About Working with Mass Property Parameters
The density parameter for any material is PTC_MASS_DENSITY. When you edit the density of a material, the value of this parameter is updated.
The alternate mass property parameter for an assembly, part, or body is PRO_MP_ALT_DENSITY.
The reported density parameter for an assembly, part, or body is PRO_MP_DENSITY. In case of an assembly or a part with different materials, the value of this parameter is the average density.
Changing Material Density
You can change the density of any material in one of the following ways:
• Click > 
Parameters. The Parameters dialog box opens. Click Look In and select the part, a body, or a material. Change the value of PTC_MASS_DENSITY. If you select the part, the density of the master material changes. If you select a body, the density of the material assigned to it changes. If you select a material, its density changes.
Parameters. The Parameters dialog box opens. Click Look In and select the part, a body, or a material. Change the value of PTC_MASS_DENSITY. If you select the part, the density of the master material changes. If you select a body, the density of the material assigned to it changes. If you select a material, its density changes.• On the Model Tree, right-click a material and click Edit Definition. The Material Definition dialog box opens. Change the value in the Density box.
 | When you change the density of the material assigned to a body, all the bodies in the current part, with that material assigned, are affected. |
Computing Mass Properties
Creo Parametric can compute the mass properties of a body, part, or assembly either based on the actual geometry of the object, or based on user-assigned parameter values. For example, when you create a simplified part for an assembly, you may want its mass properties to correspond to a fully detailed part. You can assign mass properties to a body, part, or assembly either by assigning values to alternate mass parameters, or by using a mass properties file.
| | When you open a model saved in Creo Parametric 6.0 and earlier, the mass properties of the body in that model appear to be zero. They are updated the next time mass properties are calculated for the model. |
When working with the mass properties of a body, part, or assembly, you can at any time generate a mass properties report based on either of the following sources:
• Geometry—Calculates mass properties based on model geometry. For information on generating a mass property report based on model geometry, go to To Generate a Mass Properties Report Based on Model Geometry.
• Geometry and Parameters—Calculates mass properties based on the assigned parameter values and uses the model geometry wherever you have not input parameter values. For information on assigning alternate values to certain mass property parameters, go to To Assign Parameters and Generate a Mass Properties Report.
| | You cannot select Geometry and Parameters as the source when you generate mass properties report of a body. |
• Fully Assigned—Applies the alternate parameter values to generate a mass properties report. The values can be changed or assigned by the mass properties file. For information on assigning mass property values by using a file, go to To Use a File for Assigning Mass Properties.
| | When the assigned materials have missing densities, use the Assign Material button to assign different valid materials. When the single assigned material has missing density, use the Material Definition button to edit the density of the material. |
We recommend that you generate a mass properties report using the Geometry or Fully Assigned source.
When you generate a mass properties report, it is displayed in an information window and written to a file in the current working directory, named objectname.m_p, where objectname is the name of the body, part, or assembly.
Reported and Alternate Parameters
The values generated in the mass properties report are stored in the model as its reported mass property parameters. You can view them by clicking > Parameters and selecting Reported Mass Properties or Extended Reported Mass Properties from the list at the bottom of the Parameters dialog box.
Parameters and selecting Reported Mass Properties or Extended Reported Mass Properties from the list at the bottom of the Parameters dialog box.You cannot modify values of reported parameters, they are derived from the last generated mass property report. To change the reported parameter values, you can specify alternate mass property parameter values and generate a report using Fully Assigned as the source.
If you generate a report using Geometry as the source, the reported parameter values are based on the model geometry. Before you calculate model mass properties for the first time, all the reported parameter values are zero.
Alternate mass property parameters are also stored in the model. You can modify values of these parameters using either of the following methods:
• When generating the mass properties report, set the source to Geometry and Parameters or Fully Assigned and modify the values.
• Click > Parameters and select Alternate Mass Properties from the list at the bottom of the Parameters dialog box. Type the parameter values in the appropriate boxes.
Parameters and select Alternate Mass Properties from the list at the bottom of the Parameters dialog box. Type the parameter values in the appropriate boxes.• Click > 
Relations and add relations to the model to define the appropriate parameter values.
Relations and add relations to the model to define the appropriate parameter values.After you change the alternate parameter values, use one of the following ways to make the changes reflect in the reported parameters:
• Generate a mass properties report with Geometry and Parameters or Fully Assigned as the source.
• Make sure the PRO_MP_SOURCE parameter is set to PARAMETERS or ASSIGNED, and the configuration option mass_property_calculate is set to automatic, and regenerate the model.
You can use both reported and alternate mass property parameter values in relations, to drive other model parameters.
Legacy Parameters
In Creo Parametric 7.0 and later, we recommend that you use the density parameter PTC_MASS_DENSITY to access or drive the density of the master material and the materials assigned to bodies. For a single material model, you can still use the legacy parameter MP_DENSITY and modify its value as follows:
• Click > Parameters and select Legacy from the list at the bottom of the Parameters dialog box. Type the parameter value in the appropriate box.
Parameters and select Legacy from the list at the bottom of the Parameters dialog box. Type the parameter value in the appropriate box.Configuring for Mass Property Computations
You can use the following configuration options when working with mass property parameters:
• Set the configuration option mass_property_calculate to automatic to automatically calculate all mass properties. Every time you regenerate the model, the reported parameters automatically update based on the PRO_MP_SOURCE parameter value.
• Set the configuration option mp_calc_level to all_models to include the summary of assembly components, details of assembly components, and the summary of bodies in the assembly mass property report, and the summary and details of bodies in the part mass property report.
If the report is longer than 2,000,000 characters, the objectname.m_p file is written to your working directory, instead of showing it on screen.