3D printing liquid bath

With This 3-D Printer, Objects Emerge From a Plastic Soup

It might be the future of manufacturing, but 3-D printing is built on a 2-D foundation: A MakerBot is essentially an inkjet printer that spits out plastic instead of ink. Keep printing in the same spot, over and over, and the layers will eventually form a 3-D object from the bottom up. But an outfit called Carbon3D is taking the opposite tack: Its new rig creates objects from the top down, in one continuous motion. It’s faster and eliminates the layering that can result in weak, jagged objects.

Inspired by the mercurial T-1000 bot from Terminator 2, University of North Carolina professor Joseph DeSimone wanted to make objects emerge from liquid. The process is based on a 30-year-old printing technology called stereo­lithography. It starts with a bath of liquid resin that hardens when exposed to UV light. A projector underneath deliv­ers targeted blasts of UV to shape the form from below as the overhead platform lifts, drawing the object out of the soup.

The method has some limits. Oxygen inhibits the chemical reaction that solidifies the resin, slowing the process some­what. But rather than fighting that limitation, DeSimone harnessed it. A sheet of glass between the projector and the resin is gas-permeable like a contact lens, and the oxygen keeps the resin from hardening too soon, before the object is com­plete.

1. Object-building platform
2. UV-curable liquid resin
3. Microthin layer of oxygenated resin
4. Oxygen-permeable glass
5. Ultraviolet-light projector
BROWN BIRD DESIGN

Even with this effect, the Carbon3D can print up to 100 times faster than leading 3-D and stereolithographic printers. In a video that ricocheted around the Internet after DeSimone pre­sented it at TED, the device pulls a model of the Eiffel Tower out of the goo, as if it had just been sitting in the liquid all along.

Carbon3D has a team developing new materials for the printer. “We're pioneering new resins for our machine and also working with the chemical industry to evolve what’s already available,” says Rob Schoeben, the com­pany’s chief marketing and strategy officer. “As long as a material is in the polymer family, we should be able to do it.”

The machine has vast potential. Rather than warehousing and shipping car parts, technicians could make components for older models on the spot from designs stored in the cloud. Aeronautical engineers could print high-strength, low-weight lattice structures to replace, for example, components in passenger seats, lightening the payload and increasing fuel efficiency in planes. And Carbon3D could prove invaluable for medical applications: Custom molds could be made onsite at a dentist’s office, and stents or other emergency implants could be custom-printed on-demand in the hospital.

Right now, Carbon3D has prototypes running at auto behemoth Ford in Dearborn, Michigan, at an athletic apparel company, and at a special-effects house in San Fernando, California, with an eye to hitting the market in 2016. But it has no shape-shifting bots that are hell bent on destroying humanity. Yet.

New Multimaterial SLA 3D Printing Method: Skipping the Liquid Bath with Aerosol Jet Printing - 3DPrint.

While SLA 3D printing is extremely popular among many different types of users today, there are drawbacks in post processing, as users are forced to take a more laborious step following the layer-by-layer method in using a liquid bath. While many are glad to continue this way, and are used to conforming to this traditional process, it is also limiting. German researchers have created a hybrid form of SLA 3D printing to streamline and expand production, which they explain in their recently published work, ‘Multimaterial bathless stereolithography using aerosol jet printing and UV laser based polymerization.’

Iterative layer-by-layer process of hybrid stereolithography

Rather than continuing with the normal bath used in SLA 3D printing, the authors have created a spray coating device instead:

“The AJS is able to process inks in the range between 10 and 1000 mPa s,” state the researchers. “Therefore, UV curable materials with greater viscosity compared to inkjet based raw materials can be used to establish a material layer and open the field for a wide range of materials.

“The modified system allows the mixing of two different materials through the addition of a second spray generator. This enables the printing of two pure materials as well as a theoretically continuous gradient.”

The AJS system is made up of:

• Two atomizers
• Two virtual impactors
• Mixing module
• Nozzle

Compared with a conventional inkjet system, the AJS is superior in processing liquids, relying on two atomizers. These components competently control the flow of materials, ultimately mixing the two (with one flow coming from each atomizer). The system also ensures good performance in printing as the combining of flows is exact, and with no backflow present. As the authors explain, push flow must be the same in both mixing areas, with the flow then accelerated by the nitrogen.

