Marika Hirvimäki

Evaluation of Different Monitoring Methods of Laser Additive Manufacturing of Stainless Steel

Different monitoring methods for the laser additive manufacturing process were studied in this study. Possibilities and downfalls of three different methods were compared to each other to define their applicability in future on-line and adaptive monitoring use in LAM processes. The material used on all the LAM process tests was EOS StainlessSteel PH1 in fine powder form. In this study, e.g. parameters like scanning speed, layer thickness and hatch space were tested. Based on the results of this study, the pyrometer seems to be more easily adaptable to continuous monitoring than the spectrometer or systems based on active illumination imaging system. It seems that the pyrometer is a promising method for quality control. The ability to control quality through on-line measurements can be further utilized in future e.g. for on-line quality control and dynamic process control, i.e. the ability to change and correct parameters on the fly.

Laser assisted manufacturing of microscale chemical device of TT reactor

The latest development trend even in chemical industry is to use smaller components even in mill and micro meter scale. Microscale devices and systems have a number of advantages for process development and reaction studies in chemical engineering. Microreactors are small-scale reactors or other processing units for chemical industry with typical channel or chamber diameters in the range of 10-500 micrometers. One of the main features of microreactors is their high surface area to volume ratio, which leads to high heat and mass transfer rates. The advantages of microreactors compared to the conventional reactors are e.g. more optimal reaction conditions, efficient temperature control and smaller volume of raw materials. In process development, number-up by microreactor units would guarantee identical process conditions and eliminate costly redesign and pilot experiments that are usually routines in conventional scale-up and thereby the development time from laboratory to production is shortened.The laser micro processing is one of the fastest spreading and developing areas of laser processing. The processes of laser micromachining are numerous: micro cutting, welding, marking, drilling etc. This wide field of different processes makes laser a novel tool for micro processing and gives lots of new ideas, solutions and applications for designing of microscale process devices for chemical industry. With the use of lasers engineers are given an opportunity to design reactors based on process rather than manufacturing technologies.Aim and purpose of this study was to manufacture a microstructured TT-reactor with laser processing. Material used for this study was HDPE (high density polyethylene) and laser equipment used were IPG 200 W fibre laser and Laserline 200 W diode laser. The lasers were selected in order to test the productivity and reached quality of low power CW lasers.It was concluded that laser processing provides a unique tool for industrial manufacturing of these devices, even in planning and testing stage of these devices in laboratory cases. When a certain structure is proven to be most efficient in a laboratory, number-up means only production of larger number of similar structures.The latest development trend even in chemical industry is to use smaller components even in mill and micro meter scale. Microscale devices and systems have a number of advantages for process development and reaction studies in chemical engineering. Microreactors are small-scale reactors or other processing units for chemical industry with typical channel or chamber diameters in the range of 10-500 micrometers. One of the main features of microreactors is their high surface area to volume ratio, which leads to high heat and mass transfer rates. The advantages of microreactors compared to the conventional reactors are e.g. more optimal reaction conditions, efficient temperature control and smaller volume of raw materials. In process development, number-up by microreactor units would guarantee identical process conditions and eliminate costly redesign and pilot experiments that are usually routines in conventional scale-up and thereby the development time from laboratory to production is shortened.The laser ...

Rapid Prototypes as Openers of an Innovation Block

Thepurposeofthisresearchwastofindoutwhatvaluerapidprototyping(RP)addstoinnovationand creativeactivity,whatchallengesitentails,andwhatsortofinnovationitisespeciallysuitedfor.The researchwasimplementedasaqualitativecasestudyoftencases.Accordingtothestudy,RPisan importantpartoftheinnovationprocessregardlessofitstinkeringreputation.Itopensupaninnovation block,addscreativity,engagespeople,andhelpstoestimatethepotentialofidea ́soriginalityand effectiveness.RPhasapositiveimpactonpeople’sworkenjoymentduetoitsplayfulandcommunal nature.Andanyonecanparticipate.Therefore, thecreativity isamatterofeverybody.Themain limitationoftheresearchwasexaminingRPasastaticeventinonephaseoftheinnovationprocess. Aspracticalvalue,thisarticleencouragesorganisationstoincreaseRPintheirinnovationactivities. KeywORDS Creativity, Fuzzy Front End Innovation, Innovation Block, Mock-Up Prototype, Prototyping, Rapid Prototyping, Value Innovation

