Juan Luis Hernández-Arellano

Additive Manufacturing: Fused Deposition Modeling Advances

The paradigm of the manufacturing systems was broken in 1980 with the beginning of the Additive Manufacturing (AM). This technology has been considered as the complement of the classic manufacturing technology, where the material is removed from a raw material until getting the final product. The addition of material in layers have been considered the new alternative to face the impact in the environment, the economy of materials and process, and the opportunity to generate new complex shapes limited by the classic manufacturing technology. The present chapter exposes the advances of the Fused Deposition Modeling (FDM), one of the seven technologies of AM which is mostly used during the past three decades. In this field, different adaptations and investigations of the technology have been focused on the increment of the capacity of the production system and improve the quality generated by this technique. The methodology used to determine the advance of AM was to employ a Systematic Literature Review using databases. The search was developed considering the keywords of AM for the construction of specific search syntax of documents associated with this technology. The documents obtained were analyzed to identify the progress in this technology. The results present the advancements of the FDM as a technology that change the industrial processing to customize the process, where the globalization makes possible to have this technology available at each desk.

Methodology to Determine Product Dimensions Based on User Anthropometric Data

The determination of product dimensions is usually a complicated task developed during the design process. Typically, product dimensions are developed using wrong percentiles and wrong anthropometric data, i.e., designers use data from other populations. This chapter proposes a method for dimensioning products based on user–product interactions and the user’s anthropometric dimensions. The methodology includes 7 steps: (1) determine the objective of the product, (2) identify the interactions user–product, (3) assign a name to the product dimensions, (4) identify the user dimensions to design the product, (5) determine the percentiles and Z-scores for each product dimension, (6) calculate the percentiles, (7) determine the dimensions of the product. In order to exemplify the proposed method, two examples were developed using the methodology. The first was related with the design of a conventional bench, and the second was related with design of an adjustable school desk. After applying the proposed method, both products were successfully dimensioned.

Workload and Fatigue Among Assembly Operators. A Structural Equation Modeling Approach

This study used Structural Equation Modeling (SEM) to test the relationship between workload and fatigue dimensions, using data obtained from among Constant Velocity (CV) joints assembly workers in Mexico. Three years before this study, assembly workers had complained about how their job’s high workload had increased their levels of fatigue. The NASA-TLX and the Swedish Occupational Fatigue Inventory ware used to collect data on the effects of workload on fatigue from 116 assembly workers. A structural equation model was used to test five hypotheses associated on the effects of workload on lack of energy, physical effort, physical discomfort, lack of motivation, and sleepiness. All relationships were significant and had associated positive load factors. As a result, the modified structural equation model showed statistical significance, as well as good mode fitness. From these results, fatigue was supported as being substantially affected by the workload.

Burnout Syndrome and Musculoskeletal Complaints in Mexican Middle School Teachers in Ciudad Juarez

Teachers face highly demanding situations every day. Their jobs are physically and cognitive challenging diminishing their health. The objective of this paper is to determine the level of burnout syndrome (BS) in Mexican middle school teachers and find the association of BS dimensions with musculoskeletal complaints. As methods, the Maslach Burnout Inventory (MBI) and the Bodymap were administered to 168 middle school teachers. Spearman correlation index was applied. Results show that educators suffer from a medium level of BS on the three dimensions. Emotional exhaustion is correlated with pain in the eyes, neck, wrists, shoulders, ankles, the whole arm, the lower leg, and the back. Depersonalization is correlated with complaints in the left shoulder, the left hand, and the knees. Finally, lack of professional efficacy is associated with pain in both arms, hands, wrists, ankles, and the lower back. It is concluded that preventive actions must be taken to avoid serious burnout consequences in vulnerable professions.

Lean-Six Sigma Framework for Ergonomic Compatibility Evaluation of Advanced Manufacturing Technology

In this chapter an Ergonomic Compatibility Evaluation Model for the selection of Advanced Manufacturing Technology (AMT) into a Lean Six Sigma Manufacturing Framework is proposed. The approach was applied on the selection of CNC plastic molding machines for an AMT training center. The purpose of this model is to constitute a decision aid for decision makers to perform evaluations of AMT in a more complete manner, while considering human factors and ergonomic aspects. These aspects are found to be scarce in actual AMT evaluation and selection models. Model was created using a multi-attribute axiomatic design perspective supporting the selection of AMT. In this chapter a theoretical Lean Six Sigma Framework was proposed for its application. A numerical example is presented by the application of the model with the participation of three experts. A procedure including phases with several steps was deployed using the Define, Measure, Analyze, Improve and Control (DMAIC) stages for AMT evaluation. The alternative which best meet established Design Ranges in terms of Ergonomic Compatibility was selected among three alternatives, according to the Ergonomic Incompatibility Content in a fuzzy environment.