Resin VS Powder: Comparison of 3D Printing Materials

Different materials can be used in different 3D printing processes, but due to the wide variety of materials, it can be very difficult for users to choose. Whether it is plastic, ceramic or even metal, the combination of 3D printing materials may be the first problem for users entering the field of 3D printing.

Today, Mohou.com will focus on two polymer materials: resin and powder. Note that there are many powder and resin materials on the market today, such as metal powders or ceramic resins, but this article only focuses on polymers.

There are two types of plastics for 3D printing: thermosets and thermoplastics, and the main difference between these two materials is how they behave when heated. Thermosetting plastics break down as they harden and do not reform once cooled. Thermoplastics are the most commonly used. When heated, they can take the desired shape and undergo various melting and solidification processes. Their properties change slightly each time they are reheated.

Resin and powder

△Plastic powder can be used in many fields, such as the automotive industry (Image source: EOS)

These two types of materials are the most commonly used in additive manufacturing. For plastic powders, according to the Linker report, the market is expected to reach $3 billion by 2029; for resins, according to Fortune Business Insights, the market is expected to exceed $750 billion by 2029. Each material is compatible with different 3D printing processes, such as laser melting for powders and material jetting or photopolymerization for resins, which are detailed below, as well as post-processing, pricing, material properties, manufacturing. Wait !

Properties and properties of plastic powders and resins

1. 3D printing polymer resin

In today’s polymer market, there are different resins that have different applications in different fields depending on their properties. 3D printing with resin allows you to create small objects with fine structures. Commonly used resins in the market include:

●Standard resins: These are one of the cheapest and most widely used resins on the market, easy to process and grind, and soft to the touch. However, they are also fragile and break easily and are mainly used for rapid prototyping.

●Flexible resins: These are often used for printed objects that can be bent or compressed, and are extremely flexible and can adjust Shore hardness.

●Water-washable resins: As the name suggests, these resins do not need to be washed with isopropyl alcohol, but simply with water. They have low odor, dry surfaces and low viscosity.

●Industrial resin: suitable for manufacturing parts requiring hard surfaces, mainly divided into two types:

▷Temperature Resistant Resin: Capable of withstanding temperatures up to 238°C, used to produce prototypes requiring finer details, high precision and high thermal stability.

▷Sintered resin: This is a resin with a high degree of detail and excellent surface finish, and its curing process is faster than other resins. The main feature is that the process after pouring is clean and leaves no residue.

●Dental resins: In dentistry, there are special resins that can be colored, clear, softer or harder depending on the needs and are used in the manufacture of bridges, crowns, retainers or splints, these resins must therefore be sterilizable .

△Resins play an important role in the dental industry (Image source: Formlabs)

2. 3D printing polymer powder

In the thermoplastic polymer powder market, there are many types of plastics, among which nylon is the most common:

●Nylon: Also known as polyamide, the most commonly used are PA12 and PA11. Both types of nylon absorb very little water and are used, for example, in the automotive industry due to their strength and friction.

▷Nylon PA12: Made from petroleum, this material can withstand large temperature variations and erosion from various chemicals.

▷Nylon PA11: it is a biosourced polymer containing castor oil. It has good heat resistance, high elasticity and is more environmentally friendly than PA12.

●PEEK: It is a semi-crystalline thermoplastic capable of replacing certain metals in industry thanks to its mechanical properties, its resistance to heat and wear and thanks to its high specific resistance. However, it is a difficult material to use, particularly with regard to temperature. This material is therefore mainly used in the automotive, aerospace and medical industries.

●Composite materials: Composite materials are composed of matrix polymer and short or long fibers. The most commonly used are carbon fiber and fiberglass. Carbon fiber is made by mixing a polymer with carbon fiber, resulting in a lighter, stronger and stiffer material. Fiberglass is a mixture of polymer and fiberglass, as strong as carbon fiber. , but with lower hardness and higher density.

●Polypropylene: This thermoplastic (PP) is also semi-crystalline and is characterized by resistance to chemicals, good electrical insulation and lightness, but is difficult to print because its heat treatment must be controlled.

●TPU: Thermoplastic polyurethane is a very durable and flexible material during processing. Although it cannot withstand high temperatures, it also has high impact resistance, wear resistance and treatment resistance.

