What is the difference between SLA and DLP?

Stereolithography (SLA) and Digital Light Processing (DLP) are both based on the polymerization principle of liquid photopolymer resin, and the three-dimensional structure is completed by curing the resin material layer by layer. In terms of technical implementation paths, there are obvious differences between the two: SLA uses ultraviolet laser to scan point-by-point to draw a single-layer outline; DLP uses a digital micromirror device (DMD) to project a complete cross-sectional mask pattern in one go. In terms of printing results, the SLA process has the advantage of excellent surface finish, which is especially suitable for precision manufacturing fields with strict surface quality requirements; With the characteristics of full-layer parallel curing, the DLP process has more outstanding printing efficiency and cost control. This article will compare SLA and DLP in detail from the dimensions of technical differences, applicable materials, and printing processes.

How do SLA and DLP printing speeds compare?

In the field of photocuring 3D printing, SLA (stereolithography) and DLP (digital light processing) are the two mainstream technologies, and printing speed is often a key consideration when users choose. The following is a concise table comparing SLA and DLP 3D printing speeds, covering the core dimensions and technical differences:

Key conclusions

1. DLP has obvious speed advantages: the whole-layer curing mechanism makes it much more efficient than SLA, especially suitable for mass production of small and medium-sized parts.
2. SLA is applicable to fine scenes: in complex structures or large models (such as industrial prototypes), SLA has higher controllability due to point-by-point scanning, and its speed disadvantage may be offset by the accuracy requirements.
3. Balanced choice: choose DLP for fast iteration, and choose SLA for extreme accuracy and complex design.

Which one has higher accuracy, SLA or DLP?

In the field of 3D printing, accuracy is one of the key indicators to measure the value of technology, and SLA (stereolithography) and DLP (digital light processing) in light curing technology are often compared by users. LS will analyze the accuracy difference between the two through technical principle disassembly, actual measurement data comparison and industry application scenarios, and help you choose the best solution according to your needs.

1. Technical principles determine the upper limit of accuracy

(1)SLA: The “micron-level art” of laser point-by-point engraving

• Core mechanism: The ultraviolet laser controls the spot path through the galvanometer system, scanning the surface of the liquid resin point by point, and triggering the photopolymerization reaction.
• Accuracy Advantage:

1. XY axis: determined by the laser spot diameter, down to 10 microns (e.g. Formlabs Form 3).
2. Z-axis: The thickness of the layer is controlled by a precision lifting platform, and the theoretical limit is 0.01mm (supported by low-viscosity resin).

• Applicable scenarios: dental implant guide plate (error < 0.1mm), microfluidic chip (50 micron channel) and other ultra-fine fields.

(2)DLP: “Batch Accuracy” for Pixel Projection

• Core mechanism: The UV projector projects the entire layer of pattern onto the resin surface through a DMD chip (digital micromirror device) and cures it at one time.
• Accuracy characteristics:

1. XY axis: Determined by the projected pixel size, up to 22 microns for high-end devices (e.g. Anycubic Photon Ultra).
2. Z-axis: Similar to SLA, the theoretical minimum layer thickness is 0.01mm, but the resin fluidity requirements are higher.

• Applicable scenarios: mass production of invisible braces (± 0.1mm tolerance), jewelry master pattern casting and other small and medium-sized components.

2. Comparison of measured data: SLA and DLP precision hard indicators

3. Who is better? Analysis of scenario-based accuracy requirements

(1)SLA accuracy crushing scenario

• Ultra-precision medical treatment: such as neurosurgery guides, requiring sub-50 micron errors.
• Micro-mechanical parts: gear sets with a diameter of 1mm, the pitch tolerance needs to be <0.02mm.
• Artistic micro-carving: restore hair texture or hollow relief in cultural relics restoration.

(2) DLP alternative scenarios

• Small and medium-sized batch parts: such as printing 10 invisible braces at a time, the accuracy meets clinical needs.
• Regular geometry: standardized industrial fixtures or electronic housings, without extreme details.
• Post-processing optimization scenario: cover pixelated burrs (such as hand-made models) by polishing or painting.

4. Hidden factors affecting accuracy: the “secret battle” between equipment and materials

(1) Differences in equipment performance

• SLA galvanometer calibration: high-end equipment (such as 3D Systems ProX 800) reduces scanning deviation through closed-loop feedback.
• DLP projection chip: 4K/8K resolution chips (such as TI 0.47-inch 4K DMD) reduce the pixel size to 22 microns.

(2) Resin material properties

• Low viscosity resin: Improve the leveling between SLA layers and ensure Z-axis consistency.
• High response resin: DLP needs to be matched with fast-curing resin to reduce edge blur caused by light scattering.

