CNC (Computer Numerical Control) machining is a manufacturing technique in which a material such as metal, plastic, wood, foam or any other is cut by a computer controlled machine tool into a specific shape or dimensions. Asking for custom parts to be cnc machined can be a good option for the prototype or when small runs or when parts have complex shapes are needed. This is an article that contains an overview of some essential facts that you may be interested in or should know about CNC machining.
How CNC Machining Works
CNC machining is a manufacturing process that is informed by a computer that operates machinery to shave material in a predetermined manner to achieve the desired part geometry. It commences with the desire geometry of the part using a digital 3D modeling package converting into CAM (Computer Aided Manufacturing) programming code that contains all the directions on how the tools in the machines will manufacture the part with the raw material by applying tool paths of subtracting material.
CNC machines employed in machining operation include the milling machines, lathes, routers, grinding machines and electrical discharge machines (EDM). The computer influences the movements and functions of the tools through the machining process with an extremely high level of precision and consistency. In fact, the cutting tools or abrasive wheels mounted on the machinery merely cut, drill or grind the raw material away in accordance with the instructions and program until the final dimensions of the part are attained.
Computer numerical controlled machining is a high-precision type of machining that is ideal for creating numerous small runs or even a single unit of a highly specialized design. Design changes are easily made through modifications in the digital CAD model and the software used to control the machining process. This makes CNC an ideal approach particularly when an inventor who wants to prototype an idea or a company which wants to innovate new products using metals, plastics and other raw materials.
CNC machining is a manufacturing process which utilizes Computer Numeric Control technology to operate and control machine tools used in the shaping and forming of materials.
There are several specific CNC machining processes offered by machine shops and contract manufacturers:There are several specific CNC machining processes offered by machine shops and contract manufacturers:
- CNC Milling: CNC Milling is a process in which a block work piece is fed to a cutting tool in the form of a rotary cutter. Generally used milling processes are face milling process, plain milling process, side milling process, and profile milling process. CNC mills are very versatile and can produce practically any features such as slots, holes, edges, pockets, surface textures and more by slowly taking away material as instructed until the final cast of the 3D model in the CAD program is produced.
- CNC Turning: CNC lathes turn the block material and the non-rotating cutting tools are passed over it to cut and format it to cylindrical shapes and to certain dimensions. The workpieces can then be subjected to other milling operations for increased complexity and shape. This innovative lathe is perfect for manufacturing rotationally symmetric parts for automotive, aerospace, medical industries and others.
- CNC Drilling: Computer-controlled multihole patterns are easy to program and drill on a computer numerical control machine. Some of the mills and lathes are programmed to hold automatic tool changers to allow them to change drills at very high speeds. It enables the generation of many-holed patterns that are almost impossible to make through manual intervention.
- CNC Boring: While drilling is used to make through holes, boring is used to create precise internal diameters to a very close tolerance with cored holes, or by enlarging the diameter of a hole. Boring bars can create holes that are parallel to the shaft or perpendicular to the shaft. This is particularly relevant to cylindrical components such as tubes, gun barrels and bearings, hydraulic parts, etc, where fine internal diameters need to be produced.
- EDM (Electrical Discharge Machining): Non ferrous metals that are otherwise difficult to cut using other tools such as tool steel carbide titanium and stainless steel can be cut by EDM. It employs the use of electrical impulses that discharge for a given time to remove material and achieve a burr-free cutting of intricate contours on even the most unusual materials such as the exotics. It is not based on the concept of cutting forces. Some of the major subtypes of the electro-discharge machines include wire EDM and sinker EDM.
Advantages of CNC Machining
Some key advantages that make CNC machining popular for custom part creation include:Some key advantages that make CNC machining popular for custom part creation include:
- Precision and Accuracy: Newer control technology of CNC machines is capable of holding precision of below 5 microns (0. 005 mm), far much better than if one were to do it manually. This results in quality high performing components in the production line.
- Low Setup Time: By adopting CNC automation and tool changing, transition from one product to another is easily addressed. Automation can be preferred as new jobs can be established faster when compared to manual equipment.
- Speed and Efficiency: CNC carries out cutting operations at night and during the day and at other off-hours at work. It also significantly reduces machining time as more than one axis can be machined at an equal time.
- Improved Quality and Consistency: The computer numeric control also eliminates possibilities of inconsistency that arises from manual operations. This leads to high degree of consistency in the finish and quality of machine parts produced from one part to the other.
- Complex Geometries: When internal details are very sophisticated and the organics are intricate, CNC poses no challenge whatsoever, while such a part cannot be machined by hand.
- Scalable Production: CNC techniques are more efficient and adaptable in the range of low to moderate production of batches and therefore, customers do not have to purchase far more parts than what is actually needed for their demand, even if it is small.
CNC machining is a versatile method that can be applied in various situations within a production process but here are some guidelines on when CNC machining could be effectively used.
CNC machining is used when you want rigid metal or plastic custom parts with perfect shape and tolerance, or when they are complicated. It is very suitable for one-off or small production runs, bridge tooling in the actual production process, specialised clamps and holders, jigs and fixtures, mounts, and connectors, special machinery parts, aerospace and defense technologies, surgical instruments and tools, products of emerging technology research and development and any other designs which involve fine details that can otherwise not be economically produced by other means.
It is to be noted, however, that CNC machining does generate more waste material compared to other processes such as injection molding. Nevertheless, it is still fairly economically feasible when dealing with small batch quantities of 1-500. And, there is no need for expensive mold tools and this makes the designers capable of experimenting with different designs. Hence, these characteristics are more suited for innovation and to bring new products to the market in a quicker way.
