1. Fusion, Friction, & RF Welding Shawn Andres, James Szymanowski, & Dario Kis PLET 370

2. Purpose • To familiarize the class on the joining of composite plastic parts • Specifically fusion, friction, and RF welding

3. Presentation Outline • Plastics Welding Generalities • RF Welding • Introduction • Theory and Background • ADV/DISADV • Basic Operation • Procedure • Equipment Used • Design Requirements • Examples • Conclusion • Fusion Welding (same) • Friction Welding (same) • Extra Info

4. Plastics Welding Generalities • Definition: • Uniting parts by joining their heated surfaces and allowing them to flow together • Welding terminology • Thermowelding • Heat sealing • Dielectric heating • Cannot be used on thermosets • Best for semicrystalline materials with good heat stability • Different than adhesion bonding

5. Welding Generalities Cont. • Importance when combining plastic components over • Molded in components • Simple assembly • Material Compatibility Issues • Melt Temperature/Degradation • Mechanical Properties • Melt Strength • Others

6. Generalities - Influence of Additives/Fillers • Can add or detract w/ respect to weldability • Glass fillers • Colorants/Lubricants • Talc filled

7. Generalities - Methods of Heat Application • Gas • Electric Gun • Heated Tool • Induction Heating • Friction (spinning)

8. RF Welding (sealing) Introduction • Also known as • Dielectric welding • High Frequency Welding • Definition • Process of fusing materials together by applying radio frequency energy

9. RF Welding Theory & Background • History • WWI and WWII detecting underwater subs with radio waves • 1963 First application to rigid thermoplastics • First application • Joining film in the 1950’s • 1963 Applied to rigid thermoplastics

10. RF Welding Advantages/Disadvantages • Advantages • Only heated during RF generation • RF tooling is usually run “cold” • Clean, fast welds • Economical • Resultant joint strength = parent material(s) • Disadvantages • Joint design • Application contingencies • Material-to-material differences

11. RF Welding Basic Operation & Process • Process • High frequency emission • Alternating current switches polarity • Causes back and forth molecular movement • In turn causes localized heating/bonding

12. RF Welding Equipment • Equipment • Machined brass die • RF machine (Platen) • Mech NRG to vibration NRG converter • Horn • Stand • Programmer

13. Pictures of RF Welding Machines

14. RF Welding Design Requirements - Material Characteristics • Melt Temperature • Similar between materials • Ex) PE cannot go with PS • Modulus of Elasticity • More rigid, easier to weld • Low modulus mat’ls (PP & PE) can be welded, need proper horn positioning

15. RF Welding Design Requirements - Material Characteristics Cont. • Impact resistance of composite part • Strong weld necessary • Coefficient of friction • Similar and higher is better • Thermal conductivity • Similar and high or low depending on wall thickness

16. Example Materials Used in RF Welding • PVC • PU • PE • Acrylic • Polychlorotriflouroethylene • Others

17. RF Welding Examples of Common Applications • Where fluid-proof seal is necessary • Medical industry • Health care industry • Industrial applications • Consumer products

18. RF Welding Conclusion • Polar and non-polar plastics can be joined w/ special equipment • Materials as thin as .00025 in w/ special equipment • Economical • Fast

19. Fusion Welding Introduction • Definition • Portions of the parts to be joined are heated to softening and pressed together • Types • Plate Bonding • Butt Welding (Uniform bead) • Electrofusion (Coupler)

20. Fusion Welding Advantages & Disadvantages • Advantages • Welds stronger than parent components • Simple joints • Disadvantages • Butt joints • Only used for pipes

21. Fusion Welding Basic Operation • Procedure • Initial heating • Pressing • Video • http://www.mcelroymfg.com/fusion/flash/fusion101.html

22. Fusion Welding Equipment Used • Equipment • Welder • Warming Collar • Clamping/Holding Equipment

23. Fusion Welding Design Requirement Pictures • Correct Welding • Incorrect Welding • Considerations during Fusion welding • Localization of heat at selected area (deformation of other areas) • Use materials with wide melting range

24. Fusion Welding Examples

25. Fusion Welding Conclusion • Used for joining pipe • Clear weld areas • Warming time • Warming surface depth • Joining time (pressure application)

26. Friction (Spin) Welding Introduction/ Theory and Background • Definition • Heat required to soften and fuse two materials achieved by friction generated from two materials moving while in contact • Component-to-component similarities • Mechanical properties • Physical properties • Geometry • First application – sealing water filled compasses

27. Friction Welding Advantages & Disadvatages • Advantages • Oxygen is excluded from the joint (direct contact) • Weld strength=parent material • Good appearance • Disadvatages • Configuration limited to circular parts • Flashing

28. Friction Welding Basic Operation • Procedure • Component rotation • Pressure Contact • Heat Production • Concluded by Forge Force

29. Friction Welding Equipment • Equipment • Standard shop equipment • Lathes • Drill presses

30. Friction Welding Design Requirements/Considerations • Smooth surfaces • Low melting temps. • Surfaces are free of contamination • Large surfaces are difficult to weld • Circular areas can be molded in

31. Friction Welding Considerations Cont. – Weld Quality Factors • Joint geometry most important • Surface velocity • Contact Pressure • Coefficient of Friction • Heat transfer capacity of material(s)

32. Friction Welding Examples • Floats • Aerosol bottles • Joining studs to plastic parts • Automotive • Electronics • Furniture • Toy • Appliance Industries

33. Friction Welding Conclusion • Flashing may occur • Must be circular weld joints • Good weld strength • No air entrance • Inexpensive tooling

34. Extra Info - Other Methods of Welding Plastics • Sheet • Hot air/gas • Track • Speed • Tractor/Machine • Linear Vibration • Induction/Electromagnetic

35. Extra Info - Weld Testing • Importance of joint strength • Factors that affect joint strength • Test Methods/Tools/Ops

36. Questions???