2、So if you compare learning to write CNC programs to learning a foreign language having only 50 words, it shouldn't seem overly difficult to learn CNC programming. 本句中if引导的条件状语从句中有两个to。第一个to与 learn构成learn to do sth.“学习做某事”；第二个to与compare构成固定搭配， 译为：“将……比作……”。本句译为：所以如果您将学习写计算机数控机 床程序比作是学习一门只有50个单词外语的话，那么计算机数控机床编程 似乎并不十分难学。 3、As it reads the program, the CNC control will activate the appropriate machine functions, cause axis motion, and in general, follow the instructions given in the program. 这句中as引导时间状语从句。后面的主 句中主语为CNC control，谓语为三个动词：activate，cause，follow。本 句译为：当读程序时，计算机数控机床的控制器会使适当的机床功能生效并 产生轴的运动，总之，会执行程序中的指令。
Hale Waihona Puke The CNC control
The CNC control will interpret a CNC program and activate the series of commands in sequential order. As it reads the program, the CNC control will activate the appropriate machine functions, cause axis motion, and in general, follow the instructions given in the program. In general, the CNC control allows all functions of the machine to be manipulated.
How CNC works
CNC machines are programmed by a CNC programmer, who uses a machining print to determine X, Y, and Z, coordinates for each cutting tool inside the CNC to move to. This causes, the part that is load to be cut, drilled, tapped, bored, counter bored, chamfered, etc. Everything that an operator would be required to do with conventional machine tools is programmable with CNC machines. Once the machine is setup and running, a CNC machine is quite simple to keep running. In fact CNC operators tend to get quite bored during lengthy production runs because there is so little to do. With some CNC machines, even the work-piece loading process has been automated
Part I Technical and Practical Reading
Passage A
Basics of Computer Numerical Control
What is CNC? CNC stands for Computer Numerical Control and has been around since the early 1970's. Prior to this, it was called NC, for Numerical Control. While people in most walks of life have never heard of this term, CNC has touched almost every form of manufacturing process in one way or another.
EXERCISE 1
Mark the following statements with T (True) or F (False) according to the passage.
1. CNC stands for Control Numerical Computer and has been around since the late1970’s.
The CNC Program
A CNC program is nothing more than another kind of instruction set. It's written in sentence-like format and the control will execute it in sequential order, step by step. A special series of CNC words are used to communicate what the machine is intended to do. CNC words begin with letter addresses (like F for feed-rate, S for spindle speed, and X, Y & Z for axis motion). When placed together in a logical method, a group of CNC words make up a command that resemble a sentence. For any given CNC machine type, there will only be about 4050 words used on a regular basis. So if you compare learning to write CNC programs to learning a foreign language having only 50 words, it shouldn't seem overly difficult to learn CNC programming.
Notes
1、CNC machines are programmed by a CNC programmer, who uses a machining print to determine X, Y, and Z, coordinates for each cutting tool inside the CNC to move to. 此句中who引导非限制性定语从句，先行词为 programmer。而who引导的定语从句当中有两个动词：use和coordinate。 整句可译为：计算机数控机床由数控编程员来编程控制，他用加工板来决定 X，Y和Z，协调数控机床内部的每种切割工具的移动。
Coolant Many machining operations require coolant for lubrication and cooling purposes. Coolant can be turned on and off from within the machine cycle.
Motion Control
All CNC machine types share this commonality: They all have two or more programmable directions of motion called axes. An axis of motion can be linear (along a straight line) or rotary (along a circular path). One of the first specifications that implies a CNC machine's complexity is how many axes it has. Generally speaking, the more axes, the more complex the machine. In the beginning stepper motors, which rotate in increments, or steps, were the standard in motion control technology. Positional accuracy defines the precision with which a system can control the actual placement of the X, Y, and Z axes. Three-axis systems are the norm today, although some machines control five to seven axes of motion
Spindle speed and activation
The spindle speed (in revolutions per minute) can be easily specified and the spindle can be turned on in a forward or reverse direction. It can also, of course, be turned off.