Why Early-stage Prototyping?

The best way to improve communication and facilitate better feedback and decision-making from stakeholders is with prototypes.
Early-stage prototyping not only helps you more effectively convey design ideas, but also helps you identify and address potential issues early in the development process, so you're able to have design validation and iteration.

Using the right material enables functionality testing under real-world conditions, ensuring the final product meets performance requirements. Cost savings are achieved by preventing expensive mistakes and reducing overall development costs.

Rapid prototyping accelerates the product development process, leading to faster time-to-market. So how do you do it right?

Choosing the Right Material and Finish for Prototypes

Choosing the right material and finish for prototypes is #1 and depends on the following requirements: functional, aesthetic, and production, as well as budget/cost.

FUNCTIONAL

Mechanical Properties: Consider strength, flexibility, and durability. For example, nylon is strong and durable, making it suitable for functional prototypes, while PLA is more brittle but easier to print.

Thermal Resistance: If the prototype is exposed to high temperatures, materials like Ultem (Polyetherimide) or certain resins may be necessary.

 

AESTHETIC

Surface Finish: Depending on the prototype’s purpose, the surface finish might need to be smooth and polished. SLA and MJF provide better surface finishes compared to FDM, but post-operations may be needed to meet requirements

Color and Transparency: Some materials offer a variety of colors or transparency options, which might be important for visual prototypes.

 

PRODUCTION

Resolution and Precision: High precision and fine details may be required, which would make SLA the clear leader.

Post-Processing Needs: Consider the amount of post-processing required to achieve the desired finish. Are those processes automated or manual, do they affect precision and function? SLS parts often need more post-processing than SLA or FDM parts.

 

COST CONSIDERATIONS

Material Costs: Some materials are more expensive than others, which can impact the overall prototyping budget.

Manufacturing Costs: The technology used can affect the cost, with FDM generally being more cost-effective for simple prototypes.

 

Most Effective Technologies for Rapid Prototyping

By understanding the strengths and limitations of each technology, engineers can make informed decisions to select the best material and prototyping method for their specific project requirements.

Technology	How It Works	Advantages	Disadvantages	Best For
Fused Deposition Modeling (FDM)	Extrudes thermoplastic filament through a heated nozzle, depositing material layer by layer.	- Cost-effective - Wide range of thermoplastics - Easy to use	- Lower resolution and surface finish - Structural limitations with complex geometries and overhangs	Low-cost, quick iterations, simple mechanical parts, proof-of-concept models
Stereolithography (SLA)	Uses a UV laser to cure liquid resin, building the part layer by layer.	- High resolution - Excellent precision - Smooth surface finishes	- Limited to photopolymer resins - Requires post-processing	Detailed visual models, small precise parts, and high-accuracy prototypes
Selective Laser Sintering (SLS)	Uses a high-powered laser to fuse small particles of polymer powder, building parts layer by layer.	- Strong and durable parts - Handles complex geometries well  - No need for support structures	- More expensive than FDM - Often requires post-processing for a smooth finish	Functional prototypes, complex geometries, parts needing mechanical stress endurance
Multi-Jet Fusion (MJF)	Spreads a layer of powder and selectively applies a fusing and detailing agent, fused by infrared light.	- High detail and surface quality - Consistent superior  mechanical properties - Faster production speed	- Limited material options (primarily nylon) - could be more expensive than FDM - requires post-processing	Functional prototypes, high-detail parts, medium to large batch production

 

Fused Deposition Modeling (FDM)

 

Best For: Low-cost, quick iterations, simple mechanical parts, and proof-of-concept models.

 

FDM extrudes thermoplastic filament through a heated nozzle, depositing material layer by layer.

Advantages

Cost-Effective: Generally the least expensive option, both in terms of equipment and material costs.

Material Variety: Compatible with a wide range of thermoplastics, including PLA, ABS, and PETG, and specialty materials.

Ease of Use: Widely accessible and straightforward to operate.

Disadvantages

Lower Resolution: Typically offers lower resolution and surface finish compared to SLA and MJF.

Structural Limitations: Can struggle with complex geometries and overhangs.

 

Stereolithography (SLA)

 

Best For: Detailed visual models, small precise parts, and prototypes requiring high accuracy and smooth finishes.

 

SLA uses a UV laser to cure liquid resin, building the part layer by layer.

Advantages

High Resolution: Produces highly detailed and smooth surface finishes.

Precision: Capable of fine details and complex geometries.

Disadvantages

Material Limitations: Limited to photopolymer resins, which may not be as durable as thermoplastics.

Post-Processing: Requires post-processing, including cleaning and curing.

 

 

Selective Laser Sintering (SLS)

 

Best For: Functional prototypes, complex geometries, and parts that need to withstand mechanical stress.

 

SLS uses a high-powered laser to fuse small particles of polymer powder, building parts layer by layer.

Advantages

Material Strength: Produces strong and durable parts suitable for functional testing.

Complex Geometries: Excellent for creating intricate and complex designs without the need for support structures.

Disadvantages:

Cost: Generally more expensive than FDM.

Surface Finish: Often requires post-processing to achieve a smooth finish.

 

 

Multi-Jet Fusion (MJF)

 

Best For: Functional prototypes, high-detail parts, and end-use parts requiring high strength and durability.

 

MJF spreads a layer of powder and selectively applies a fusing and detailing agent, which is then fused by infrared light.

Advantages

High Detail and Surface Finish: Offers excellent resolution and surface quality.

Consistent Mechanical Properties: Produces parts with uniform strength and durability – the best layer strength than any other technology.

Speed: Faster than SLS for certain geometries, making it cost-effective for medium to large batches.

Disadvantages

Material Options: Currently limited to primarily nylon and similar polyamides, but can also do polypropylene and TPU.

Cost: Similar to SLS, it can be more expensive than FDM.

 

 

Technology Comparison Summary

 

FDM: Best for cost-effective, quick iterations, and simple prototypes. Offers a wide range of thermoplastics but has a lower resolution and surface finish.

SLA: Excellent for detailed and precise parts with smooth finishes. Ideal for visual models and small, intricate prototypes but limited to resins.

SLS: Suitable for functional prototypes requiring durability and complex geometries. Offers strong material properties but often requires post-processing.

MJF: Provides high detail, consistent mechanical properties, and efficient production for medium to large batches. Ideal for functional and high-detail parts but is primarily limited to nylon materials.

SLS & MJF are both powder bed technologies. MJF has better density and strength than SLS. SLS has been around longer and has more material options. Post-processing is about the same for both.

 

 

Best practices for early-stage prototyping include defining clear objectives, selecting appropriate materials and technologies, iterating quickly and frequently, incorporating stakeholder feedback early, and documenting changes and learnings.

 

By following best practices, engineers can improve their design process, enhance product quality, and achieve more efficient and successful project outcomes.