When surface modeling is needed in Solidworks - Step-by-Step Guide

Introduction

Surface modeling helps create complex shapes that are hard to make with solid parts. It is useful when you need smooth, curved, or thin features that solid modeling cannot easily handle.

When designing a car body with smooth, flowing curves.

When creating a product with thin walls or shells like a phone case.

When modeling organic shapes like a shoe sole or a bottle.

When you need to repair or modify imported 3D scan data.

When combining multiple complex shapes that do not form a solid easily.

Steps

Step 1: Open SolidWorks and start a new part

- Start page

A new blank part workspace appears

Step 2: Select the Surfaces tab

- CommandManager toolbar

Surface modeling tools become visible

Step 3: Click on the 'Extruded Surface' tool

- Surfaces tab

Sketch plane selection prompt appears

Step 4: Create or select a sketch with the desired profile

- Graphics area

Sketch profile is ready for surface extrusion

Step 5: Set extrusion parameters and confirm

- PropertyManager

A surface is created following the sketch profile

Step 6: Use other surface tools like 'Lofted Surface' or 'Boundary Surface' for complex shapes

- Surfaces tab

Complex curved surfaces are created

Before vs After

Before

Only simple solid shapes can be created, complex curves are difficult or impossible

After

Smooth, complex curved surfaces are created that can be thickened or combined into solids

Settings Reference

Surface Thickness

📍 PropertyManager when using 'Thicken' tool

Adds thickness to a surface to create a solid body

Default: No thickness (surface only)

Direction of Extrusion

📍 PropertyManager in 'Extruded Surface'

Controls how the surface extends from the sketch

Default: One Direction

Merge Result

📍 PropertyManager for surface features

Determines if the new surface merges with existing bodies

Default: Unchecked

Common Mistakes

Trying to create complex curved shapes using only solid features

Solid features are limited to simpler shapes and cannot handle complex curves well

Use surface modeling tools like lofted or boundary surfaces for complex curves

Not setting surface thickness when a solid body is needed

Surfaces alone have no volume and cannot be used for manufacturing

Use the 'Thicken' tool to add thickness and convert surfaces into solids

Summary

Surface modeling is used to create complex, smooth, and thin shapes that solid modeling struggles with.

It is essential for designing organic or flowing shapes like car bodies or consumer products.

Remember to add thickness to surfaces if you need a solid part for manufacturing.

Practice

1. Which situation best describes when you should use surface modeling in SolidWorks?

easy

A. When you want to quickly create a solid cube

B. When making simple box shapes with straight edges

C. When creating complex, curved shapes that are hard to model as solids

D. When you only need 2D sketches without depth

Solution

1. Step 1: Understand surface modeling purpose

   Surface modeling is used for complex shapes that are difficult to create as solid bodies.

2. Step 2: Match scenario to surface modeling

   Complex, curved shapes require surface features to build the shape's skin before making solids.

3. Final Answer:

   When creating complex, curved shapes that are hard to model as solids -> Option C

4. Quick Check:

   Complex curved shapes = Surface modeling [OK]

Hint: Use surface modeling for complex curves, not simple boxes [OK]

Common Mistakes:

• Confusing surface modeling with solid modeling for simple shapes
• Using surface modeling for 2D sketches only
• Thinking surface modeling creates solids directly

2. Which of the following is the correct way to start a surface feature in SolidWorks?

easy

A. Select a 3D solid and click 'Extrude Boss/Base'

B. Select a 2D sketch and use 'Revolve Boss/Base'

C. Select a face and use 'Fillet' tool

D. Select a 2D sketch and use 'Surface Extrude'

Solution

1. Step 1: Identify surface feature start

   Surface features start from 2D sketches but use surface-specific tools like 'Surface Extrude'.

2. Step 2: Compare options

   'Extrude Boss/Base' and 'Revolve Boss/Base' create solids, not surfaces. 'Fillet' modifies edges, not start surfaces.

3. Final Answer:

   Select a 2D sketch and use 'Surface Extrude' -> Option D

4. Quick Check:

   Surface features start with 'Surface Extrude' [OK]

Hint: Surface features start with 'Surface Extrude' from sketches [OK]

Common Mistakes:

• Choosing solid extrusion tools instead of surface tools
• Confusing fillet with surface creation
• Using revolve boss/base which creates solids

3. What will happen if you try to create a solid body directly from multiple open surfaces in SolidWorks?

medium

A. You will get an error because surfaces are not closed

B. The software will create a solid automatically

C. The surfaces will merge into a single surface but not a solid

D. The surfaces will be deleted

Solution

1. Step 1: Understand surface vs solid bodies

   Surfaces are skins and must be closed to form solids. Open surfaces cannot form solids directly.

2. Step 2: Predict software behavior

   Trying to create a solid from open surfaces causes an error because the shape is not closed.

3. Final Answer:

   You will get an error because surfaces are not closed -> Option A

4. Quick Check:

   Open surfaces + solid creation = Error [OK]

Hint: Open surfaces can't form solids; must be closed first [OK]

Common Mistakes:

• Assuming surfaces merge into solids automatically
• Thinking surfaces get deleted when combined
• Confusing surface merging with solid creation

4. You created several surfaces but cannot form a solid. What is the most likely problem?

medium

A. You used the 'Surface Extrude' tool instead of 'Extrude Boss/Base'

B. The surfaces are not trimmed properly and do not form a closed volume

C. You forgot to save the file before creating the solid

D. The sketch used was 3D instead of 2D

Solution

1. Step 1: Analyze why surfaces don't form solids

   Surfaces must form a closed volume to create solids. Open or untrimmed surfaces prevent this.

2. Step 2: Evaluate options

   Using surface tools is correct; saving files or sketch dimension type does not prevent solid formation.

3. Final Answer:

   The surfaces are not trimmed properly and do not form a closed volume -> Option B

4. Quick Check:

   Open surfaces prevent solid formation [OK]

Hint: Check if surfaces form a closed volume before solidifying [OK]

Common Mistakes:

• Blaming file save status for modeling errors
• Confusing tool choice with surface closure
• Ignoring surface trimming and gaps

5. You need to design a car body with smooth, flowing curves. Which approach should you take in SolidWorks to create a solid model?

hard

A. Use surface modeling to create the curved skins, then knit surfaces and form a solid

B. Use only solid extrusions and cuts to approximate the shape

C. Draw 2D sketches and extrude them directly as solids without surfaces

D. Create multiple solid blocks and merge them without surfaces

Solution

1. Step 1: Understand complex shape modeling

   Car bodies have complex curves best created with surface modeling to form smooth skins.

2. Step 2: Combine surfaces into solids

   After creating surfaces, knit them to form a closed volume, then convert to a solid body.

3. Step 3: Evaluate other options

   Using only solids or blocks cannot capture smooth curves well; surfaces are necessary.

4. Final Answer:

   Use surface modeling to create the curved skins, then knit surfaces and form a solid -> Option A

5. Quick Check:

   Complex curves + knit surfaces = solid [OK]

Hint: Model curves with surfaces, then knit to solid [OK]

Common Mistakes:

• Trying to model complex curves only with solids
• Skipping knitting surfaces before solid creation
• Using block merging which lacks smoothness