Computer Numerical Control

Showing posts with label Programmable Logic Controller. Show all posts

Motion Control - The Heart of CNC

What is Motion Control?

Motion control can be applied in many categories such as robotics, CNC operated machine tools and Kinematics, wherein motion control in kinematics are usually simpler. It can be mainly used nowadays with packaging, textile, assembly industries, printing, and semiconductor production. The hardware of a motion controlled machine usually consists of drive systems, motors, a computer, a PLC or Programmable Logic Controller to run the programs, and an amplifier.

The basic design of a motion control system would include a motion controller to produce a set of points including closing a position, a drive or amplifier to convert the control signal of the motion controller into a high power electrical current, an actuator, one or more feedback sensors, and mechanical components to convert the motion of the actuators to the desired motion.

CNC machines use programmable commands to make inputting motion to the machine easier rather than using cranks or other conventional machine tools. Almost all CNC machine tools can have programmable motion type (whether it would be rapid, linear or circular), the amount of motion, the feedback rate, and the axes to move.

Motion control is the simplest function of any Computer Numerical Control (CNC) machine. It is precise, consistent, and automatic system of control. CNC equipments need two or more modes of direction to which they are called axes. There are two common axis types and they are called linear and rotary. The linear axis type of motion control is driven along a straight path while the rotary axis type is driven along a circular path.

The operator of the motion controlled machine counting the number of revolutions made on the handwheel, added the generations of the dial would accomplish accurate positioning. The drive motor of the machine would be rotated to a resulting amount, which would then drive the ball screw, which would cause the linear motion of the axis. The feedback device at the end of the ball screw would confirm its revolutions.

The same linear motion can be found on a table vise. When you rotate the vise crank, it would also rotate a lead screw, which would then be able to drive the movable jaw in the table vise. In comparison to a motor controlled CNC machine, the linear axis in it is extremely precise compared to that of a table vise. This is because the number of revolutions of the axis drive motor in the CNC machine accurately controls the amount of linear motion along the axis.

A CNC command programmed and executed within a control of a machine would tell the drive motor of the machine as to how many number of precise times it would rotate. This in turn would rotate the ball screw then the ball screw would drive the linear axis. After the process has started, a feedback device located at the end of the ball screw would confirm the programmed number of rotations that the machine would run has taken in effect.

How would axis motion be controlled?

Utilizing a form of coordinate system would make axis controlling a whole lot simpler and more logical to the CNC control. Two coordinate systems that are being used in CNC machines that have been popular are rectangular and polar coordinate system, to which the more popular of the two is the rectangular coordinate system.

Graphing is a common application for the rectangular coordinate system and is needed to cause movement in a CNC machine.

Practical Applications of CNC

Sphere: Related Content

Manufacturing anything that requires exact measurements requires cutting edge precision and nimbleness from the worker. Most of the time manufacturing these kinds of products requires weeks or months to finish therefore slowing down productivity as well as consistency of the manufacturers.

Computer Numerical Control or more commonly called as CNC’s are the new trend in machine shop manufacturing and practice. Any manufacturing environment owns one or is basically acquainted to this kind of device because of its capability to increase productivity as well as consistency on the products being produced.

Benchmarked from Numerical Control (NC) during the late 50’s, Computer Numerical Control incorporate the functionality of a Programmable Logic Controller (PLC), meaning you could program it to execute different functions depending on the type of manufacturing that the industry needs.

Given this kind of quality what does the Computer Numerical Control do in the practical application concept? CNC can do a variety of things depending on how the machine operator would program the system. The more acquainted the machine operator is to the CNC machine the more complex applications as well as programming can be made. Practical applications of CNC range from drilling, lathes, multi-axis spindles, milling machines, laser cutting machines, and wire electrical discharge machines.

Let’s discuss some of these common applications further. In Metal fabrication, Computer Numerical controlled Lathe’s are used to fabricate metal sheet by shearing, flame or plasma cutting, punching, laser cutting, forming and welding. Most CNC Lathe’s are used for designing modern carbide tooling. The design could be created with the Computer Aided Manufacturing (CAM) process, and when done, the CNC could start creating the product automatically with little supervision from the machine operator.

Electrical discharge machining (EDM) is the process of removing metal with the use of electrical sparks to take away the metal. These Electrical Discharge Machine has two types, the vertical EDM and wire EDM. Vertical EDM uses an electrode that is the shape of the cavity to be machined into a work piece. Wire EDM is used to create punch and die combinations in the fabrication industry. Computer Numerical Control EDM’s are not usually known because it is mostly incorporated to other CNC process.

Drilling is the most common machine process. Computer Numerical Controlled Drilling is used to create precise right circular cylinders over a certain material, the CNC could be programmed to create holes on different standards, most of the time this is the gaps between these holes. Drilling is commonly used in wood working manufacturing process in which other process is also involved such as milling, turning and grinding.

Several tools for creating holes with CNC’s involve varied hole sizes as well as drill press for creating different depths on its holes. CNC drills are equipped depending on the type of hole that the machine operator is drilling.

Applications stated above are just a few examples on what the Computer Numerical Control could execute. Depending on how you want it to perform, more complex designs can be made and a lot of things can be made in a shorter period of time, therefore the key concept for the proper use of CNC’s is that the machine operator must know what he or she wants to do.

This makes the CNC an indispensable tool for the Manufacturing Industry nowadays.