AS LEVEL Section D FACT FILES Technology & Design For first teaching from September 2011 For first award in Summer 2012 Processing Unit 1.30 Processing that hasbeentreated inthisway canbeprone to twisting. outinawarmatmosphere.position to settleanddry Wood thenneedstowhile itisstillpliable. beheldinitsbent It aspossible,should beclampedinajigorformer asquickly be bent. When the steam treatment iscomplete thework beforeneed upto onehourper25mmofthickness theycan steam bendingvariesfrom timberto timber–sometimbers a temperature of100°C. The amount oftime neededfor wood placed withinitwithsaturated steam, maintaining semi–plastic andcompressible. Asteam chest(Fig. 1)treats treatment -thesupplyofheat andmoisture makesitsoft, recreated to bendsolidwood itto by heat subjecting because ofitshighmoisture content. This effectcanbe A bent twig, initsunseasoned ‘green’ state isspringy Steam-bending timber • be ableto: Aofthespecification students should Section Compulsory 1.6and1.7of additionto thosecontainedIn inparts - - - - - following processes: demonstrate andunderstanding of the knowledge - - - - - 1.30 Processing CNC router, millingandlathes. laser cutting; die cutting; steam bending; laminating; Learning Outcomes Course Content Fig. 1 Fig. 2 bent across thegrain asshown below. a low curvature. Consequently laminated timberisbest alongthegrainBending willtend to causesplittingat quite angles to thegrain flow becauseofits grain structure. only bebent significantly namely, inonedirection, rightat timber incomparison withsteam-bending. Timber can Improved precision isamajoradvantage oflaminating Laminating timber planned. must becarefullythe sameway assheetmetalblanking fit conveniently on to standard sheets to avoid waste, injust use iteconomically. that thedesigned shapes isimportant It consider carefully whichisthebestchoice, andbesure to mm indicates across-grained board. The designer should x 1220mmindicates board anormal and1220 x2440 dimension gives thestrength alongthegrain –i.e. 2440 be remembered whenordering that plywood thefirst back veneers toshould lyingperpendicular thebend. It also possibleto withthegrain bendplywood infront and grain inalternate layers to perpendicular oneanother. is It then itispossibleto laminate sheetmaterial withthe strengthIf isrequired bothalongandacross thegrain, taken into account by thedesigner. ofthecompleted lamination,properties and thismustbe This will, ofcourse, leadto agreat difference inthestrength 1 Unit 1.30 Processing Fig. 4 means ofascrew (Fig. 4). follows theshapeofformer andpressure isexertedby flexible bandinplace ofonethe formers. The band you want thecurve to makeissuitable,If you canusea Fig. 3 bend to the shapeofthejigand ‘set’ together. of aformer orajigusingcramp pressure (Fig. 3). The layers Aerolite306) andare sandwichedbetween thewaxed faces The layers are gluedtogether withastrong adhesive (e.g. grain).has interlocking followingsame direction, (unlikeplywood, which thecurve assembled sothat thegrain ofeachlayer isrunninginthe veneers,constructional orsaw cutsstrips. They are (‘lamina’). The layers may bethinveneers, thicker This involves form withlayers buildingupthecurved A more accurate methodofshapingwood islaminating. Fig. 5 together. atmospheric pressure onthelaminaandpresses them acts usingavacuum pump.the airextracted The consequent into abag.which isinserted The bagisthensealed and to aformer andplaced onto aprepared baseboard, withthinlamina. small curves The gluedlayers are taped press (Fig. 5). This technique ismostusefulfor forming Another methodofapplyingpressure isby using abag gluing. while thenetsleave themachineandare stackedready for form pushthewaste away onto aconveyor beltfor disposal stage to oftheirwaste. bestripped pinsonthedie- Ejector matrix strips. Once cut, thesheetsare pulledto thenext creasing rulespushthecard into thegroove formed by the cutting rulescutrightthrough the cartonboard, the hardpushing thecartonboard againsttherulers. The below thedie-form. The platen isthenforced upwards, satisfied, eachprinted sheetis fed onto aplaten, directly sheet iscutandadjustments made. andcorrections Once ismounted onthemachine,After thedie-form atest appropriate printingprocess, suchasoffset lithography. guillotine. isthenprintedThe usingthe cartonboard sheets for thejobare andcutto size selected onapower isbeingmadethecartonboard While thedie-form CuttingDie strength andadvantages oflow cost. ofgoodglossand of printed dueto products itsproperties provides awiderange ofusesacross thewholespectrum through aheating wedge underhighpressure. Lamination polypropylene (PP)filmthat is glued to the paperasitis fed ofpaperandboard. Commercialsurface laminating usesa Laminating appliesatransparent plasticfilm to the Paper andBoard Laminating asaFinishing Process for 2 Unit 1.30 Processing • • • • Advantages oflasercuttingover mechanicalcutting: • • ways: theprintingindustry,In lasersare usedinthefollowing material. powered pulsedlaserbeamthat slowly makesaholeinthe is madebefore cut. Piercing every usuallyinvolves ahigh- cuttingfrom somewhere otherthantheedge,start apierce cuts throughorder theaxisofbeam.In to beableto (equivalent to themill)enters form thesideofsheetand machine would for insheetmaterials. working The laser Lasercutters usuallywork muchlikeamilling sheet acrylic. signage,is idealfor manufacturing for example, from surface. leaving anedgewithahigh-quality This process The lasereithermelts, burns, orvaporisesaway thematerial controlleddirectly by computer system. usingaCAD/CAM eliminates theneedfor expensive tooling asthelaseris also It be problematic oreven impossibleto die-cut. to producemanufacturing features would that otherwise laser to cut materials, andisusuallyusedinindustrial Laser cuttingisatechnology that usesahighpowered