DLP stands for Digital Light Processing, and in simple terms, DLP is simply a source of UV light from a projector. DLP projectors are used below a transparent print window in what is called a vat. The name for this process is called “vat photopolymerization”. Similar systems will use a laser instead, in others it is an LCD screen. Light travels through a transparent window, through a membrane (designed for easy release), where light will meet with a photo-polymer and harden that resin based on the pattern of light being projected.
What is DLP Printing?
Problems with Vat Photopolymerization
Whenever a layer is hardened, the space between the newly formed solid layer and the surface where it printed is reduced to less than a couple of microns, and for that reason, when moving the newly formed layer away from this surface, the layer acts as a suction cup. Vat Photopolymerization companies try a variety of methods to reduce this “suction cup” effect. Some use oxygen, others use pneumatic, sliding, or twisting systems. At the end, the goal is the same, to move away from the print surface as quickly and as easily as possible.
What has NewPro3D done differently?
NewPro3D started in 2015 and from its inception, the majority of its research activities have revolved around solving the above-mentioned pull force problem. The company has tested over 400 membrane formulations and types. Tests and products have included membranes made from hydrogels, silicones, liquids, and much more. Today, the membrane consists of various layers of materials that together, allow for super low pull forces, wide resin compatibility, high print speed, and a resilient print membrane.
High Pull Force
Low Pull Force
Here is a list of considerations for a viable membrane product:
- Wide resin compatibility
- Low pull forces (10-20 times less than the competition using standard PDMS or PDMS with a film)
- Durability (more than 2 weeks of nonstop printing)
- Low cost of consumable components (things wear out and must be replaced, and those replacement should not add up to a large number)
- Ease of consumable replacement (time is money, and replacements can become expensive if exchanging them is time consuming)
- Resilient: hard to scratch, dent, tear, fatigue.
- Easily detectable signs of end of product life: You do not want to find out that your membrane needs exchanging because parts are failing. This is expensive and time consuming.
- High temperature compatibility: Whether the print chamber is being heated to reduce the viscosity of resins, or whether the interface temperature is running hot from the exothermic print reaction, a good membrane should handle high temperatures well without accelerated degradation.
Aside from a high-performance membrane, the NewPro systems use a variety of sensors and smart algorithms to optimize print times.
DLP vs SLA vs LCD vs Other Print Technologies
Why DLP? Both SLA (laser based systems) and DLP offer a high degree of isotropy. This means that the mechanical properties of a printed part will be the same or very similar in all directions. FDM (or “FFF”) for example, does not offer the same. These objects are weaker along the layer lines from poor chemical bonding between each layer.
Laser systems typically are too slow for many modern operations that require same-day prints.
Another source of light is LCD screens. The challenge with LCD is that they typically print at a higher wavelength than the traditional 405 nm. There are just not as many good materials commercially available at 420-450 nm. Additionally, LCD systems require a very close distance between the source of light and the print surface, significantly preventing the use of many advanced membrane technologies today. LCD light sources at 405 nm have heat and light uniformity issues. At least for now.
Below is a time lapse of a fast print with super low pull forces.
Aside from print speeds, low pull forces also means that your part will require fewer supports. Not only will you save material, but post processing will be faster and simpler. Pull Forces dictate print speed, support size and quantity, material used, post processing time and complexity, ability to print soft materials, wearing out of membranes, and stress on parts.