processes that we see in the machine tool world from other grinding technologies like handheld angle grinding. In many cases industry will refer to this process as just Grinding or Abrasive Cutting. The material removal process is however nearly identical to what you may see when using a handheld power grinder. As opposed to using the cutting action of a drill or end mill, in this case an abrasive surface is used to spin at high rates of speed and when put in contact with the work piece, material is removed. Think of sandpaper on wood. All of the rough edges on the abrasive tool come in contact with the surface of the workpiece and material is then stripped away.

Of all of the above technologies Precision Grinding can achieve the highest finish specifications and tightest tolerances. Much like milling and turning machinery, grinding machinery can either be CNC or manually controlled. So in general grinding can be ideal low volume and high volume production. Like EDM technology grinding can also be used for high hardness materials. 

There are several different grinding technologies available each designed to support different surface geometries and features. More about the specific manufacturing processes of grinding equipment, along with our approach to this technology can be found on the Precision Grinding Services page.