CNC - computer-aided woodworking

I was writing not long ago about Alexander Grabovetskiy and how he carves wood with a chisel like his great-grandfather used to do, making true works of art. When there is no pretense of making unique works, all this work can be done with the help of machines that can produce drawings and sculptures and reproduce them identically at any time. These are CNCs, or CNC routers, to use an international term.

The name CNC stands for Computer Numerical Control and refers to the fact that woodworking tools are controlled by numerical commands from a computer. The machines are not specific to the woodworking industry as they are also used to cut metals, plastics, polyurethane foam, etc. The idea of sending commands to a machine goes back a long way, the first such devices being a loom in the 1720s which used punched paper cards to embroider or the mechanical flute, invented in 1860, which used a roll of paper with holes in it. Technology evolved and in 1955 the first industrial CNC machines were sold. With the advent and development of computers and IT technologies, CNC machines have achieved remarkable performance.

Any CNC uses a computer program to drive a mechanical system. The machining is done very accurately, is reproduced identically, and the machine does the job better than an operator. In general, the computer coordinates the movements of the mechanical system in the 3 Cartesian directions x, y and z, i.e. length, width and height, creating a 3D image. The x-direction is responsible for the front-back movement of the machining tool, the y-direction for the left-right movement and the z-direction for the up-down movement. In addition to these standard directions, there are also machines with 4- or even 5-direction movements. In addition to the tool directions, the rotary movement is also performed in one or two planes. The machines can produce very fine work, even sculptures.

CNC machines are very diverse, ranging from high-performance, high-productivity and highly efficient models designed for large-scale industry to designs that fit perfectly in a workshop. Regardless of size or performance, they all have a few main components:

• CNC computer and controller is basically the brain of the machine that transmits to the tool the commands needed to realize the movement. Basically everything starts from a digital drawing which is transformed by a program into codes transmitted to the tool. The computer converts the commands into digital signals and the CNC controller into pulses that control the mechanical system.
• Router is the assembly containing the tool (cutter, drill, knife, etc.) and the device that rotates it. The speed of rotation is adjustable, in the case of woodworking tools, between 8000 and 30,000 rpm. Woodworking machines can also process non-ferrous metals (aluminum). Cooling systems are required for iron objects because the tools heat up as a result of friction. Depending on the model and its performance, the computer can vary the rotational speed according to the material, control automatic tool change or tool sensors.
• The clamping system, which is intended to hold the workpiece fixed and secure it for machining. There are various forms or systems for clamping, the most important being clamping with clamps or suction (vacuum). Modern systems use a combination of the 2.
• Linear guidance system is what moves the router on the 3 axes of movement. The movement is realized with the help of the motor which is the link between the electronic and the mechanical part.

By size, machining capacity and efficiency, CNC machines can be divided into 4 broad categories:

• Industrial - are large and rather expensive machines, designed for long working hours and heavy operating conditions. They are equipped to be primarily efficient, having high machining speed, automatic tool change, wood dust suction system, advanced clamping system. They can be equipped for many types of materials. In the wood industry they can be used both for furniture production, as well as for doors or special logos, designs or signs.

• Middle class (for workshops) - are smaller and lighter. They can range in size from small CNCs that can be placed on a desk, to medium sized 1.5/3m. They can basically do the machining that industrial ones do, but with fewer features (no suction system, special sensors on the tool, etc). Some manufacturers also offer CNCs, medium class CNC machining centers with maximum facilities. I'm machinery suitable for small producers of musical instruments or makers of wooden signs and logos.

• Multiax - are machines to which additional axes are added when machining on the 3 Cartesian axes. They can be 4 - rotation in one plane or 5 - rotation in 2 planes. They are used for making sculptures, plaques or trophies.
• Hobby - cars made by enthusiasts. They are unique cars that bear the manufacturer's stamp. They're made for each owner's needs, so they can't be categorized or grouped.

The use of CNCs in production has many advantages: speed of production, flexibility, reproducibility, efficiency, increased quality, reduced labor requirements. The disadvantages are not many, but they are not negligible either: high investment, higher maintenance costs, higher qualifications of the operators (programmers), high production costs for small production runs. You only have to weigh up the pros and cons to see whether or not it is worth the investment.

Dust and chips from wood and wood-based panels have always been a problem, but there are smart tools that can increase dust removal efficiency reducing energy consumption.