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SLA (stereolithography) and DLP (digital light processing) are two mainstream technologies that are two types of 3D printing that build parts by polymerizing liquid photopolymer resins. SLA uses a UV laser to trace the shape of each layer. On the other hand, DLP projects a mask of entire cross-sectional layers at once. SLA produces parts with smoother surface resolution, while DLP prints faster and cheaper. SLA printing is ideal for applications that require detailed surface resolution. This article will compare SLA vs. DLP in terms of differences, materials, and printing techniques.

 

What is SLA 3D printing?

SLA (Stereolithography) 3D printing, also known as stereolithography 3D printing, is one of the earliest practical rapid prototyping technologies. It uses a laser of specific wavelength and intensity to focus on the surface of the light-cured material, so that it solidifies sequentially from point to line and from line to surface to complete a layer of drawing operations.

Working principle

SLA 3D printing technology solidifies liquid photosensitive resin into a solid layer by layer by controlling the position and intensity of the laser beam or UV beam. Specifically, the UV laser is used as a light source,and the galvanometer system is used to control the laser spot scanning to outline the shape of each layer of the object on the surface of the liquid resin. Subsequently, the manufacturing platform descends a certain distance and immerses the cured layer in the liquid resin for the next layer of curing. This is repeated until the entire object is printed.

Features

High precision: SLA 3D printing technology is capable of achieving very high printing accuracy, often in the micron range.
Relatively slow printing speed: The SLA technology prints relatively slowly due to the time-consuming drawing process for each layer.
Wide range of applications: SLA 3D printing technology can manufacture very fine and complex parts and models, which are widely used in jewelry, medical, automotive, industrial design, and other fields.

What is DLP 3D printing?

DLP (Digital Light Processing) 3D printing is a 3D printing method that uses digital light processing technology. It uses a digital projector to project light onto the surface of liquid photosensitive resin and build 3D objects by curing layer by layer.

Working principle

DLP 3D printer breaks down the 3D model into many very thin layers and outputs them layer by layer to a liquid crystal display (or digital micromirror device DMD). This display is used as a mask to solidify the resin by placing the pixels of each layer on the resin surface and controlling the exposure of light.After each layer is completed, the printing platform moves down to make the next layer of the model available and start the next print.

Features

High speed: Since DLP technology can solidify the entire layer at the same time, the printing speed is faster than the point-by-point scanning SLA technology.
High precision and high quality: DLP 3D printers can usually achieve extremely high resolution and fine details, suitable for scenes requiring high precision and high surface quality.
High material cost: DLP 3D printing requires special photosensitive resins and displays, which are expensive.
Scope of application: Since the resin needs to be solidified, DLP 3D printers are usually used to make small and precision parts, such as jewelry, medical equipment, dental models, etc.

How do SLA and DLP print speeds compare?

1.Print speed core difference

Technology	Curing method	Speed bottleneck	Speed ​​advantage scenario
SLA	Laser beam scanning point by point curing	Scanning point by point takes time,and the time complexity is proportional to the model complexity	Large-size single pieces, complex details, high-precision requirements
DLP	Surface light source projection solidifies the entire layer	The curing time of a single layer is fixed, regardless of the complexity of the model	Mass production, small-scale models, thin-layer printing

2.The underlying reason for the speed difference

SLA Speed Limit:

• Point scanning time: The laser beam needs to cover each layer point by point, and the time complexity is proportional to the complexity of the model, and the time time taken by large-scale models is longer.
• Accuracy-first strategy: In order to maintain high accuracy, SLAs need to reduce scan speeds, further impacting overall efficiency.

DLP speed advantage:

• Surface curing efficiency: curing the entire layer in a single projection, the time complexity is independent of the layer area, only the number of layers, especially suitable for mass production (such as 100 pieces of the same model) and small size models (such as jewelry wax molds).
• Thin layer optimization: At 0.05mm layer thickness, the curing efficiency of DLP is significantly higher than that of SLA, and the speed can reach more than 3 times.

