# Enhanced Adhesion--Efficient Demolding Integration DLP 3D Printing Device
## 1 Introduction  
Three-dimensional printing, also known as additive manufacturing (AM), is a processing method for creating three-dimensional objects by printing powder layer by layer [1]. Compared with the subtractive manufacturing methods, additive manufacturing technology is a \"bottom-up\" material accumulation method [2]; its unique processing method has prominent advantages in mass customization and being lightweight. Combined with the data and Internet integration of industry 4.0, it will have higher efficiency, more utility and more eco-friendly production potential [3]. Its principle is the process of slicing the 3D model to obtain the 3D coordinates of the model contour by software and then stacking the slicing layer by layer into the real object [4]. Its molding process can be divided into: Stereo Lithography Apparatus (SLA) [5], Selective Laser Sintering (SLS) [6], Laminated Object Manufacturing (LOM) [7], Fused Deposition Modeling (FDM) [8] and other technologies. Digital light processing (DLP) 3D printing technology belongs to the subdivision of SLA technology [9]. Because DLP 3D printing technology uses a surface light source, compared with other 3D printing technologies, DLP 3D printing technology has the advantages of high efficiency [10], high precision and individualization. Therefore, it is widely used in dentistry [11], jewelry [12] and other precision fields. DLP 3D printing technology first obtains two-dimensional slice images from a three-dimensional model, and then the projection system is controlled to realize the projection of the images, the mechanical structure is driven to complete printing layer by layer and the model is finally manufactured [13]. Although DLP photocuring formed equipment has been well applied, there are still problems such as weak adhesion of the forming layer and excessive separation force when the printing platform rises [14]. This separation forcemainly comes from the adhesion of the cured resin and the vacuum suction caused by the topical negative pressure when the resin is not filled in time as the printing platform rises [15]. In order to reduce the separation force, [PERSON] et al. [16] proposed enhancing the adhesion by means of over-curing, but this would reduce the accuracy and printing speed of the model. The dual-channel method proposed by [PERSON] et al. [17] can also reduce the separation force through the lateral movement of the liquid tank, but it will greatly increase the printing time. A new technology, continuous liquid interface production, was proposed by researchers at the University of North Carolina in 2015 [18]. The technique utilized oxygen polymerization to create a tiny \"dead zone\" between the solidified layer and the bottom of the tank, significantly reducing the separation force. However, the Teflon film is expensive, limiting the development of the technology. The above methods solved the problems by reducing the separation force; this paper aims to improve the adhesion between the model and the printing platform by changing the mechanical structure and improving the demolding efficiency and success rate of the printing model by combining the structure with the demolding device. In this work, through the design of the key components of the mechanical movement system, hardware and control system, a DLP 3D printing forming device equipped with a porous printing platform that is easy to be replaced and a swing mechanism for the liquid tank is manufactured. The equipment uses \(Z\)-axis slide rail and limit switch as a mechanical motion system, Raspberry PI as the control core, an LED UV light machine as the light source and the expansion board for driving the movement of the stepping motor to achieve the movement and control of DLP 3D printing equipment.