5. User Selection Guide: The Balance between Precision and Cost

✅ 3 Types of Users Who Give Priority to SLA

• Medical/Research Institutions: Require reliable micron-level precision.
• High-end Manufacturing Companies: Such as Precision Prototype Verification in Aerospace.
• Jewelry Designers: Pursue Zero-Defect Wax Model Surface.

✅ 3 Types of Users Who Give Priority to DLP

• Dental Clinics: Batch + Fast Delivery, As Long as the Precision Meets the Standard.
• Small and Medium-sized Studios: Limited Budget but Require Medium Precision (such as Cultural and Creative Products).
• Education: Students Practice Balancing Cost and Visual Details.

SLA has an advantage in absolute accuracy, especially in the ultra-precision field; while DLP has become the preferred choice for small and medium-sized batch production due to its balance between efficiency and cost. In the future, with the iteration of light-curing technology, the accuracy gap between the two may narrow, but the core difference is still determined by the principle. When choosing, you need to focus on the application scenario, budget range and post-processing capabilities, so that accuracy can truly serve value creation.

What materials are available for SLA and DLP 3D printing?

In the field of photocuring 3D printing, the technical differences between SLA (stereolithography) and DLP (digital light processing) directly affect the material adaptability. This section will deeply analyze the material selection logic of the two technologies from three dimensions: material formula characteristics, special resin types, and industry application cases, to help users accurately match their needs.

1. How do technical differences affect material adaptability?

2. Types and representative products of SLA special resins

(1)High-precision engineering resins

• Characteristics: Dual initiator system (e.g. TPO 819), suitable for high energy density of laser.
• Representative products:

Formlabs Rigid 10K: Flexural strength 210MPa for aerospace functional parts.

Liqcreate Composite Tough: Filled with glass fiber, tensile strength 65MPa.

(2) Biocompatible resins

• Medical certifications: ISO 10993/EN ISO 13485.
• Representative products:

Formlabs Dental SG: Dedicated to dental surgical guides, certified for sterilization compatibility.

Detax Freeprint Model: TÜV certified for long-term oral contact.

(3) High temperature resistant resin

• Performance: HDT (Heat Deflection Temperature) > 200°C.
• Representative products:

Loctite IND405: 250°C temperature resistance for automotive engine compartment prototypes.

3D Systems Accura Fidelity: Chemically resistant for mold casting.

(4)Flexible/elastic resins

• Characteristics: 30A-90A shore hardness, compressible rebound.
• Representative products:

Formlabs Flexible 80A: Simulates rubber texture for seal testing.

Liqcreate Flexy: 5MPa tear strength for wearable devices.

3. Core categories and innovative solutions of DLP special resins

(1) Fast leveling resin

• Viscosity requirements: < 300cP (25°C) to ensure fast interlayer flattening.
• Representative products:

Phrozen TR300: 250 cP viscosity with 40% faster Z-axis printing.

BASF Ultracur3D® RG 3280: Medical grade with low viscosity for dental mass production.

(2) High toughness functional resin

• Characteristics: Impact strength>50MPa, alternative to engineering plastics.
• Representative products:

Siraya Tech Blu: Impact resistant 75MPa for industrial fixtures.

Carbon EPX 82: Automotive grade fatigue resistant, certified to VW TL 52630.

(3) Transparent optical resin

• Transmittance: >90% (400-700nm wavelength).
• Representative products:

Anycubic Transparent: Post-processing polishing up to glass-grade transparency.

Stratasys VeroClear™: Medical-grade transparency for microfluidic chips.

(4) Casting resin

• Characteristics: Ash < 0.02%, complete combustion at high temperature.
• Representative products:

Peopoly CastPro: Lost-wax casting of jewelry with no residue on the surface.

Zortrax Inkspire Cast: Suitable for precious metal casting, with a shrinkage rate of <2%.

4. Industry Scenarios and Material Selection Guide

(1) Medical Dentistry

• SLA Preferred: Formlabs Dental SG (guide), Detax Model (long-term implant).
• DLP Preferred: BASF RG 3280 (invisible braces), Peopoly CastPro (implant casting).

(2) Industrial Manufacturing

• SLA Preferred: Loctite IND405 (high temperature resistant parts), Liqcreate Tough (functional prototype).
• DLP Preferred: Carbon EPX 82 (automotive parts), Siraya Blu (wear-resistant fixture).

(3)Cultural and Creative Jewelry

• SLA Preferred: Castable Wax (precision wax carving).
• DLP Preferred: Phrozen TR300 (batch master mold).

SLA dominates the field of high-performance engineering resins by virtue of its laser energy focusing advantage, while DLP has become the first choice for rapid mass production by virtue of its low viscosity adaptability. In the future, with the development of hybrid resins and dual-cure systems, the material boundaries between the two may become blurred, but the core differences will still exist for a long time. When choosing, it is necessary to focus on the three major factors of performance requirements, cost budget and equipment compatibility to maximize the value of the technology.

