Tillverkningsteknik

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• Explain the significance of surfaces in the context of manufacturing. Provide some examples of properties influenced by material processing they impact the functionality, aesthetics and performance. Properties that are influences are for example functionality and performance since surface smoothness affect how product slides and how long they last
• what are the four major manufacturing process control aspects maximizing quality, improving productivity, improving flexibility, reducing cost
• what is the concept of structural loop is an assembly of mechanical components which maintain a relative position between specified components
• what is damping damping is the capacity to reduce intensity of a vibratory process
• what is the stiffness in a structural loop stuffiness is the capacity to sustain loads without excessive changes of its geometry
• describe the two major types of motors Linear synchronous motor: single sided magnets assembly, disturbing effects of friction and force ripples arising from irregular magnetic field, Linear induction motor: the force is produced by a moving linear magnetic field acting on conductors in the field
• what are the main elements of machines for metal forming drive, frame, guides and controls
• define static stiffness as it pertains to a press compliance G is inversely proportional to stiffness k. compliance is the ratio of deformation to force causing this deformation
• Explain the different working principles of press machine Energy driven press:operates without feedback, force driven press: Required a current feedback loop, hydraulic press, has a constant force, path driven: has a position feedback loop, the primary control is the displacement or stroke length of the press
• Servo drive presses have several advantages over conventional presses, discuss Flexible servo drive programming optimizes forming speed for materials and enables additional operations like punching. Benefits: precision, energy savings, tool longevity
• which physical interaction govern the mechanics of metal cutting. these phenomena are complex, highly localized and difficult to measure stress, strain, strain rate, temperature
• name and briefly describe the three types of chips that occur in metal cutting discontinuous chip: they consist of small, individual segments seperated by micro cracks, continuous chip: long continuous chip, ribbon like structure, chip formed over bult up edge: follows the surface the tool
• why is the shear plane angle an important point of focus in machining because it significantly influence the cutting process, tool life and quality of the machined surface
• what is a orthogonal cutting operation? why is it useful in metal cutting in orthogonal cutting the cutting edge is perpendicular to the cutting speed. it is useful since It simplifies complex 3d machining to 2d
• identify the four forces acting on the chip in orthogonal cutting but cannot be measured directly friction force, normal to friction force, shear force, normal to shear force
• identify the forces that can be measured in orthogonal cutting cutting force and thrust force
• elaborate on thermal aspects of metal cutting the heat generated at the tool interface is a major importance in relation to performance and is particular significant in limiting the rates of metal removal. Thermal aspects of metal cutting is important for optimizing machining process, tool life, workpiece quality and efficiency
• what are the main task of metalworking fluids in machining? Name them and explain their effects Cooling: reduce thermal load on tool, workpiece, and machine, lubrication:reduce friction, forces and heat generation, clear the chip: clear the chips from workplace, tool and machine
• what are the roles of emulsifiers in mwfs emulsifier: is a surface-active agent, or surfactant, that is at least partially soluble in both liquids of an emulsion, and stabilizes one in the other, additive: is a chemical substance formulated into wmf to provide specific performance properties not provided by the base
• what are the role of additives in mwf additive: is a chemical substance formulated into wmf to provide specific performance properties not provided by the base stock
• what are the main advantages of emulsion over straight oil? emulsion is cheaper and has better cooling. emulsions also has better surface finish because of the cooling, its also safer since they are less flammable
• the use of mwfs is associated with sustainability concerns, why? many mwfs contains hazardous or toxic chemicals which can lead to pollution soil and water resources, its better to use water based mwfs
• what basic conditions seem to be necessary to facilitate dry machining?which alternative method to flood cooling do you know? dry machining is most suitable for materials that generates low level heat. you want lower cutting speed to minimize heat and lower cutting force. alternative method is mql and side cooling
• what is mql stands for minimum quantity lubrication that eliminates the need for large quantities of water and straight oil fluids and replace them with lubricant mixed with air. used in automotive industry to reduce cost energy and waste
• what is crygenic machining? advanced technology thet involves the use of extremely high temperatures often is liquid nitrogen used. through-tool cooling and external jet cooling are metods
• Describe the most common pump used in wj and awj its intensifier pump and it is a hydraulic device that increases the pressure of the incoming water to achieve the high pressure levels required. consist of hydraulic piston and plunger and attenuator which stabilize pressure
• explain how pure water jet cuts materials, for instance a rubber of soft plastic uses a high pressure jets of water provided by pressurizing pumps that deliver a supersonic stream. It has no chamber or nozzle, just a thin focused stream
• what material removal mechanisms are involved in awj? Cutting wear: chip removal mechanism acting when the grain hits the surface at a shallow angle. in the cut kerf this is found at the top, deformation wear: grains hit the surface at a larger impact angles. subsequent hitting of multiple grans causes plastig deformation, hardening then fracturing. this is found at the bottom of the cut
• shortly describe some advantages as well as disadvantages of awj for cutting applications. also point out some typical applications advantages: flexibility with respect to geometry, can cut thick and thin, no heat affected zone, disadvantages: low cutting speed, expensive, typical applications: precision cutting of metals in automotive industry
