Top-down DLP resin 3D printing vs. bottom-up printing

Carima’s DM400A uses top-down DLP technology, which offers significant advantages over the more common bottom-up printer setup.

But first, what is DLP 3D printing? DLP stands for Digital Light Processing, a technology where an optical engine lamp projects light onto a layer of resin. The light, which is projected into a specific layer’s shape thanks to a mirror system, cures entire layers at a time.

This technique is faster than laser SLA (stereolithography) all while being less expensive. There are two ways in which the projector can be configured: below the tank, or above the tank.

When below the tank, the projector’s light hits the bottom of the resin tank, which is often made up of a very thin, transparent film. The build platform starts at the very bottom of the tank and is completely immersed in the resin, moving upwards as each layer is cured.

Top-down 3D printers work in the opposite way; the projector is located above the resin tank, and the build platform moves downwards. Nothing stands in between the light and the resin, so the projector’s light hits the resin directly.

Advantages of top-down resin 3D printers

The main advantage of having the platform move downwards (with the printed object on top) is very simply linked to gravity. With bottom-up printers, prints can easily fall off the print platform – or parts of the print can break off – and splash into the resin tank. After hours of printing a large object, this frustrating type of failure wastes a lot of time and material.

Another advantage of top-down printing is that since you’re not working against gravity, you don’t need to add as many support structures. Support structures can add up to a lot of material usage and waste, and they also imply more post-processing (e.g. surface finishing to remove the marks left by the support structures).

Last but not least, maintenance. During the resin 3D printing process, tiny bits of non-intentionally hardened resin can fall to the bottom of the tank. This means that light will be blocked in certain areas, which is why bottom-up tanks must be cleaned after each print, or why their transparent film must be changed (another time-consuming task) after several runs. Top-down 3D printers offer easier, cleaner workflows.

Overall, top-down printers enable larger, heavier prints that won’t fall off the print bed, and the smoother process is less prone to failures.

A closer look at the DM400A

The DM400A is the world’s first large, top-down DLP 3D printer with a dual 2K light engine. This high definition doubles down on resolution and makes it possible to cover a large build area of 400 x 330 x 500mm.

Its large area paired with DLP technology’s high speed means that the Carima DM400A is more than capable of handling mass production applications. An entire build plate with, for example, 57 dental pieces, can be printed in just over an hour and a half. It can also 3D print larger, heavier parts than small dental models with very slim failure rates thanks to its top-down configuration.

The printer also boasts Carima’s Precise Dual DLP Engine Alignment Technology and offers native 132-micron pixel size, for high-quality surface finishes. The DM400A features a 50°C heated chamber as well, meaning it can handle highly viscous materials of up to 6,000 cps.

Build size	400 x 330 x 500 mm
Available layer thicknesses	50, 100, 125, 150 microns
Engine light source	LED UV 405 nm
Engine resolution	Dual 2K high UV LED 2560×1600
Pixel size (XY)	132 microns
Machine weight	800 kg
Resin tank capacity	220 L
Machine dimensions	1050 x 1200 x 1900 mm

Large resin prints require an XXL-sized curing machine

For post-curing, Carima provides a large-sized curing machine, CL1800, which offers a curing full base of ⌀520 x 450mm. Its powerful 1800W UV LED cures large prints in approximately 10 minutes (e.g. with Elastic ToughRubber 90 standard material).

Carima partners with Adaptive3D for wider choice of resins

Adaptive3D is a leading AM polymer resin supplier. They are especially known for developing the toughest polymers on the market for additive manufacturing.

DM400A’s 6,000 cps viscosity capacity makes it possible to print Adaptive3D’s rubber-like materials, which are optimized for top-down DLP printers.

These are the different types of rubbery materials that the DM400A can 3D print:

Material	Use cases
Elastic ToughRubber 90	Primary: Mid-soles & heel-cups Secondary: Impact parts, recoil pads, door boots & wire guides, tough enclosures, seals
Soft ToughRubber	Primary: Audio earpieces Secondary: Wearable electronics, anatomical medical models, insoles
Elastic ToughRubber 70	Primary: Mid-soles & heel-cups Secondary: Impact parts, recoil pads, door boots & wire guides, tough enclosures, seals

Interested buyers in the United States can contact Adaptive3D for DM400A inquiries.