CNC and CAM — from drawing to program
How you work with infections safely
The CNC machine is today the cabinet maker's most important work tool. But the machine is only as good as the program it is given to work after — and according to the regulation on vocational training for cabinet makers, a qualified tradesperson must independently be able to program set up and operate NC and CNC-controlled machines and robotic systems (§ 4 no. 6 and 26). Here you get an overview of how a drawing becomes a safe and precise machine program.
§From CAD drawing to CAM programme
Work starts in CAD (Computer Aided Design) where the part is drawn accurately in 2D or 3D. The regulation precisely requires that you can, in cooperation with others, produce accurate digital working and projection drawings (§ 4, nos. 12 and 36). When the geometry is fixed the CAM program (Computer Aided Manufacturing) takes over: here the drawing is converted into actual machine movements — which tools to use, in what order and with what cutting parameters.
- 01Choose topic, material and clamping
- 02Load or draw the geometry in the CAM program
- 03Define tool paths for each operation
- 04Choose tool, speed and feed rate
- 05Generate and transfer machine program (item)
§G-code — the machine's own language
Behind the CAM Program's Graphical Surfaces Usually Lies G-Code: a Series of Short Commands that Tell the Machine Exactly Where the Tool Should Move, at What Speed and in What Coordinate System. You Don't Need to Write G-Code From Scratch to be Good at CNC, but You Must be Able to Read and Understand It — It's Often the Way to Quickly Find the Reason When a Program Doesn't Behave as It Should.
§Simulation and test drive before the machine really cuts
A new or modified program should always be simulated before it runs in the real material. Most CAM programmes can show the tool path as a 3D animation so you can spot collisions between tool clamps and item before they happen in reality. Then comes a physical test run often in cheaper scrap material where the first piece is thoroughly measured afterwards before the series is started.
§The typical sources of error
Most CNC errors do not arise in the program itself but in the setup around it — an incorrectly entered zero point, a loosely clamped workpiece or a tool that is not the length the machine thinks. Therefore it is a fixed part of professionalism to be able to recognize the error pattern and trace it back to the cause.
| Error type | Typical cause |
|---|---|
| The part moves during machining | For low clamping force or incorrectly placed clamping irons |
| The surface becomes rough or burnt | For cutting speed too high or too low relative to the material |
| The dimensions do not match the drawing | Incorrect zero point or tool length not measured in correctly |
| The tool breaks or goes dull quickly | Incorrect feed rate or worn tool inserted without checking |
§Robots and automation in production
In many modern wood industries, CNC machines are supplemented by robotic systems that feed parts in and out, stack finished parts or move them between machines. This requires you to understand the interaction between machine, robot and safety equipment so the automation is both efficient and safe to work around.
“A good CNC program is not one that just works the first time — it is one that still runs accurately after a thousand items.”