How to Bring Real Manufacturing Data into Your 3D CAD Simulation - Closed Loop
by Jason Brehmer, on Apr 20, 2015 3:20:00 PM
How to Bring Real Manufacturing Data into Your 3D CAD Simulation
3DCS Variation Analyst and QDM - Quality Data Management Systems can be used together to create a Closed Loop approach to quality. This creates feedback loops in process, bringing inspection data from manufacturing into the 3D CAD model for root cause analysis, design optimization and continuous quality improvement.
So how does this solution work?
This week's blog post shows the steps with examples for applying Actual Measurements in QDM and 3DCS, and how these two solutions interact.
Example of a Closed Loop approach using DCS Solutions.
The purpose of implementing Closed Loop processes is to provide a coordinated quality strategy for dimensional simulation, physical measurements, statistical analysis, reporting, problem solving and correlation of manufactured product results to simulation results, based on actual measurements of the product.
Actual Measurements are the result of a variable measuring process executed with some type of instrument, machine or device for the purpose of determining the amount of deviation from the engineering defined product specification. Some examples include CMM's (Coordinate Measuring Machines), laser scanners, visual scanners, handheld laser gages and hand gages.
To get started, let's get some techical terms out of the way:
Technical Terms and Requirements
- Naming Convention: 3DCS and QDM will use the name of features or combined features, creating long chart or measurement names. Creating a naming convention or abbreviating names will reduce feature or chart names, improving the overall view of the Template or Simulation Results.
- Directions: The Measurement Data and Plant Data (DCSDB2) require each point to have X, Y, and Z directions. Removing or adding a direction may result in file corruption.
- Multiple Data sets: A model or assembly may contain multiple parts. Each part would need to have a Plant Data file (DCSDB2).
- Measurement Plan: Is referring to data coming from a 3DCS Tolerance Model
- Plant Data: Is referring to data coming from QDM-Web and/or actual measurement data from the shop floor.
- Adding the DLL (CMMDev2.dll): When importing Plant Data into 3DCS, the data will need to be added to a User DLL. The CMMDev2.DLL is available to all 3DCS users.
- Modeling Points: Is referring to points that are used in a model in Moves, Tolerances, GD&T, and Measures that would correlate to points available in Plant Data.
- Sensitivity: The value from a DCSDB2 uses the Min and Max values to calculate the range in the sensitivity; this range is divided by 2 and displayed as the offset
- Export Zero-based from HST: This is a setting available in 3DCS preferences under the validation tab. The purpose is for using simulated data from a 3DCS Simulation histogram. For a Closed Loop model, this setting is not necessary.
The example Closed Loop begins with Variation Analysis, using 3DCS. In this case, as the variation analysis is not the primary focus of the example, you can see how this is done by viewing DCS's video here.
Once complete, you will need to create a Measurement Plan.
Technical Process: Creating the Measurement Plan
Next, export a Data Set as a DCSDB2 file. The DCSDB2 file is used to export the available points in the model to communicate the locations to QDM. The file will have each point and one sample. Here is how to export a DCSDB2 File:
- Go to File -> Export and select DCSDB2 File… (Available in versions 184.108.40.206 and above).
- In this example, select the Rocker part in the tree. Select a folder location to save the file.
Here is an example of what your file might look like:
Next, we use QDM Analyst, the module for report authoring in the QDM System (this is available as a stand alone product or as part of a system setup).
Create the Measurement Plan in QDM Analyst:
1. Create a new template
2. Import the CAD files, go to File -> Open: Select the Rocker.hsf (this uses the 3DCS CAD. QDM works with all major CAD files from CATIA, Solidworks, NX, etc...)
3. Import the Measurement Plan (DCSDB2) exported earlier from 3DCS. Go to File -> Import and select Data.
Note: Make sure when importing the data it’s specified as DCSDB2 (.csv)
Above: The template with the points imported and a sample.
So let's recap on what we have done.
Using GD&T and tolerancing strategies, we've created a model in 3DCS (for this example. A model in NX or CATIA with PMI will work as well).
We've exported the measurement points (setup in 3DCS) and tolerance points as a spreadsheet, but without data. These are often referred to as KCC's (Key Control Characteristics).
That spreadsheet has been imported into QDM Analyst, along with the CAD model, showing the points we want to measure and track on the CAD model for reference.
CAD Model with tolerances/measurements --> export KCC's --> Import KCC's into QDM Analyst --> Import CAD into QDM Analyst
Technical Process: Plant Data
Now we need the measurement data from the plant. This can be gathered in a number of different ways, from a manually updated excel spreadsheet on the shop floor using a gap gun to a CMM machine. The coordinates can be exported from QDM Analyst for easy use in a CMM machine or can be communicated using a report (as a pdf or document).
Once the inspection data has been collected, it needs to be brought into QDM Analyst.
QDM Analyst can import raw data from any inspection device or from an excel spreadsheet.
In this case, a CMM machine was used, giving a text output. That output was imported into QDM Analyst, which analyzes and applies the data to the points in the template. This aligns the measurement points imported from 3DCS with the measurement data from the CMM machine. Once this is done, a new DCSDB2 file can be exported from QDM Analyst, which has the measurement points like before, but now also contains the plant data.
For simplicity, the process is as follows:
1. Export CMM coordinates from QDM Analyst
2. Use the CMM to measure parts from the plant.
3. Import the raw text output from the CMM into QDM Analyst.
4. Export a new DCSDB2 file (.csv). This file contains the points and plant data together.
Bringing Plant Data into 3DCS Variation Analyst
Now that the Plant Data is available, we need to bring it into 3DCS. To do so, we used a custom module called a User DLL. (This feature is slated to be integrated in an upcoming release).
Begin by adding the User DLL from the Tolerance Menu.
- Add the DLL by clicking on Load DLL
- Select Add DLL and select dcu_cmmdev2.dll from the file (this is the general dll for plant data, not just CMM data)
- Create a new Tolerance under the Rocker part, and select User-DLL as the type
- In the new tolerance, change the Routine to: dcsTICmmDev2
- In the Tolerance, select Add and Modeling Points
- Select More… and then the Strings… buttons
- Add the Plant Data (DCSDB2 file)
Activating the Plant Data in a 3DCS Model
In order to implement the Plant Data in the 3DCS model, all other tolerances and GD&T need to be deactivated. The reason for this is that importing the new data adds that information to the same points that your simulation used, mixing the data together. By deactivating the previous tolerance data, you can isolate the plant data in your model, letting you analyze and work with just the measured information.
To deactivate the simulation data, Right-click on both Tolerance and GD&T nodes and select On/Off to deactivate all available tolerances.
Note: If any datums are available in the model, they will not deactivate when using the On/Off function. (They do not need to be activated)
Above: Deactivating the simulation data.
Analyzing the Plant Data
Now let's do a basic analysis of the plant data vs the simulation data.
Click Nominal Build and run a Simulation. You can see in the lower right image the Plant Data with High-Low-Mean (HLM) values, as well as the Key Contributors to Variation.
The simulation data is on the left for comparision.
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For best results, use 3DCS version 220.127.116.11 or later and QDM Analyst version 18.104.22.168 or later.
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