Information Embedding in Additively Manufactured Parts Through Printing Speed Control

Abstract

Information lithography in manufacturing is a broad set of techniques for encoding sequences of bits as physical or behavioral features in physical parts. It is an effective approach for part traceability and anti-counterfeiting. Several techniques have recently been proposed for embedding 2D codes in 3D printed parts by local control of geometry or material. This paper presents an approach to embed and retrieve information in additive manufacturing (AM) parts by controlling the printing process parameters. The approach leverages variations in printing speed to encode information on the surface of AM parts. Optical imaging devices, such as 2D scanners and optical profilometers, are employed to read the embedded information, enabling the capture of local height differences on the part surfaces that embody 2D codes such as QR codes. The retrieved information is processed using computer vision techniques such as morphological segmentation and binary classification. First, the impact of variations in the encoding parameters on the information retrieval accuracy is characterized. Then, the feasibility and effectiveness of the proposed scheme are demonstrated through experimental results, showcasing a high accuracy in retrieving encoded messages and successfully distinguishing subtle surface features resulting from varying printing speeds. The proposed approach offers an inexpensive and efficient method for information lithography, allowing for the secure embedding of information, e.g., serial numbers and watermarks, while addressing counterfeiting and security concerns in diverse industries.