In this study, pico-scale droplet behaviors in one non-coated coat layer and three types of coated paper are discussed by X-ray CT (computed tomography), cross-sectional SEM (scanning electron microscope) and two-dimensional numerical simulation. With an x-ray computational tomography measurement with contrasting ink with potassium bromide, the droplet penetrating regions are measured three-dimensionally. These penetrating regions are compared to the paper structure measured by the cross-sectional SEM observation. The experimental results show that, in the coating paper with two coat layers, the droplet penetrates only into the outer coat layer. The numerical results show that this penetrating only into the outer coat layer is originated from a smaller pore size of the outer coat layer than that of the inner coat layer.

This paper offers an overview of theoretical models and simulation studies about evaporation and penetration in inkjet printing technology. After deposition of droplets on a printing media, evaporation and penetration happen simultaneously. These phenomena are very complicated and difficult to understand without theoretical considerations and simulations. Isothermal and diffusion-limitted evaporation model is popular for study of evaporation. However, recent studies reveal that the effect of temperature-drop due to evaporation, Marangoni flow in a droplet and air convection around ink have a great influence on the evaporation phenomena. For analysing penetration of ink into media, Lucas Washbern model is used for theoretical estimation of penetration volume. Even if the effect of solid content on penetration should be considered with pigment ink, theoretical model for pigment ink is not established yet. Typical researches of theoretical analysis and simulation of both evaporation and penetration will be introduced in this paper.

This paper offers an overview of researches of RICOH Collaborative Research Program on Advanced Digital Printing Technology at Tokyo Institude of Technology. The Program started in 2019 and we are engaged in studying inkjet technology. Inkjet printer generates images with many droplets ejected from nozzles. The process is very simple, but it is difficult to understand phenomena after deposition on a media;evaporation and penetration, without theoretical consideration and simulation. We have been struggling with these phenomena, and have reported our studies at conferences and journals;mainly of the Imaging Society of Japan. These reseaches will be introduced in this paper.

In electrophotographic technology, the developer unit has the function of charging the toner and moving it to the electrostatic latent image on the photoreceptor, so it has a high contribution to image quality and has a large effect on product quality. However, since toner is a powder and its characteristics have a distribution, it is difficult to theorize the behavior of the toner, and the distribution changes with repeated printing, so it takes a lot of manpower and development period. In this report, we introduce a developer model using design parameters with the aim of improving the efficiency of developer unit development. In this model, each function around the developing roller is connected on the model, and the distribution of toner characteristics is introduced, so it is possible to predict the deterioration of the function due to the change in the distribution of the characteristics. Furthermore, by combining it with a simulation technology suitable for each function, it can be expanded to a model that is easier to use in product design.

Robust quality engineering is a method of the technique development built by Dr. Genichi Taguchi (1924-2012), so that's called Taguchi method, and its feature is in improvement of a generic function in the manufacturing upper stream. Generic function is the fundamental performance and basic principle requested of a product and a system. Looseness of generic function generates much quality problem. Therefore when it's possible to improve a basic function by the stage of the development early stage and make them stabilize, quality problem at a market is prevented from happening. This paper includes some practical examples, and introduces the effects and the attention points of Robust quality engineering with computer simulation (CAE;computer aided engineering). Robust quality engineering with CAE improve the efficiency of the technical development on leaps and bounds.

Now that the environment is changing rapidly, it is essential that manufacturing is more and more valuable to humans. High efficiency and low cost are also essential for this development. In order to achieve these, it is important to optimize multi-performance at an early stage of design. In addition, as a system, it is also extremely important to have wide view through one thing, and to co-create it. In October 2018, the author established the NVH (noise, vibration and harshness) Model Study Group, which think the functions of product by Functional Simulation Model, in cooperation with companies and universities. Functional Simulation Model is intended to expand the design space at the initial stage of design, and is described by mathematical formulas and data. The model development is carried out in among industries with universities as linking bridge. We collaborate and co-create how to get a wholly overview and how to realize multi-performance optimization with the developed model through the model. As an example of the approach, a model for road-noise problem is introduced and the applications of the idea of the model are presented.

We applied materials informatics (MI) to existing experimental data for the elastic modulus of polypropylene (PP) composites. Explanatory variables were described by a combination of 0 and 1 representing polypropylene, or by the content ratio of filler and additive, without using materials property data. We constructed a predictive model for the elastic modulus of polypropylene composites using a partial least square regression (PLS) model with dummy variables. The validity of the predicted model was evaluated by comparing observed and predicted elastic moduli for new polypropylene composites. We improved the accuracy of the prediction for composites with high filler content ratio by applying a nonlinear support vector regression (SVR) model. The predictive model is useful for identifying suitable combinations of polypropylene, filler and additive to achieve a desired elastic modulus.

We adopted and verified reinforcement learning, which is an automatic design technology for control software for mechatronics products. Reinforcement learning is learning using an actual machine in order to determine the optimum operation according to the state of the controlled object by repeating trial and error without knowing what kind of operation should be performed. If you do, the actual machine may be damaged. Therefore, it is imperative to use simulation. However, since the simulator used this time cannot express the uncertainty of the actual machine, it may not be possible to operate it normally on the actual machine. This time we will introduce future issues.

We introduce some recent technologies and achievements about utilizing simulation in manufacturing process by 3D data format FAV (fabricatable voxel), as well as for latest effort, we describe optimal design of pattern structure by FAV with some application. In 2019, 3D data format FAV was registered as JIS (Japanese Industrial Standards). FAV expresses 3D model including internal structures by arranging voxels, which can be used consistently in various 3D data handling and conversion in manufacturing processes. In FAV, each voxel can hold various attribute information. Also, FAV has highly affinity with simulation because voxel itself can be regarded as finite element mesh moreover it is possible to reflect result of simulation in design of 3D model faithfully.