What Is Selective Deposition Lamination (SDL) And What Does It Have to Do With Paper 3D Printing?
The 3D printing and rapid prototyping industry is full of them – acronyms for all of the different technical processes used by 3D printers and rapid prototyping systems- DLP, SLA, PP, SLS, SHS, EBM DMLS, FDM and LOM, to name a “few.” The appearance and disappearance of different processes and their acronyms is a normal and healthy part of an industry’s evolution.
Well, we’re adding another acronym to the list: SDL, or Selective Deposition Lamination.
Here’s why. Sometimes people inaccurately mistake our paper-based 3D printing technology for the old LOM (Laminated Object Manufacturing) process of many years ago. I wrote about the distinct differences between Mcor’s paper 3D printing technology and LOM in a previous blog.
We realised that the term ‘paper 3D printing,’ while true to the material used – ordinary sheets of A4 and letter paper – doesn’t encapsulate the technical process involved in creating a physical 3D model. And, while a subset of users, particularly in emerging application markets, don’t really care, as long as the technology does what they want it to do, others who have been involved with the technology for many years and/or who are involved in manufacturing and industrial applications, care very much about how it all works and prefer to categorize the technology.
Settling on the phrase, Selective Deposition Lamination or SDL was easy. We like SDL because it perfectly describes the process behind paper 3D printing and differentiates it from other technologies.
Let’s examine this more closely.
This is arguably the most important word in the phrase and refers to the selective method that the printer uses in depositing the adhesive to bond the sheets of paper. A much higher density of adhesive drops are deposited in the area that will become the part, and a much lower density of adhesive is applied in drops in the surrounding area that will serve as the support. This results in very quick and easy weeding or excavation of the part out of the supporting paper when printing is complete.
In the old LOM process, everything was glued together, including the support material around the model with the same intensity. Excavating the model was an ordeal, often resulting in part breakage.
Deposition refers to the method of applying the adhesive in droplets onto a sheet of ordinary paper following the cutting of the profile of the part in that sheet (this process is repeated for each sheet of paper that will be used to create the part).
This is quite different from the LOM process where the adhesive was pre-applied to the proprietary material in equal amounts across the entire surface of the material before cutting took place.
Lamination describes the process of building up successive layers of a substance – in our case, regular office paper – and bonding them to form a durable finished product. And, although prototypes built with our printers are made from ordinary paper, they are incredibly durable! They don’t have to be post-processed to make them strong; you can safely use them right out of the printer. They are not brittle and therefore don’t break or shatter when dropped, and if desired, they can be drilled, threaded, tapped or made water resistant with a quick dip in a sealant.