Manual Data Input
Manual and computer-assisted part programming require a relatively high degree of formal documentation and procedure. There is lead time required to write and validate the programs. CAD/CAM part programming automates a substantial portion 01 the procedure, but a significant commitment in equipment. software, and training is required by the company that utilizes CAD/CAM programming. A potential method of simplifying the procedure is to have the machine operator perform the part programming task at the machine tool.This is called manual data input (abbreviated MOl) because the operator manually enters the part geometry data and motion commands directly into the MCU prior to running the job. MDI. also known as conversaaonat programming [9J, is perceived as a way for the small machine shop 10 introduce NC into its operations without the need to acquire special NC part programming equipment and to hire a part programmer. MDI permits the shop to make a minimal initial investment to begin the transition to modern CNC technology. The limitation, or potential limitation, of manual data input is the risk of programming errors as jobs become more complicated. For this reason, MDT is usually applied (or relatively simple parts.
Communication between the machine operatorprogrammer and the MOl system is accomplished using a display monitor and alphanumeric keyboard. Entering the programming commands into the controller is typically done using a menudriven procedure in which the operator responds to prompts and questions posed by the NC system about the job to be machined. The sequence of questions is designed so that the operator inputs the part geometry and machining commands in a logical and consistent manner.A computer graphics capability is included in modem MOl programming systems to permit the operator to visualize the machining operations and verify the program. Typical verification features include tool path display and animation of the tool path sequence
A minimum of training in NC part programming is required of the machine operator. The skills needed are the ability to read an engineering drawing of the part and to be familiar with the machining process. An important apphcatlon note in the use of MDI is to make certain that the NC system does not become an expensive toy that stands idle while the operator is entering the programming instructions. Efficient use of the system requires that programming for the next part be accomplished while the current part is being machined. Most MDI systems permit these two Iunctiuns to be performed simultaneously 10 reduce changeover time between jobs