One of the advantages of plastic powders is their recyclability. Since the powders used for SLS and MJF are thermoplastics, they can be sieved and mixed with new powder after the sintering process to reuse excess material and avoid waste.

△Image source: BASF

Digital 3D printing workflow

1. Resin

For resin 3D printing, one of the most commonly used methods is photopolymerization technology. This includes SLA, DLP and LCD processes and uses ultraviolet (UV) light to cure the resin. The difference between these processes is the light source used. For example, SLA uses a laser to cure resin point by point, while DLP uses a projector to cure the entire resin tray in a single projection. Another completely different, resin-compatible process is material jetting technology, in which multiple resins are used. are used simultaneously, including the use of transparent resin possibilities.

Now we have to talk about post-processing. After printing, there is often a sticky resin residue left on the surface of the part that must be cleaned with a solvent to remove it. Isopropyl alcohol is the most commonly used solvent and the one that works best. The printer will also need to remove any supports added during the design process, depending on the geometry of the part. It is best to perform this step with pliers. Finally, because not all curing reactions need to be completed immediately after printing, resin parts must undergo additional heat treatment. There are many ways to achieve this, ranging from simple light curing (e.g. in the sun) to using curing equipment. Curing time varies depending on the part. Finally, when finishing, surface treatments such as machining can be used to smooth the surface and strengthen the part itself, creating a beautiful surface.

A peculiarity of the resin is its toxicity, which can often cause serious irritation and allergies upon contact with the skin, especially when exposed to the ultraviolet rays of the sun. Also be careful of inhaling vapors when handling the resin, as they can cause dizziness in the user due to their high toxicity, so it is important to wear adequate protection.

△Resin post-processing steps (Image source: Formlabs)

2. Powder

For 3D printing using plastic powders, there is a difference between SLS, MJF and SAF from Stratasys. In SLS technology, after a thin layer of powder is deposited on a build plate, a laser is used to selectively sinter the powder and harden selected areas. HP’s Multi Jet Fusion process, after applying a layer of powder, selectively deposits the flux in areas where particles need to be fused. At the same time, applying thinner reduces edge fade of the part, resulting in clean, smooth edges. In the case of SAF (Selective Absorption Fusion), the main difference is that this technology uses a high energy absorbent fluid that absorbs energy once deposited.

Unlike resin, polymer powders do not require a support. In fact, the 3D printed part is supported during the printing process by being in what is called a “powder block”. In the post-processing process, the first step is to remove the part from the powder block. This involves a cooling process that can take up to 10 hours depending on the part. Next comes depowdering, which can be done manually or automatically using a machine. Operators must wear special protective equipment, as inhaling the powder can pose health risks and many additional finishing steps are required for plastic parts, such as galvanizing, painting or grinding.

Which manufacturers are there on the market?

The best-known material manufacturers on the market are the chemical companies responsible for producing the raw materials, and the 3D companies which then use them and sometimes even develop them in collaboration with chemical groups.

●In terms of resinous raw materials, renowned material manufacturers include Loctite Henkel, Covestro Additive Manufacturing, BASF and Arkema. BASF and Arkema cooperate with 3D printer manufacturers and often develop their own materials. zortrax, Formlabs and EnvisionTEC also do good work in these areas.

●For plastic powders, the best-known suppliers are Arkema, BASF and Evonik, which cooperate with HP and EOS. Powder manufacturers AM Polymers or Fabulous also have their place on the market. There are currently more proprietary resins available, because some resin machines are still closed, i.e. they are only compatible with materials developed by the manufacturer itself.

Resin and powder applications

For resins, application situations generally require certain precision requirements. For example, tiny parts, more colorful components used in industries such as entertainment or jewelry. The resin is also appreciated in the medical field, particularly in dentistry, notably for the production of surgical guides, crowns or implants.

In terms of possible applications of plastic powders, they can be used in the hygiene sector. Nylon is biocompatible, which makes it ideal for making prosthetics since it can be in direct contact with the skin. The manufacturing industry also frequently uses this type of materials since they are used for functional prototypes, small and medium series. For example, it can be used to make gears or even hinges.

Source: Antarctic Bear