LPKF WeldingQuipment GmbH. Michel Kist Sales Manager. Design guideline s for laser plastic welding Sales Training 2018

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Andra Edwards
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1 LPKF WeldingQuipment GmbH Michel Kist Sales Manager Design guideline s for laser plastic welding Sales Training 2018

2 Agenda General design requirements General design requirements hybrid welding LPKF Laser & Electronics AG 2

3 General Design laser beam laser absorbing part laser transparent part clamping force clamping force Press fit (preferred) or Angled surface LPKF Laser & Electronics AG 3

0,02-0,05 mm welding distance + distance during cooling phase = total welding distance/collapse total welding

4 3 2 1 General Design laser transparent (LT) laser absorbing (LA) 1 R 0,1 0,5 1 laser beam welding distance/collapse: 0,2 0,3 mm distance (holding time) during the cooling phase: approx. 0,02-0,05 mm welding distance + distance during cooling phase = total welding distance/collapse total welding distance approx. 0,22-0,35 mm min. 1 mm all around for clamp device space for weld flash LT LA after the welding process LPKF Laser & Electronics AG 4

5 General Design shadowing laser beam laser transparent part design modification no shadowing reasons for shadowing geometry of the laser beam angle of the scanning unit parts clamp device solutions changes at parts design use another lens (bigger working distance -> smaller angle of the laser beam -> less shadowing) tele centrical lens (laser beam always vertical) tool with mirrors laser absorbing part shadowing depends on optic configuration beam diameter LPKF Laser & Electronics AG 5

6 General Design transparent part A circumferential same thickness thickness approx. 0,5 3 mm max. thickness depends on the transmission and material min. thickness depends on clamp device, the forces applied through the clamping pressure must be transmitted into the part (stiffness, deforming) A = ~ B absorbing part / welding rib B circumferential same thickness width of the welding rib approx. 0,5 2 mm max. thickness depends on beam diameter min. thickness depends on stability (stiffness, deforming) B = ~ A A B laser beam transparent part absorbing part LPKF Laser & Electronics AG 6

so big, that the whole weld flash can be placed left or right of the welding rib

7 General Design laser transparent part welding area space for weld flash laser absorbing part enough space for weld flash necessary space for weld flash should be so big, that the whole weld flash can be placed left or right of the welding rib the volume of the weld flash depends on the welding distance LPKF Laser & Electronics AG 7

exactly in the middle on the welding rib for repeatable alignment -> pins for

8 General Design Positioning of the transparent part laser transparent part welding area welding rib the positioning of the transparent part should be done exactly in the middle on the welding rib for repeatable alignment -> pins for centering material: black laser transparent pins for centering LPKF Laser & Electronics AG 8

9 General Design Injection Point disadvantageous position for injection point good position for injection point low transmission at the injection point injection point not in the welding area injection point in the middle of the cover and far away from the welding area LPKF Laser & Electronics AG 9

10 General Design Absorbing part welding rib top view on the welding rib geometry requirements welding rib as possible big radius in the contour as possible in one level circumferential same size and width tolerance of the flatness ± 0,1 mm housing has to be fixed under the welding rib surface finish in the welding area: R Z 1,6 molding: no ejector and parting plane in the welding area wrong correct LPKF Laser & Electronics AG 10

11 General Design Transparent part geometry requirements transparent part circumferential same thickness in the welding area molding: no ejector and parting plane in the welding area molding: injection point in the middle of the cover and not in the welding area as possible high stiffness by using ribs cover design so, that the cover will stay in the correct position when handling the part surface finish in the welding area: R Z 1,6 LPKF Laser & Electronics AG 11

12 General Design Materials, Molding, Others no use of recycled material constant transmission of the laser transparent part is very important constant absorption of the laser absorbing part is very important no use of releasing agent in the molding tool (some releasing agent have a negative influence on the process) no use of silicone or fat, if necessary they have to be tested no binding line in the welding area parts filled with pottant: no pottant on the welding rib not too much pottant in the housing -> this can have an influence on the welding distance movement LPKF Laser & Electronics AG 12

13 Agenda General design requirements General design requirements hybrid welding LPKF Laser & Electronics AG 13

14 General Design For Hybrid Welding transparent part Typical thickness A: 1 mm 3 mm - max. thickness depends on the transmission properties - min. thickness depends on clamp device (stiffness, deforming) Optimal: circumferential same thickness absorbing part - Due to tolerances of the lens, rib is on the absorbing partner not on the lens! Width of the welding rib B: 1 mm 3 mm Height of welding rib C: 0,5 mm 1 mm D = B + 1 mm Circumferential same size of welding rib laser beam A C laser transparent part laser absorbing part B D LPKF Laser & Electronics AG 14

contour Housing is fix because of centering units and fixture Lens is movable, contour wouldn

