Increasing the Sustainability of the Hybrid Mold Technique through Combined Insert Polymeric Material and Additive Manufacturing Method Design

To reduce plastic waste generation from failed product batches during industrial injection molding, the sustainable production of representative prototypes is essential. Interesting is the more recent hybrid injection molding (HM) technique, in which a polymeric mold core and cavity are produced via additive manufacturing (AM) and are both placed in an overall metal housing for the final polymeric part production. HM requires less material waste and energy compared to conventional subtractive injection molding, at least if its process parameters are properly tuned. In the present work, several options of AM insert production are compared with full metal/steel mold inserts, selecting isotactic polypropylene as the injected polymer. These options are defined by both the AM method and the material considered and are evaluated with respect to the insert mechanical and conductive properties, also considering Moldex3D simulations. These simulations are conducted with inputted measured temperature-dependent AM material properties to identify in silico indicators for wear and to perform cooling cycle time minimization. It is shown that PolyJetted Digital acrylonitrile-butadiene-styrene (ABS) polymer and Multi jet fusioned (MJF) polyamide 11 (PA11) are the most promising. The former option has the best durability for thinner injection molded parts, and the latter option the best cooling cycle times at any thickness, highlighting the need to further develop AM options.

Design and Development of Broaching Machine for Splines: A Case Study

Broaching machine is mainly developed for special purposes where cycle times are less and number of job quantity is very high. Only at such points development of broaching machine is justified. Design of such broaching machine is totally customizable. This paper discuss about frame design of machine, selection of guideways, design of hydraulic power pack for hydraulic operated machine and also selection of various cylinders, pipe fittings, mandrels, pump, motor, etc. So, main purpose of this paper is designing the broaching machine which includes all its components. This paper focuses on selection of bought out parts too.

HARVESTER PRODUCTIVITY AND COSTS IN CLEAR CUTTING Pinus taeda STANDS UNDER DIFFERENT MANAGEMENT REGIMES

The increased demand for several forest products makes it necessary to apply different management regimes in forest stands, which may influence the wood harvesting operations. This study aimed to evaluate the effect of average individual tree volumes obtained through different management regimes on harvester productivity and costs, thereby enabling to generate information for forest managers. The study was carried out in three Pinus taeda L. stands under clear cutting with different average individual tree volumes (AIV): I (0.367 m3); II (0.582 m3); and III (0.766 m3). Working cycle times, productivity per productive machine hour, energy yield and production costs were obtained by a time and motion study, in which the average values obtained were compared by the Tukey-Kramer test (α ≤ 0.05). The work elements of the harvester’s work cycles were affected by forest management regimes, mainly the movement and the processing, with significant statistical difference between stands, but no difference between total working cycle times. The management regime applied to forest stands influenced the spacing and whole trunk volume which consequently increased the average productivity of the machine from 36.8 to 74.1 m³ per productive machine hour in treatments I and III, respectively, and reduced production costs by 50%. The forest management regimes influenced the clear-cutting operation with harvester.

Adsorption performances and electrochemical characteristics of methyl blue onto magnesium-zinc ferrites

A novel and facile rapid combustion approach was developed for the controllable preparation of small size and easy recovery magnesium-zinc ferrites for methyl blue (MB) removal in dye solution. The effects of prepared criteria of x value, calcination temperature, and the amount of ethanol on the average grain sizes and magnetic property were reviewed. The characterization results displayed that Mg0.5Zn0.5Fe2O4 nanoparticles met the expectations of the experiment at the calcination temperature of 400℃ with absolute ethanol volume of 20 mL, and they were selected to remove MB. The adsorption process belonged to chemical adsorption on the basis of the pseudo-second-order model. The electrochemical characteristics of MB onto the prepared nanoparticles were analyzed by cyclic voltammetry (CV). The influences of pH and cycle times on the removal efficiency were investigated. When the pH went beyond 3, the removal efficiency of MB onto the magnetic Mg0.5Zn0.5Fe2O4 nanoparticles maintained above 99%，the maximum adsorption capacity was 318.18 mg/g. After seven cycles, the relative removal rate of MB remained 96% of the first one.

Process design of a novel combination of peel grinding and deep rolling

Grinding is mostly considered as a finishing operation by which a high surface quality is achieved. An increase in productivity is therefore limited by maintained surface properties such as the roughness or tensile residual stresses. Thus, a roughing operation is inevitable followed by a finishing operation, while both operations are separated, leading to larger cycle times and process costs. In this paper, a novel process combination is investigated in which the roughing is done by grinding and the finishing operation by deep rolling within one tool setup. In this way, both processes are conducted parallel within the primary processing time. The objective of this study is the knowledge of the characteristics of this process combination with regard to the workpiece surface integrity. Therefore, shafts are ground in peel grinding with varying grinding wheel types and process parameters and subsequently machined with deep rolling. The process combination is evaluated with regard to the process forces and the resulting surface properties. In addition, experiments using the process combination were conducted in order to investigate the transferability of the results towards the process combination. By this approach, it was found that the surface roughness was reduced up to 80% by deep rolling showing the potential of the process combination.

