Calculation of Cusp Error

Cusp Error is a measure used to quantify the deviation between the designed and manufactured part. The cusp error has an effect on the surface finish of the manufactured part. This tool calculates the cusp error with respect to every facet of the CAD body and the average cusp error for the entire part build. All the facets satisfying the specified threshold cusp height are highlighted in green and the rest are highlighted in red specifying out of spec areas. The user can specify different input parameters such as orientation of the part, layer thickness and threshold cusp height and perform analysis to determine the suitable build parameters for good surface finish.

Installation Manual

1. Download and extract the contents of the .zip file named Cusp Error.zip.

2. Open the extracted folder named Cusp Error.

3. Open the folder named ug_customization. Right click on the Windows Batch File named nx and open with Notepad/Notepad++.

4. Find the current file path of the nx file in your computer (Right click >> Properties). Copy the file path and paste it in the first line (the highlighted portion in the notepad as shown in Figure 1).

Notepad view showing path and version

Figure 1

5. Change the version of Siemens NX to the one you are using (module works for Siemens NX 10.0, 11.0, and 12.0) in the third line of the notepad file (as highlighted in Figure 2).

Notepad view showing version

Figure 2

Once these steps are carried out, you have completed the installation procedures before launching the application.

6. Now, double-click nx to launch the Windows Batch File. This will launch the Siemens NX window and a terminal window (you can minimize it or close it – it contains the information you input in steps 4 and 5). You may notice the UC AM Modules tab in the top toolbar. Click on it. The Cusp Error module will be visible.

7. Before using the module, user is supposed to import/create a Parasolid File of a part within Siemens NX. For illustration purposes, the Part File (. prt) and Parasolid File (.x_t) is given in the folder named Example Parts. Import the Parasolid file into Siemens NX. Follow the step mentioned below to import a Parasolid file of the part.
Open >> (Choose the file location of Cusp Error Folder) >>
Example Parts >> Part_1.x_t >> Ok

Cusp error icon

8. Once the file is opened in Siemens NX, you can click on Cusp Error button on the Command Ribbon. The button will look like the "Button" image on the right. 

The Cusp Error GUI is shown.

Figure 3

9. The Cusp Error GUI is shown in Figure 3. The detailed explanation of each option in the GUI is given below.

a. Select Body
This option is used to select the body for which Cusp Error needs to be calculated.

b. Rotation along X axis
Rotation along X axis (value to be entered in degrees) will rotate the selected part along the X axis.

c. Rotation along Y axis
Rotation along Y axis (value to be entered in degrees) will rotate the selected part along the Y axis.

d. Layer thickness
The body will be sliced in to number of layers based on the specified layer thickness.

e. Threshold cusp height
The cusp error made by each facet is compared with the specified threshold cusp height to highlight the facets in green (below threshold) or red (above threshold).

The output window of the Cusp Error module is shown below. The results consist of number of facets of the body, cusp error of each facet and the average cusp error. Please watch the video tutorial of the module conducted on an example part given with the module.

Facets with cusp error greater than threshold value (red) and less than threshold value (green)

Figure 4

Facets with cusp error greater than threshold value (red) and less than threshold value (green)

Output from the GUI

Output from the GUI

Example Problem

Use the Parasolid File named Part_1.x_t in the Example Parts folder attached in the Cusp Error module folder that you have extracted from the website.

Try out the following input configurations to note the changes in number of facets, cusp error of each facet and the average cusp error.

  1. Rotate the part along X axis by 30 degrees and rotate the part along Y axis by 45 degrees Input Layer thickness as 2.00 mm and Set Threshold cusp height as 1.5 mm
  2. Rotate the part along X axis by 45 degrees and rotate the part along Y axis by 60 degrees Input Layer thickness as 1.00 mm and Set Threshold cusp height as 0.5 mm

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