A Computer Numerical Controller refers to a computer that reads machine code instructions in order to control a machine tool. Computer Numerically Controlled, (CNC), Machine tools are usually used for machining raw material stocks into completed designs by undertaking a series of such instructions. CNC low volume machining are probably the most widely known use of this engineering science. They spin a block of material so it can be cut, sanded, drilled or finished, with the end result being a completed three-dimensional item. In reality, CNC lathes are simply the same as an old-fashioned turret lathe, but running under computer control.
The invention and proliferation of electric motors in the early twentieth century inevitably led to traditional types of lathes becoming electric powered. This was the first major step towards today’s computer controlled lathes, and came about as manufacturers sought to increase productivity and reduce costs.
Constituent Parts / Components
Modern CNC lathes are a combination of a computer with a lathe machine and a controller that converts each digital signal into the desired action. Specialized software is first used to create the required design that needs to be replicated physically on metal, wood, etc. The work piece is next fitted on the chuck and rotated at slow or high speeds depending on the material and the type of cut or centering required. The computer then controls the cutting action of the lathe as required in order to produce the finished product. Modern lathes can have multiple spindles so that multiple transformations can be carried out on the end product without having to stop and reload it in a different orientation.
CNC lathes are typically equipped with three jaw hydraulic chucks. Holding of the raw material to be transformed is usually done with hard jaws or bored soft jaws. Lathes may also have a collet chuck. This allows for variable size and precision holding without the need for soft jaw boring. When equipping a lathe with a collet chuck, it may be necessary to modify or change the draw bar connecting the actuator to the chuck.
The tool pieces that are required to cut through steel are usually made of titanium carbide, tungsten carbide, and other hard alloys depending on the material that needs to be cut. The tool bits are utilized until the tolerance levels are maintained after which they are either sharpened where possible, or replaced with a new bit.
Despite their precision, CNC lathes generally require a good operator to oversee the mechanised process. This is still a much quicker, more productive and more cost effective solution than traditional lathes could achieve. A developer is also required to compile the program commands needed to instruct the equipment in the first place.
Programming a CNC lathe firstly requires a blueprint of the item to be created. After the blueprint is analysed, the programming of the cutting tools required for making each part can then be started. Every move in three dimensions is programmed, in extremely fine detail. A lot of skill and quality review is required at this stage to ensure no problems occur once the program is running in the live environment.
Practical Applications of CNC Lathes
CNC lathes are often used on hard materials such as metal, that require the material to be processed, usually through turning at high speed. They are also used to drill precise holes, including exactly centered holes usually in blocks of metal. The material does not have to be metal, as other materials such as wood and plastics can also be processed quickly and effectively by a CNC lathe. They are commonly used in light, medium and heavy engineering shops for creating many of the objects we see in everyday use. There is still a place for more traditional manual and electric lathes however. Usually this is where craftsmanship is a key part of the finished product, or where low production volume does not warrant the cost of a CNC lathe.
Advantages / Benefits
CNC Lathes have rapidly replaced the older manual lathes due to their ease of programming and operation. They provide a more rapid turn-round time for complex one-off parts and ensure consistency in quality control and design tolerances. They are very much leading edge technology in engineering circles and embody the latest processes and design principles. Three further benefits are reduced production time, reduced inventory and reduced set up times. With the general rise in production levels, automated CNC lathes ultimately offer higher production volumes, with greater precision and fewer errors.