How does laser plastic welding stack-up to the competition? A breakdown and comparison of the laser plastic welding process and other plastic joining methods.

1. Plastic Joining: Process Comparison
How Laser Plastic Welding Stacks Up to the Competition
• Short cycle times
Introduction • Low total cost of ownership – few failed parts,
Laser plastic welding is well suited to work with most any minimal system maintenance and no consumable
plastic joining need. However, each joining method has required in process.
its own set of advantages and disadvantages. This paper
Disadvantages
will walk you through the pros and cons of each method,
to help you determine which process is best for your • Initial capital investment – although systems have
application. become much more affordable they tend to cost
more than systems from competing methods.
Laser Plastic Welding • Tight part tolerances – process is not forgiving to
poorly molded pieces.
This process involves passing laser radiation through an
• Special plastics characteristics required – due to the
upper laser transmissive layer where it is then absorbed
at the surface of a lower absorptive layer, creating heat nature of the process plastics must have certain
and a weld under clamping pressure. laser transmissive/absorptive properties (see LPKF’s
Design Guidelines Document for more information).
Advantages
• Flexible – capable of welding complex, intricate, Applications and Industries
large and 3D part geometries. • Automotive – sensor housings, tail lights and
• Process monitoring – multiple, sophisticated online manifolds.
process monitoring techniques allow for excellent • Medical – microfluidic devices and catheters
quality control and fewer bad parts. • Consumer electronics – electric shaver face plate,
• Minimal part stress – well suited for sensitive make-up application brushes and digital display
applications. covers.
Ultrasonic Welding
Internal friction induced by ultrasonic oscillation melts
the boundary surfaces of the joining partners. Fusion of
the parts is reached by applying a certain pressure.

2. LPKF Laser & Electronics 2011
Advantages Parts are rubbed together, the friction created from this
• Very short cycle times – cycle times often under 5 process generates heat at the contacting surfaces where
seconds the plastic becomes molten and weldable.
• Limited 3D contours – joints do not have to be Advantages
completely flat • Cost – friction welding is an inexpensive process and
• Low maintenance costs the systems are priced competitively.
• Low maintenance – low maintenance means
Disadvantages
minimal downtown and cost savings.
• Flash– flash or excess melted plastic will likely
• Low cycle times
protrude from joint.
• High mechanical load – resonance frequencies will Disadvantages
exist throughout the entire part and can potentially • Flash – large amount of flash generated, also dust-
effect/damage the part outside of weld zone. like particulates.
• Particulate development – dust-like particles left • High mechanical load – resonance frequencies will
behind that may cause part contamination exist throughout the entire part and can potentially
effect/damage the part outside of weld zone.
Notable Applications
• Limited design freedom – only two-dimensional
• Mobile phone housings, bumper reinforcements and
contours possible.
intake manifolds.
• Large weld line width – greater than 10mm in some
Hot Plate Welding cases.
Joining partners are heated at joint by putting them in Notable Applications
contact with a heated metal plate. Once molten the plate • Manifolds, housings, bumper reinforcements, pipes
is removed and the pieces are fused under compression. and large profiles.
Advantages
High Frequency Welding
• Cost – hot plate welding is a very inexpensive
process as it requires no consumables, low Oscillation of polar molecules is induced by an electrical
equipment costs and part size is a non-issue. field alternating with high frequency, which results in
• Handheld devices are possible – less complex heating of the polymer.
applications can be bonded by handheld devices. Advantages
• Low thermal load – heating is localized to joint.
Disadvantages
• No surface marring or damage – the process is touch
• Simple part geometry required – simple contours are
less.
possible, but intricate designs are not.
• Minimal flash – melt blow-out is minimized do to a
• Flash – flash or excess melted plastic will protrude
small heat affected zone.
from joint.
• Tack – molten plastic may stick to hot plate. Disadvantages
• Expensive equipment – large capital investment for
Notable Applications
HF generator.
• Large profile applications, center consoles in
• Limited material choice – only polar polymers are
automobiles, fishing buoys and glove box lids.
weldable, PVC and PA.
• High protection regulations – electromagnetic
radiation is produced from process.
Friction Welding
www.lpkfusa.com/lq
1-800-345-LPKF

3. LPKF Laser & Electronics 2011
Notable Applications If you would like more information on laser plastic
• Housings and any continuous welding applications. welding please feel free to request a copy of LPKF’s
Design Guidelines document; this document will give an
Conclusion in depth look at design requirements, limitations and
process considerations.
As stated before each application will have its own set of
specific requirements that may suit it to one particular Also, please don’t hesitate to contact LPKF with any
process or another. questions, feasibility help or sample requests using the
information below:
Laser plastic welding is excellent for complex
applications that have yet been possible with other Written by:
joining methods. Laser plastic welding has opened doors Josh Brown
for many innovative devices, especially devices that Marketing Development Representative
require extreme precision, tight weld seams and a clean LPKF Laser & Electronics
joint. jbrown@lpkfusa.com
503.454.4231
About the author
For general questions or information regarding design and feasibility, please contact:
Josh Brown
Marketing Development Representative
LPKF Laser & Electronics North America
Email: jbrown@lpkfusa.com | Direct: 503.454.4231
Check out -> www.laserplasticwelding.com your laser plastic welding resource.
,
Don’t forget to download a copy of LPKF’s Laser Plastic Welding Design Guidelines, a document for engineers
and designers in the concept and design stage of an application.
Download the PDF now!
www.lpkfusa.com/lq
1-800-345-LPKF