CNC vs manual: which of these two technologies is better? Why are more and more machine shops choosing computer numerical control? To work out which of these two machining approaches suits you, you need to know the characteristics of each.
What are conventional machine tools?
Machine tools have been around for thousands of years. The lathe is said to have been the first machine tool ever invented and, of course, it was very different from the way we know it today. Throughout human history, and until the arrival of CNC, conventional machine tools served their purpose: making people's work easier.
Conventional machine tools include lathes, milling machines, drilling machines, grinding machines, presses, bending machines and many more. All of these machines have something in common: operator involvement. In other words, to work properly, factory operators have to apply their knowledge, skill and strength to machine the part.
Some very complex parts require very tight tolerances. With conventional machines, this type of part can only be machined on, for example, grinding machines. The grinding machine is an incredibly effective machine, but it demands great precision and a lot of work from the operator. It is also a fairly slow machine in itself.
Working with standard machines requires skilled operators. That is how trades such as that of turner-milling machinist came about.
Advantages of conventional machines
CNC vs manual: what are the benefits of the latter for the metalworking industry? A manual machine is considerably cheaper than one that runs on computer numerical control. This makes it the best option for workshops that do small production runs or have a limited budget.
For example, if turning is routine in your workshop but the machine is not used that much, one of the various types of lathe available is enough. If, on the other hand, you run series production and this is your most-used machine, you may need a CNC. Manual machining is also ideal for working metal parts, as well as plastic ones. The metal parts concerned are simple ones. The cost of machining is also lower than with other methods.
CNC vs manual: why computer numerical control?
Computer numerical control, or CNC, unlike manual machines, works through a computer. This makes machine tools automatic. Machines with this technology, which can also be lathes, milling machines, drilling machines and so on, have an integrated computer that runs the machining process required on the part.
The machine itself, with its sophisticated tool holder, can switch between milling cutters and drills, for example, when two different machining operations are needed on the same part. For this tool change to happen, a prior design of the part is needed. This is done on external computers using computer-aided design software (CAD) and manufacturing software (CAM).
Once the part is designed, the operator must enter it into the machine translated into alphanumeric CNC language. The machine can be programmed manually or loaded with an existing program. That is all it takes for the computer to know what it has to do to turn the computer design into reality.
What are the benefits of CNC?
CNC vs manual: why is CNC the best option? CNC is a good choice if you have a machine shop where series production of parts or the manufacture of very complex parts is required. This is because CNC, despite its many advantages (which we will look at below), is an expensive technology. The investment in a CNC machine can be paid back over time, provided the production rate is good.
A computer numerical control machine is very versatile and precise, which is why many large industries use them. The parts are incredibly complex and all kinds of materials can be worked: from metal cutting to laser engraving or glasswork. Also, because CNC machines are automatic, they require minimal human intervention; a single operator can work with several CNC machines at the same time.
Because CNC is a technology that runs through a computer, human error is practically eliminated. The computer does all the calculations needed for the job. The machine determines the tool it needs, the cutting speed, the depth of cut and so on. As a result, the output is high quality, with great precision and demanding tolerances if the part requires them.
CNC machines can carry out different types of machining on the same part without the part having to be repositioned. The operator mounts the part in the chuck (a robotic arm can also do this) and the machine starts working; if the machine needs to switch from the milling cutter to the drill, it changes the tool automatically. If a greater tilt angle is needed, the machine positions the part as required, with no operator intervention.
Finally, machining is faster, which shortens lead times and improves the production rate.