It's been over a year since the column with this title appeared in Modern Machine Shop (January 1999). In it, I addressed how we can change the perceptions of the general public about manufacturing and encourage young people to enter this field.
In a previous column I gave some custom macro B techniques for testing offset values for correctness. But the previous column required that the cumbersome commands related to testing offset values be included within the main program.
Machine tool builders can provide special interpolation types based upon their customers' specific needs. Some three-axis (X, Z and C) turning centers, for example, are equipped with live tooling.
Fixture offsets are used on machining centers to assign program zero. Most controls come with a limited number of fixture offsets (Fanuc provides six fixture offsets as a standard number).
You know that all current model CNC controls have some very important program verification functions. Dry run, single block, feed hold, feedrate override and rapid override are among the most helpful functions when it comes to determining what might be wrong with a given program.
I thought that program was proven!
Many manufacturing people, especially upper management, feel that if a program has been verified and has been used to successfully complete one production run, there should be no problems when running the job in the future.
In reality, any number of things could be different the next time a job is run.
Machining centers traditionally have three linear axes—X, Y and Z. If the machine is equipped with additional axes, they are usually rotary axes (A, B and/or C).
The most basic application for mirror image is when machining left and right hand workpieces. Say you want to set up and run 500 of one hand, tear down, and then set up and run 500 of the opposite hand.
Most turning center users use wear offsets for the purpose of holding size over the course of a production run. And with most of the tools used on turning centers (turning tools, boring bars, grooving tools, among others), all production run sizing should be done with wear offsets.
Almost all current model CNC machine tools have a special reference position. For machines having Fanuc or Fanuc-compatible controls, this special position is called the zero return position.