Standard mates (coincident, concentric, distance) in Solidworks - Step-by-Step Guide

Introduction

Standard mates in SolidWorks help you connect parts in an assembly so they fit and move correctly. They solve the problem of positioning parts precisely by defining how surfaces or axes relate to each other.

When you want two flat faces of parts to touch exactly without gaps or overlaps.

When you need two cylindrical parts to share the same center axis, like a bolt in a hole.

When you want to keep a fixed distance between two parts, such as a spacer between plates.

When assembling parts that must align perfectly for correct function, like gears or shafts.

When you want to control movement limits by setting a specific gap or overlap.

Steps

Step 1: Open your assembly file

- SolidWorks main window

The assembly with parts is visible on screen

Step 2: Click Mate button

- Assembly tab on the CommandManager toolbar

Mate PropertyManager opens on the left side

Step 3: Select the first face or edge on the first part

- Graphics area

The selected item highlights and appears in the Mate selections box

Step 4: Select the second face or edge on the second part

- Graphics area

Both selections appear in the Mate selections box

Step 5: Choose the mate type: Coincident, Concentric, or Distance

- Mate PropertyManager under Standard Mates

The preview updates showing how parts will align or space

Step 6: If Distance mate, enter the desired gap value

- Distance input box in Mate PropertyManager

The preview shows parts separated by the entered distance

Step 7: Click OK (green checkmark)

- Mate PropertyManager

The mate is applied and parts move or align accordingly

Before vs After

Before

Two parts in assembly float separately with no defined position relative to each other

After

Parts are connected so their selected faces or axes align exactly or maintain a set distance

Settings Reference

Mate Type

📍 Mate PropertyManager under Standard Mates

Defines how two selected entities relate spatially

Default: Coincident

Distance Value

📍 Distance input box in Mate PropertyManager

Sets the exact gap or offset between parts for Distance mate

Default: 0

Flip Mate Alignment

📍 Mate PropertyManager near preview

Changes the direction of the mate alignment if parts are reversed

Default: Off

Common Mistakes

Selecting faces that are not compatible for the chosen mate type

The mate preview will fail or produce unexpected alignment

Choose faces or edges that logically match the mate type, like flat faces for Coincident or cylindrical edges for Concentric

Forgetting to enter a distance value when using Distance mate

The mate defaults to zero distance, causing parts to touch unexpectedly

Always enter the exact distance needed before confirming the mate

Not checking the Flip Mate Alignment option when parts align incorrectly

Parts may face the wrong direction or overlap

Use the Flip option to reverse alignment preview before applying the mate

Summary

Standard mates connect parts by aligning faces or axes with Coincident, Concentric, or Distance options.

They help position parts precisely for correct assembly and movement.

Always select compatible geometry and verify alignment direction before confirming mates.

Practice

1. Which type of standard mate in SolidWorks makes two faces or edges touch exactly?

easy

A. Coincident mate

B. Concentric mate

C. Distance mate

D. Parallel mate

Solution

1. Step 1: Understand the Coincident Mate

   A coincident mate forces two faces or edges to touch exactly, aligning them perfectly.

2. Step 2: Compare with Other Mates

   Concentric mates align circular parts along the same axis, and distance mates keep parts a fixed space apart, so they do not make faces touch.

3. Final Answer:

   Coincident mate -> Option A

4. Quick Check:

   Faces touching = Coincident mate [OK]

Hint: Faces or edges touching? Choose coincident mate [OK]

Common Mistakes:

• Confusing concentric with coincident
• Thinking distance mate makes parts touch
• Mixing parallel mate with coincident

2. Which of the following is the correct syntax to apply a concentric mate between two circular edges in SolidWorks?

easy

A. Mate.AlignCenters(edge1, edge2)

B. Mate.Add(edge1, edge2, 'distance')

C. Mate.SelectFaces(face1, face2).ApplyCoincident()

D. Mate.SelectEdges(edge1, edge2).ApplyConcentric()

Solution

1. Step 1: Identify the correct method for concentric mates

   The method to apply a concentric mate involves selecting edges and applying the concentric constraint, matching Mate.SelectEdges(edge1, edge2).ApplyConcentric().