How do the post-processing steps of SLA and DLP differ?

The following is a detailed analysis of the post-processing steps of SLA and DLP 3D printing, covering the core process differences and the relevance of technical principles:

Post-processing process comparison table

Analysis of key technical differences

(1)Differences in cleaning methods

• SLA：
  Ultrasonic cleaning (frequency 40 kHz) is used to penetrate the interior of complex structures (such as micropores) through high-frequency vibration to completely remove residual resin. The time needs to be strictly controlled (timeout can easily lead to embrittlement of the model).
• DLP：
  Due to the relatively simple surface of the model (few deep hole structure), manual soaking and brushing can meet the needs, but it is necessary to focus on the pixelated edge gaps.

(2) Necessity of surface treatment

• SLA Benefits:
  The laser scans the point by point to form a naturally leveled surface with a layer height difference of <5 μm, requiring only light polishing to achieve a mirror effect (e.g. a jewelry master pattern).
• DLP pain points:

Projection pixelation results in stepped burrs (about 22-50 μm per pixel) that require mechanical grinding or nano-coating filling (e.g., 3D Gloop! resin glue).

(3)Differences in secondary curing parameters

Typical post-processing scenarios in industrial applications

In industrial applications, the post-processing of SLA and DLP 3D printing technologies varies depending on the application:

Medical field (surgical guides)

• SLA-printed surgical guides are first ultrasonically cleaned, sterilized with 75% alcohol, cured for 30 minutes, and sterilized by gamma radiation.
• DLP-printed guides are isopropyl alcohol cleaned, UV-cured, and sprayed with a medical-grade coating to prevent biofilm adhesion.

Jewelry casting (lost wax method)

• If SLA is made of a special casting resin (ash content < 0.03%), the printed parts can be incinerated directly into the casting process without surface treatment.
• DLP-printed jewelry models are pixel patterned and sanded, then filled with pitts with beeswax and embedded in plaster castings.

Industrial Prototyping (Functional Testing)

• SLA-printed industrial prototypes, sandblasted with alumina particles, primed, and finally CMM verified for accuracy.
• DLP prototypes need to be infused with epoxy resin to enhance mechanical properties, and critical mating surfaces need to be CNC finished.

Choice suggestion: Trade-off between cost and efficiency of post-processing

• SLAs are more appropriate if minimal post-processing steps are required or biocompatibility certification is required, especially for precision tool manufacturing.
• DLP is more cost-effective due to its rapid prototyping properties if it can withstand grinding for about 30 minutes and requires high productivity at scale, such as 50 dental appliances per day.

Due to laser scanning, SLA has good surface quality and simple post-processing, which is suitable for high-value precision scenes. DLP has pixelation issues, but the gap with SLAs is narrowing through process optimization and the application of new materials. In practical application, it is necessary to combine time cost, surface quality requirements and long-term operation and maintenance investment to maximize benefits.

Which Is Better for Dental Applications?

Overview of the core conclusions

1. If the goal is the mass production of invisible braces, DLP technology is more recommended. With its high printing efficiency, it can meet the needs of mass production, and the accuracy of ±0.1mm is enough to meet the production requirements of invisible braces.
2. When making implant or orthognathic surgical guides, the SLA technique is more appropriate. With an accuracy of < 0.05mm, this high accuracy is crucial to ensure the success rate of the surgery.
3. For larger dental practices, consider a hybrid deployment with both SLA and DLP devices. SLA is used to produce high-precision monolithic models, while DLP is used for rapid mass production to maximize benefits.

Technical comparison: DLP and SLA in dental practice

(1) Accuracy and clinical error control

Key conclusions:

• SLA’s laser point-by-point scanning can ensure sub-millimeter accuracy of the implant guide drilling site (literature data: SLA guide error 0.04mm vs DLP guide 0.12mm), while DLP fully meets the standard in invisible correction scenarios within the ±0.1mm error tolerance.

(2)Production efficiency and economic comparison

Key conclusion:
DLP crushes SLA in cost efficiency in mass production with its whole-layer projection curing mechanism. Taking invisible orthodontic appliances as an example, Carbon M2’s daily production capacity can reach 80 times that of SLA, and the cost per piece is only 1/10.

Selection guide for six major dental scenarios

(1) Invisible aligner master pattern production → DLP is required

• Demand pain points: Hundreds of requirements per day, which need to be iterated quickly.
• Advantages:

1. DLP 200 appliances for a single print (e.g. 6 h/batch for Spark Aligner).
2. Material costs as low as $0.5/piece (with BasQ resin).
3. Representative device: EnvisionTEC Vida (DLP for dentistry, accuracy ± 0.1mm).

