TABLE OF CONTENTS Each numerically controlled machine using an automatic tool changer must have a special tool function (T function) that can be used in the program. This function controls the behavior of the cutting tool, depending on the type of machine tool. There are noticeable differences between T functions used on CNC machining centers and those used on CNC lathes. There are also differences between similar controls for the same machine type. The normal programming address for the tool function uses the address T.
For CNC machining centers, the T function typically controls the tool number only. For the CNC lathes, the function controls indexing to the tool station number, as well as the tool offset number.
All vertical and horizontal CNC machining centers have a feature called the Automatic Tool Changer, abbreviated as ATC. In the program or MDI mode on the machine, this feature uses the function T, where the T address refers to a tool number selected by the programmer. The subsequent digits describe the tool number itself. On CNC machines with a manual tool change, the tool function may not be required at all.
Before programming for a particular CNC machining center begins, the type of the tool selection for that machine must be known. There are two major types of tool selection used in automatic tool change process:
Fixed type
Random memory type
To understand the difference between them, the first step is to understand the...
