Documentation process of CNC programming

Introduction and Overview

CNC programming is a segment of the CNC process. CNC machining cannot be performed without CNC programming. The CNC operators need to document and send an alpha-numeric CNC code to the control panel of CNC machines, to enable an automated CNC machining process in a specific sequence.

the CNC coding is the last stage of the overall CNC process. There are pre-programming steps to be followed for successful CNC programming. This article will guide you through a process to develop efficient programs.

The input elements for this process are the technical drawing of the part to be produced, the machines and means available in the workshop.

The CNC programs are documented in reference to the CAD design of the final products. The CAD drawing gives insights into the dimensions of the workpiece and the dimensions and features of the final part.

To begin we will deal with a simple example of a part to be made on a CNC lathe.

Before creating a CNC program, the CNC programmer must develop documentation by following these steps:

1. Determine the processing sequence and the machining operation to be performed:

This involves understanding the part’s design and deciding the type of machining operation(s) needed. planning the order of operations for efficiency and accuracy. All operations carried out without changing the position of the part or the tool are grouped into sequences.

05 -Define the dimensions of the stock and choose the program origin

3 jaws chuck

10 -Facing

CNMT Right Hand

20 -Contour turning: Step turning

CNMT Right Hand

30 -Finishing contour  

VNMT Right Hand

40 -Groove 

OD Grooving Tool

50 –Threading

OD Threading Tool

60 –Drilling

Drill

70 -Boring  

ID Boring CNMT

60 -Drilling  

Drill

80 -Cutoff  

Cutoff Tool

2. Perform mathematical operations :

This involves calculations for determining the coordinates, angles, and dimensions necessary for the machining operations, planning how the part will be held in place during the machining process.

The programmer needs to define dimensions of CNC machining processes; therefore, the calculations must be made. The calculations include the length of tool motion, feed rate, spindle speed, drill depth, etc (Machining Cutting Conditions).

3. Write the CNC Program:

This involves writing the CNC program using a specific syntax or language, typically G-code.

The CNC program is a set of CNC codes that define different machining actions, dimensions, and process parameters for the specific machining action. These CNC codes are alpha-numeric sets defined in a numeric computer programing language. The CNC codes are of two types, namely, G-codes and M-codes.

The G-codes are codes for defining the machining parameters. These codes define what type of machining activity should be performed by the CNC machine for what dimensions, at what feed, or for what duration.

The M-codes define the miscellaneous functions of a CNC machine. This includes starting and ending locations of the CNC tools, timer settings, coolant settings, etc.

The CNC program includes multiple CNC G and M codes to strategically guide the CNC machine for performing the CNC machining process.

Each of these steps requires careful planning and consideration to ensure the part is machined accurately and efficiently. The CNC programming software can help with creating, editing, simulating, and managing CNC programs. It’s crucial to select the appropriate software that suits the requirements and capabilities of your CNC machine.

programmer must document a CNC program. The sequence of G and M codes of CNC programming must be followed and cross-checked.

If all these above-mentioned steps are followed, a successful CNC program can be written. However, verification of the correctness of the program is essential.