Creating Contoured and Plastic Parts - Autodesk Inventor 2010: No Experience Required - page 424

2. Create a Mate constraint between the front of the housing and the
back of the grill, as shown in Figure 8.68.
FIGURE 8.68 Mating the grill to the housing
3. Click Apply to create the constraint.
4. Create Mate constraints with Flush solutions between the YZ and XZ
planes of the grill and the assembly. Doing so centers the grill on the
assembly. See Figure 8.69.
FIGURE 8.69 The grill constrained into place
5. Start the Place from Content Center tool.