The ‘working distance’ created manages proper deposition and eliminates any chance for clogging. In conclusion, the researchers stated the following regarding potential for this process:

“This enables the freeform fabrication of parts with undercuts, as demonstrated in a 3D printed part. Due to two available atomizers in the AJS device, the materials are mixed on the fly for desired material compositions. Hence, a transition from one pure material to the other is demonstrated with three intermediate material compositions. This opens the possibility to fabricate parts with varying material properties. This is a promising technique to establish multimaterial printing for the stereolithography and widens the range for possible applications.”

Hearing aid component, CAD file (left), printed by hybrid stereolithography (right).

The SLA 3D printer is known as the original 3D printing system, created in the 80s; yet while it may be one of the oldest methods of 3D printing, it is still one of the frontrunners behind innovations today. Researchers and manufacturers continue to forge ahead with this technology, reformulating resins, improving multi-material processes, and creating useful products like ceramic molds. What do you think of this latest technology news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard. com.

Modules of the hybrid stereolithography (deposition, polymerization, and stages).

[Source / Images: ‘Multimaterial bathless stereolithography using aerosol jet printing and UV laser based polymerization’]

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Tagged with: 3d printing research • AJS • Hybrid SLA system • multimaterial 3d printing • sla 3d printing • SLA hybrid 3D printing • stereolithography

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Choosing a liquid photopolymer for a 3D printer. Classification of materials for SLA/DLP 3D printing.

Contents:

1. Introduction
2. SLA Overview
3. SLA Standard Resins
1. Standard photopolymer resin - Standard
2. Clear Photopolymer Resin - Clear
4. Engineering photopolymer resins
1. Rigid photopolymer resin - Tough (like ABS)
2. Durable photopolymer resin - Durable (PP-like)
3. Heat resistant photopolymer resin - Heat resistant
4. Rubber-like photopolymer resin - Rubber-like (Elastic)
5. Ceramic photopolymer resin - Ceramic filled (Hard)
5. How to choose the right resin for your application
6. Dental and medical SLA resins
1. Medical Device Photopolymer Resin - Custom Medical Appliances (Class I Biocompatibility)
2. Dental Long Term Biocompatible Resin (Class IIa Biocompatible)
3. Biocompatibility class I vs biocompatibility class IIa
7. Cast SLA resins
1. Cast resin for jewelry making
8. Generalized rules

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This article compares photopolymer resins using Formlabs SLA 3D printing products –

Catalog of photopolymer 3D printers

Photopolymers from FormLabs

Detailed review of the Formlabs Form 3 3D printer

Introduction

The stereolithography prints plastic parts with high resolution, good fine detail and smooth surface. Due to the variety of photopolymer resins available for SLA, this technology is used in many different industries:

• "Standard" photopolymers are used for prototyping

• Engineering photopolymers have certain mechanical and thermal properties

• Dental and medical photopolymers have biocompatibility certificates.

• Cast photopolymers have a zero ash content after burning.

SLA 3D Printing Resin Overview

SLA uses a laser to cure a liquid photopolymer resin. This process is called photopolymerization. Various combinations of polymers and other additives that are part of the resin allow you to get different material properties.

The main advantages and limitations that are common to all resins in SLA 3D printing are:

Benefits:

Weaknesses:

Base Resins for SLA

Post-Processing SLA/DLP 3D Printing Article

Standard resins produce parts with high stiffness, detail and a smooth surface. The low cost of resins, from $250 per liter, makes them ideal for prototypes.

The color of the resin also affects its properties. For example, in FormLabs products, gray resin is suitable for models with fine details, and white resin for parts that require the smoothest possible surface.

Benefits of using Standard grade resins:

Cons Standard:

Also included in the class of "Standard" photopolymer resins from FormLabs is the Color KIT - a set of special dyes and "Color Base" photopolymer resin for mixing and obtaining a variety of color solutions. This eliminates the need for painting parts after 3D printing.

FormLabs Engineering Photopolymer Resins

Engineering resins have a range of properties for injection molded plastics.

All engineering resins require additional UV curing, such as using the Form Cure, to achieve their maximum properties.

Tough resin was developed for models that need to withstand high loads and be durable.

This material produces strong, shatter-resistant parts and functional prototypes such as snap-on housings.

Pros:

Cons:

Ideal for: functional prototypes, mechanical parts

Durable resin is a wear-resistant and flexible material with mechanical properties similar to polypropylene.

Durable photopolymer produces models with a smooth glossy surface and high resistance to deformation.

Durable Resin is ideal for:

• Bushings and bearings;
  
• Various functional compounds

Pros:

Cons:

• Not suitable for thin wall parts (recommended minimum wall thickness 1mm)

• Low heat distortion temperature

• Low flexural strength (lower than hard resin)

Ideal for: functional prototypes.