• Define and explain at least three macro geometrical defects one might find on an awj cut part. Explain the cause of tree effects taper: cut being wider or narrower then the other, occurs due to natural divergence, kerf width variation: refers to irregularities in the width of the cut, corner overcut: cutting stream extending slightly beyond indented cutting path, occurs by natural widening of stream
• what is taper compensation and why is that of interest is a technique used to automatically adjust the cutting process to minimize taper. used to get improved precision, reduced material waste and enhanced surface finish
• why are pulsed laser of interest, how can quality be improved? pulsed lasers are of unstressed since high peak power leads to material melting faster. Have minimal heat affected zone which leads to less risk of material deformation and improve quality
• how can oxygen be used in laser cutting? oxygen can be used to enhance cutting process, it will cut faster
• laser light have som particular properties, which are these monochromatic=same wave length, coherent=in phase, directed=close to parallel
• the dielectric fluid in edm has several function, name 2 cooling: the dielectric fluid circulates around region carrying away heat, flushing: helps remove eroded material
• why is making die and molds and important application for edm? describe the process chain for die/mold making it gives better precision and can cut hard and difficult to machine materials. non hardening piece of steal--roughing--semi finishing--hardening--edm--finishing--manual finishing
• describe wire edm, function, type of dielectric used and important characteristics involves the use of a thin, electrically conductive wire as an electrode to create controlled electrical discharges between wire and the workpiece. It has high precision, no contact between wire and workpiece
• What is an old and how do you use it? what information is necessary for it to being used its a graphical representation used in sheet metal forming to predict and access the formability of a material. if the strain point falls within the safe region the process is considered feasible, if over it may lead to defects. you need material properties and strain data
• two types of anisotropy is of importans in forming. which are these? define them and discuss normal anisotropy: tells us if the material will deform more easily in the plane than in the thickness direction, this leads to better formability. planar anisotropy: causes earring, materials deforms more easily in different directions in the plane. this comes form that sheet is rolled and crystals are directed, it affects the appearance
• which material properties affect formability? explain how and why they affect strain hardening: at the beginning necking, the neck is strengthened and deformation continues outside of the neck, prolonging the forming possibility, anisotropy: if material deform more easily in the plane than in the thickness direction which leads to better formability, stress strain behavior:high strength material are more brittle, less formable
• explain how lubrication could affect formability in general A big starting diameter for deep forming requires a strong blank-holder force to prevent wrinkles. High friction can cause stretching and fractures. Lower friction allows a higher blank-holder force without risking issues
• for hydroforming describe why and how wrinkling occurs wrinkling is mostly associated with a too high indeed where to much material will be presented. the risk decreases slightly if we pressures more. fracture are associated with too high internal pressure
• in hydroforming an advantage mentioned is that wall thickness Is more uniform. why would that be the case and compared to what compared to deep drawing and stretched then joined parts, these do not have uniform thickness. however an inflated tube, the pressure acts radially and thus wall thickness reduction will ideally be totally uniform
• describe the four main characteristics of the difficult to cut materials such as ni-based superalloys strength: maintained at high temperature during machining, work hardening: occurs rapidly during machining, high abrasive wear: owing to the presence of hard abrasive carbides, poor thermal diffusivity: nickel based alloys often generates high temperature at the tool tip
• long unbroken chips should be avoided during machining, why? describe 3 ways to avoid it winding around tool and workpiece which can lead to breakage and unsteady process, to avoid it increase feed rate, depth of cut and use high pressure coolant or select sealer nose radius
• what type of chip formation is more often when machining iso_N materials? hos about ISO-s and ISO-k chip formation us influenced by material properties. iso-n materials result in flow chip formation due to ductility, iso-s materials discontinuous chip due to high shear strength and iso-k materials gives lamellar chip due to high strength
• what do we mean by bue information? why should it be avoided? how it can be avoided? bue information is when a thin layer of material adhering to the tool cutting edge. It accelerate tool wear and get surface defects. you can avoid it by selecting appropriate tool materials and maintain cutting conditions, use sharp tools
• explain the reason why the type of chip formation at very low and very high feeds should be avoided very low feed rate can lead to clogging and excessive heat generation, high feed rate result in excessive tool wear and elevated temperatures
• what are the basic constituents of a grinding wheel? what are the four hard materials typically used as abrasives in grinding wheels basic constituents are grits, bond, pores and the four materials are aluminum oxide, silicon carbide, cubic boron nitride, diamond
• what are the three mechanisms of grinding wheel wear? abrasive wear, bond wear, porosity
• why are thermal loads so much higher in grindning compare to milling? thermal loads are higher in grinding since we have a higher friction. we also have smaller contact area and get a more concentrated heat
• grinding creates high temperatures. how is high temperatures in grinding the high temperatures produced in grinding can cause burning on the workpiece and softening the surface layer, cracks, thermal expansion can cause inaccuracies
• Identify and elaborate on the three main aspects of grindability mechanical:material flow, strain rate, hardness, tribological: friction and wear, thermal:susceptibility to thermal damage, tensile residual stresses, rehardening
• define specific grinding energy and elaborate on its implications. what is the size effect a fundamental parameter derived from the power of grinding conditions is the specific grinding energy, which is define as the energy per unit volume of material removal. Size effect mechanical properties and behavior of a material change as a function of the material's size or dimensions
