Fusion, Friction, & RF Welding
Shawn Andres, James Szymanowski, & Dario Kis
PLET 370
Purpose To familiarize the class on the joining of
composite plastic parts
Specifically fusion, friction, and RF welding
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
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
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
Generalities - Influence of Additives/Fillers Can add or detract w/ respect to weldability
Glass fillers Colorants/Lubricants Talc filled
Generalities - Methods of Heat Application Gas Electric Gun Heated Tool Induction Heating Friction (spinning)
RF Welding (sealing) Introduction Also known as
Dielectric welding High Frequency Welding
Definition Process of fusing materials together by applying radio
frequency energy
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
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
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
RF Welding Equipment Equipment
Machined brass die RF machine (Platen)
Mech NRG to vibration NRG converter Horn Stand Programmer
Pictures of RF Welding Machines
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
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
Example Materials Used in RF Welding PVC PU PE Acrylic Polychlorotriflouroethylene Others
RF Welding Examples of Common Applications Where fluid-proof seal is necessary
Medical industry Health care industry Industrial applications Consumer products
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
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)
Fusion Welding Advantages & Disadvantages Advantages
Welds stronger than parent components Simple joints
Disadvantages Butt joints Only used for pipes
Fusion Welding Basic Operation Procedure
Initial heating Pressing
Video http://www.mcelroymfg.com/fusion/flash/fusion101.html
Fusion Welding Equipment Used Equipment
Welder Warming Collar Clamping/Holding Equipment
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
Fusion Welding Examples
Fusion Welding Conclusion Used for joining pipe
Clear weld areas
Warming time
Warming surface depth
Joining time (pressure application)
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
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
Friction Welding Basic Operation Procedure
Component rotation Pressure Contact Heat Production Concluded by Forge Force
Friction Welding Equipment
•Equipment–Standard shop equipment–Lathes–Drill presses
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
Friction Welding Considerations Cont. – Weld Quality Factors Joint geometry most important
Surface velocity
Contact Pressure
Coefficient of Friction
Heat transfer capacity of material(s)
Friction Welding Examples Floats Aerosol bottles Joining studs to plastic parts
Automotive Electronics Furniture Toy Appliance Industries
Friction Welding Conclusion Flashing may occur
Must be circular weld joints
Good weld strength
No air entrance
Inexpensive tooling
Extra Info - Other Methods of Welding Plastics Sheet Hot air/gas Track Speed Tractor/Machine Linear Vibration Induction/Electromagnetic
Extra Info - Weld Testing Importance of joint strength
Factors that affect joint strength
Test Methods/Tools/Ops
Questions???