What is a CNC machine?
CNC or Computer Numerical Control machines are machines that can mill, cut, drill, or engrave workpieces. automatically The user must create a design as desired on the computer. And give commands to the computer system to control the operation of the CNC machine. The machine will drive the cutter head (mill bit) to move to the desired material and cut out the meat of the part. Only the required parts will be left according to the designed file. Materials that can be milled may include wood, acrylic, plastic, aluminum, steel, etc., depending on the specifications of the machine.
What can a CNC machine do?
From the work features mentioned above Users can apply it to various tasks. There are many more, for example:
– Work on carving The workpiece is a wooden sign. Illuminated acrylic sign aluminum sign Product number engraved Engraved logos or symbols wood carving Carved gable work, mold/block work, high relief – low relief work, destroying PCB circuit boards, etc.
– Work on cutting pieces The workpiece is the front plate of the speaker cabinet. audio parts Cutting furniture components, making cabinets, tables, storage shelves, parts of tools or machines, etc.
– Work in drilling The workpiece is a cover plate with holes for inserting screws, a grille plate, or a lattice panel with cooling holes, etc.
Working principle of CNC machine
Here, I would like to mention a very important part, consisting of 2 main working parts: (1) the drive system and (2) the milling head system.
1. Drive system
A typical drive system consists of at least 3 drive axes as follows.
– The X axis (X Axis) controls the movement of the cutter head in the left-right direction.
– Y axis (Y Axis) controls the movement of the cutter head in the front-back direction.
– Z axis (Z Axis) controls the movement of the cutter head in the high-low direction. The milling head is mounted on this Z axis.
1.1 The drive for a CNC machine is an important part that drives the various axes. Move to the desired location with speed and precision as specified by the user. There are many types of drivers, for example:
– Feed Screw system consists of a nut and threaded shaft. When the motor works and causes the threaded shaft to rotate, This will allow the nut to move around. This system has the advantage of being easy to manufacture, cheap, but with low accuracy and high wear rates. Requires frequent adjustments and repairs Compared to the Ball Screw system
– The Ball Screw system (ball bearing threads) is different from the Feed Screw in that inside the nut there are many ball bearings that can move along the threads when the threaded shaft rotates. and the threaded shaft will look like a round thread. To conform to the shape of the ball bearing This Ball Screw drive system is expensive and has high accuracy. and more durable than the Feed Screw system. In addition, some types of Ball Screws are designed to protect against various dirt. Do not allow it to accumulate inside the ball bearing and threaded shaft.
– The Rack and Pinnion system consists of a bridge gear (Rack) and a pinion gear (Pinnion). The bridge gear has a serration along the length of the drive shaft to support the movement of the pinion gear. When the motor rotates This will cause the gears to rotate according to the revolutions of the motor and move back and forth along that axis. This system is accurate. (but less accurate than Ball Screw) Suitable for large machines due to the large drive part. and can be used with very long moving axes
1.2 The driving force holder (Linear Guide) is the part that when there is a command to drive the shaft. The shaft is driven by traction along this part. There are many types, for example:
– Scroll wheel system It consists of wheels that rotate and support movement along the specified tracks. This system is easy to build, simple and inexpensive. The tolerances are very high.
– Round axle rails consist of a cylindrical rail along the length of the drive shaft and a slide block (Slide Block) with ball bearings sliding inside as it moves so that it can glide along the surface of the rail. That cylinder Round shaft rails are not expensive. The disadvantage is that it can twist along the curved rail surface, which can lead to loss of accuracy.
– Square rails consist of rails that are similar to squares. The sides of the square rails are designed to have small grooves. along the length To conform to the shape of the Slide Block and support the movement of the ball bearings in the Slide Block to be able to hold with high precision within the grooves of the square rails. and greatly reduces the twisting of the slide block while moving.
2. Milling head or working head system
There are many different types of milling head or working head systems, for example:
– Engraving bit holder type (CNC Router) is a motor cutter head that holds the bit to rotate at high speed (Spindle), which has a variety according to various manufacturers. It is designed for use according to the manufacturer, or Trimmer and Router type cutters used for woodworking may be installed, etc.
– Plasma cutting machine type (CNC Plasma), which can use a plasma cutting machine. For cutting steel and metal work, comes installed to cut into shapes automatically with a CNC machine.
– Waterjet type (CNC Water Jet) that uses water propulsion. (or together with other objects mixed with water) that have very high power to cut various materials
