FDM vs SLA: A Detailed Comparison

3D printing has changed the way we make things, but not all 3D printing technologies are the same. Two of the most common methods are Fused Deposition Modeling (FDM) and Stereolithography (SLA).

In this guide, we’ll compare FDM vs SLA in simple terms so you can choose the right one for your needs.

What is FDM?

Fused Deposition Modeling (FDM), also called Fused Filament Fabrication (FFF), is the most common type of 3D printing. FDM is one of the first types of 3D printing, invented by Scott Crump, a founder of Stratasys.

FDM printers come in different sizes and can use a variety of materials. Prices range from $5,000 to $500,000, depending on the machine’s capabilities.

Common materials include plastics like ABS, ASA, and PLA. Some advanced printers can also use stronger materials, such as carbon-filled plastics and nylon, for more durable prints.

How Does FDM Work?

It works a lot like a hot glue gun. A spool of plastic filament is heated until it melts. The melted plastic is pushed through a nozzle to create a thin layer on the build platform, moving side to side (X and Y axes).

The plastic cools and hardens quickly. Once a layer is done, the platform moves down, and more melted plastic is added on top, building the object layer by layer (Z axis).

What is SLA?

Stereolithography (SLA) 3D printing started in the 1980s and quickly became popular with manufacturers and product companies.

Unlike FDM, which uses filament, SLA printers use photopolymers– a special liquid that hardens when exposed to light.

Instead of a nozzle, SLA printers use a laser to turn the liquid resin into a solid part through a process called photopolymerization.

This printing method allows you to create high-resolution parts that are strong, waterproof, and consistent in all directions. Photopolymers are different from thermoplastics because they permanently harden when cured.

Just like FDM printers, SLA printers come in different sizes, material options, and price ranges.

How Does SLA Work?

The SLA process starts with a platform submerged in liquid resin. A laser, controlled by precise mirrors, shines onto the resin, hardening it layer by layer to form the part.

The first layers printed are support structures, which keep the part attached to the platform and provide stability. As the laser cures each layer, a recoater blade spreads fresh resin over the surface, ensuring the build continues smoothly.

The part is created from the bottom up, one layer at a time.

Properties Comparison Table Between FDM vs SLA

The table below shows common differences between SLA and FDM and how they compare.

FDM vs SLA Comparisons

Below is a detailed comparison between FDM and SLA.

Technologie

FDM and SLA work in different ways. FDM is simpler– you can set one up with basic technical skills. It melts plastic and lets it cool to form a part. SLA, on the other hand, uses a laser to harden liquid resin, requiring specialized knowledge and tools.

Materialien

SLA printers use liquid resin, which is often specific to each printer and comes in limited colors. FDM printers use plastic filaments available in many colors, including reinforced options like carbon fiber. Most FDM printers can use materials from different suppliers, so they are more flexible.

Print Volume

FDM printers come in various sizes, from small desktop units to large industrial machines that can print parts up to a cubic meter. SLA printers are generally smaller because they need to store liquid resin inside the machine.

Printing Speed

Regarding FDM vs SLA speed, 3D printing is quicker than traditional methods, but speed isn’t always the most important factor. SLA prints detailed parts with smooth surfaces but can take longer, especially for big prints.

FDM is faster because you can use bigger nozzles (0.6mm, 1mm, 2mm), but this makes the surface rougher. You need to choose between speed and quality based on your needs.

Strength & Durability

Prototypen go through heavy testing, so they need to be strong. You need to know FDM vs SLA strength to choose which one to use. FDM materials are tougher than SLA. ASA resists UV rays, so it’s great for outdoor tools. Nylon is durable for automotive parts.

SLA parts can break or wear out in tough conditions. When choosing between SLA and FDM, think about where your parts will be used. They need to work in real life, not just look good in a lab.

A 3D-printed FDM carabiner can hold 500kg, proving its strength.