15 General Design For Hybrid Welding Bad design Good design Laser beam Laser beam Welding rib on lens Welding rib on housing Welding rib must be on the housing side due to position of the contour Housing is fix because of centering units and fixture Lens is movable, contour wouldn t be on the rib Due to the mold, more tolerances on the lens side. LPKF Laser & Electronics AG 15

16 General Design For Hybrid Welding A. Dimensions of radius R 1 and R 2 should be as high as possible. R 2 also can be small R1 minimum = 5 mm B. Undercut to support the housing For welding process needed high pressure can move the parts in other positions or deform them. Therefore undercuts will help to keep the part in right position. R 2 tool / support welding rib laser absorbing part R 1 LPKF Laser & Electronics AG 16

General Design For Hybrid Welding To realize a contact between the rib and the housing there should be a additional rib in the corners at the lens side.

17 General Design For Hybrid Welding To realize a contact between the rib and the housing there should be a additional rib in the corners at the lens side. Other than that, you will have no or too less contact between the lens and the housing as shown in the drawing underneath. No contact = no good welding gap LPKF Laser & Electronics AG 17

General Design For Hybrid Welding Accessibility for the

reasons for shadowing geometry of the laser beam parts

modify position or design of clamp device modify

18 General Design For Hybrid Welding Accessibility for the laser and the roller is important for welding good parts. reasons for shadowing geometry of the laser beam parts clamp device hard stops solutions modify design of parts modify position or design of clamp device modify position or design of hard stops LPKF Laser & Electronics AG 18

19 General Design For Hybrid Welding LPKF Laser & Electronics AG 19

20 General Design For Hybrid Welding To avoid that the housing is buckling => stiffening rib housing is exposed to much heat => not stiff enough LPKF Laser & Electronics AG 20

21 General Design For Hybrid Welding Reference side for having a fix block. The biggest lens should fit on the smallest housing and the smallest lens should fit to the biggest housing Lens to big Important: reference side side where tolerances can flow out (opposite side) Advantage: Tolerances can be compensated Better conditions for mould process stability LPKF Laser & Electronics AG 21

22 General Design For Hybrid Welding Old design: Not possible to weld with the roller due to the shapes Therefore: redesign of the contour LPKF proposal Old Design Radius min 5mm Enough space for roller (min 10mm) LPKF Laser & Electronics AG 22

23 General Design For Hybrid Welding Also such shapes must be in 10 mm for access of the robot. The design of the screw of the roller can be different. If there is a need because of the design of the lens, the screw can be smaller. screw Radius min 5mm Enough space for roller (min 10mm) LPKF Laser & Electronics AG 23

24 General Design For Hybrid Welding The area where the roller should move, has to be min. 10 mm. Due to the roller, there must be a min. distance for applying the pressure properly. bad good 10 mm LPKF Laser & Electronics AG 24

25 Fixture Design Swing clamping units Clamping units have to lift for passage of welding head to avoid shadowing Fixture LPKF Laser & Electronics AG 25

26 Fixture Design No shadowing of the laser beam => permanent clamping possible clamping units clamping rim in housing necessary! Fixture LPKF Laser & Electronics AG 26

27 General requirements to the assembly Process variant chosen? Material weld able? Laser absorbing part is actually absorbing? Laser transparent part is actually transparent? Is the accessibility of the laser beam given? Positioning between the two parts given? Is collapse distance considered, if necessary? Is there space for the melt flash? Is the melt flash covered? LPKF Laser & Electronics AG 27

Thank you for your attention! LPKF WeldingQuipment GmbH www.lpkf-laserwelding.com Alfred-Nobel-Str.

28 Thank you for your attention! LPKF WeldingQuipment GmbH Alfred-Nobel-Str Fürth Tel: , Fax: Mail:

GUIDELINE LASERWELDING OF PLASTICS. Evosys Laser GmbH, Schallershofer Straße 108, Erlangen

GUIDELINE LASERWELDING OF PLASTICS Evosys Laser GmbH, Schallershofer Straße 108, 91056 Erlangen Content 1. Foreword 2. Procedural principle 3. The process variants 3.1 Contour welding 3.2 Quasi-simultaneous