2. Step 2: Eliminate incorrect options

   Mate.Add(edge1, edge2, 'distance') applies a distance mate, Mate.SelectFaces(face1, face2).ApplyCoincident() applies coincident on faces, and Mate.AlignCenters(edge1, edge2) is not a valid SolidWorks syntax.

3. Final Answer:

   Mate.SelectEdges(edge1, edge2).ApplyConcentric() -> Option D

4. Quick Check:

   Concentric mate syntax = Mate.SelectEdges(edge1, edge2).ApplyConcentric() [OK]

Hint: Select edges then apply concentric mate method [OK]

Common Mistakes:

• Using face selection for concentric mate
• Confusing distance mate syntax with concentric
• Using non-existent methods like AlignCenters

3. Given two cylindrical parts with axes aligned, what is the result of applying a concentric mate between their circular edges?

medium

A. The parts are fixed at a set distance apart.

B. The parts' axes align and their circular edges share the same center axis.

C. The parts' flat faces touch exactly.

D. The parts rotate freely without alignment.

Solution

1. Step 1: Understand the effect of a concentric mate

   A concentric mate aligns the axes of circular edges so they share the same center line.

2. Step 2: Compare with other mate effects

   Distance mates keep parts apart, coincident mates make faces touch, and free rotation means no mate applied.

3. Final Answer:

   The parts' axes align and their circular edges share the same center axis. -> Option B

4. Quick Check:

   Concentric mate aligns axes = The parts' axes align and their circular edges share the same center axis. [OK]

Hint: Concentric mate aligns circular axes, not faces [OK]

Common Mistakes:

• Thinking concentric sets distance
• Confusing coincident with concentric
• Assuming free rotation after mate

4. You tried to apply a distance mate between two parts but the parts snap together instead of staying apart. What is the likely cause?

medium

A. The distance value was set to zero.

B. You applied a coincident mate instead of a distance mate.

C. The parts are fixed and cannot move.

D. You applied a concentric mate by mistake.

Solution

1. Step 1: Check the distance mate value

   If the distance is zero, parts will snap together, appearing coincident.

2. Step 2: Rule out other causes

   Applying coincident or concentric mates causes different behaviors; fixed parts do not move but distance mate with zero causes snapping.

3. Final Answer:

   The distance value was set to zero. -> Option A

4. Quick Check:

   Distance zero snaps parts together = The distance value was set to zero. [OK]

Hint: Check distance value; zero means no gap [OK]

Common Mistakes:

• Confusing coincident with distance mate effect
• Ignoring zero distance input
• Assuming concentric mate affects distance

5. You need to assemble a shaft inside a hole so that the shaft's axis aligns with the hole's axis and the shaft is exactly 5 mm away from the hole's bottom face. Which mates should you apply?

hard

A. Apply a distance mate of 5 mm between shaft and hole edges only.

B. Apply two coincident mates: one for axes and one for bottom faces.

C. Apply a concentric mate between shaft and hole edges, then a distance mate of 5 mm between shaft bottom face and hole bottom face.

D. Apply a concentric mate and a coincident mate between bottom faces.

Solution

1. Step 1: Align shaft and hole axes

   Use a concentric mate between the circular edges of shaft and hole to align their axes.

2. Step 2: Set the gap distance

   Apply a distance mate of 5 mm between the shaft's bottom face and the hole's bottom face to maintain the required space.

3. Final Answer:

   Apply a concentric mate between shaft and hole edges, then a distance mate of 5 mm between shaft bottom face and hole bottom face. -> Option C

4. Quick Check:

   Concentric for axis + distance for gap = Apply a concentric mate between shaft and hole edges, then a distance mate of 5 mm between shaft bottom face and hole bottom face. [OK]

Hint: Use concentric for alignment, distance for spacing [OK]

Common Mistakes:

• Using coincident mate for axis alignment
• Applying distance mate between edges only
• Mixing coincident and concentric incorrectly