Catálogo de publicaciones - libros

In today’s increasingly volatile and dynamic global markets it is increasingly important to react to changing market demands and reduce the time-to-market. The design and re-design of assembly systems has a significant impact on the product development time. This paper reports on the effort that has been put into developing an assembly process decomposition and modular assembly equipment configuration methodology that takes advantage of the current trend towards modular equipment solutions and is expected to reduce design time and improve the design process integration. A general framework for the proposed methodology has been outlined and an ontology for the design of modular assembly systems is being discussed.

The Eupass project (www.eupass.org) proposes to develop assembly systems, especially in the field of ultra precision assembly, with evolvable skills to fit a wide range of products being assembled by applying a “Zero-Engineering” approach for the switch-over from one product to another. The Eupass partners are currently developing a machine line network with new and additional machine and device discovery mechanisms, synchronization and data exchange capabilities. By means of a common behavioral model, machines and devices connected to a network can jointly be discovered, commanded and execute any programmed activity in a collaborative way — developing evolvable skills exceeding the skill set of the singular machines.

The microfactory paradigm means the miniaturisation of manufacturing systems according to the miniaturisation of products. Some benefits are the saving of material, energy and place. A vision based solution to the problem of supervision of microfactories is proposed. It consists in synthetising a high resolution global view of the work field and real time inlay of local image in this background. The result can be used for micromanipulation monitoring, assistance to the operator, alarms and others useful informations displaying.

The paper is dealing with the development of a new class of multipurpose multi-degrees-o-freedom (MDOF) Positioning Systems (PS) to be used as precision devices in a cell manufacturing desktop environment. Based on a structural investigation and systematization with imposed criteria, PM with 2dof actuators on the base was proposed. In its first modular design concept, each of the members -Positioning units (Pu), having at least 2DOF motion capabilities over a large workspaces, are symmetric parallel mechanisms (PM) architectures, fully actuated, by in-parallel linear-linear (L-L) actuation modules(aM) . The kinematics and design aspects for the representative cases — 2, 4 and 6 DOF Pu, by using planar motors and scissors (and/or, parallelograms) as transfer of motion modules(TofM) are presented, as they exhibit, both, an increased stiffness and speed features, respectively.

Assembly of high precision products is often done manually. The main reasons are the complexity of automation and the production volumes that often remain small to medium. Watches, medical devices and sensors are some examples of products requiring high precision assembly: often expensive products with high margins. It is interesting to notice that achieving higher assembly yield allows for relative quick pay-back of equipment. This is also the reason why western European countries remain competitive in this field. In this paper, the important points to remember when selecting a solution to efficiently assist operators in their assembly tasks are highlighted. Good assistance should lead to higher yields, higher throughputs and better quality. One should take into account assembly processes and their difficulties, as well as production volume and economic profitability.

This article presents a case study in the design of a modular semi-automated reconfigurable assembly system using life cycle cost analysis methodology. To ensure that an assembly system is appropriately designed, system measurement schemes should be established for determining and understanding design effectiveness. Understanding life cycle costs is the first step toward increasing profits. The authors are developing an analysis tool that integrates Overall Equipment Efficiency (OEE), Cost of Ownership (COO), and other analysis methods to improve the design of flexible, modular reconfigurable assembly systems. The development is based on selected industrial standards and the authors’ own experience in modular assembly system design and simulation. The developed TCO (Total Cost of Ownership) methodology is useful in system supplier and end-user communication and helps in trade-off analysis of the system concepts.

This article shows the consequences of using parts with scrap in an automatic assembly system. The scrap is the percentage of parts that do not reach the required conformity and will cause either a defective assembly or a jam in the system. The two consequences considered here are extra cost and loss of productivity. To show this, we will focus on one part assembly operation anywhere in the process, which consists of feeding, assembling the part and inspecting the resulting sub-assembly. We will show that the effect of scrap can be huge and depends strongly on how the bad part is detected. 4 cases are considered: 1.The parts are sorted before feeding 2.The bad parts jam in the feeder 3.The bad parts jam while assembling 4.The sub-assembly with bad parts is ejected after inspection. By evaluating each case in 3 examples, we will show that case 3 is often the worst. We will also define the conditions where it is better to sort the parts first (1), let them jam in the feeder (2) or sort the sub-assemblies (4).

The use of bonding as a joining technique is gaining more and more importance in micro manufacturing. There is a demand for systems which are capable of reliably dispensing tiny amounts of adhesive, especially under industrial conditions. By integrating sensors into the dispensing system or checking process results there is the possibility to become aware of the system specific problems and options of improvement. Methods and systems of investigation have been developed and realized at the Fraunhofer IPA.

Packaging is the last process of microsystem manufacturing. There are mainly two kinds of packages: plastic or metallic. The two main components of the package (base and cover) may either be glued or soldered. Each of these techniques has its advantages and drawbacks, and the choice should be driven by the functionality of the microsystem. The advantage of gluing is that it is quite an easy production process. The drawback is that glue, like all polymers, is not hermetic on the long term. This is a problem when the package should protect the microsystem from oxygen or water vapour, an example being OLED displays (Organic Light Emitting Diodes). The advantage of soldered metallic packages is that they are hermetic. The drawback is that the welding process takes place in an oven, and that the whole microsytem is heated to the fusion temperature of the joint. This is a problem for many microsystems, typically biomedical MEMS and OLEDS again. The LPM-EPFL is working on the development of a two-part sealed packaging. One part of the package is metallic, the other part is made of glass. The goal of the project is to soft solder the two parts of the package by the mean of a laser diode. The advantages of the laser soft soldered joint are: its water and air-tightness in regard to glue or a plastic joint the possibility to heat only the solder joint, and not inside the package.

The main difficulties encountered in the development of microscale fluidic pumping systems stem from the fact that these systems tend to comprise highly three-dimensional parts, which are incompatible with traditional microproduction technologies. Regardless of the type of pumping principle, most of the hydraulic systems contain valves and in particular a one-way valve. This paper presents the design and modelling of an ortho-planar one-way microvalve. The main advantages of such a valve are that it is very compact and can be made from a single flat piece of material. An analytical model of the spring deflection has been developed and compared to FEM. A prototype with a bore of 1.5 mm has been build using a micro EDM (electro discharge machining) machine and also tested.