APT (programming language)

APT or "Automatically Programmed Tool" is a high-level computer programming language used to generate instructions for numerically controlled machine tools. By many Douglas T. Ross is considered to be the father of APT. APT is a language and system that makes numerically controlled manufacturing possible. The use of this early language was used widely into the 1970s and is still a standard internationally. [http://www.smartcomputing.com/editorial/dictionary/detail.asp?guid=&searchtype=1&DicID=17045&RefType=Encyclopedia Ross, Douglas] . Smart Computing Encyclopedia. Retrieved 22 September 2008.]

Overview

APT is used to program CNC machine tools to create complex parts using a cutting tool moving in space. It is used to calculate a point-to-point path that a tool must follow to generate a desired form. APT is a CAM system based on a special-purpose language. It was created and refined during the late 1950's and early 1960's to simplify the task of calculating geometry points that a tool must traverse in space to cut the increasingly complex parts required in the aerospace industry. It was a direct result of the new CNC technology becoming available at that time, and the daunting task that a machinist or engineer faced calculating the movements of the CNC for the complex parts for which it was capable. APT was created before graphical interfaces were available, and so it relies on text to specify the geometry and toolpaths needed to machine a part.

APT shares many similarities to computer programming languages like Fortran. A general-purpose computer language takes source text and converts the statements to instructions that can operate the internals of a computer. APT converts source statements into programs for numerically- or computer-controlled machine tools. Typically, this is a text file that contains CNC-vendor dependent commands to generate tool motions and machine states. Most commonly, this is some form of G-code.

Example Program

:PARTNO / APT-1:CLPRNT:UNITS / MM:NOPOST:CUTTER / 10.0:$$GEOMETRY DEFINITION:SETPT = POINT / 0.0, 0.0, 0.0:STRTPT = POINT / 70,70,0:P1 = POINT / 50, 50, 0:P2 = POINT / 20, -20, 0:C1 = CIRCLE / CENTER, P2, RADIUS, 30:P3 = POINT / -50, -50, 0:P4 = POINT / -30, 30, 0:C2 = CIRCLE / CENTER, P4, RADIUS, 20:P5 = POINT / 50, -20, 0:L1 = LINE / P1, P5:L2 = LINE / P3, PERPTO, L1:L3 = LINE / P3, PARLEL, L1:L4 = LINE / P1, PERPTO, L1:PLAN1 = PLANE / P1, P2, P3:PLAN2 = PARLEL, PLAN1, ZSMALL, 16:$$MOTION COMMANDS:SPINDL / 3000, CW:FEDRAT / 100, 0:FROM / STRPT:GO/TO L1, TO, PLAN2, TO, L4:TLLFT, GOFWD / L1, TANTO, C1:GOFWD / C1, TANTO, L2:GOFWD / L2, PAST, L3:GORGT / L3, TANTO, C2:GOFWD / C2, TANTO, L4:GOFWD / L4, PAST, L1:NOPS:GOTO / STRPT:FINI

References