• using the theory of aggressiveness, if I increase the rpm, will I do more cutting or mor rubbing? will the surface get smoother more rubbing and surface get smoother
• using the theory of aggressiveness, if I double the federate and double the wheel speed, how much will aggressiveness increase? will I do more rubbing or cutting and will surface get smoother more cutting and rougher surface
• what are the role of dressing, in reference to conditioning of grinding wheels? make the grinding wheel sharp, put the correct geometry form on the wheel. wheel dressing include turning and sharpening. turning refers to removal of material from cutting surface of a grinding wheel. dressing is the process of sharpening the wheel
• what is the difference between uni-directional and anti-directional rotary dressing uni-directional dressing tool rotates in the same direction as the grinding wheel and for ani-dressing it rotates in opposite direction of the grinding wheels rotation
• definition of finishing technology. how are finishing operations positioned in the manufacturing value chain? finishing is the final step in manufacturing which require highest quality
• what finishing operation do you recommend for producing parts what require longer fatigue life and lower noise? Describe the reason gear honing is recommended. since honed components have a proven lower noise due to their specific curved surface structure
• describe the attributes of abrasive finishing technology in comparison to the grinding technology grinding has high cutting speed, high removal rate and high machine temperature and abrasive finishing has low cutting speed, low removal rate and machine temperature. grinding has sub-surface damage and abrasive finishing have damage free surface. grinding is motion controlled and the abrasive pressure controlled
• what is super finishing? difference between stone/tape superfinishing superfinishing is a fine finishing process which uses abrasive grits bonded in a stone. stone superfinishing is frequently used on larger shafts where the tool will be traversed over a long distance. tape superfinishing is best suited for applications where there are a variety of material and sizes
• what is the difference between lapping and polishing? lapping is the process where abrasive grains are dispersed either in a paste or a fluid are applied to moving surface of an opposing formed tool so they follow a path. polishing use loose abrasive rubbet against workpiece with a pad
• in soldering and brazing explain how the joining is made from the physical point of view, how do materials stick together and what mechanisms are involved? heating the two surfaces of the base material to be joined. use of flux to remove oxides and increasing wetting. then a solder or filler material is added. it has a melting temp well below base material. the solder is melted. then diffusion takes place in between solder and base material and a diffusion zone is created
• what is wetting, and how can it be measured? why is it important? how can you ensure that good wetting will take place= wander above for soldering and adhesive joining measure by wetting angle. soldering: important to make sure that solder wets the surface and thus creates the joint by creation of the diffusion zone. wetting is also important for capillary action. good wetting typically by fluxing also removes oxides. adhesives: with good wetting the liquid adhesive will come close enough for the molecular adhesion to take place. good wetting ensured by good choice of adhesive but also by cleaning or preparing the surface before adding adh
• what is so called solder paste and what does it contain? what role does each of constituents play? also explain shortly the sequence and point out he role of the paste. what is typical application it contains tiny solder metal particles and a cleaning agens called flux. it is used to connect components to circuit boards. solder metal particles are tiny metal bits melt when heated. flux is a cleaning agent helps remove dirt
• mentioned and shortly discuss some advantages of adhesives joining compared to other joining technologies many materials and combination of materials can be joined, large area bonding, sealing and electric Insulation, low temperature process. other joining methods have higher strength
• describe how two pieces of material are joined by soldering or brazing. that is what keeps the parts toghetter? also shortly in very general terms describe the procedure for soldering/brazing in both soldering and brazing a filler material, the solder is added. it is melted and added In between the surfaces. the two surfaces have been pre heated but not melted. during the process a diffusion takes place and a diffusion zone is formed which joins the parts
• what role does the surface tension scale play? how can it be used for selection adhesives it influences how well the adhesive interacts with and adheres to the surface. you want to choose an adhesive with a surface tension what matches with the surface energy
• describe how spot welding works. include 2 process parameters in your awnser metal sheets are being fused without filler material. two geometrically opposed round shaped cu electrode tips are applied by a piece and pressure is applied over sheets. shortly after a high electric current flows through the contact area. heat is created through the resistivity in te joined and interface which melts the material in a nugget from in between the sheets. welding time and current should not be to long
• compare ordinary laser welding with raw. shortly describe the pros and cons based on the functions or principles of each process laser welding: one sided acess=design advantages. can weld on top of tape. row:simpler technology and hus cheaper than an advanced laser source. simpler fixture
• what is remote laser welding, what is the particular advantages and what is then typically compared with small weld paths are made in a circle, square or similar. the laser is action from a distance and directed by mirrors to the wanted location and the procedure is repeated until welded. advantages are redirections is very fast and thus productive. thermal energy can sped more evenly
• brazing is sometimes used in car body assembly. why I that of interest, what situation is it used for? what property or properties of brazing makes it interesting for car body assembly? brazing provides a nice fillet type geometry because the material is wetting the surfaces. it gives good appearance. laser is used with the beam not focusing directly on the target thus heating the parts surfaces.

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