Precision & Quality

Precision depends on your design needs. If you plan to use injection molding, SLA is a good choice. But for industrial parts that need strength, FDM works better.

Factory tools, for example, need to function well, not just look perfect. Choose the right 3D printing method based on your product’s purpose.

Oberfläche

SLA produces smoother parts with fine details, while FDM prints have visible layer lines that often need extra finishing, like sanding or vapor smoothing.

Kosten

SLA is more expensive because it uses specialized materials and a high-precision laser. An entry-level SLA printer costs around $1295, while you can get an FDM printer for as low as $200.

Applications & Industries

3D printing is becoming more common in different industries. Over 70% of businesses are finding new ways to use it, and more manufacturers are using it for full production. Here are some of the industries:

Luft- und Raumfahrt

The aerospace industry is leading in 3D printing. However, because planes and spacecraft need strong, durable materials, some types of 3D printing, like SLA, don’t work well in harsh environments.

FDM printing, which uses strong thermoplastics, is commonly used for making prototypes and airplane interior parts. One big benefit of FDM is that it creates lightweight parts, which is important in aerospace.

Automobilindustrie

The car industry often uses strong plastics like ABS and PP. Since these materials need to handle tough conditions, FDM printing is the most popular. It’s used for prototyping, making tools, and producing small batches of parts.

Some car parts, like reflectors and lighting components, need clear materials, which is where SLA printing is useful.

Konsumgüter

Companies that make everyday products need to bring new ideas to market quickly. 3D printing helps by allowing them to test designs fast.

Many products use both types of 3D printing. For example, a handheld device might have an FDM-printed plastic shell with a soft SLA-printed grip. SLA printing is often chosen for making high-detail prototypes.

Gesundheitswesen

Healthcare uses 3D printing for medical tools, training models, and custom dental or hearing aid products. Medical devices need to be sterilized, so they must be printed with heat-resistant materials. Both SLA and FDM offer suitable materials, but you need to choose carefully.

For high-detail models, like those used in medical training, SLA printing is best. Dental products mainly use SLA, while hearing aids can be made with either method.

Education

Many schools and universities use 3D printing for student projects and research. Nearly every university has a makerspace, and more high schools are starting to use 3D printers.

Students and researchers prefer FDM because it’s affordable and easy to use. SLA printing requires more post-processing, so it is less convenient for beginners. However, FDM is expected to improve with better materials in the future.

FDM 3D Printing: Pros and Cons

Pros of FDM Printers

FDM printers use many types of plastics. They can print larger objects than SLA printers. They are useful for prototypes and small production runs.

New filaments offer more strength, chemical resistance, and low friction. Some, like carbon fiber blends, make lightweight but strong parts. FDM is great for functional parts like car components and aerospace tools. High-end models print with fine layers for a smoother finish.

Cons of FDM Printers

FDM prints often show layer lines, so you may need sanding or polishing for a smooth surface. Temperature changes can also cause warping or layer separation. Since FDM printers have many moving parts, any small issue can ruin a print. You need to check the settings and materials carefully before printing.

SLA 3D Printing: Pros and Cons

Pros of SLA Printers

SLA printers create super smooth, highly detailed prints– perfect for prototypes, jewelry, and intricate designs. They are also more precise than FDM because they don’t shrink or expand with heat. They are great for small and accurate parts.

Cons of SLA Printers

SLA prints can be fragile, so they aren’t great for parts that need strength. Stronger resins exist, but they’re still weaker than FDM materials like nylon. SLA printing is also more expensive, and printers have smaller build areas, so they are less useful for large or high-volume jobs.

FDM Considerations

FDM is a low-cost 3D printing method using common plastics like ABS, PLA, and PETG. Unlike SLA, which requires expensive liquid resin and extra equipment, FDM only needs the printer. Many filaments come in different colors, so no painting is needed.

FDM saves material with infill, creating hollow parts with a strong lattice inside instead of solid plastic. This lowers cost and speeds up printing.

