Gunnar Sohlenius

Advantages of Sub-Batch Principle in Flexible Automatic Assembly as Used in the IVF-KTH Concept Mark II

Summary The sub-batch assembly principle combined with an appropriate layout, is suitable for small volumes. Reasons: –One (1) robot can assemble a large number of different part-types, thus avoiding a coupling between the number of parts in a product and the system capacity. –Working cycle time can be made short as the gripper exchange time is reduced and as the handling distance can be very short. –Product specific assembly equipment can easily be brought to and from the system in connection with automatic set-up. A flexible automatic sub-batch assembly system has been built at IVF and KTH, to verify the above mentioned advantages. It incorporates vision (very suitable for sub-batch assembly systems) and helps to integrate parts manufacturing and assembly.

Development of a Droplet-Based Manufacturing Process for Free-Form Fabrication

Summary Droplet-Based Manufacturing processes are now widely used in many industrial applications, including spray forming and rapid prototyping. Application of these processes to freeform fabrication, however, has been greatly hampered by the lack of accurate control over droplet generation and droplet deposition. In order to overcome such shortcomings, a high-precision, uniform-droplet deposition process has been developed. This paper presents the design rationale for the process and its use to determine a key process parameter, the in-flight droplet liquid fraction.

Scientific and structural base of manufacturing

Abstract Science comes from Latin scientia meaning knowledge. Science is difficult to define, but we can obtain an understanding of what we mean. Knowledge, however, is wider in scope than what we generally define as science. Engineering, of which manufacturing is a part, requires creativity, fantasy, scope, and imagination as well as scientific knowledge. These elements are also needed in the scientific work itself. Scientific quality and language to tell the result must be considered separately from each other. Scientific quality means true and accurate knowledge, and the language must be adapted to the problem and to the receiver of the scientific result. Axiomatic decision-rules are being proposed as a scientific method to help in sorting out good solutions in engineering. The manufacturing system can be described and analysed as three main production systems: the manufacturing production system (MPS), the data production system (DPS), and the innovation production system (IPS).

A system for automatic assembly of different products

Summary A system for flexible automatic assembly has been built at PS-Lab IVF/KTH. The system is capable of assembling a number of different products and variants in small batches ( The system consists of four industrial robots, a pallet conveyor, moulded fixtures, interchangeable grippers and fingers, standardized pallets for feeding of parts, partly standardized magazines, conventional and flexible feeders. The paper deals with the philosophy behind the system. The system concept and technical solutions are described. Examples of products that are assembled in the system are given. Conclusions based on the experience from the system are drawn.

Principles of multidisciplinary cooperation in research, especially behavioural science and manufacturing

Summary This paper introduces a framework for systematically and strategically using behavioural sciences in order to achieve more far reaching results from longterm, visionary technical R&D work. The framework describes the most important aspects of interdisciplinary work, which an: the integration components” and the “integration dimensions” for achieving the utmost level of integrated, cooperative work. Reflecting upon 20 years of empirical data it is clear that different levels of integration during the research process will lead to different types of reports with a predetermined quality - as to the achieved multidisciplinary integration. Furthermore, the successive specification of he framework and its application - “the total integration principle”, developed for longterm R&D work - resulted in a research tradition change.

Computer integrated manufacturing and the society

Abstract CIM, Computer Integrated Manufacturing, is the highly productive, high-technology production of today. CIM systems are our advanced tools that have a potential to increase the standard of living throughout the world if they are properly used. CIM gives us a possibility to more easily give each customer products with the functions he/she needs; quality in right time for reasonable costs; productivity . CIM also gives us possibilities to create more human working-conditions concentrated to day-time where people can develop themseelves at work. CIM also gives us better tools and economic conditions to minimiz pollution and recycle material into new generations of products and to process waste back into nature. To obtain these goals, however, requires skilled engineering based on science. Advanced research and education in manufacturing engineering in international cooperation gives us the best possibilities to obtain these desirable goals and to avoid possible bad side-effects.

Increasing Availability and Efficiency by Monitoring the Cutting Process in a Lathe During Production with Limited Manpower

Abstract In a machine tool equipped with DC motors for the spindle and feed movements, the armature currents in the drive motors adjust themselves to the total load torque on the motor shafts. It is possible to detect load variations on the machines cutting tool by measuring the armature currents in the machines (in this case a lathe) spindle and feed motors. By studying the no-load currents in the drive motors for the spindle and the feed systems, it is possible to monitor their condition. This permits scheduled stoppages for service and maintenance. Variations are obtained in the armature currents in the motors when the tool undergoes wear. By calculating the change in direction of the cutting force resultant per unit time within one cut during the machining process, it is possible to determine a suitable time for an automatic tool change before the tool becomes unusable. Monitoring of the tool permits the use of smaller safety margins in the choice of speeds and feeds and enables the tool to be used for a maximum cutting time. An automatic tool change eliminates lost machining process time due to tool breakdown during an unmanned shift. Tool monitoring contributes both to a higher machine availability and to a higher degree of efficiency in the cutting process. Monitoring of the cutting process via the armature currents is limited to a relatively slow monitoring during rough machining. This is due to the fact that the armature currents in the drive systems have poor dynamics and sensitivity for variations in the load on the tool.

Economic Growth, Business Innovation and Engineering Design

Scientific knowledge of engineering within innovative industrial decision processes has a great potential to improve quality and productivity in industrial operations and hence improve profitability. This is a precondition for economic growth, which in turn is necessary to improve welfare. Innovative processes have to combine creativity with quality and productivity in order to achieve profitability and growth. The most important ways to improve profitability in industrial production are through an improved ability to meet more advanced requirements in new products and processes by using new knowledge and inventions and higher productivity through investments in more advanced and automatic tools. This is the fundamental mechanism behind industrial production seen as an engine of welfare. Besides the real world of the products and the production processes, the mechanisms for this development can be classified into three worlds. These are the decision world, the human world and the model world. In striving to obtain increased welfare through industrial production, fundamental knowledge about these worlds and about their relations to the products and processes has to be developed. This paper is a contribution to this understanding, which is necessary in order to combine Total Quality Management, (TQM) and Total Productivity Management (TPM) into Total Effective Management (TEM) by understanding Means.

Competence Requirements and Their Impact on Manufacturing System Performance

Abstract Research into “Next generation manufacturing systems” stresses the use of semi-automated systems to handle short product life cycles and customer oriented production. Despite increasing dependency on technology, the importance of humans is expected to increase and to provide a realistic basis for decision support, both technical and organisational processes must be included in simulation models. In a rapidly changing environment, skill development is also important and should be considered when developing simulation models. This paper describes two case studies where competence and skill development were modelled using learning curves to obtain a more representative simulation of system performance.

Grippers, tools and fixtures for flexible automated assembling

The flexibility of an automatic assembly system is a function of the least flexible subsystem. An optimal system design requires a balance of flexibility between these subsystems. An assembly operation is composed of, at least, the following functional subsystems: - System for the sequence of gross motions - System for the insertion of parts - System for gripping an holding parts - Programmable servo controls, sometimes with real time sensory feedback, form the base for high flexibility of the first two subsystems. For the third it is necessary to rely on mechanical design to obtain adequately defined part positions. This often limits the resulting system flexibility. This paper deals with the design for highly flexible grippers, assembly tools and fixtures. Design philosophy and principal solutions are discussed. Experiments involving industrial robots for assembly are demonstrated and analyzed. Conclusions for robot assisted automated assembling are drawn.