docAdhesive studs based on radiation curing adhesives
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Adhesive studs based on radiation curing adhesives
Adhesive studs based on radiation curing adhesives Dipl.Wirt.-Ing. Franz Drüke Böllhoff Verbindungstechnik GmbH Prof. Dr.-Ing. Gerson Meschut Dipl.-Ing. Sebastian Süllentrop Laboratorium für Werkstoff- und Fügetechnik Fügen im Karosseriebau Bad Nauheim 25.04.2012 Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut n Introduction n Radiation curing n Adhesive studs n Technology and application n Variety of products Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Technical environment Increasing shift of complex assemblies in the pre-assembly operations Trend towards modularisation Need for a flexible method for mounting of modules on the overall structure Use of functional elements Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 3 Motivation and challenge for adhesive studs Drawn arc stud welding is the standard technique for punctual mounting elements allowing high automation and low process-times The development of adhesive fasteners is motivated by special requirements: n n n n High demands on the visual apperance of the joining partners Special material properties of the joining partners Flexibility of the joining technique Process requirements The economic efficiency of adhesive studs depends on the process engineering and production process n Very fast process required n To replace previously used techniques, the same level of automation should be reached Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 4 n Introduction n Radiation curing n Adhesive studs n Technology and application n Variety of products Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Basics of photoinitiated adhesives A distinction is made between radical curing adhesives (light curing) and cationic curing adhesives (light activation) Photoinitiated curing Light- and UV- curing adhesives Light-activated adhesives Chemical Base Chemical Base Acrylate or modified acrylates - Urethanacrylates - Epoxideacrylates - Siliconacrylates Epoxide Epoxidefunctional Prepolymers Cycloaliphatic Epoxides Focus of the presentation and application: light- and UV-curing adhesives Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 6 Light- and UV-curing adhesives Principle n Adhesive is cured by irradiation with UV - light or visible light Chemical reaction: Radical polymerisation n Photoinitiator generates a radical by irradiation n Radical reacts with the C-C double bonds of acrylic resins n Chain reaction results from the reaction with further double bonds ! ! ! .+C R C R C C . . R Curing takes place only where the radiation can reach the adhesive layer Reaction rate depends on the reactivity of the adhesive and radiation intensity Reaction just proceeds as long as the adhesive is irradiated Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 7 Technical basics Electromagnetic spectrum n Wavelength range of light must be adjusted to the photoinitiators Absorption spectrum of the photoinitiators should be within the emission spectrum of the light source Source: DELO Industrieklebstoffe Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 8 n Introduction n Radiation curing n Adhesive studs n Technology and application n Variety of products Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Process Dosing n Applying the one-component, light-curing Acrylate adhesive DELO PHOTOBOND Positioning n Positioning of the stud on the surface n At least one partner must be transparent, allowing the light to reach the whole adhesive layer Curing n Illuminate the adhesive until the curing is completed (< 10 seconds) Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 10 Stud Onsert® threaded stud n M5 steel stud n Transparent base made of PC (Ø 25 mm) n Thread height: 18 mm Steel n Total height: 23 mm n Adhesive layer is set via spacers to approx. 0.15 mm PC n Effective adhesive area: approx. 478 mm² n Weight: approx. 7 g Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 11 Conditions of illumination Illumination n 10 LEDs arranged in a ring n Adjusted to the stud base LED Stud base n Wavelength range: 395 ~ 410 nm Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 12 n Introduction n Radiation curing n Adhesive studs n Technology and application n Variety of products Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Mechanical properties Onsert stud M5 n n n n n n n FA Material Surface Adhesive Thickness of bond line Light source Exposure time Lamp distance Steel KTL PB AD494 0,2 mm DELOLUX 80 12 sec 32 mm Strength limit often defined by the failure of the element sample 1 2 3 4 average value FA [kN] 1,70 1,80 1,30 1,80 1,65 M L [Nm] 8,60 7,90 8,20 9,20 8,48 ML deviation F A [kN] + 0,15 0,35 deviation M L [kN] + 0,73 0,57 Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 14 Mechanical properties Onsert stid M5 Aging test according to VDA n n n n n Element Adhesive Thickness of bond line Light source Exposure time Stud bolt (PC) PB AD487 0,2 mm DELOLUX 04 4 sec ü no decline of joint strength after 4 weeks storage Storage in Skydrol (hydraulic liquid for aerospace industry) n n n n n Element Adhesive Thickness of bond line Light source Exposure time Retainer (PPSU) PB AD492 0,1 mm DELOLUX 03 S 180 sec ü no significant decline of joint strength after 1.000 h Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 15 Motivation for bonding of functional joining elements Material properties of joining partners implicate special requirements on the joining process n High tensile steel n Thin metal sheets à often no thermal processes wanted, heat input in joining zone à usage of mechanical joining limited by material strength à thermal processes for thin sheets can be complex à usage of mechanical joining processes though punctual load application often not appropriate Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 16 Motivation for bonding of functional joining elements n Reinforced plastics n Prepared surfaces à thermal processes often not appropriate à mechanical joining processes often not appropriate (mostly not deformable) à blind riveting due to madotary holes / expensive and often not appropriate (damage of fibre structure) à thermal processes not appropriate à solvable connections only feasible with high effort (Coated, polishes, etc.) n Glass Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 17 Motivation for bonding of functional joining elements High optical requirements on joining partners Mounting of tubes in injection molded parts often leads to blowholes and shape distortion (inserts, direct Screw coupling): à Shrink marks, shape distortion, blowholes vs. increasing cycle times Einfallstellen distortion sink marks shrinking hole Lunker Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 18 Motivation for bonding of functional joining elements High optical requirements on joining partners Connection points on cover parts / face plates made of iron sheets à optical damage on visible face and joining site n Thermal processes n Riveting n Blind riveting à à à discoloration, deformation mechanical stress on both sides bore hole necessary Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 19 Fields of applications Aerospace n Connection of joint points on lightweight structures (sandwich materials, CFRP, aluminum) n Easy handling due to optimised and flexible processing devices n Easily controllable/reproducible process Automotive industry n n n n Bodyshell, car structures Mounting of coverings Connection of fixing points after cathodic dip coating Alternative to welding elements on materials which are not suitable for thermal joining and very thin-walled components n Independent from previous processes and flexible in use n Easy repair solutions Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 20 n Introduction n Radiation curing n Adhesive studs n Technology and application n Variety of products Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Onsert® joining elements All demanded geometries are thinkable, which are feasible by injection molding. The elements function covers a wide range of possible applications. n Screw coupling in plastic formed part n Removable and permanent snap-joint Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 22 Onsert® joining elements n SnapLoc® elements for bonding n Stand-offs for aerospace Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut 23 Thank you! Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut Laboratorium für Werkstoff- und Fügetechnik Universität Paderborn Prof. Dr.-Ing. Gerson Meschut