FDM parts are durable, especially with ABS or nylon. Unlike SLA, which can become brittle over time, FDM prints last longer. However, parts can break along layer lines, so you must consider how force is applied when designing.

FDM prints have visible layer lines and may need post-processing for a smooth finish. Cooling plastic can also cause warping, especially with sharp corners or overhangs.

SLA Considerations

SLA prints in very thin layers– starting at 0.004 inches (0.102mm)-- which means you’ll see fewer layer lines compared to FDM printing, which usually starts at 0.008 inches (0.2mm).

The UV laser in SLA printers is extremely precise, like using a fine-tipped pen. It can create tiny details as small as the thickness of a sheet of printer paper. This makes SLA perfect for detailed parts like microfluidics or miniatures for tabletop games.

However, SLA parts don’t last long. They are mainly used for prototypes or single-use items. Because the material is cured with UV light, the parts can be brittle and will break down over time, especially when exposed to more UV rays. They may also turn yellow or become weaker.

In most cases, SLA parts start to degrade within 8 to 12 months.

When to Choose SLA Over FDM

High Quality 3D Printed Parts

Choose SLA if you need smooth, detailed, and accurate prints. While it’s pricier and needs post-processing, it offers professional results that FDM can’t match.

SLA is best for precise parts like dental models and jewelry. It uses a laser to harden liquid resin, ensuring tight tolerances. FDM, which melts plastic, can have slight inconsistencies. SLA prints come out smooth, ideal for prototypes and medical devices. FDM prints show layer lines and need sanding.

SLA excels at small, intricate details like thin walls and sharp edges. FDM may blur fine features due to melted plastic.

Fully Dense 3D Printed Parts

SLA prints are fully dense and leak-proof. FDM prints can have tiny gaps, so they are less reliable for holding liquids or handling pressure. SLA produces truly clear prints, while FDM’s air gaps make prints look cloudy.

SLA prints are equally strong in all directions. FDM prints are weaker in the vertical (Z) direction.

Temperature-Resistant 3D Printed Parts

SLA prints won’t melt, that’s why they are ideal for high-temperature uses like engine testing. FDM materials soften under heat. SLA prints withstand sterilization– they are great for medical tools and surgical guides.

SLA creates strong, heat-resistant molds and tools at a lower cost than metal or CNC alternatives.

Alternatives to SLA and FDM

SLA and FDM aren’t your only choices for 3D printing. PolyJet and Carbon DLS might also work well for your needs.

PolyJet Printing

PolyJet works by spraying tiny drops of liquid photopolymer layer by layer, which instantly hardens under UV light. It creates 3D pixels (called voxels) that combine flexible and rigid materials, known as digital materials.

Each layer is 30 microns thick, helping produce detailed and accurate parts. PolyJet prints come in different hardness levels and are reasonably priced. You can even create prototypes with overmolded parts.

Carbon DLS Printing

Carbon DLS uses CLIP (Continuous Liquid Interface Production) to shape parts with light and oxygen. A UV light shines through an oxygen-permeable window into a resin tank. As UV images are projected, the resin hardens, and the build platform lifts the part. This method is fast and creates strong, durable parts.

Schlussfolgerung

Now you know the key differences between FDM and SLA 3D printing. If you want low-cost, strong parts and easy setup, use FDM. But if you need smooth surfaces and fine details, go with SLA.

Unter DEK, we make your ideas real. We have reliable FDM and SLA 3D printing services, and we’re here to help you get it done right. Send us your files, we’ll take care of the rest with professional, on-time service.

FAQs

What is the main difference between FDM and SLA?

FDM melts and pushes out plastic to build a 3D object layer by layer. SLA uses a UV light to harden liquid resin into solid layers.

Which technology is more cost-effective, FDM or SLA?

FDM is usually cheaper because its materials and machines cost less. But the total cost depends on what you’re making and the materials you need.

Which technology is better for creating highly detailed parts?

SLA is better for detailed parts because it can create smoother surfaces and finer details.