cuttingandEngravingLaser decorationSurface usingCAD/CAM CuttingLaser impossible to cutby more traditional means. materialsSome orfeatures difficultor are very cut, aslasersystems have asmallheat affected zone Reduced chance ofwarpingthematerial that isbeing computer controlled Precision, asthere isnowear on thelaseranditis clean edge Lack ofphysical withthematerial contact produces a colour reproduction. steep, smoothedgesto give ahighstandard ofprocess dioxide laserheadto form relief sharp imageswith usingahigh-powerprinting plates carbon andcylinders laserengravingDirect offlexographic and gravure fromdirectly digital data. unwanted material andform negative printingplate dioxideusing carbon laserimaging headto away burn laserimaging oflithographicDirect printingplates Fig. 6 • • Disadvantages include: industry cutswithan intense beamoflight. industry Laser cutters Co2 LaserSystems only usedinschools. In contouring operationsLathes for andcylindrical allturning contours profiles. aninternal and external versatile machinetools ableto produce themostcomplex centresMilling This classification includessomeofthemost grooves andprofiles Routers andengravers for producing light normally work, Types ofCNCmachines program andthemachinetool. is neededto ensure thecompatibility between theCAD transmitted to themachine. additionalsoftware Sometimes can beusedto generate coded information that canbe mathematically by thesoftware. This meansthat they based uponlinesandpoints that are linkedto eachother ProDESKTOP orSolidWorks. Vector baseddrawings are whether theseare suchas parametric drawing packages scale. isusedto create Software vector baseddrawings, areThe ofCAD/CAM principles thesameirrespective ofthe (CNC). process –computermanufacturing control numerical by acomputer that guidesthemachinethrough an entire machines andlasercutters. These machinesare controlled machines, butthemostcommon are lathes, routers, milling system products. into CAMcaninvolve actual arange of converts drawings that have beenproduced usingaCAD Computer-aided (CAM) manufacture isaprocess that CNC router, millingmachinesandlathes High energy consumptionHigh required to power lasers. Very expensive machinery 3 Unit 1.30 Processing Fig. 7 of thework and–Zwillmakeitshorter. thatdirection cuts. For example –X willreduce thediameter When asolidbaronthelathe turning –indicates the between the2axes +and-. XandZthedirections On thelathe theotheraxisisX.Fig.7 shows therelationship machine thisisthetool. thecaseofalathe,In andonamilling thisistheworkpiece ‘Y’ and ‘Z’. The Zaxisistheofmachinethat rotates. defined by aletter anda+or–sign. The letters usedare‘X’, a lathe orthework onamillingmachinetakesplace is of both. The inwhichmovement direction ofthetool on cutting tool, ormostcommonly through acombination CNC machinescutby moving eitherthework piece orthe tools. between two points’ andiscommon to allCNCmachine the coolant. For example, code G01means, ‘straight line stopping on andturning suchasstarting, other functions the movement ofthework. ‘M’ codes are concerned with with themovement ofthetool, andonamillingmachine, appear as ‘G’ and ‘M’ codes. Onalathe the ‘G’ codes are to do developed to machiningoperations. describe The codes tools aninternational system ofstandard codes hasbeen orderIn to helpbothusersandsuppliersofmachine Programming CNCMachines Fig. 9 Fig. 8 Fig. 10 CNC millingmachine other liketheaxes ofa graph. axes are themovements ofthe table at rightanglesto each regarded asanadditionalaxisdefined ‘W’.) The Xand Y movement isthetablerather thanthetool, thenthisis up.just beaplungedown andalift theupanddown (If programming andhasto beadjusted by handoritmay on mostsmallmachinesthisisnotcontrolled by the The Zaxisistheoneparallel to therotation ofthetool, Fig. 10shows thethree axes millingmachine. ofavertical 4 Unit 1.30 Processing Table 1Computer-aided machining Fig. 12 CNC router Fig. 11 Fig. 13 Laser cuttersLaser machines Milling Routers Lathes CNC machine Materials cut • • • • • • • Card Wood Plastic Metals Foam Wood Metals

Applications • • • • • • • • • Can cutbothsimple andcomplex shapes Material does not require clamping Cuts withintense beam oflight work to fine tolerances industry In Produce shapes flat and complex curved Can cut2Dand3Dshapes Used for blockmodelling Similar to materials millingmachinebutusingsofter produce onhandoperated lathes Produce accurate andcomplex shapesthat would bedifficult to Fig. 15 Fig. 14 CNC laser 5 Unit 1.30 Processing 4. 3. 2. 1. flexible. reliable and, becausetheycanbereprogrammed, are very theyproduceproducts are consistently accurate. They are day withlittlehumanintervention. They ensure that the considerable. The machinesare ableto work 24hoursa made andthesystem isprogrammed theadvantages are up CAMsystems canbehigh,butonce theinitialcosts are There are many advantages to CAM. The cost ofsetting suitable. giving your answers infull, why your material is selected a school Technology State, andDesign department. a smallCNCmillingmachinethat might befound in Name amaterial that issuitablefor machiningwith tools. compared ofmachine by othertypes to manufacturing disadvantages by ofmanufacture aCNCmachine ofoperation.its principle Explaintheadvantages and Explain what theinitialsCNCstandfor anddescribe (b) (a) desired curve. glued andclampedaround aformer to produce the of laminated ofbeechthat strips have beensteamed, The chairare rockers rocking to ofamodern bemade (b) (a) manufacturing thetwo rockers inthisway?manufacturing What problems would you bewatching for in Why islamination agoodchoice for chairrockers? place easily? How doesthesteaming enablethebendingto take predetermined curve? steaming timberinorder that itcanbebent to a What are theadvantages anddisadvantages of Revision questions 6