Introduction

Sizing the right positioner is about having the correct mass data of the part and fixture. It is important to note that MotoSize needs to calculate the mass data for EVERYTHING connected to the headstock…not just the part being calculated…the part fixture is just as important.

Below are instructions to configure Solidworks CAD data, export it to MotoSize, and calculate the results for the best headstock positioner.

STEP 1: Check CAD model Integrity

In Solidworks make sure the following are completed for the part/fixture:

1. All relevant components are represented (anything that generates sufficient mass.)
   • Part
   • Fixture (pay attention to the clamps, if any)
   • Fasteners…if numerous
2. Verify there are no redundant component copies.
3. All relevant models are solid bodies; not surface bodies (surfaces have no volume to calculate mass).
4. All manufactured models have the correct material applied (steel, aluminum, plastics, rubber, etc.), giving it a density that mass can be calculated from.
5. All purchased components have the correct material applied, or the mass is over-ridden with a value provided by the manufacturer.

STEP 2: Setup Second Coordinate System

It is critical that the coordinate system is located accurately. It will affect the center of gravity and moments of inertia.

The origin needs to be located at the connection point where the fixture is fastened to the Headstock faceplate.

For simplicity make sure the Z axis is normal to the headstock face (see Figure 1).

1. In the Solidworks Assembly tab select Reference Geometry/Point and select the surface that will mount to the Headstock faceplate.

A point will appear at the center of that surface.

2. Select Reference Geometry/Coordinate System and a new coordinate system will appear on the point previously created.

Use the X, Y, Z options to align to match Figure 1

Figure 1:Z is normal (away) from the Positioner Mounting plate.

STEP 3: Configure & Output the Mass Data

After the models and origin have been configured, the next step is the mass properties output.

It can be found on the Evaluate Tab, Mass Properties

Figure 2: Mass Properties

STEP 4: Enter the Data in MotoSize

Login to MotoSize.motoman.com

STEP 5: Review the Results

As can be seen, everything is GREEN. This model can safely be used with all current Headstocks. The headstocks are evaluated by: Rated Bearing:  Amount of reducer bearing moment load generated by the application. Given as a % of the reducer bearing capacity.Inertia Ratio: The (reflected load inertia)/(motor inertia) ratio. Servo control stability requires this ratio stay below 5.Motor Hold/Rated: Amount of motor torque required to hold the load in a worst-case position. Given as a % of rated motor torque.RMS/Motor Rated: RMS current requirements for the entire simulated duty cycle (motion and dwell) based off the application. Given as a % of rated motor torque.

STEP 6: Saving the Results

Once satisfied with the results, they can be saved to a PDF.

1. Select Create New Headstock Report

2.Fill in the Customer field and any other optional field desired.

3. When ready, select View Report

4. The finished report will appear…select Printer Friendly Page

5. The printer friendly page will display a message reminding the user to verify their browser background graphics are enabled in the printer settings. If not, then the color key will be gray and harder to interpret.

7. Select the Hide button to remove the message.

8. Use the browser to print to PDF.

9. Done