Introduction
Stereo-lithography (SLA) is able to produce plastic parts with high resolution, high accuracy, fine details, smooth surfaces. As there are variety of resins for SLA, it has widely application in diverse industries.
Standard resins are applied for general prototyping.
Engineering resins have excellent mechanical and thermal properties.
Dental& medical resins are bio-compatible.
Castable resins will left zero ash-content after burnout.
We will introduce the most common SLA materials, summarize the key advantages of each resin, and provide the actionable guidelines for you. In order to help you to select the most suitable resins for your specific applications.
SLA Materials Overview
SLA apply the UV laser system to solidify liquid resin in printing process, we notice this as photo-polymerization. Different combinations of monomers, oligemers, photo-initiators and other additives will result to different properties of resins.
SLA creates parts in thermoset polymers, so there are the main advantages and disadvantages of common SLA materials.
Advantages:
Smooth surface finish(injection mold-like)
Fine features and high detail
High stiffness
Disadvantages:
Low elongation and relative brittle
Not suitable for outdoor application, material change once overexposure to UV radiation
Susceptible to creep
We will offer the materials properties of each specific SLA resins.
Standard SLA Resins
Standard Resin
Standard resins are used for high stiffness, high resolution and smooth surface finish parts production. It is the ideal materials for prototyping applications. The resin color also affect its final properties, such as gray color is more suitable for fine details, while white resin for more smooth surface.
Suitable applications: concept modeling, rapid prototyping, art models.
Advantages:
Fine features & high detail
Smooth surface finish
Most economic material
Disadvantages:
Low elongation and brittle
Low impact strength
Low heat deflection temperature
Clear resin
Clear resins have similar mechanical properties as standard resins, in addition, these materials can be post-processed to optical transparency level.
Applications: internal features show, LED housing.
Advantages:
Fine features & high detail
Smooth surface finish
Transparent
Disadvantages:
Low elongation and brittle
Low impact strength
Not suitable for outdoor application, material change once overexposure to UV radiation.
Engineering SLA Resins
Engineering resins have similar properties as injection-molded plastics, it provide a wide choice of materials for prototyping, testing and manufacturing. All engineering resins need post-curing by UV system to achieve the maximum mechanical properties.
Tough resin (ABS-like)
Tough resin is created for application materials with high withstand stress and strain. This resin parts have tensile strength of 55.7 MPa and modulus elasticity of 2.7GPa. It is widely used for sturdy and shatter-resistant parts production, functional prototypes.
Applications: functional prototypes, mechanical assemblies.
Advantages：
High stiffness
Excellent cyclic loading resistance
Disadvantages:
Not suitable for thin wall parts
Low heat deflection temperature
Low elongation and brittle
Durable resin (PP-like)
Durable resin has similar mechanical properties to Polypropylene (PP), it is wear-resistant and flexible. It normally applied for high flexibility, low friction and smooth surface finish parts production. It is more suitable for consumer products prototyping, snap fits and low friction parts.
Application: functional prototypes, consumer products, low friction and low-wear parts.
Advantages:
High wear resistance
Flexibility
High impact resistance
Disadvantages:
Not suitable for thin wall parts
Low tensile strength
Heat resistant resin
Heat resistant resin is the best option for parts with high thermal stability, which can operate at high temperatures. These resins will defect at temperature between 200 to 300 ℃, so we always apply these resin to produce heat resistant fixtures, mold prototypes, casting and therm-forming tools.
Applications: mold prototyping, casting and therm-forming tools.
Advantages:
High heat deflection temperature
Smooth surface finish
Disadvantages:
Low elongation and brittle
Not suitable for thin wall parts
Rubber-like resin
Rubber-like resin simulates rubber properties as soft to touch, this material has low tensile modulus, high elongation. It is more suitable for parts to be bent or compressed. It always applied for parts with ergonomic features and multi-material assembly, such as packages, stamps, wearable prototyping, handles, grips.
Application: wearable prototyping, multi-material assembly.
Advantages:
High flexibility
Low hardness
High impact resistance
Disadvantages:
Not suitable for thin wall parts
Materials properties degrade once exposed to UV radiation
Requires extensive support structure
Less mechanical properties than true rubber
Ceramic filled resin
Ceramic filled resins (Rigid resins) are filled with glass or other ceramic particles, which have high stiffness and rigidness with very smooth surface finish. Rigid resins have good thermal stability and heat resistance, high modulus and low creep, but more brittle. These resin are also suitable for thin walls and small features.
Applications: molds, jigs, fixtures
Advantages:
High stiffness
Suitable for fine features
Medium heat resistance
Disadvantages:
Brittle
Low impact strength
Dental & Medical SLA Resins
Custom medical resin (Class I bio-compatible)
Class I bio-compatible resins are applied for custom medical equipment, like surgical guides. These resin parts can be steam sterilized by autoclaves for operating room application.
Applications: surgical aids and appliances
Advantages:
High precision
Smooth finish
Short term usage
Disadvantages:
Medium wear and fracture resistance
Dental bio-compatible resin(Class IIa bio-compatible)
This resin is special for long term orthodontic appliances, it can be in contact with human body for a year. Its high fracture and wear resistance is perfect for hard splints or retainers production.
Applications：long term dental appliances, hard splits, retainers.
Advantages:
High accuracy
High fracture and wear resistance
Disadvantages:
High cost
Castable SLA Resins
Castable resin for jewelry
This resin will provide sharp details and smooth finish for final parts, it will burn out clean without ashes or residue. Castable resin can enable part production form digital design to investment casting by a single 3D printed part. It is suitable for jewelry, small and intricate components.
Application: jewelry manufacturing, investment casting.
Advantages:
Fine features and high details
No ash content after burnout
Disadvantages:
Low impact and wear resistance
Need post-processing