Harri Eskelinen

Manufacturability analysis a useful subset of systems engineering

The application of manufacturability analysis to the design of mechanical parts in electronic systems improves quality, performance and reliability. Typical interest areas include equipment enclosures, transducers and high-tech microwave modules. New performance levels are feasible due to improved surface quality, stability, reduction of seam widths or the use of sophisticated materials. The stepwise procedure points out attractive solutions for challenging airborne, maritime or space sensor platform environments. A thorough understanding of manufacturability judgement and knowledge about current milling, welding and coating processes is essential as well as the earliest application of the formulated principle.

Leakage-proof nozzle design for RepRap community 3D printer

The RepRap 3D printer development project is a fast growing, open-hardware initiative relying on the input of hobbyist designers. One of its key components is the printer nozzle. The performance and reliability deficiencies of currently available nozzle designs are common topics in the RepRap community, and our own experience with a RepRap 3D printer has identified a need for improvement in a few particular areas. We set out to eliminate melt leakage, improve thermal isolation, and develop a more effective method of nozzle assembly attachment. Here, we review the issues, describe design efforts, and report results.

Review of Design for Manufacturing and Assembly Aspects to Designing Modern Micro-Wave and Sheet Metal Products

In this paper, we present different points of view to make the sheet metal and micro-wave product as manufacturing friendly as possible. Within DFM(A)-research (Design for Manufacturing and Assembly), engineering design and manufacturability of Micro-Wave (MW) and sheet metal products has been studied. Other aspects of DFM(A) have risen from novel material applications and the development of CAD (Computer Aided Design) environments. In this paper, practical examples are presented to show how to apply DFMA-rules to MW- and sheet metal components, in particular, and how to develop DFM(A)-rules for these purposes.

A Look at Optimised Laser Processing for the Manufacturing of Passive Microwave Modules

Simulated designs and prototype measurements suggest that various passive microwave elements, e.g. cavity resonators, module enclosures and highly selective, low-loss RF filters for cellular mobile networks can be based on optimized laser welded solid metal structures capable to withstand the most stringet environmental stresses also in corrosive tower installations. Key improvements include a superior shielding characteristic of the necessary joints, a better surface quality and e.g. easily adjustable transmission line impedances, if needed, by laser cut sections. Suitable frequencies cover most known analog and digital phone systems including the starting UMTS at 2 GHz. New performance levels and cost reductions are feasible due to interactive design changes, improved stability, or the use of sophisticated materials. The applied design process must be optimized both regarding the microwave design, material selection and manufacturing facilities.

Novel DFMA-Tools For Passive MW- And RF-Components In Cost-Effective Mass Production

Because of the large production volumes of MW- and RF- technology even slight improvements of design methodologies or manufacturing technologies would give possibilities for cost reduction. Modern tools for cost-effective DFMA (Design for Manufacturing and Assembly) for passive components and modern antenna constructions should be easy to integrate with the tools for electrical design. Furtheron design methodologies for mechanical components should be tuned for this specific branch of science and for the specific product type. Recently this kind of development has been seen in antenna design and the results of reducing the design and manufacturing costs have been promising [1]. We have designed and manufactured a prototype of a smart antenna and its all passive components for mobile communication. To increase the flexibility of the mobile systems those wide band designs are used which are able to provide electronic real-time beam stearing through analog technologies or digital beam forming. We have gathered novel DFMA-aspects [2] during this design project and tested virtual engineering (VE) tools to improve products performance and to increase the cost-effectiveness of the design and manufacturing processes.

Performance-Oriented Manufacturability Analysis of a 5 GHz Satellite Oscillator

Modern communication and radar systems, especially if used for space or defense applications, need signal sources having high spectral purity and ultimate frequency stability. Most current and future designs must also include some way of frequency tuning. Digital synthesizers and multipliers are the conventional electronic solutions to these challenges, but unfortunately, they suffer from increased phase noise. The idea in the present survey was to study the feasibility and performance of fundamental frequency microwave dielectric resonator oscillators (DRO’s) as a substitute to frequency synthesis. If atomic frequency standards (such as cesium clocks or hydrogen masers) are excluded, all resonator-type oscillators (quartz crystals, dielectric resonators, surface acoustic wave devices) are of the mechanical vibration type. Dimensional tolerances and constructional rigidity issues, particularly in the resonator element itself, are thus of vital importance. The sharpness of the resonance curve defines the frequency accuracy to a certain extent, and therefore, we need the highest possible quality factor of the resonator, which calls for uncompromised surface quality. Usually, the electrical performance of this type of component is ensured with some computer-assisted tools before manufacturing the first prototype. This research showed that it is useful to simulate also the manufacturing stages beforehand to be able to find solutions for possible bottlenecks in the production. One of the key findings of the computer aided manufacturing (CAM) simulations was the importance of utilizing the optimum combination of the milling tool path, tool diameter, and the stepover to maximize the Q-value of the resonator but keeping the production at a reasonable level.

DFMA-aspects of sheet metal product in case of low-cost strategy

This document is illustration of one real sheet metal product, which manufacturing is really challenging and many problems occur in production. In this paper there is given some point of views, which should be take into consideration before the part can be produced without (or some minimal) problems.

Observations of applying DFM(A) in MW mechanics and sheet metal work

In this paper, approaches to apply DFM(A) (Design for Manufacturing and Assembly) in practice are reviewed based on both the research results of the areas of MW mechanics and sheet metal work achieved at Lappeenranta University of Technology. These results are supported by a literature review. In this paper, we present five view-points on how to apply DFM(A) in practise in the previously mentioned research areas. The view-points are as follows: applied DFM(A) rules for sheet metal work, utilization of lists and forms to analyze MW constructions, development of traditional design methodologies, development of manufacturing technologies for easy production, integrated DFM(A) approaches which aim to control and manage both the product design process and its costs.

A Millimeter Wave System for The Analysis of Logs

The measurement resolution of the internal structure of logs and sawn timber can be enhanced by using the transmission and reflection of Ka-band millimeter wave energy injected with a selected polarization into the test samples. Particularly, the size, number and location of knots and other similar defects e.g. due to insects can be recorded in nearly real time with a spatial resolution of 1 mm and a positioning accuracy of 3 mm. Most sensitive test parameters are phase changes up to several hundred degrees and attenuation dips of 10 - 30 dB. The base attenuation in dry knot-free timber is typically 300-700 dB/m. Thus, with an output power of 0 dBm, samples having a diameter of 200 mm or less can be measured. A simultaneous recording of reflection can reduce errors caused by non-significant surface deformations.

A High-Isolation S-Band Ring Hybrid Combiner

Through careful dimensioning, avoidance of line transition discontinuities and by using special blocking elements to reduce stray couplings across the internal airgap together with inductive fine-tuning posts, a conventional ring hybrid can be an attractive RF power combiner for L- or S-band transceiver applications, where a high isolation is desired between the transmitter output arrangement and the receiving front-end, or for antenna arrays. When typical commercial units hardly exceed 40 dB, an improved narrow-band isolation up to 90 dB and more is demonstrated here while keeping the residual attenuation for desired coupling below 0.15 dB. The required milling and mounting uncertainty for a successful and repeatable result in a combined metallic / PTFE stripline form was found to be 0.01 mm.