A Longitudinal Comparison of Telemedicine Versus In-Person Otolaryngology Clinic Efficiency and Patient Satisfaction During COVID-19

Objectives: Telemedicine was increasingly adopted in otolaryngology as a result of the COVID-19 pandemic, but how it compares to in-person visits over the longitudinal course of the pandemic has not been characterized. This study compares telemedicine visits to in-person visits on measures of clinical efficiency and patient satisfaction. Methods: We examined all in-person and telemedicine encounters that occurred during the 13-month period from April 1, 2020 to April 30, 2021 at a pediatric otolaryngology clinic associated with a large tertiary care children’s hospital. We compared patient demographics, primary encounter diagnoses, completions, cancellations, no-shows, cycle time, and patient satisfaction. Results: A total of 19 541 (90.5%) in-person visits and 2051 (9.5%) telemedicine visits were scheduled over the study period. There was no difference in patient age or gender between the visit types. There was a difference in race (75% White or Caucasian for in-person and 73% for telemedicine, P = .007) and average travel distance (53.3 miles for in-person vs 71.0 for telemedicine, P = .000). The most common primary diagnosis was Eustachian tube dysfunction for in-person visits (11.8%) and sleep disordered breathing for telemedicine visits (13.7%). Completion rate was greater for telemedicine visits (52.4% in-person vs 62.5% telemedicine). Cancellations were greater for in-person visits (42.6% in-person vs 24.2% telemedicine), but no-shows were greater for telemedicine (5.0% in-person vs 13.3% telemedicine, all P = .000). Average cycle time was shorter for telemedicine visits (56.5 minutes in-person vs 47.6 minutes telemedicine, P = .000). Patient satisfaction with provider interactions and overall care experience was high for both visit types. Conclusions: Telemedicine was utilized more during months of heightened COVID-19 cases, with higher completion rates, fewer cancellations, shorter cycle times, saved travel distance, and comparable patient satisfaction to in-person visits. Telemedicine has the potential to remain an efficient mode of care delivery in the post-pandemic era.

Explicit Modelling of Multi-Period Setup Times in Proportional Lot-Sizing Problem with Constant Capacity

The planning horizon of small bucket models is often divided into many fictitious micro-periods, with non-zero demand only in the last micro-period of each real (macro-)period. On the one hand, such models ensure schedules with short cycle times and low work-in-process inventory in multilevel systems; on the other, they make setup times that are longer than a single period more likely. This paper presents a new mixed-integer programming model for the case with setup operations that overlap multiple periods. The new model assumes that the capacity is constant in the whole planning horizon and explicitly determines the entire schedule of each changeover. Moreover, a two-level MIP heuristic is presented that uses model-specific cuts to fix a priori some minor decisions. The results of the computational experiments show that the new model and MIP heuristic require a substantially smaller computational effort from a standard MIP solver than the known models.MSC Classification: 90B30 , 90C11

Catching-up and Leapfrogging in Key Manufacturing Sectors

Chapter 6 assesses China’s catching-up and leapfrogging in key manufacturing sectors compared with the Korean experience. It explains the varying records of market catch-up by referring to diverse aspects of technological and market regimes, such as modularity, degrees of embodied technical change, tacitness of knowledge, knowledge accessibility, and frequency of innovations. Easy access to foreign technologies from developed countries (mobile phones vs. semiconductors), high degree of modularity (mobile phones vs. automobiles and semiconductors), and frequent changes in the generations of technologies or short cycle times of technologies (mobile phones and telecommunications systems vs. automobiles) generally help latecomers catch up. More importantly, sectors with a high degree of tacit knowledge (e.g., automobiles) tend to show a slower speed of catch-up than the manufacturers of telecommunications equipment with a high degree of explicit knowledge. Whether markets feature segmentation (or the existence of low-end niche segments for Chinese latecomers) seems to play an important role in the market regimes. Chinese firms manage to achieve initial success from a low-end market in segmented market conditions (e.g., telecommunications equipment and mobile phones) or markets protected by the government (e.g., telecommunications equipment). Conversely, they face high entry barriers in markets with no such segmentation (e.g., memory chips), which is one of the reasons for their slow progress in the memory chip sector (see also Chapter 4). These cases also suggest that technological regimes are not the only paramount determining factor; the outcomes are affected by the roles of actors, including firms and governments.