The basic CNC machining process includes the following stages:

• Designing the CAD model

• Converting the CAD file to a CNC program

• Preparing the CNC machine

• Executing the machining operation

CNC machining is a manufacturing process suitable for a wide variety of industries, including automotive, aerospace, construction, and agriculture, and able to produce a range of products, such as automobile frames, surgical equipment, airplane engines, gears, and hand and garden tools. The process encompasses several different computer-controlled machining operations—including mechanical, chemical, electrical, and thermal processes—which remove the necessary material from the workpiece to produce a custom-designed part or product.   The most common mechanical CNC machining operations including:

• Drilling

• Milling

• Turning

In the case of CNC drilling, the CNC machine usually advances the rotary drill bit perpendicular to the plane of the workpiece surface. This technique produces vertically aligned holes. Their diameter is equal to the diameter of the drill bit used for drilling. The operational capabilities of the drilling process include counterboring, milling, reaming, and tapping.

During CNC milling, the CNC machine feeds the workpiece to the cutting tool in the same direction as the rotation of the tool.   This is not the case with manual milling.   Here, the machine feeds the workpiece in the opposite direction to the rotation of the cutting tool.   The operational capabilities of the milling process include :

• Face milling: cutting flat, shallow surfaces and flat-bottomed cavities in the workpiece;

• Peripheral milling: cutting deep cavities in the workpiece, such as slots and threads.

The subtractive process of CNC machining provides multiple benefits for both prototyping and low-volume production parts.

• Precision and repeatability

• Tight tolerances

• Production-grade materials

• Fast Turnaround

Which material to choose for CNC machining?

CNC Metals 

Applications that require high strength, hardness, and thermal resistance exploit metals or, rather, metal alloys. 

• Aluminum: used to create custom metal parts and prototypes.

• Stainless steel can be easily welded, machined, and polished. 

• Mild steel, or low-carbon steel: used for machine parts, jigs, and fixtures. 

• Alloy steel contains other alloying elements in addition to carbon to improve hardness, toughness, fatigue, and wear resistance. 

• Tool steel is advantageous for fabrication tools such as dies, stamps, and molds.

• Brass is ideal for applications that require low friction and architecture to design gold-looking parts for aesthetic purposes.

Plastics are lightweight materials with different physical properties, often used for their chemical resistance and electrical insulation characteristics. 

• ABS: often used to manufacture prototypes before mass production by injection molding.

• Nylon, or polyamide (PA): mainly used for technical applications because of its excellent mechanical properties, impact strength, and high resistance to chemicals and abrasion.

• Polycarbonate is generally optically transparent, making it ideal for many applications, such as fluid devices or automotive glazing.

• POM (Delrin) is the material of choice for CNC machining when parts require, which is high precision, high rigidity, low friction, excellent dimensional stability at high temperatures, very low water absorption.

• PTFE (Teflon) has resistance to operating temperatures above 200 °C and is, therefore, an outstanding electrical insulator. 

• High-density polyethylene (HDPE) is suitable for outdoor use and piping. 

• PEEK: mainly used to replace metal parts due to its high strength-to-weight ratio. Medical grades are also available, making PEEK also suitable for biomedical applications.

• The Aerospace Industry

• The Medical Industry

• The Transportation Industry

• The Oil and Gas Industry

• The Military and Defense Industry

• The Electronics Industry

• The Maritime Industry