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Exploring additive innovation: 3D printing clear parts with resin

The additive manufacturing landscape is evolving constantly, particularly in the material space – where providers must improve, and adapt their outputs to meet manufacturer needs. Modern 3D printing technology has an array of additive materials with which to create opaque, plastic-like parts but when it comes to making transparent or translucent parts material choices can be more challenging.

 

There’s no shortage of manufacturing projects that need some degree of transparency or translucency and that would, therefore, benefit from a clear resin build option. Light pipes, for example, have broad application in consumer electronics, dental surgery equipment, and microfluidic devices – amongst other industrial end-uses. Similarly, clear 3D printing resin can be used to create an array of optical parts, including lenses, light fittings, and see-through housings. Given the potential applications, it makes sense to explore how clear resin fits into the additive manufacturing process.

Can I 3D print clear plastic parts?

There is a perception across the additive manufacturing market that clear resin 3D prints pose manufacturing challenges that other materials do not – including longer print times, requirements for labor-intensive finishing processes, or lower quality final parts. Those factors have lent clear resins a reputation for being cost prohibitive and for having a limited set of applications.

 

However, while certain additive production challenges exist, it is entirely possible to create clear or translucent plastic parts using 3D printing technology, with the same speed, accuracy, and cost-efficiency benefits as other additive materials. In some cases, clear parts may require finishes and post-processing to achieve greater clarity – but these considerations may be factored-in to the design process in the same manner as opaque part production.

 

With that in mind, if you’re searching for a resin to meet your project’s clarity requirements, let’s take a look at some of the most effective materials and their respective additive manufacturing processes.

Clear resin 3D printing materials

IND 405 – Carbon® Digital Light Synthesis (DLS)™

A clear resin developed by Carbon® for the Digital Light Synthesis (DLS)™ 3D printing process, LOCTITE 3D IND 405 is a one-part resin – which means it can be printed quickly and easily. Once cured, IND 405 parts have a frosted surface appearance – after sufficient post-processing, it is possible to enhance that clarity.

 

LOCTITE 3D IND405 Clear Listing
(c) 2020 Carbon, Inc. Used with Permission

 

IND405 was developed following specific feedback from engineers who wanted an easy-to-print 3D printing material that had more durability and impact-resistance than its counterparts but that offered a degree of improved clarity to increase its design flexibility. With that in mind, IND405 is strong and tough and useful for applications including fluid analysis devices, lens prototypes, clear housings and enclosures, and surgical guides.

 

IND405’s mechanical specifications include:

  • Tensile strength at break: 42 MPa
  • Young’s modulus: 1500 MPa
  • Elongation at failure: 120%
  • Impact strength — IZOD Notched: 50 J/m
  • Heat deflection temperature at 0.455 MPa: 53 °C

CE 221 – Carbon® Digital Light Synthesis (DLS)™

Cyanate Ester (CE 221) is another Carbon®-developed resin for the digital light synthesis (DLS) additive manufacturing process. Comparable to 14% glass-filled Nylon 6, CE 221 is known for its high temperature resistance and rigidity.

 

Orange plastic part

 

CE 221’s key properties include UV resistance, biocompatibility, and chemical resistance to household and industrial chemicals,acids, alcohols, and bases. CE221 is semi-transparent, with an orange coloration.

 

CE 221’s mechanical specifications include:

  • Tensile strength at break: 85 MPa
  • Young’s modulus: 3900 MPa
  • Elongation at failure: 3 %
  • Impact strength — IZOD Notched: 15 J/m
  • Heat deflection temperature at 0.455 MPa: 230 °C

Clear resin – Stereolithography (SLA)

Clear is a resin developed by Formlabs for stereolithography (SLA) 3D printing, which produces parts using a photopolymerization process. Ideal for creating parts that require translucency, or that need to showcase internal functionality, Clear resin is commonly used to make optical components and lighting parts.

 

In order to achieve improved clarity, however, Clear resin requires significant post-processing. In practice, this means manually sanding or polishing parts or applying spray coating or clear coating.

 

Clear resin’s mechanical specifications include:

  • Tensile strength at break: 65 MPa
  • Young’s modulus: 16 GPa
  • Elongation at failure: 6.2 %
  • Impact strength — IZOD Notched: 25 J/m
  • Heat Deflection Temperature @ 0.455 MPa/66 psi: 73.1 °C

High Temp – Stereolithography (SLA)

High Temp is a resin developed for the stereolithography process by Formlabs. Clear with a slight orange tint, it stands out from other clear 3D printing resins because of its strength and temperature resistance: High Temp can withstand temperatures of up to 238 °C with minimal loading, and so is recommended for applications such as clear housings and fixtures, or hot air, gas, and fluid flow functions where clarity is a requirement.

 

Like Clear resin, High Temp requires post-processing to enhance its clarity. Its mechanical specifications include:

  • Tensile strength at break: 58.3 MPa
  • Young’s modulus: 2.6 GPa
  • Elongation at failure: 13 %
  • Impact strength — IZOD Notched: 18.2 J/m
  • Heat Deflection Temperature @ 0.455 MPa/66 psi: 142 °C

Durable – Stereolithography (SLA)

Durable is a resin developed by Formlabs to be capable of withstanding impact, wear, and extreme deformation before it breaks. Ideal for creating engineering prototypes, Durable is also useful for parts that require slight pliability, or that need low friction surfaces.

 

Durable resin is semi-transparent with a clarity similar to frosted glass, and can be sanded to a smooth finish. Durable resin’s mechanical specifications include:

  • Tensile strength at break: 28 MPa
  • Young’s modulus: 1000 MPa
  • Elongation at failure: 55%
  • Impact strength — IZOD Notched: 114 J/m
  • Heat Deflection Temperature @ 0.455 MPa/66 psi: 41 °C

Elastic – Stereolithography (SLA)

Formlabs’ Elastic resin, is a transparent elastomeric material that offers low durometer, high elongation, and high energy return, which means that it will bend, stretch, and compress well. Elastic is a useful alternative to silicone, and is particularly suited to sof-touch parts that need to be flexible, durable, and shatterproof.

 

Elastic Resin Listing

 

Elastic resin is commonly used to make medical models and prototypes, particularly patient-specific anatomical models. It’s also used to make wearables and consumer goods, and special effects, models, and props.

 

Elastic resin’s mechanical specifications include:

  • Tensile strength at break: 3.23 MPa
  • Young’s modulus: –
  • Elongation at failure: 160%
  • Impact strength — IZOD Notched: –
  • Heat Deflection Temperature @ 0.455 MPa/66 psi: –

Clear parts: Finishing and post-processing

Parts manufactured in clear resin may not achieve levels of desired optical transparency until suitable finishes have been applied, or until they have gone through post-processing. The relevant finishes and processing options used to reach transparency offer different advantages and challenges.

 

With that in mind, Fast Radius has developed a number of techniques to improve the clarity of printed parts, including sanding and clear coating. We perform case-by-case analysis to determine which techniques to utilize for a specific geometry and we’ll work with you to help achieve the best possible level of clarity that you need for your part.

 

If you want to learn more about Fast Radius’s capabilities, or are interested in using clear resin in your next project, please contact our team today.

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