Some great benefits of DLP 3D printing

3d printing

Dental products like these arches are an important market for Origin and other DLP-based printer manufacturers. origin

Stereolithography (SLA) is one of the oldest and most mature 3D printing technologies. His skills are well understood; The resin selection is wide; and it can be used to 3D print accurate and often functional prototypes and end-use products.

However, as with many additive manufacturing processes, the SLA build speed is limited. Since each layer has to be traced with a beam of ultraviolet laser light just a few hair widths in diameter, printing with SLA is similar to shaping a Mona Lisa with a 3D etched sketch.

There are of course alternatives. One of them is digital light processing (DLP). There are several types of DLP systems available, but they all have a common thread: DLP printers project a series of images onto resin and cure each layer one at a time and almost instantly. This approach results in faster construction speeds and eliminates the need for expensive lasers and galvanometers.

Like SLA, DLP builds parts from a photoreactive resin and has a movable building plate. However, DLP’s UV light source is more of a high resolution digital projector than a laser beam. The projector flashes individual images of a digitally cut CAD model upwards onto a transparent plate at the bottom of the resin tank, thus linking the molecules directly on the opposite side. While the digital “film” is being played back, the construction plate moves upwards, pulling the workpiece along with it and exposing fresh resin.

After completion, the green workpieces are cleaned and, depending on the brand of the 3D printer, cured in an oven or a UV light chamber.

Enter the dead zone

As you would expect, every DLP printer manufacturer has a unique view of the technology. What often sets one system apart from another is the polymerization process.

Carbon Inc., Redwood City, California, uses its Continuous Liquid Interface Production technology along with a number of proprietary resins to provide Digital Light Synthesis (DLS). According to the company, the 3D printing process can print parts 100 times faster than SLA.

Rob L’Heureux, Senior Marketing Manager, Technical Products at Carbon, explained that DLS has many similarities to competing digital collotype systems, but is a completely different process. “Both use resins, both have a light source and build platform, and both look very similar in operation,” he said. “What sets carbon apart is the use of an oxygen-filled inhibitor barrier that we call the ‘dead zone’ and our dual hardening materials. Dual-cure materials offer improved part quality and the dead zone significantly increases build speed. “

Anyone who has seen reports of 3D printed running shoe midsoles on the Carbon website will see the potential of DLS and similar technologies. Where many AM processes are limited to prototype and small series production, so-called “continuous printing systems” promise mass production of end-use products.

L’Heureux points to the use of Carbon M2 printers by Resolution Medical in Minneapolis to produce nasopharyngeal swabs for the COVID-19 pandemic, as well as a wide range of other medical devices.

3d printing

Carbon and adidas collaborated on FutureCraft 4D, the first performance shoe with a 3D printed midsole. carbon

“We’re especially good at parts that are about two fingers wide and smaller,” he said. “This allows manufacturers to really package the build platform and maximize throughput.

“Ford Motor Co. has begun using our systems to manufacture parking brake mounts for its GT500 Mustang and HVAC service parts for the Focus,” continued L’Heureux. “And NASA has certified carbon parts in its autonomous Seeker robot for the gas nozzles designed to inspect the International Space Station and other orbiting spacecraft.”

Control forces

Carbon isn’t the only company with DLP success stories. Five-year-old San Francisco-based Origin has long used printers based on its patented programmable photopolymerization technology to print nasal swabs. Stratasys, which Origin acquired in early 2021, is marketing the swabs.

Origin also took first place in the US Air Force’s Advanced Manufacturing Olympics. Working with software company nTopology and material supplier Henkel, Origin designed and printed a multi-material hydraulic pipe clamp for F-16 aircraft. The Origin team defeated eight other contestants to win the $ 100,000 prize of the competition.

Fin Watterson, Origin director of product marketing for production photopolymers, noted that the company’s printer lacks an oxygen-fed dead zone. Instead, a pneumatic pump mechanism is used to inflate a sensor-filled, clear Teflon membrane between the pressure platform and window.

As with Carbon DLS, the membrane serves to inhibit and control the photopolymerization process and prevent the part from sticking to the window. When each layer is finished, the membrane deflates, the build platform moves up and the process repeats.

“In short, it allows us to achieve the same or higher speeds as competing oxygen-assisted 3D printers by using a simple and reliable mechanical method to control the rate of polymerization,” he said. “And because this approach reduces the peel forces required to lift the part out of the build zone, it offers the ability to print shapes and other large, block-like objects that are difficult on most DLP-based systems. We can also use nitrogen and other gases to make the environment inert, opening the door to entirely new chemicals that cannot be printed in the presence of oxygen. “

Acceleration station

Diversified Plastics Inc. (DPI), an employee-owned plastic injection molding company in Brooklyn Park, Minnesota, does not print molds on its Carbon M2 printers. However, the M2 are used to make parts by the thousands.

The company’s technical director, Vincent Pope, said DPI moved into 3D printing three years ago as part of its Acceleration Station service. The aim is to deliver prototype and production parts to customers “in days, not weeks” and without tools.

“Traditional plastic injection molding can be costly and time-consuming in trying to meet customer needs for high-speed rotating or prototypical plastic parts,” said Pope. “That’s because each partial iteration requires a shape change – or maybe a completely new shape if the change is drastic.”

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Origin 3D printed and reworked 100 camera bodies in less than 24 hours, aiming to reduce the price per part by 99% compared to CNC machining. origin

With AM, changes to part design are easy, quick and inexpensive, he said. A customer sends DPI a new file and the parts are built in hours.

Papst added that 3D printing enables the creation of complex geometries that cannot be injection molded. “Our customers shouldn’t limit their creativity with traditional manufacturing methods,” he said, adding that AM offers the opportunity to create “better products” [while] Reduce costs and speed to market. “

AM Use going forward

The enhancement of these skills is achieved through the growing number of materials that are brought onto the manufacturing table. This includes soft, flexible materials that mimic thermoplastic polyurethane. biocompatible materials, comparable to medical grade ABS; heat and flame retardant, nylon-like materials; and optically clear materials similar to polycarbonate.

Pope added that like their injection molded counterparts, 3D-printed medical devices must be sterilizable and DPI certified by the customer in order to manufacture them.

“Medicine makes up around 60% of our work. And while the number of polymers we have available for 3D printing is not comparable to the number we have for injection molding, we haven’t encountered too many barriers in meeting customer needs, ”he said.

“The aesthetics and finish of [3D-printed parts] injection molded parts are pretty close and the functional properties are just as good in most cases. When you add the greater freedom of design of 3D printing, it is clear that this will play an increasingly important role for us in the future, ”said Pope.