3.Typical scene speed comparison

Scene	SLA speed performance	DLP speed performance
Mass production (100 small models)	Print piece by piece, slow speed	Single shot cures the entire layer, increasing batch speed by 50%
0.05mm layer thickness complex model	Scan point by point, slow speed	Surface curing efficiency is improved, 3 times faster than SLA
Large size single piece over 500mm	No pixel edge distortion, stable speed	Stitching technology may be required, and edge accuracy may decrease

Key decision points for technology selection

Preferred SLA:

1. High accuracy required (e.g. medical models, micro drone parts)
2. Printing large single pieces (>500mm)
3. Models with complex details (e.g., cut-out structures,surface transitions)

Preferred DLP:

1. Need to iterate quickly (e.g., jewelry design, dental modeling)
2. Low-volume production (e.g. customized products)
3. Printing small size models (< 200mm)

4. Cost and time trade-off

• DLP cost advantage: low equipment price, high material utilization (uncured resin can be recycled)
• SLA accuracy premium: expensive equipment, but suitable for high value-added fields (e.g. aerospace)
• Time cost: DLP can shorten the delivery cycle by more than 50% in batch scenarios

Which one has higher precision, SLA or DLP?

1.XY axis accuracy core difference

Technology	Accuracy source	Typical accuracy	High-end equipment cases
SLA	Laser spot diameter	25μm level (industrial grade equipment)	Formlabs Form 3+ up to 10μm
DLP	Pixel size	50μm class (consumer-grade equipment)	Anycubic Photon Ultra up to 22μm

Key conclusions:
SLA's XY axis accuracy is generally higher than DLP, especially in high-end devices (such as Form 3+'s 10μm vs Photon Ultra's 22μm).

2.Z-axis accuracy comparison

Technology	Accuracy source	Typical accuracy	Restrictions
SLA	Laser scanning layer thickness control	0.01mm (high viscosity resin required)	Resin fluidity affects actual accuracy
DLP	Surface projection layer thickness control	0.01mm (high viscosity resin required)	Pixel edge effects may affect vertical accuracy

Key conclusions:
Both can achieve Z-axis accuracy of 0.01mm, but actual performance is affected by resin viscosity and equipment calibration.

3.Precision Advantage Scenario Comparison

Scene	SLA accuracy performance	DLP accuracy performance
Micro parts	Small laser spot, clearer details (such as 0.2mm hole)	Pixel size limits detail accuracy
Surface transition	Laser scanning path optimization, smoother surface	The step effect may be more obvious
Small batches	Stable accuracy but slow speed	Slightly less accurate but faster

Recommendations for technology selection

Select SLA:

1. Requires high-precision details (e.g. medical models, micro-drone parts)
2. Printing complex surfaces (e.g. jewelry designs, industrial prototypes)
3. High requirements for dimensional stability (e.g. aerospace components)

Select DLP:

1. Need for rapid iterative validation (e.g., consumer-grade product design)
2. Printing small batches of simple items (e.g. dental models, personalized jewelry)
3. Limited budget and non-extreme precision requirements (e.g., education, maker scenarios)

What materials are available for SLA and DLP?

Both DLP and SLA 3D printing technologies use photopolymer resins as printing materials, but each has its own specialized resin type, which is as follows:

1.DLP specialty resin

DLP 3D printers can print a wide range of materials, with specialty resins offering the following features:

• Low-viscosity formulations: DLP-specific resins often have low-viscosity formulations (e.g., <300cP), which helps ensure that the resin levels quickly during the printing process, improving printing efficiency.
• High performance: For example, Siraya Tech Blu is a DLP-specific resin with an impact strength of 75MPa for applications that require high strength and impact resistance.

2.SLA specialty resin

SLA 3D printers also use photopolymer resins, and their special resins have the following features:

• High reactivity: SLA-specific resins typically contain a dual initiator system, which allows the resin to cure quickly when exposed to UV light, increasing print speed.
• Biocompatibility: For example, Formlabs Dental SG is an ISO 10993 certified SLA-specific resin that is biocompatible for use in the dental and medical fields.

What are the differences between the post-processing steps of SLA and DLP?

There are some differences in the post-processing steps between SLA (stereolithography) and DLP (digital light processing) 3D printing technologies, which are mainly due to the differences in printing principles and material properties. Here's a detailed comparison of SLA and DLP post-processing steps:

DLP post-processing steps

1. Isopropyl alcohol cleaning: Usually takes about 3 minutes.
2. Objective: To remove the residual photosensitive resin on the surface of the model to prevent incomplete resin curing or affecting the surface quality of the model.
3. Note: Because DLP printing can produce surface pixel patterns,sanding may be required after cleaning to improve the smoothness of the model's surface.
4. Post-processing: Depending on the specific needs, UV secondary curing, coloring, painting, etc., may also be required to enhance the mechanical properties of the model or improve its appearance.

