What is SLA Printing

First Look at SLA Printing

SLA stands for stereolithography. It is a way to make things in 3D. SLA uses a vat of liquid resin and a UV light to make solid parts. The light draws on the resin and makes it hard. This is how we get 3D parts!

SLA is good for making:

• Small parts with lots of detail
• Dental tools
• Medical items
• Cool models

SLA is part of a big group called additive manufacturing. This means it adds stuff bit by bit to make things.

How SLA Printing Works

SLA is easy to get if you know the steps:

1. A UV laser draws on top of the liquid resin
2. The resin gets hard where the light hits
3. The build platform goes down a tiny bit
4. New resin flows over the top
5. The laser draws the next layer
6. This keeps going until the part is done
7. Then we do post-processing (wash, cure, take off supports)

The most key parts in a SLA printer are:

• Laser that makes the resin hard
• Resin vat that holds the liquid
• Build platform that moves down
• Galvo mirrors that aim the light

There are two kinds of SLA printers:

• Upside-down (most common)
• Right-side-up (more for big things)

SLA vs. Other 3D Printing Types

Let’s see how SLA is not like other ways to print in 3D:

SLA vs. SLS

SLA vs. FDM

SLA is not like the kind of 3D printing that uses plastic string. SLA makes parts that are:

• More smooth
• More precise
• Less strong
• More costly

If you need parts that look good, use SLA. If you need parts that work well, you might want SLS or injection molding.

What Can You Make With SLA?

SLA is good for lots of things:

Medical and Dental

• Surgical guides to help doctors
• Orthodontic models for teeth
• Hearing aids that fit just right
• Medical implants that are biocompatible

Making Test Parts

• Parts to see how they look
• Parts to test how fluid moves
• Clear parts to see inside

Jewelry

• Very fine detail for rings
• Castable resins for making metal parts

Small Science Things

• Microfluidic devices
• Lab-on-a-chip items
• Small parts with tiny channels

You can use SLA for tiny parts that need to be very precise. This makes it good for dental applications and jewelry design.

What Stuff SLA Uses

SLA uses photopolymer resin. This is a liquid that gets hard when UV light hits it.

Types of Resin:

• Standard Resins
  • Rigid (hard and stiff)
  • Flexible (can bend)
  • Clear (see-through)
• Special Resins
  • Biocompatible (safe for body)
  • High-temperature (won’t melt easy)
  • Ceramic-filled (like clay)
  • Dental SG resin (for teeth work)

Each resin has good and bad points. Some are not very strong and can break. Some get bad in the sun (UV degradation).

Good and Bad Things About SLA

Good Things:

• Very precise (±25–100 μm accuracy)
• Best surface smoothness of all 3D printing
• Many material choices
• No nozzle to get stuck
• Good for isotropic parts (same strong all ways)
• Makes very fine details

Bad Things:

• Small build volume (not for big parts)
• Must do post-processing
• Resin can be not safe (toxicity)
• Need PPE (gloves, mask)
• Parts can be brittle
• More costly than some other ways
• Anisotropic behavior can make weak spots

For big parts, you might want to use CNC milling instead of SLA.

Tips for Good SLA Prints

If you want to make good SLA parts:

1. Put the part at a good angle
   • Less supports means less marks
   • Think about how overhangs will print
2. Make walls thick enough
   • At least 1 mm thick to not break
3. Make big parts hollow
   • Save resin
   • Less warping
4. Use the right post steps
   • Wash in the right stuff
   • Cure with UV for the right time
   • Take off supports with care
5. Know your printer’s limits
   • How small it can print
   • How big it can print

How Much SLA Costs

SLA can cost more or less based on:

Printer Costs

• Small home ones: $3,000
• Big work ones: $250,000+

Resin Costs

• Basic resin: $50 per kg
• Fancy resin: $200+ per kg

Other Costs

• Wash station
• Post-curing box
• Gloves and safety stuff
• Time to clean parts

SLA is good for:

• Small runs of parts
• Parts that need to look nice
• Test parts

For lots of the same part, injection molding is better.

Questions People Ask

End Notes

SLA is a cool way to make very nice looking 3D parts. The stereolithography way uses light to make liquid resin into hard parts bit by bit.

SLA is best for:

• Small parts with lots of detail
• Clear parts you can see through
• Test parts that look like the real thing
• Dental and medical tools

But SLA has some bad points too:

• Parts can break easy
• Need care when using resin
• More steps after printing
• Not for big parts

If you need strong working parts, you might want to look at precision CNC machining or 5-axis machining for more choices.

SLA is one tool in the big world of making things. Knowing when to use it will help you make the best parts for your needs!