DMLS 3D Metal Printing
Metal 3D printing is becoming more and more commonplace in today's design and production workflows. This additive manufacturing process can produce prototypes, end-use parts, strong but lightweight structures, and complex shapes that can’t be accomplished by using traditional manufacturing processes, all with little to no waste. There are many different types of metal 3D printers on the market today, however, most of them fall into one of four categories: powder bed fusion, direct energy deposition, material extrusion, and binder jetting.
Direct Metal Laser Sintering (DMLS) was the first type of metal 3D printing that a patent was filed for. DMLS 3D printing falls under the powder bed fusion category and is a very popular technology for a variety of reasons - such as its ability to generate complex parts, strong fully dense parts with good mechanical properties, as well as lighter parts through topology optimization. The printing process works by using a laser to selectively melt metal powder particles together (into a melt pool) on a build plate, layer by layer. After the first layer is melted together, the build plate lowers and a new layer of powder is spread across the build plate with a recoater blade. The process continues, layer by layer, until the part is complete.
Also, it may be of interest to clarify the inherent misnomer/confusion in considering DMLS as a form of “sintering”. Check out this post to better understand DMLS vs. DMLM.
DMLS 3D Design Considerations – A Different Way of Thinking
To get the most out of DMLS 3D printing, it’s important to understand the different design considerations that will allow you to get the most out of the capabilities this technology brings to the table. Considerations such as supports, post-processing, surface finish, and tolerances all need to be considered in the design process. Careful DMLS 3D metal printing design considerations can improve part manufacturability, increase part aesthetics and, importantly, lower production times and costs.
DMLS 3D Printing Guidelines
- Here are some guidelines and best practices that will help to produce the most optimal parts at the lowest cost possible. These guidelines are especially critical when using a metal 3D printing service, as 3D print service providers typically don’t offer design services and are actually not allowed to make any design changes, due to various reasons, including maintaining certifications in certain industry sectors. Wall Thickness: Too thin of walls can cause unstable parts, while too thick of walls can lead to part stress and cracking. A good rule of thumb is to use minimum wall thicknesses of 0.4 mm to add stability, and if you are designing much thicker walls, consider using internal honeycomb structures to eliminate part stress.
- Support Structures: Are required for features such as overhangs, angles, and holes. (But don’t worry about it – we take care of it). Supports enable the printing of features that are not directly touching the build plate, by printing a structure that provides a platform for that feature to be printed on once that layer is reached. When we design your support structure, we try to minimize the areas where the support touches the actual part, as this will lead to less post-processing and an improved surface finish.
- Overhangs: If you are designing a part with overhangs or cantilevers of more than 1 mm, we will need to add support under those areas in order for them to print successfully.
- Part Orientation: It’s best to orient parts so that the need for support structures is minimized. You’ll also want to keep in mind the surface finish. Upward facing features will result in the best surface finish.
- Channels and Holes: When designing channels and holes into parts, 0.4 mm is the minimum size that can be produced with DMLS 3D Printing. Likewise, holes and channels larger than 10 mm will require support.
At GPI Prototype, we can recommend design guidelines to our customers, but it is up to the customer to implement those guidelines before submitting them to DMLS 3D printing RFQ’s to GPI. We do provide all support structure and orientation recommendations to fit your needs.