3D printing (additive manufacturing) manufacturing methods in the focus
Additive manufacturing methods such as 3D printing are well on the way to fundamentally changing production processes. They cut mould costs, reduce development times and offer manufacturers considerable design freedom. Significant advances have already been made in rapid prototyping – the computer-aided, cost-effective production of models and prototypes.
Current developments are focusing on further design optimization, greater functionality and, first and foremost, expansion into industrial mass production. However, other challenges exist, such as high production costs and the limited availability of materials.
While the consulting firm Roland Berger forecasts a fall in process costs of up to 60 percent over the next five years, Covestro, formerly Bayer MaterialScience, is driving forward the development of high-performance polymers for existing 3D printing processes. These include thermoplastic polyurethanes (TPU), raw materials for polyurethane (PU) coatings and adhesives, and polycarbonates.
“The development of appropriate materials, in particular, plays a key role in the continued expansion of additive production methods,” says Dr. Thomas Büsgen, Senior Project Manager 3D Printing Technology at Covestro. “We aim to enable significantly more functions than in the past.”
In fused filament fabrication (FFF), a plastic filament is liquefied or heated to deposit lines and dots on to a surface, which then harden when cooled. By repeating this process numerous times, a three-dimensional solid object is created layer by layer.
Covestro sees a wide range of applications for TPU, in particular, as a large proportion of the current Desmopan® portfolio is suitable for the FFF method.The characteristic melting and hardening behavior of TPU results in a permanent bonding between applied layers, while the outstanding abrasion resistance and elasticity of TPU are maintained.
Polycarbonate is also ideal for this method. Covestro’s initiatives in this area include working in partnership with Chinese filament manufacturer Polymaker, which has recently launched polycarbonate-based materials for the FFF method onto the market (further information: http://3dprint.com/95697/polymaker-covestro-filament/, see also the video). Matthias Rothe from the Polycarbonates Business Unit of Covestro appreciates your interest in polycarbonate-based solutions.
Selective laser sintering is also used to create 3D structures layer by layer in rapid prototyping. This involves using a laser beam to sinter a plastic powder. Covestro developed the TPU material Desmosint® for this purpose a few years ago. The product is processed by partner Lehmann&Voss&Co. into a powder suitable for laser sintering and marketed under the trade name Luvosint®. Georg Fuchte is contact partner at Covestro for 3D printing applications using TPU.
The product offers a number of advantages over the materials used previously, which are brittle, less elastic and form rough surfaces. The characteristic melting and hardening behavior of TPU results in comparatively isotropic material properties and good abrasion resistance and elasticity.
In binder jetting, a thin layer of powder consisting of plastic, ceramic or metal particles is spread across the surface. A liquid binding agent is then applied to the layer of powder from an inkjet print head at particular points, where it forms a bond. The next layer is applied and bonded to this, resulting ultimately in a three-dimensional structure that can subsequently be infiltrated for further hardening. Covestro offers various polyurethane products for the powder, infiltrate and binding agent for this method.
Covestro polyurethanes are also ideal for the rapid multijet fusion method. This involves using inkjet printing technology to apply a heat-absorbent ink onto a powder bed, which is then cured using an infrared lamp.
Stereolithography is the 3D printing process with the longest history of use to date. A workpiece is gradually lowered into a liquid photopolymer bath. A UV laser that initiates hardening of the polymer is used to create the layered structure. The 3D objects formed in this way reproduce the required shape exactly. The materials currently available are not usually very temperature- and light-resistant, nor are they particularly elastic. This offers opportunities for UV-curing resins based on polyurethane raw materials from Covestro.
Polymer jetting also uses photopolymers that are cured using UV radiation. In this method, the polymers are sprayed through print heads onto a platform. A number of materials with various colors or mechanical properties can also be used to build up structures layer by layer. Here, too, UV-curing resins based on polyurethane raw materials from Covestro may offer advantages over materials currently in use.
With 2014 sales of EUR 11.7 billion, Covestro is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and sports and leisure industries. The Covestro group has 30 production sites around the globe and employed approximately 14,200 people at the end of 2014. Covestro, formerly Bayer MaterialScience, is a Bayer Group company.