ELEMENTS OF CNC SYSTEM

Describe the properties and applications of CNT’s.

CNC PART PROGRAMMING

Which is the major component of CNG?

Read the passage and fill in the blank WITH NO MORE THAN THREE WORDSHow to Operate a CNC Machine?A computer numerical control (CNC) mill is capable of cutting and drilling many different types of material including steel, aluminum, wood and plastic. An CNC mill operator is in charge of making sure that the parts coming out are well within the specifications dictated by the print. By cleaning the contact surfaces and making sure that tools are in good shape, he can keep a production run going without any wasted raw material. This waste can cost a manufacturing company thousands of dollars, so a good, knowledgeable operator is essential.Clean off the table and tooling after every cycle. It is important to make sure that the machine is clean and that the vise or fixture is free from chip build up. If a chip gets under a piece of raw material, the dimensions of that finished part may be compromised. Chips on the flutes of a drill may also cause breakage, so tooling must be blown off after the cycle is finished.Check the tips of end mills and drills to make sure that they are still usable during the production run. A chipped end mill or drill can cause a machine overload. Overloads can damage the machine as well as the part that is being cut. To prevent these types of tooling failure, an operator must not only check the tooling when the machine is stooped, but they must pay careful attention to load meters to watch for overloads.Adjust the tooling offsets for worn tools that do not need to be replaced. By stopping the run and checking a part, an operator can take control of sizing and assure that no pieces are off. The operator can also re-teach any tools that have been changed at this time and clean off the table and get the machine ready for the cycle.Check the parts for size as they come out of the machine. After a part is done and another one is put in for machining, it is always best to check very third piece or so to make sure that are the key dimensions are on point and within the tolerances in the print. Certain dimensions can be fixed with tool offsets on the control of a CNC mill or lathe.De-burr the parts to take off sharp edges. Operators must de-burr all cut edges so that the next person to handle the parts is not cut. In many cases, the machining of the part is the last process, so de-burring the parts will get them ready for powder-coating or assembly. need cleaning to keep a production run going without wasted material.When a chip gets under a piece of raw material, the may be compromised.Test the tips of end to make sure that they are still good while the production runs.If you don’t want to replace worm tools, re-tension the for them.Sometimes the of components is the last process, so de-burring them will get ready for powder-coating or assembly.

Passage 1 (2 points): Read the following text and complete the summary WITH NO MORE THAN TWO WORDS.What is CNC?Nothing is more than a simple Mill or Lathe with a computer control accompanied to control its working.Conventional MachinesConventional mills/lathes are controlled by machinists. They can freely control the axis movements, can choose spindle speed of their liking and can change the tool at their will.CNC MachinesOn a CNC machine, every step tool-change/spindle-speed/axis-movement is controlled through CNC machine control. A CNC machinist can only Start/Stop/Control-tool-cutting.Every CNC program block might consist of multiple instructions (called G-Codes/M-Codes, etc.). These programs are made or written by CNC-Programmers. In the past, most of the programs were written by hand, but nowadays multiple software is available which ease this whole process.Part program is stored inside the CNC machine memory called CNC Programs Directory. Therefore, CNC machinists select the required part program for execution. That part program is run by CNC machinist by pressing Cycle-Start, and the control is transferred to the CNC machine control which reads the part-program and instructs different parts of CNC machine to do the required operation. By this way, the part-program instructions are executed block by block.If during this whole process, anything goes wrong then CNC machinist can stop the cutting tool motion (Feed-Hold), or he can completely stop the machine (Cycle-Stop). Even CNC machinist can press Emergency-Stop-Button if anything dangerous happens or is going to happen. If everything goes well during part-program execution then machine automatically stops at the end of part program.SUMMARYOn conventional machines, a machinist can decide the (1) , spindle speed or change the tool. On a CNC machine, CNC machine (2) does all the steps. A CNC machinist only needs to press the control buttons. CNC programs are written by CNC programmers. They use a wide variety of available (3) to write the program instead of doing it mechanically. Part program is stored in CNC programs Directory. All of its part-program (4) are executed block by block. During the whole process, in case of having problems, CNC machinists can decide what to do by pressing buttons to control. If the process goes well during part-program execution, automatically the machine (5) at the end of part program.