Multi-Dimensional Printing on Polymers and Other Materials, Asim Kumar Roy Choudhury, Retired Prof.

Two dimensional traditional printing processes are well established in textile, paper, plastic and various consumable and non-consumable products. 2D printing refers to the process of reproducing images or text onto a flat surface, typically textile, paper or other substrates. The 2D printing process involves creating a digital file, preparing the image, and using various technologies to reproduce text or images on a flat surface. The technology encompasses various methods since ancient times, namely wooden block, flat and rotary screen, engraved roller printing. In modern days, these methods have been largely substituted by inkjet and recently by laser printing, each with its own operational mechanics. In recent years, Multi-dimensional printing, namely 3D, 4D, 5D, 6D printing methods are coming into existence and are rapidly penetrating into printing market. 3D printing, also called additive manufacturing, is the process of making a three-dimensional object from a digital file by building it up one thin layer at a time. Instead of cutting or hollowing material away, a 3D printer adds material only where it is needed, each layer a thinly sliced cross-section of the final object, until the whole thing exists. The popular types of 3D printers are Fused deposition modelling (FDM), Stereolithography (SLA), Selective laser sintering (SLS), Multi-Jet Fusion (MJF), Digital Light Processing (DLP), Continuous Liquid Interface Production (CLIP), Material jetting photopolymers (MJ), Binder Jetting, Sheet Lamination, Directed Energy Deposition (DED) etc. Today, professional, low-cost desktop and bench top 3D printers have accelerated innovation and support businesses in various industries including engineering, manufacturing, dentistry, healthcare, education, entertainment, jewellery and of course, textile manufacturing including smart textiles and innovative garments. 3D printing eliminates many labour-intensive processes from the complete apparel manufacturing cycle, reducing the labour costs. 3D printing offers improved quality, as the occasional human error is eliminated from the manufacturing process. However, Current 3D printed textiles and garments fail to offer comfort and flexibility that a garment is expected to provide. They do not absorb moisture as the layers of the raw material fuse with each other, leaving no air gaps. 3D printed textiles cannot be sewn into garments like traditional manufacturing. 4D printing relies on the combination of responsive materials with additive manufacturing technologies, enabling the fabrication of smart architectures able to evolve with time in response to external stimuli. Among the external stimuli, solvent, pH, magnetic field and temperature are most exploited till date. Common thermo-responsive polymers include hydrogels, liquid crystalline elastomers and shape memory polymers (SMPs). While the foundations of 3D printing technology are well-known and widely-utilised, 5D printing is a new technique that offers more versatility and capabilities. The principal difference lies in the way the printers move during production. 5D printers have a moving plateau that allows the print-head to create pieces from five dimensions, including curved layers, whereas 3D printers generally produce flat layers on a fixed plateau. This unique ability to produce curved layers results in more complex, stronger, and versatile parts, While 3D printing involves the layer-by-layer deposition of material to create physical objects, 6D printing takes this a step further by incorporating smart materials and additional dimensions. 6D printing uses intelligent materials that can adapt and respond to external stimuli, such as light, temperature, and pressure. This innovative approach has rapidly gained attention in various industries, including the food industry.