Investigation into current applications of additive manufacture in conservation and its suitability of use
Additive Manufacture (AM), known also as 3D-Printing or Rapid Prototyping, is an expanding field that is currently being explored within conservation. Additive Manufacture adds material in layers through a variety of processes, rather than subtracting as with carving or other methods. This paper reviews the various ways that AM has been used within the field of conservation so far, including the application of AM to reproductions, replacing sections, casting with AM, packaging, as well as looking at the preservation of AM products. Additionally, the paper introduces tests to determine the viability of AM to conservation. This paper focuses on Fused Deposition Modelling (FDM) since it is the cheapest, and one the more accessible, AM processes available. The common AM materials of Polylactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) are examined. Although a specific printer is tested, the experiments are used to highlight how to test any printer or material.
Using an M3D Printer, four materials from M3D were tested. These were purportedly: one ABS and three PLA based (designated as PLA, CLR and BLK in this paper), with the three PLA based materials having different properties. An initial test was performed to test the accuracy of the printer, before tests were done to artificially age materials by subjecting the samples to heat, light and high relative humidity (RH). The change in dimensions, colour, hardness and strength were measured and presented in the paper. An experiment, comparable to the Oddy test, was performed to see if the materials produce by-products subjected high temperature and relative humidity.
The results showed that the printer could only produce sufficiently accurate samples with ABS, all PLA samples didn’t conform. ABS showed no harmful by-products but is very hard at room temperature. It is therefore most suitable to make reproductions or replacing sections within an object. The pure PLA released by-products and showed dimensional change from the model and after aging. This suggests it is not suitable for conservation use over a long period but knowledge of its aging is still needed for prototypes made of this material. The altered PLA samples, CLR and BLK, have high flexibility at room temperature, poor dimensional accuracy and produce no by-products. Making them more suitable to storage and packaging.
The Oddy Test is considered appropriate for testing AM materials while the heat, light and RH tests depend upon the end purpose. The printer test introduced in this paper is proposed as a standard test to check the viability of the printer or material to a design.
Key Words: Additive Manufacture, 3D-Print, Fused Deposition Modelling, Polylactic Acid, Acrylonitrile Butadiene Styrene