(2) Implant surgical guide → SLA is required

• Accuracy requirements: drilling site error<0.05mm (ISO 13485 standard).
• Advantages:

1. The laser scans avoid pixelated edges and ensure that the guide is 100% consistent with the CT data.
2. Biocompatible resins are in direct contact with tissues (e.g., Formlabs Dental SG).
3. Representative device: 3D Systems NextDent 5100 (medical grade SLA).

(3) Denture prototype/gum model → Flexible selection

• Accuracy requirements: ±0.2mm (SLA is required for key areas of the occlusal surface, and DLP is required for non-functional areas).
• Cost Optimization:

1. Functional areas were printed using SLA (15/piece), and the rest were printed using DLP (3/piece)
2. Hybrid solutions reduce overall costs by 30%-50%.

(4) Orthognathic surgical guide → Mandatory SLA

• Risk control: The error of the osteotomy guide should be <0.1mm, otherwise it may damage the neurovascular.
• Case data:

1. The postoperative deviation of the SLA guide was 0.07 mm (J Oral Maxillofac Surg data).
2. The average deviation of the DLP guide is 0.15mm due to the pixel ladder (not up to standard).

(5) Temporary crown bridge → Priority DLP

• Efficiency requirements: Delivery within 2 hours at the chair (e.g. emergency for restoration rupture).
• Advantages:

1. DLP prints temporary crowns in as little as 40 minutes (as in the CEREC SpeedFire process).
2. Adaptable materials (e.g. Bego Varseo, Smile Crown Plus).

(6) Bite Inducer for Children → DLP is recommended

• Product features: simple structure, mass customization.
• Cost control:

1. DLP costs $2-3 per unit (pediatric facility purchase price).
2. It can produce 3000 pieces per month to meet the needs of chain clinics.

Conclusion

The essential difference between DLP (digital light processing) and SLA (stereolithography) stems from the technical principle: DLP uses a projector to solidify the resin in a whole layer, which is fast and low-cost, and is suitable for mass production of small and medium-sized parts (such as invisible braces); while SLA relies on laser point-by-point scanning, with an accuracy of up to 10 microns, and specializes in ultra-precision and complex structures (such as surgical guides). In terms of cost, DLP equipment and consumables are more affordable, but pixel post-processing is required; although SLA has high investment, it is irreplaceable in high-value-added medical and industrial scenarios. In the future, although technological innovation may narrow the gap between the two (such as DLP’s 8K accuracy and SLA’s multi-laser speed-up), the core difference is still determined by the underlying curing mechanism. When choosing, you need to anchor your needs – choose DLP for efficiency, choose SLA for extreme precision, and hybrid deployment (such as dental clinics that take into account both guides and appliances) can maximize the technology dividend.

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The content appearing on this webpage is for informational purposes only. LS makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through LS’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please contact to our for more information.

Team LS

This article was written by various LS contributors. LS is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding,metal stamping and more.

FAQs

1. What is the difference between SLA and DLP printing?

SLA (stereolithography) is solidified by ultraviolet laser point-by-point scanning of liquid resin, with high accuracy (up to 10 microns), suitable for ultra-precision scenarios such as surgical guides, but the speed is slow; DLP (Digital Light Processing) uses a projector to cure a whole layer of resin at one time, which is 4-8 times more efficient, and is suitable for mass production of invisible braces, but may require additional polishing due to projection pixelation. The core difference between the two lies in the light source technology (laser vs projection) and the application focus (accuracy vs efficiency).

2.What is the difference between DLP and SLS?

DLP is a light-curing technology, which uses liquid resin and ultraviolet light to cure layer by layer, and the finished product has a smooth surface but weak mechanical properties; SLS (Selective Laser Sintering) is a process of laser sintering powder materials (such as nylon, metal) that are stacked layer by layer, without the need for a support structure, and the finished product has high strength and high temperature resistance, which is suitable for the manufacture of functional parts, but the surface is rough and the equipment cost is high. The essential difference is between the material form (liquid resin vs. powder) and the process principle (light-curing vs. thermal sintering).

3. What is the difference between a resin printer and a 3D printer?

“Resin printer” refers to a 3D printer that uses light-curing technology (such as SLA and DLP), uses liquid resin as raw material, cures it by ultraviolet light, and is good at high-precision details; The term “3D printer” is a general term that covers a variety of technologies, such as FDM (fused deposition, using plastic wire), SLS (powder sintering), etc. Resin printers are a subset of 3D printing, with core differences in material type (liquid resin vs. plastic/powder) and process (light-curing vs. melting/sintering).

4. What is the difference between SLA and SLS?

SLA cures liquid resin by ultraviolet laser, with high precision (25 micron level), suitable for medical guide plates, jewelry models, but the material is brittle; SLS utilizes laser sintering of nylon or metal powders without the need for support structures, and the finished product has excellent mechanical strength and can be used directly for functional testing or end parts, but with a rough surface and high equipment costs. The core differences are material morphology (liquid vs. powder) and performance orientation (precision vs. strength).