SLA post-processing steps

1. Ultrasonic cleaning: To use the vibration of ultrasonic waves to remove residual resin from the surface and internal channels of the model more effectively.
2. Advantage: Ultrasonic cleaning removes resin residues more thoroughly than simple soaking or rinsing, improving the cleanliness of the model.
3. Secondary curing: Energy density: typically 15J/cm² or higher is required.
4. Objective: To improve the mechanical properties and dimensional stability of the model by re-exposing it to ultraviolet light to completely cure the resin in the model.
5. Why it matters: Secondary curing is an integral step in SLA post-processing, as it can significantly improve the hardness and durability of the model.

Comparison of SLA vs. DLP post-processing steps

• Cleaning method: DLP is mostly cleaned by isopropyl alcohol immersion, while SLA is more preferred to use ultrasonic cleaning to improve the cleaning effect.
• Secondary curing: Secondary curing is a necessary step in SLA post-processing, and has high requirements for energy density. While secondary curing may also occur in DLP post-processing,the specific requirements and steps may vary depending on the material and application.
• Surface Treatment: Additional sanding may be required due to the fact that DLP printing may produce surface pixel patterns; Whereas, SLA prints typically have a higher surface quality and may not require or require only a slight surface treatment.

Which one has lower operating costs, SLA or DLP?

Equipment cost comparison

Technology	Industrial equipment price range	Typical equipment cases	Cost conclusion
DLP	$8,000-$50,000	Carbon M2 (consumer grade starting at about $5,000)	Low initial investment, suitable for budget-sensitive scenarios
SLA	$12,000-$200,000+	3D Systems ProX 800 (high-end model)	High initial investment, suitable for high value-added fields

Consumables cost comparison

Technology	Resin price range	Typical application scenarios	Cost conclusion
DLP	$120-$300/kg（Universal type）	Dental models,consumer products	Low consumables cost, suitable for mass production
SLA	$200-$800/kg（Special type）	Medical equipment, aerospace parts	Consumables cost more, but performance is more stable

Comparison of maintenance costs

Technology	Major Maintenance Items	Average Annual Maintenance Cost Estimate	Long-term Economy
DLP	Light source replacement, resin tank cleaning	$500-1,500/year$	Low maintenance costs make it suitable for long-term high-frequency use
SLA	Laser tube replacement, optical system calibration	$2,000-$5,000/$year$	High maintenance cost, but long life

Integrated operating cost model

Formula:
Total Cost = Equipment Depreciation + Consumables Consumption × Print Volume + Maintenance Costs

Key variables:
Print volume: DLP has significant cost advantages in high-volume scenarios (such as mass production).
Precision requirements: Extreme precision requirements (e.g., medical implants) SLAs are irreplaceable

Which is better for dental applications, SLA or DLP?

1.Comparison of core requirements matching

Application scenarios	Accuracy requirements	Productivity requirements	Material biocompatibility	Cost sensitivity
Invisaligns	±0.1mm (batch)	High (200 sets at a time)	ISO certification is required	High
Surgical guides	0.05mm or less (absolute)	Low (one-piece customization)	Medical-grade certification required	Minor

2. Technical characteristics and dental scene adaptation

DLP advantage scene: invisible braces production

• Production efficiency:Surface projection technology can print 200 sets at a time, which is suitable for large-scale production (such as batch orders of brands such as Invisalign).
• Precision matching:±0.1mm accuracy meets the requirements for braces adaptation, and the production capacity can be further improved by connecting multiple machines in parallel.
• Cost-effectiveness:The cost of general resin (120-300/kg) is combined with high throughput, and the cost per piece can be reduced to 5-10.

SLA cannot be replaced by scene: surgical guide

• Ultimate accuracy:The laser spot reaches 10μm (Form 3+), and with CT data, it can achieve an absolute accuracy of less than 0.05mm, which meets the navigation requirements of cranial surgery.
• Material properties:Special medical-grade resins (such as Formlabs BioMed) are ISO 10993 certified and support high temperature and high pressure sterilization.
• Stability:Layer-by-layer curing reduces interlayer stress and prevents guide deformation from affecting surgical accuracy.

