?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F297%2F&rft.title=Laser+drilling&rft.creator=%3D%2C+%3D&rft.subject=Materials&rft.description=Since+the+first+demonstrations+of+the+ruby+laser+in+1960%2C+the+laser+quickly+took+an+important+place+in+various+domains+of+industry.+This+is+mainly+because+of+its+concentrated+and+contactless+energy+supply.+This+has+led+to+many+applications+in+the+domain+of+laser+materials+processing.+The+most+important+applications+in+this+domain+are+cutting%2C+welding+and+marking.+Laser+drilling%2C+the+topic+of+this+article%2C+is+a+niche+application.%0D%0A%0D%0ALaser+percussion+drilling+(drilling+by+multiple+shots)+is+for+instance+used+in+the+process+of+gas+turbine+manufacturing%2C+because+of+the+fact+that+the+components+to+be+drilled+are+made+of+superalloys+which+are+very+hard+to+machine+by+conventional+techniques.+To+fix+ideas%2C+the+typical+hole+diameter%2C+hole+depth+and+pulse+length+are+0.5+%3A+1.0+mm%2C+3+%3A+10+mm+and+1.0+ms%2C+respectively.+Laser+percussion+drilling+is+favoured+over+alternative+drilling+processes+like+spark+erosion+drilling+and+laser+trepanning+drilling+because+it+is+by+far+the+fastest+process.However%2C+it+suffers+of+problems+with+the+quality+of+the+hole.+The+main+quality+aspects+are%3A%0D%0A%0D%0A-+Tapering+(Decrease+of+hole+diameter+with+depth)%0D%0A-+Recast+layer+(Re-solidified+material+at+wall+of+hole)%0D%0A-+Bellow+shape+(Local+increase+of+hole+diameter)%0D%0A%0D%0AThe+laser+drilling+process+depends+on+the+material+properties+and+on+the+laser+beam+characteristics%3A+wavelength+and+intensity+as+a+function+of+space+and+time.%0D%0A%0D%0AThe+main+goal+of+the+research+being+started+at+the+study+group+is+to+come+up+with+a+simulation+model+based+on+a+mathematical+model+which+includes+all+relevant+physical+features.+This+model+is+needed+to+get+a+better+understanding+of+the+process+and+to+be+able+to+select+proper+settings+of+the+process+parameters.+Once+well+validated%2C+this+model+will+be+used+to+define+the+specification+of+the+ideal+laser+used+for+drilling.+The+major+problem+will+be+to+handle+the+different+phases+and+in+particular+the+modelling+of+the+interaction+of+the+beam+with+the+vapour+phase.&rft.date=1998&rft.type=Study+Group+Report&rft.type=NonPeerReviewed&rft.format=application%2Fpostscript&rft.language=en&rft.identifier=http%3A%2F%2Fmiis.maths.ox.ac.uk%2Fmiis%2F297%2F1%2Fverhoeven.ps&rft.identifier=++%3D%2C+%3D++(1998)+Laser+drilling.++%5BStudy+Group+Report%5D+++++