Large format industrial
LCD 3D printer

When using high resolution LCD screens, 460nm polymerisation allows consistent and repeatable cure through depth, across the build area and across different Magna printers.

3D printing with resin (stereolithographic printing) by laser, DLP or LCD systems and powder bed fusion 3D printing (SLS and MJF) have the highest tolerances of commercially available plastic 3D printing technologies. Compared to machined accuracies, resin and powder 3D printing tolerances fall between standard machining and fine machining tolerances.

These are the terminologies when discussing accuracy:

Accuracy

Accuracy is how close a measurement is to true value, which is derived from comparing the measured value from a Magna part to the dimensions designed in CAD.

Precision

Precision is the repeatability of a measurement, which means how much you can rely on Magna to produce your expected results, every time.

Tolerance

Tolerance is how precise the critical elements of a part need to be, generally, achieving tighter tolerances means higher manufacturing costs, Magna’s pixel pitch is a factor in determining this.

Tolerancing in 3D Printing

In traditional machining, tighter tolerances are exponentially related to increased cost. Tighter tolerances require additional and slower machining steps than wider tolerances, so machined parts are designed with the widest tolerances allowable for a given application.

Unlike machining, 3D printing has a single automated production step. Tighter 3D printing tolerances may require more effort in the design stage, but can yield significant savings in time and costs in prototyping and production.

Part design and preparation

Designing the model to suit large format LCD Additive Manufacturing is essential in achieving print success. The orientation of the part to position the leading angle correctly, its support network and the design of high aspect ratio thin walls are all critical in avoiding warpage. Our Customer Service department will assist you in learning how to orientate and support your type of geometry and share with recommendation on how to design your models for Magna. All different categories of geometry require different treatment, and we can provide guidelines.

Post processing

Magna comes as part of a full eco-system with Air Wash L and Cure L2 units. This enables the parts to maintain isotropy by being washed and post exposed on the platform. The wash solution is designed to remove excess of resin while not reducing mechanical integrity. The combination of heat and double wavelength light fully cures the parts and removing the possibility of warping.

Finishing

Finishing steps for 3D printed parts assemblies commonly include de-supporting, sanding support artefacts and spray painting. Sanding an active surface is a reasonable method for achieving the correct fit if the part is a one-off, because less tolerancing work is required in the design phase, but with larger assemblies, or when producing multiples of something, proper dimensional tolerancing is essential.

Material selection

Resins that print successfully provide a compromise between the desired end use properties and the temporary green strength (modulus before post-curing) necessary to hold the weight of the part and withstand the shrinkage forces that are exerted during printing. Bottom-up printing is more physically demanding on the green state of a part than printing top-down. It is always the case that the immediacy of rapid double bond conversion is an advantage in end-use properties and a disadvantage in part creation. Poorly formulated resins can exhibit very high green strength achieved by high functionality of the monomers and then lead to significant shrinkage and warpage. The effects of this are more evident in large parts. Photocentric select the chemical raw materials carefully to deliver the necessary short terms properties while still delivering the essential long-term functionality.

In addition to resin formulation optimisation, compensation factors in every Photocentric resin print profile are tailored to deliver accurate parts.

The minimum z built resolution starts at 25µm, the pixel pitch is a factor in creating the resolution in the x:y axes, and the minimum feature size is typically formed from 2 or 3 pixels combined.

We print test cubes and large structures and then measure all the elements of the parts, relative to each other.

Build volume accuracy

You will be able to achieve within +/- 0.10% volumetric accuracy in printed parts compared to CAD.

Build volume repeatability

When printing a full platform of aligner dental models with Magna and scanning each model, 90% of the scanned data aligns within +/- 100µm compared to the CAD data, irrespective of the model’s position on the platform.