CNC Milling Programming. Linear & Circular interpolations for a workpiece

Research Paper (postgraduate), 2017

9 Pages


Table of contents

Executive summary

Table of contents

1. Background to CNC machining
1.1 Advantages and disadvantages of CNC machining
1.1.1. Advantages
1.1.2. Disadvantages

2. Motivation

3. Methodology
3.1 Procedure
3.1.1 Modelling
3.1.2 Programming
3.1.3 Machining
3.2 Precautions

4. G-code (10cm by 10cm)

5. Engineering drawing


Executive summary

A combined 3D linear and circular interpolation principle is developed on the basis of the 3D linear and circular interpolation principles. The task was to choose and design a creative item to be machined using CNC machining, which then required to write a code using CNC language. Prior to the machining process, we did a Computer Aided Design (CAD) drawing of the workpiece. The drawing was further modified with the final model drawn using Auto Desk Inventor. We used foam for our model and a 31 diameter end mill tool. The main problem that was experienced was the cutting time; the model took longer to be complete. The cutting time was affected by the complexity of the design, chosen tool size and the cutting technique. Besides, we learnt from the demonstration that the shorter the constructed code the more robust it is, using a bigger tool is more efficient in terms of saving energy and time, and that if the code is correct the CNC machine model becomes identical to that of the product Design.

1. Background to CNC machining

Computer Numerical Control (CNC) machining is a process that involves the use of computers to control machine tools [1]. This process is mostly used in manufacturing industries. A computer numerical control system is made up with three components:

- Machine Control Unit :

The CNC reader that follows instructions from the part program

- Part program :

Set of instructions produced to produce a part.

- Machine tool :

The hardware that receives instructions from the Machine Control Unit and machines the part.

The part program contains a set of instructions (G-code) written using a CNC machining language to control various features of the machine tool such as location, coordination, speed and input parameters such as the feed rate, depth of cut and so forth . The cutting tool can only move in the vertical direction. A machine unit a small computer used for storing and for executing the G-code. Machine tools such as lathe, grinder, router and mill are programmable using such a language [2].

1.1 Advantages and disadvantages of CNC machining

1.1.1. Advantages

- CNC systems are easy to operate, people with little experience can operate them unlike with manual milling/lathe machine which require people with high skill set.
- CNC machines produce quality products at a high speed with high level of accuracy [3].

1.1.2. Disadvantages

- CNC machines are expensive compared to conventional machinery.
- The introduction of CNC machines has resulted in a decline in the need for skilled manual lathe workers and therefore people losing their jobs [4].

2. Motivation

- To get an appreciation of the friendly-use of the CNC machine and to obtain the experience of using the machine.
- To develop the skill of programming and understanding the language of the machine.

A common misconception is that writing the program is the main job involved in CNC machining, and that knowing how to write a program is enough to turn out parts from a CNC machine. The fact is that only a small amount of thinking is involved in actually writing the program.

For purposes of the current project, the G-code program will be using linear interpolation and circular interpolation for a workpiece. In fact, the design chosen for this project was inspired by activities behind any workpiece after being machined; the complete sequence of steps involved in generating a machined part from the drawing.

- To understand how the subroutines are generated and can remain hidden from the person or software package that generates the part program, and from the machine operator, for whom the controller simply appears as a standard “G-code” machine.

The activities with the implementations from a design and the effects it may implicate on production such as wastages. Thus this assignment aims at understanding how CNC machining works and producing designs that allows CNC milling programming.

Afterward, an engineering drawing of the design will be produced and a CNC program must be written and verified with the CNC laboratory.


Excerpt out of 9 pages


CNC Milling Programming. Linear & Circular interpolations for a workpiece
University of the Witwatersrand
Catalog Number
ISBN (eBook)
File size
738 KB
milling, programming, linear, circular
Quote paper
Roland Nathan Kalonji (Author), 2017, CNC Milling Programming. Linear & Circular interpolations for a workpiece, Munich, GRIN Verlag,


  • No comments yet.
Read the ebook
Title: CNC Milling Programming. Linear & Circular interpolations for a workpiece

Upload papers

Your term paper / thesis:

- Publication as eBook and book
- High royalties for the sales
- Completely free - with ISBN
- It only takes five minutes
- Every paper finds readers

Publish now - it's free