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CNC programming is an integral part of the CNC process. CNC machining cannot be done without CNC programming. A CNC operator needs to record and send alphanumeric CNC codes to the control panel of the CNC machine in order to enable the automated CNC machining process in a specific sequence. Many people may think that CNC coding is just like any other coding and requires no preparation. However, this is not the case, CNC coding is the second final stage of the overall CNC process. To be successful in CNC programming, pre-programming steps need to be followed. This article provides guidelines for documenting CNC programs for an efficient CNC process.

Before we get into the guide, let's discuss what exactly a CNC program is and how important it is in the CNC machining process.

CNC program introduction

A CNC program is a set of CNC codes that define different machining actions, dimensions and process parameters for specific machining actions. These CNC codes are alphanumeric sets defined in a numerical computer programming language. There are two types of CNC codes, G codes and M codes.

G code is a code used to define processing parameters. These codes define what type of machining activity the CNC machine should perform for what size, at what feed or for what duration.

M codes define other functions of CNC machine tools. This includes CNC tool start and end positions, timer settings, coolant settings, and more.

A CNC program includes multiple CNCG and M codes to strategically direct the CNC machine to execute the CNC machining process.

6 Guidelines for Documenting Successful CNC Programs

Documenting a CNC program is not limited to writing some CNC code. Processing is a gradual process. Therefore, the CNC machining activities and their parameters must be recorded in the proper sequence by the CNC program. The following steps must be followed when recording a CNC program.

Determine the CNC technology list according to the CAD design:

The CNC program is recorded with reference to the CAD design of the final product. CAD drawings provide insight into the dimensions of the workpiece and the dimensions and features of the final part. A programmer must know all the CNC techniques to be used throughout the CNC process.

Determine the sequence of the CNC machining process:

Once the CNC machining is determined, the order must be determined. For example, manufacturing a tapered shaft with a counterbore might include the following machining sequence: turning (for the largest diameter), followed by taper turning (for the reduced/tapered diameter). The counterbore will be formed after the tapered turning is completed.

Calculate:

The programmer needs to define the dimensions of the CNC machining process, so calculations must be made. Calculations may include length of tool motion, feed rate, spindle speed, drilling depth, etc.

Determine the workpiece and tool orientation:

The workpiece must be mounted in place and the tool must interact with the workpiece in order to remove material with a set accuracy. Since the tool orientation and tool movement parameters are defined through the CNC program, the programmer must determine these factors before programming.

Consider CNC machining tools:

Different processing techniques require different types of cutting tools. For example, CNC turning is done with single-point cutters, while milling requires multi-point cutters.

Record CNC program:

Once all the above factors are considered, and the steps are executed, the programmer must record a CNC program, which must follow the sequence of G-code and M-code for CNC programming and cross check.

If you follow all the above steps, you can write a successful CNC program. However, verifying the correctness of the program is essential in order to ensure error-free CNC machining.