The Essential Guide to 3D Printing Techniques in Mechanical Design

Understanding 3D Printing in Mechanical Design

In the modern world of mechanical design, 3D printing has transformed from a rapid prototyping novelty into a powerful manufacturing method. Whether you’re validating a concept, producing functional parts, or creating molds for low-volume manufacturing, knowing which 3D printing technique to choose—and how to design for it—is crucial.

Each method has its strengths, limitations, and design considerations. Let’s break down the three most common 3D printing processes used in engineering and product development today: FDM, SLS, and SLA.

FDM (Fused Deposition Modeling)

How It Works

FDM printing builds parts layer by layer by extruding melted thermoplastic filaments such as PLA, ABS, or PETG through a heated nozzle.

Best Used For

• Low-cost prototypes

• Fit and assembly testing

• Large, non-aesthetic components

  
  

Design Guidelines

• Minimum wall thickness: 1.2–1.5 mm for structural integrity.

• Orientation: Place overhangs at ≤45° to minimize the need for supports.

• Holes and gaps: Avoid designing holes smaller than 2 mm as they may close up due to material flow.

• Tolerances: FDM accuracy typically ranges from ±0.3 mm to ±0.5 mm.

  
  

Design Tip in SolidWorks

Use the “Draft Analysis” tool to check for overhangs and unsupported surfaces. You can also define printing orientation and clearances by creating custom reference planes during the design stage.

Post-Processing

• Support removal (mechanical or soluble)

• Sanding and smoothing for visible layer lines

• Vapor smoothing for ABS to improve surface finish

• Painting or coating to enhance durability and aesthetics

  
  

SLS (Selective Laser Sintering)

How It Works

A laser fuses nylon or composite powder layer by layer, forming a strong, functional part without the need for support structures.

Best Used For

• Functional prototypes

• Complex geometries

• Batch production of mechanical parts

  
  

Design Guidelines

• Minimum wall thickness: 1 mm for small features, 2 mm for large flat surfaces.

• Clearances: Minimum 0.2 mm between moving parts to prevent fusing.

• Embossed details: At least 0.5 mm deep for clarity.

• Orientation: Use SLS freedom to design parts as a single assembly or interlocking joints.

  
  

Design Tip in SolidWorks

SLS allows organic, topology-optimized designs, so consider using SolidWorks Simulation + Topology Study to reduce weight while maintaining strength.

Post-Processing

• Bead blasting to remove residual powder

• Dyeing for uniform color

• Polishing or coating for smoother finishes

• Heat treatment (optional) for improved mechanical performance

  
  

SLA (Stereolithography)

How It Works

SLA uses a UV laser to cure liquid resin, producing highly detailed and smooth parts ideal for presentation models or master patterns.

Best Used For

• High-detail prototypes

• Visual and cosmetic parts

• Master models for casting

  
  

Design Guidelines

• Minimum wall thickness: 0.8–1 mm

• Supports: Required for most geometries; design flat bases to reduce marks.

• Drain holes: Include 2–3 mm holes to allow uncured resin to escape from hollow areas.

• Tolerances: Excellent precision, typically ±0.1 mm.

  
  

Design Tip in SolidWorks

When designing for SLA, use the “Shell” feature to hollow out parts and reduce resin use. Apply fillets to edges that connect to supports to make post-processing easier.

Post-Processing

• Support removal and sanding

• UV curing to fully harden the resin

• Priming and painting for appearance models

• Clear coating for transparent parts

  
  

Choosing the Right Process

Process	Materials	Accuracy	Surface Finish	Strength	Cost	Applications
FDM	PLA, ABS, PETG	±0.3–0.5 mm	Fair	Moderate	Low	Concept Models
SLS	Nylon, PA12, Composites	±0.2 mm	Good	High	Medium	Functional Parts
SLA	Resin	±0.1 mm	Excellent	Moderate	Medium	Aesthetic Models

Design and Beyond

At The SolidWorks Expert, we help clients move from CAD to prototype seamlessly. Using SolidWorks, we design parts optimized for 3D printing—accounting for print orientation, material behavior, and post-processing requirements—ensuring faster production, higher quality, and reduced trial and error.

Conclusion

3D printing isn’t just one technology; it’s a toolkit of solutions. Understanding how each process works, what it’s best for, and how to model your designs accordingly can save both time and cost while unlocking better performance.

Whether it’s FDM for quick validation, SLS for functional parts, or SLA for precision models, the key is the same: design smart, print efficiently, and refine with purpose.

Let’s Build Your Next Prototype

Get your design ready for 3D printing today.