Laser welding of micro-VLE-measurement device and its practical application

The knowledge of phase equilibrium is critical for the modeling and operation of reactors and separation units. The use of incorrect vapor-liquid equilibrium (VLE) data for distillation leads to tower malfunction with varying end results. The only reliable method for obtaining valid VLE data for a non-ideal system is to measure it. When studying components that are either very expensive or hazardous the amount of chemicals used is preferably minimized. Typical volume of chemicals used in a VLE-measurement is 100 cm3 or above. In a VLE-measurement the temperature, pressure and composition of both phases are determined for a range of concentrations.The laser micro/fine processing is one of the fastest spreading and developing areas of all laser processes in the world. The wide field of applications makes laser a novel tool for micro processing and gives lots of new ideas, solutions, opportunities and applications for designing these milli and micro scale process devices for chemical industry.In this study an exceptionally small VLE-measurement device was designed and manufactured by utilization of laser processing. Even though the application itself is in micro scale the laser processing used in fine processing scale gave opportunity to reach the minimum volume. Laser welding has unique possibilities for this kind of welding when heat input can be controlled and only small heat affected zone and thereby minor distortions are caused. Laser welding also enables welding of demanding structures, like this micro-VLE-device.The volume of the measurement cell of micro-VLE-device was approximately 2.5 cm3, which was made possible by using the pressure transducer cavity as the equilibrium cell. The chemical consumption is therefore reduced by up to a factor of 50. The valves were also welded to the structure. The welding would not have been possible with conventional methods due to overheating of the transducer electronics. The cell was initially tested by measuring pure component vapor pressures of alkanes.The knowledge of phase equilibrium is critical for the modeling and operation of reactors and separation units. The use of incorrect vapor-liquid equilibrium (VLE) data for distillation leads to tower malfunction with varying end results. The only reliable method for obtaining valid VLE data for a non-ideal system is to measure it. When studying components that are either very expensive or hazardous the amount of chemicals used is preferably minimized. Typical volume of chemicals used in a VLE-measurement is 100 cm3 or above. In a VLE-measurement the temperature, pressure and composition of both phases are determined for a range of concentrations.The laser micro/fine processing is one of the fastest spreading and developing areas of all laser processes in the world. The wide field of applications makes laser a novel tool for micro processing and gives lots of new ideas, solutions, opportunities and applications for designing these milli and micro scale process devices for chemical industry.In this study a...

Laser scribing of stainless steel with and without work media

The advantages such as tight restrictions for heat and mass transfer make micro-/milli scale devices of mixing and droplet formation viable to become widely used in specialty chemical industry. Small dimensions and simple geometry ensure laminar flow and mixing through diffusion, ensuring well-defined behavior of mixing and short reaction times. Combining dry etching by laser beam with wet chemical etching is expected to reduce the production costs of these novel devices.In this study the manufacturing of grooves in stainless steel SS 316L by means of laser micro-/milli processing was investigated. Deep and narrow channels with depth to width ratio of 1:1 at least are preferable, width is allowed to vary from 10-500 micrometer. Lasers used for this study were: 5 kW IPG YLR-5000 S, 200 W IPG YLS-200-SM-WC, 1 kW IPG YLR-1000-SM fiber lasers, 400 W Powerlase diode pumped Nd:YAG laser and 14 W diode pumped Nd:YVO4 laser. Chemical assisted laser scribing is also included in this study.Preliminary results show possibility to obtain channels with desired parameters in pulsed mode laser machining. However, investment cost for CW (continuous wave) lasers per kilowatt are in order of magnitude smaller than for pulsed lasers, that’s why the study was essentially focusing on lasers operating in CW mode. Optimal scribing parameters were defined by adjusting laser power, number of repetitions and speed. Preliminary experiments done without any media resulted in low quality grooves with moderate depth and burned edges. It was concluded in this study that finding a suitable chemical to improve to scribing process is a key moment of getting channels with acceptable quality.The advantages such as tight restrictions for heat and mass transfer make micro-/milli scale devices of mixing and droplet formation viable to become widely used in specialty chemical industry. Small dimensions and simple geometry ensure laminar flow and mixing through diffusion, ensuring well-defined behavior of mixing and short reaction times. Combining dry etching by laser beam with wet chemical etching is expected to reduce the production costs of these novel devices.In this study the manufacturing of grooves in stainless steel SS 316L by means of laser micro-/milli processing was investigated. Deep and narrow channels with depth to width ratio of 1:1 at least are preferable, width is allowed to vary from 10-500 micrometer. Lasers used for this study were: 5 kW IPG YLR-5000 S, 200 W IPG YLS-200-SM-WC, 1 kW IPG YLR-1000-SM fiber lasers, 400 W Powerlase diode pumped Nd:YAG laser and 14 W diode pumped Nd:YVO4 laser. Chemical assisted laser scribing is also included in this study.Preliminary results show ...