3. Technology integration trend

Hybrid solution:

• DLP+post-processing: After batch printing of the blank, use SLA to refine the key functional surfaces (such as the buckle position of the corrector).
  Material innovation:
• Develop new resins that combine DLP printing efficiency and SLA accuracy (such as elastomer and rigid body composite resin).

4. Selection decision framework

DLP is preferred:

Annual output > 10,000 pieces
Accuracy requirement < 0.1mm
Fast delivery is required (such as immediate production in dental clinics)

SLA must be selected:
Involving implant-level accuracy (such as dental implant guides)
FDA/CE medical certification is required
Printing complex hollow structures (such as breathable correctors)

What is the difference between SLA and DLP?

Here's a table that shows the difference between SLA (stereolithography) and DLP (digital light processing):

	SLA (Stereolithography)	DLP (Digital Light Processing)
Working principle	Use a UV laser beam to scan the liquid photosensitive resin point by point to cure it	Use a digital projector to cure the entire layer of liquid photosensitive resin at once
Printing Accuracy	Extremely high accuracy, micron-level printing can be achieved	High accuracy,but usually slightly below SLA
Printing speed	Slow, point-by-point scanning method limits printing speed	Faster, cures the entire layer at one time, suitable for mass production
Material selection	A wide range of photosensitive resin materials, including highly reactive and biocompatible resins	A variety of photosensitive resin materials, including low-viscosity formulation resins
Cost	Equipment and material costs are relatively high	Equipment and material costs are relatively low
Application scenarios	It is suitable for scenarios that require extreme precision, such as dental surgical guides, jewelry, etc	It is suitable for scenarios that require rapid manufacturing of a large number of parts, such as mass production of clear aligners, small parts in industrial manufacturing, etc
Advantage	High precision, suitable for complex and delicate models	The printing speed is fast, suitable for mass production,and the cost is low
Limitations	Slow printing speed, large-size models take longer to print	Accuracy is slightly lower than SLA and may not be sufficient for applications with extreme accuracy

Summary

SLA and DLP are two mainstream light-curing 3D printing technologies, each with its own unique advantages and applicable scenarios. SLA technology is known for its high precision and is suitable for applications that require extremely high precision; while DLP technology is favored for its high-speed printing and relatively low cost, and is suitable for applications that require rapid production of a large number of parts. When choosing which technology to use, you should consider factors such as specific application requirements, budget, and equipment performance.

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FAQs

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

The main difference between SLA (stereolithography) and DLP (digital light processing) printing is how they work and their printing characteristics: SLA uses a UV laser beam to scan the liquid photopolymer for curing point by point, which can achieve extremely high printing accuracy, but the speed is relatively slow; DLP,on the other hand, uses a digital projector to cure the entire layer at once, making it faster and suitable for mass production, but it is usually slightly below the SLA in terms of accuracy.

2.What is the difference between SLA and DLP's material selection?

SLA: A variety of photosensitive resin materials can be used, including highly reactive resins and resins with good biocompatibility. The selection of these materials makes SLA technology have a wide range of application prospects in dental, medical and other fields. DLP: Again, a variety of photosensitive resin materials can be used, but DLP technology prefers to use resins with low-viscosity formulations, which help with fast leveling and improve printing efficiency.

3.What is the printing accuracy of SLA and DLP?

SLA: Known for its high accuracy, it is capable of printing extremely detailed parts and models. Due to the very small diameter of the laser beam, SLA technology can achieve printing accuracy in the micron range. DLP: It also achieves high print accuracy, but it may be slightly less accurate than SLA. However, for most use cases, the accuracy of DLP is sufficient to meet the requirements.

4.What is the difference between the print speed of SLA and DLP?

SLA: The point-by-point scanning method limits the printing speed of SLA, especially when printing large models, which can take longer. DLP: Since it cures the entire layer at once, it prints much faster than SLA. This makes DLP technology more suitable for applications that require the rapid manufacture of large quantities of the same or similar parts.

Resource

1.Stereolithography(SLA)

2.3D printing

3.Multi-material 3D printing