How to Use Mates in SolidWorks Assembly: Step-by-Step Guide

In SolidWorks assembly, use Mates to define relationships between parts that control their position and movement. You select faces, edges, or points on components and apply Mate types like Coincident, Parallel, or Concentric to fix their relative positions. This helps build a functional and constrained assembly model.

Syntax

The basic syntax for using mates in SolidWorks assembly involves selecting entities and applying a mate type:

• Select Entities: Choose faces, edges, vertices, or planes from different parts.
• Choose Mate Type: Examples include Coincident, Parallel, Perpendicular, Concentric, Distance, and Angle.
• Confirm Mate: Apply the mate to constrain the parts accordingly.

This process is done through the Mate command in the assembly toolbar or menu.

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1. Open your assembly in SolidWorks.
2. Click on the 'Mate' button in the Assembly toolbar.
3. Select the first entity (face, edge, or point) on one part.
4. Select the second entity on another part.
5. Choose the mate type from the Mate PropertyManager (e.g., Coincident).
6. Click 'OK' to apply the mate.

Example

This example shows how to mate two parts so that a hole on one part aligns concentrically with a pin on another part:

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1. Insert Part A and Part B into an assembly.
2. Click 'Mate'.
3. Select the cylindrical face of the hole on Part A.
4. Select the cylindrical face of the pin on Part B.
5. Choose the 'Concentric' mate type.
6. Click 'OK'.

Result: The pin is aligned inside the hole, allowing rotation but no lateral movement.

Output

The pin and hole are aligned concentrically, constraining their axes to be the same.

Common Pitfalls

• Over-constraining: Applying too many mates can cause conflicts and errors.
• Wrong entity selection: Selecting incorrect faces or edges leads to unexpected part positions.
• Ignoring mate order: Some mates depend on previous mates; adding mates in a logical order helps avoid errors.
• Not using flexible subassemblies: Sometimes parts need to move; rigid mates prevent this.

Always check the mate status and resolve conflicts by removing or editing mates.

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/* Wrong way: Over-constraining two parts */
Mate1: Coincident face A to face B
Mate2: Parallel face A to face B
Mate3: Distance 0 between same faces

/* Right way: Use only necessary mates */
Mate1: Coincident face A to face B
Mate2: Distance 0 between faces if needed

Quick Reference

Mate Type	Description	Use Case
Coincident	Makes two faces or edges touch	Align flat surfaces or edges
Concentric	Aligns axes of cylindrical faces	Align pins and holes
Parallel	Makes two faces or edges parallel	Keep parts aligned side-by-side
Perpendicular	Makes two faces or edges at 90°	Create right angle relationships
Distance	Sets a fixed distance between entities	Control spacing between parts
Angle	Sets a fixed angle between entities	Control angular position

Key Takeaways

Use mates to control how parts fit and move relative to each other in an assembly.

Select the correct faces or edges and choose the appropriate mate type for your design intent.

Avoid over-constraining by applying only necessary mates to prevent conflicts.

Check mate status regularly to troubleshoot and fix errors in your assembly.

Common mate types include Coincident, Concentric, Parallel, Perpendicular, Distance, and Angle.