Positioning a CFRP Part

An often-occurring challenge when manufacturing is the correct referencing of the relative offset between the machine and the layup table and the components. And there are multiple ways of telling the control system which coordinates it must move the layup-head to:

Axis Values

The CAM software exports explicit axis angles and distances for the position and orientation of the system (for instance an angle for each joint of the robot system).

This is generally an option that is not to be recommended, as any alteration to the real system (physical deformation, changes to the control system) will create a difference between the real and the digital system, which is very hard to compensate. 

Machine Coordinates

The CAM software exports the position and orientation of the layup program relative to the base coordinate system of the machine. This coordinate system is measured and available in the CAD model of the layup machine or environment.

Product Coordinates

The CAM software exports the position and orientation of the layup program relative to a coordinate system that is predefined at a position on the layup table. This coordinate system is measured and usually available in the CAD model of the machine. 

Usually, two steps are involved in positioning the part correctly:

1. For a broad positioning, the referencing coordinate system from the CAD data is taken and the programmed laminate is positioned in such a way, that its origin matches the referencing coordinate system.

2. For a finer positioning, two sets of positions are taken:

• 3 positions in the CAD model are defined
• The tool is positioned in such a way, that the 3 points are hit by the tool-center-point (a dedicated measuring tool is used)
• By comparing the target coordinates with the actual coordinates, the offset in the position and orientation can be calculated and compensated
• This compensation can either be calculated in the machine’s control system or the CAM software 

The result of these operations is an optimal match between the digital and the real manufacturing environments. With an optimal match, the digital manufacturing process can mimic the real process as close as possible. Only then, collisions and axis limits can be verified offline correctly.

In the next article, we will display, how the visualization of the tool paths of the layup tool can be used to verify the correct manufacturing process.

Until then, stay safe and stay tuned.