316L Steel

What is Stainless Steel

Stainless Steel 316L is primarily composed of iron (66-70%) and is enriched with chrome (16-18%), nickel (11-14%), and molybdenum (2-3%). It is a strong material with anti-corrosive properties. This makes Stainless Steel perfect for applications with automotive, industrial, food processing and medical industries.

Models in Stainless Steel 316L can be 3D printed with two technologies: Binder Jetting and Direct Metal Laser Sintering (DMLS). Both use a metallic powder form of Stainless Steel 316L. They differ in the mechanical properties of the final product. However, both are effective, especially for hobbyists creating scale models, miniature sets, and other decorative products.

Properties

Stainless Steel 316L is an attractive material because it offers strong mechanical properties, including hardness, tensile strength, formability and impact resistance. Further, it is inherently resistant to corrosion by the atmosphere, water, steam, crude oil, alcohol and other similar corrosive media.

For more specifications, the table below shows the exact properties of Stainless Steel 316L.

Printing Method

Direct Metal Laser Sintering (DMLS)

Direct Metal Laser Sintering is a 3D printing technique that uses a high-powered laser to print objects layer by layer from a metal powder. Each layer is formed by tracing a pattern in the powder with a laser, which melts and bonds the material together. This is actually very similar to SLS (Selective Laser Sintering), except that the temperature is high enough to melt the powder, not just sinter it (1500 – 1600 °C). Naturally, this requires a laser with much higher wattage.

When an entire cross-section is traced, the build platform lowers one layer height, and the process continues until the entire part is complete. Any powder that hasn’t been sintered remains in place to support the object that is being made, which eliminates the need for support structures.

Objects printed using DMLS have excellent mechanical properties and the available material range includes materials that are otherwise difficult to process, such as metal superalloys. Due to the high production costs, this technology is not recommended for parts that can be easily manufactured using other methods.

Binder Jetting

Binder Jetting uses a liquid binding agent, which is deposited between layers of metal powder to build an object. Following each deposition step, a layer of powder is cured, and when the entire printing process is complete, the object is removed from the printer and placed into an oven for further curing. When the printing process is complete, the build chamber is removed from the printer, and an operator carefully extracts the parts from the remaining powder.

Binder Jetting is an extremely fast 3D printing method, allowing one to print metal parts at a fraction of the cost compared to DMLS. However, since these parts tend to have a higher porosity, they offer lower mechanical properties than other industrial 3D printing techniques.

Design Specifications

Minimum Thickness & Geometry

The minimum wall thickness for Stainless Steel 316L is 2.0 mm to ensure self-standing stability. If a wall thickness of less than 2.0 mm is desired, support structures can be used for stability.

Further, it is important to consider the load different parts will carry. If a thin wall or leg is supporting a bigger weight, you may want to increase the thickness of the supporting wall/leg to ensure it will not collapse.

Details
The minimum precision of a detail is mainly determined by the resolution of our printers. However, during the cleaning process, a fine layer of detail can also be lost. In order for a detail or a text to be visible, we highly suggest you follow our recommended sizes at the very least. To ensure a better powder removal (thus a better detail precision), the width of your details must be at least as big as depth.

It is possible to 3D print interconnecting or enclosed volumes with Stainless Steel 316L. There should be a minimum of 0.2 mm between the objects to ensure they do not fuse together. However, more may be needed for bigger objects. This is specifically for the DMLS 3D printing method. Bigger models are heated longer, and therefore there is more risks for the pieces to melt together. Furthermore, it is important to allow an exit for excess powder to be blown out.

If the model will be printed in parts to be assembled, a 0.4 mm width is necessary between the different pieces to ensure fit.

 

 

Design Specifiations (Binder Jetting)
Thickness & Geometry

The minimum wall thickness for this material is 1.1 mm to ensure self-standing stability. However, this does depend on the size of your part. A larger part may need a thicker wall. If a wall thickness of less than 1.1 mm is desired, support structures can be used for stability.

Stemmed elements, where the length is twice as long as the thickness, should have a minimum thickness of 1.0 mm.

Details

3D printing Stainless Steel 316 via Binder Jetting is not well suited for enclosed volumes and interlocking parts.

If the model will be printed in parts to be assembled, a 0.5 mm width is necessary between the different pieces to ensure fit.

It is not possible to 3D print sharp corners/edges with Stainless Steel 316L via Binder Jetting. This is due to the depowdering process from 3D printing via Binder Jetting. The radius should be below 1.0 mm to avoid breakage.