Concentric Mate in SolidWorks: Definition and Usage

A concentric mate in SolidWorks aligns two cylindrical, conical, or spherical faces so their centers share the same axis. It makes parts rotate or slide around the same center line, like a wheel on an axle.

How It Works

A concentric mate connects two parts by making their circular or cylindrical faces share the same center axis. Imagine putting a pencil inside a hollow tube so the pencil can spin or slide but stays centered inside the tube. This mate locks the parts so their centers line up perfectly.

It works by selecting the round faces or edges of two parts. SolidWorks then forces those faces to share the same center line, allowing rotation or sliding along that axis but preventing sideways movement. This is useful for parts like shafts, pipes, or holes where alignment around a center is critical.

Example

This example shows how to create a concentric mate between a cylindrical shaft and a hole in an assembly using SolidWorks API code.

VBScript

Dim swApp As Object
Dim swModel As Object
Dim swAssembly As Object
Dim swMate As Object

Set swApp = Application.SldWorks
Set swModel = swApp.ActiveDoc
Set swAssembly = swModel

' Select cylindrical face of shaft
swModel.Extension.SelectByID2 "Face1@Shaft", "FACE", 0, 0, 0, False, 0, Nothing, 0

' Select cylindrical face of hole
swModel.Extension.SelectByID2 "Face1@Hole", "FACE", 0, 0, 0, True, 0, Nothing, 0

' Add concentric mate
Set swMate = swAssembly.AddMate3(4, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)

If swMate Is Nothing Then
    MsgBox "Failed to create concentric mate"
Else
    MsgBox "Concentric mate created successfully"
End If

Output

Concentric mate created successfully

When to Use

Use a concentric mate when you want two parts to share the same center line but still allow rotation or sliding. Common real-world examples include:

• A wheel mounted on an axle, where the wheel can spin but stays centered.
• A pipe inserted into a fitting, allowing sliding but keeping alignment.
• A bearing inside a housing, where the bearing rotates around the housing center.

This mate is essential for assemblies where parts must align perfectly around a circular axis but still move relative to each other.

Key Points

• Concentric mate aligns centers of cylindrical or circular faces.
• Allows rotation or sliding along the shared axis.
• Common in shafts, holes, pipes, and bearings.
• Helps maintain precise alignment in assemblies.

Key Takeaways

A concentric mate aligns two circular faces so their centers share the same axis.

It allows parts to rotate or slide around that axis while staying centered.

Use it for shafts, wheels, pipes, and bearings to keep perfect alignment.

It is essential for assemblies requiring precise rotational or sliding fit.

You can create it by selecting cylindrical faces in SolidWorks or via API.