Nanowire enhanced dimensional accuracy in acrylate resin-based 3D printing

3D printing accuracy can be remarkably enhanced by incorporating nanowires into photopolymerizable resins through the elimination of curl distortion.

Photocuring Temperature Study for Curl Distortion Control in Projection-Based Stereolithography

Polymerization shrinkage and thermal cooling effect have been identified as two major factors that lead to the curl distortion in the stereolithography apparatus (SLA) process. In this paper, the photocuring temperature during the building process of mask image projection-based stereolithography (MIP-SL) and how it affects parts' curl distortion are investigated using a high-resolution infrared (IR) camera. Test cases of photocuring layers with different shapes, sizes, and layer thicknesses have been designed and tested. The experimental results reveal that the temperature increase of a cured layer is mainly related to the layer thickness, while the layer shapes and sizes have little effect. The photocuring temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels, and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the photocuring temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion with the expense of increased building time. In addition to curl distortion control, the photocuring temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

Curing Temperature Study for Curl Distortion Control and Simulation in Projection Based Stereolithography

Polymerization shrinkage and thermal cooling effect have been identified as two major factors leading to the curl distortion in the Stereolithography (SLA) process. In this paper, the curing temperatures of built layers in the mask image projection based Stereolithography (MIP-SL) process are investigated using a high-resolution infrared (IR) camera. The curing temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the curing temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion. In addition to curl distortion control, the curing temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

Deformation Control Based on In-Situ Sensors for Mask Projection Based Stereolithography

Curl distortion is one of the main reasons for the part inaccuracy in the Mask Image Projection based Stereolithography (MIP-SL) process. During the building process, the photopolymerization of liquid resin leads to temperature increase. After cooling down, the cured layers will shrink while they are constrained by its supports or the previously built layers. Consequently, residue stresses exist in the built part and will lead to curl distortion after all the supports are removed. In this paper, we investigate the thermal effect in the building process by using an infrared (IR) camera as an in-situ temperature monitoring sensor. Test cases of cured layers with different shapes, sizes and layer thicknesses have been designed and tested. The experimental results show that the temperature increase of a cured layer is mainly related to its layer thickness, while its shapes and sizes have less effect. The temperature increase of a cured layer is also related to its building position in the Z axis. The calibrated temperature increases in the MIP-SL process can be incorporated in a Finite Element Analysis (FEA) model in order to simulate the curl distortion of a given computer-aided design model. Physical experiments of a simple test case have been built, measured, and compared with the FEA simulation result. A discussion of the curl distortion in the MIP-SL process including its prediction and compensation is given.

Distortion Correction of a Quick Response Code Image

Distortion typically occurs when images are captured from the surface of a cylindrical object. This problem is obvious in Quick Response (QR) code images, which necessitate distortion correction for subsequent information reading. Based on a detailed analysis of this distortion, we divided it into linear distortion along the generatrix direction and curl distortion perpendicular to the generatrix direction, and proposed a unified method to correct the distortion of both components. Experimental results are given to demonstrate the feasibility and applicability of the method.

The Effect of the Scanning Mode on the Finished Precision for SLA Technology

Stereo lithography apparatus is an advanced technology that uses photopolymers as the raw materials from which the prototypes are built. The RP manufacture system uses lasers or ultraviolet light to expose selectively the surface of the liquid resin and builds a three-dimensional part according its CAD model in a layer-by-layer manner. The absorption of energy causes photo-polymerization that changes the liquid resin into a solid, expanding the cured volume but shrinking simultaneously. The primary reason for the volume distortion and deformation of the stereo lithography apparatus part are the interlaminar stress generated by resin contraction. The volume shrinkage and curl distortion of the resin will lead to poor accuracy of the built prototype because the bending stress cannot be compensated for. Selecting a non-standard gear as experimental object and manufactured in the SCPS350B rapid prototyping machine. Four kinds of scanning mode, includes X-X mode, X-Y mode, XY mode and XY ST mode, are respectively carried out. From the results, it is found that SLA parameters, i.e. scanning mode and scanning speed significantly affect the forming precision of the prototype. The accuracy of the prototype with XYST mode is prior to the XY mode, and the X-Y mode is prior to the X-X mode. With the lower scanning speed and surface recoating process can further improve the finished precision.