A family of novel compliant linear-motion mechanisms based on compliant rolling-contact element pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering that COmpliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for applications of heavy load. These mechanisms are achieved by replacing four rigid pivots in a parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, structures of CORE pivot are introduced and five extended arrangements for bearing heavy load are presented. Meanwhile, motion for the CORE pivot is analyzed and preconditions for achieving a pure roll are discussed. Then, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained, and kinematics of the mechanisms is analyzed and parametric design condition for rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations and experiment tests are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

Design of a Fused Filament Fabrication (FFF) 3D-printer

A Fused Filament Fabrication (FFF) 3D-printer was designed, for fabrication by using in part locally sourced materials. The printer design was based on the Replicating Rapid Prototyper (RepRap) open source. The print volume of the printer is 200mm × 200mm × 300mm and it uses the Melzi V2 printer control board, coupled with the Repetier-Host firmware. The designed 3D-printer consists of galvanized steel frame, stainless steel threaded rods and wooded supports. The Finite Element Method (FEM) analysis was carried out on critical supporting components. The results obtained for the stresses are below the yield strength of the materials and the displacements are within acceptable limits, for high precision machines. The total power required by the 3D-printer was evaluated to be 197.93 W and it utilizes two thermoplastic materials namely; the Polylactic Acid (PLA) and the Acrylonitrile Butadiene Styrene (ABS).

A Family of Novel Compliant Linear-Motion Mechanisms Based on Compliant Rolling-Contact Element Pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering Compliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for heavy load applications. These mechanisms are achieved by replacing four rigid pivots in parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, the CORE pivot is introduced and five extended arrangements for bearing heavy load are given. Meanwhile, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained. In addition, kinematics of the mechanisms is analyzed and parametric design condition for achieving rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

Innovative Line for Door Production TechnoPORTA—Technological and Economic Aspects of Application of Wood-Based Materials

Material losses are caused by the machining process and the manufacturing process, as well as the use of excessive dimensional allowances applied to the machined materials. An adequate reduction of the planned machining allowances for wood-based panel components is possible when the machining line is properly designed and equipped with high-precision machines and devices. The aim of the study was to determine the size of material savings in relation to the most important construction materials when implementing an innovative technological line for processing industrial doors made of wood materials. The achieved savings improve the competitiveness of the door manufacturer on the market. In order to calculate the material savings obtained in the production of the most important models of door leaves that can be obtained in machining on the TechnoPORTA line, numerical data were compiled specifying the dimensions of semi-finished products, taking into account machining allowances applied before and after reduction. The implementation of the TechnoPORTA line makes it possible to reduce the negative impact on the environment by reducing the consumption of wood. It reduces the consumption of materials and the operating costs associated with the reduction of labor intensity, the load on machines and devices, and inventory levels.

Tensile Properties of 3D Printed Polymeric Pieces: Comparison of Several Testing Setups

This work aims to evaluate and compare variations of a methodology for performing tensile tests on thermoplastic specimens constructed by additive manufacturing technologies (AMT) with filament deposition modeling (FDM). The testing procedures of pieces made in FDM machines do not yet have any conclusive standards because 3D printing, as a disruptive and exponentially growing technology, has not allowed enough time to reach a definitive scientific consensus. Nowadays, testing standards for injected thermoplastic parts or laminated composites are employed as substitutes with careful implementation. A comparative study was carried out on the elasticity modulus, determined within the framework of the same standard but with different measuring devices and testing machines. These machines cover a broad range from professional automated high precision machines to lab and specialized machines. Sets of 3Dprinted specimens with identical manufacturing parameters were constructed in a commercial 3D printer. An analysis of variance was performed in order to evaluate the consistency and significance of experimental data for the same polymer, considering the machine type and its corresponding setup. From the experimental data, it is concluded that, with the due care, all evaluated testing setups can reach comparable results, especially in the absence of sophisticated and expensive measuring systems.

Optimization of Ball Screw Diameter using Finite Element Method to Achieve Minimum Deflection

Ball-Screw is a mechanical actuator that transforms the rotational motion of the motor into a linear motion of drive. The ball-screw is commonly used in industrial precision machines and due to this very reason it had been a common topic of research for many scholars, as precision in motion renders to precision in work directly. In this paper, some of the work done by different research scholars on different parametric aspects of ball screw had been discussed alongside optimization of ball screw diameter. The aspects which had been reviewed are elastic deformation & stiffness in ball screw, feed velocity and preloading, preload control in ball screw and various other aspects of preloading such as loss detection. Furthermore, the Finite elemental method had been applied to find the suitable diameter of the ball screw to render minimum deflection and stress value possible with the chosen material.

Additive Manufacturing Redesigning of Metallic Parts for High Precision Machines

The conventional approach to design and manufacturing often has geometries with an efficient material distribution. For the high-precision machines, that approach involves the design of heavy components that guarantees the stiffness requirements. However, the higher the weight of the part, the higher inertia it has. As a result, when the feed axes are accelerated, the inertial forces deform the machine components and the precision of the machine is reduced. This study investigated the designing for additive manufacturing (DfAM) and designing for assembly (DfA) to increase the material efficiency of components for high-precision applications. A new methodology which considered the design and manufacturing issues and machining as well is given. A comprehensive model for cost evaluation of the part is presented. The case study refers to the rails and the bracket that support and move the flying probe of a testing machine for micro-electromechanical systems (MEMS). The weight of the rails has been decreased by 32% and the components to be assembled have been reduced from 16 to 7. The optimized bracket is more than 50% stiffer than the original one, 10% lighter, and economically competitive.