New Methods for Sieving SLS Plastics & Polymers
As the 3D printing / Additive Manufacturing industries continue to expand, the size requirements for the powder being used continues to get more precise. The Selective Laser Sintering (SLS) process sinters powdered plastic together to build structures from the bottom up in layers. There are various powders used in this process, but the most common are Polyamide 11/12 powders (PA11/PA12), Nylon 11/12 powders, and Thermoplastic Polyurethane Powders (TPUs). There are various producers of these powders, but the typical size range required by the industry is 200 microns – 50 microns.
Sieving powders for the SLS printing process is a developing process that is being done in two separate stages. The first stage is the powder preparation stage, whereby producers of these plastic/polymer powders, manufacture and then sieve the powders into the 200um over 50um size range. The second stage where the powder is sieved is during the recycle where any powder that is not sintered can be reused again after being screened. This is typically coarser screening done at around 200 microns to remove any powders that may have “splatter” from the laser.
Powder preparation for the SLS printing process using plastics is rapidly evolving as the market demands continue to change. Most of the sieving for these industries is being done using conventional shaker screeners or ultrasonic sieves. These technologies can moderately screen at 200um, but struggle at the 50 micron size. The result is too many fines (<53um) in the product and companies are being forced to rescreen the powders several times until the specification is finally met.
Elcan Industries can help companies drastically limit downtime, by eliminating the need for any re screening to be done. The Elcan Industries’ Hi-Sifter is the only screening machine capable of efficient fine separations down to 10 microns. Unlike traditional screeners that keep the powders sitting on the screen, the Hi-Sifter has a vertical energy that keep particles elevated on the screening surface. The result of this approach to screening is higher rates and efficiencies without the potential for blinding! Elcan has successfully separated these plastics and polymers at Very small sizes. Unlike ultrasonic sieves, the Hi-Sifter never allows the particle the opportunity to blind the hole by keeping them elevated inside the screener.
For many companies producing powders for the SLS printing process, the construction of the equipment they are using is imperative. Many powders in the process can abrade organic materials and that can lead to degradation of either the balls or sliders being used in the process. This can lead to weaker, and more importantly, contaminated parts that may no longer be suitable for the end customer.
The Hi-Sifter is constructed of solely polished stainless steel. There are no screen cleaning devices so there is no outside chance of contamination of product due to material degradation. The working screen inside of the system is tension-less, which means that is a screen tear were to occur, the operator can change the screen right on the plant floor. This means no more shipping of screens back and forth, and no more expensive charges for replacing ultrasonic screens. The machine is user friendly and can easily be cleaned and used for multiple products.
Elcan Industries is the leader in difficult to sieve products. We have a toll processing facility where we sieve, repackage, and magnetically separate, millions of pounds of powder a year. We have become ingrained in the metal 3D printing market as the leader in sieving technologies and are confident these technologies will help revolutionize the SLS printing process for plastics and polymers.
Elcan Industries offers any new customers a FREE day of testing to demonstrate their advanced capabilities. Call today to find out more (914-381-7500) or check out our website www.elcanindustries.com
