An Introduction to the process and advantages of Laser Plastic Welding

The use of various plastics in manufacturing has grown immensely in the last 15 or so years. Weight savings, optical requirements, and flexibility to name a few reasons push the envelope of legacy materials and often times leave plastics as the only logical choice to meet design requirements.

As a designer or an engineer, you may find yourself trying to decide which joining method is the right one for your next plastic widget and happen to stumble across this revolutionary and seemingly “new” technology called Laser Polymer Welding (also called Laser Plastic Welding.) What is it you may ask? How does it work? What are the advantages? Will it work for my application?

What is it?

Laser Polymer Welding can be defined as: “A method of joining two plastics by subsequent transmission and absorption of laser energy.”

While Laser Polymer Welding really isn’t a new technology, it is still not quite as well-known or widely adopted as the legacy joining solutions for plastic components such as gluing, fasteners, snap fits, and ultrasonic welding. It is interesting to note that the German automotive industry was one of the first to adopt this technology around 19 years ago. In spite of the fact that it was (and still is) a revolutionary technology, it took many years for other industries to adopt it. I fully believe that in today’s market, medical device manufacturers and consumer electronics companies stand the most to gain from implementing Laser Polymer Welding.

How does it work?

When two plastics are clamped tightly together, a laser beam in the 1000nm range penetrates the upper layer and is absorbed by the lower layer which in turn is heated by the laser energy and transfers this heat to the upper layer resulting in both of the plastics melting and mixing to form a bond that is virtually as strong as the base material.

Key advantages of Laser Plastic or Polymer Welding (among others of course):

1. Precise control of the welding area
2. Aesthetically pleasing weld seams – visually OK on “class A” surfaces
3. Ability to hold tighter tolerances in the joining process
4. No damage to surrounding materials or sensitive electronics
5. A perfectly hygienic method of bonding – no particulates generated
6. Ability to miniaturize designs
7. Joining of 3D and complex shapes
8. Removal of costly and cumbersome part features
9. Eliminate consumables – fasteners, glue, etc.
10. Drastically improve quality
11. Bonding strength virtually as strong as the base material
12. The lower total cost of ownership – thinking holistically

Laser Polymer Welding picks up where other joining technologies leave off…

Will it work for my application?

With the above advantages of laser plastic welding being so attractive, quite often engineers will inquire looking to see if Laser Polymer Welding might be able to replace their current joining solution on a product that is already in mass production. In these cases, I counsel them that if the current joining solution is working and there are no prevalent issues such as excessive-quality fallout or cosmetic irregularities, then Laser Polymer Welding may not be the best approach because of the relatively high cost to implement it this late in the game.

It is highly recommended that designers and engineers reach out to an expert long before a design is frozen so they can receive proper guidance to design a laser-weldable joint and eliminate the potential for costly mistakes.

For those that are researching Laser Polymer Welding for implementation into a new product that has not been designed frozen, it would be beneficial to consider the below points:

• Part volumes typically need to be above 150k per year, or, it must be a very high-value part
• End location for product manufacturing
• Production line concept – automated vs. operator based
• Is there local or regional support for development, applications work, and mass production?
• Adopting a Total Cost of Ownership model for implementation

I would like to conclude this article with the following:

If there is a need to eliminate quality problems and miniaturize designs, all while avoiding damage to sensitive electronics… Than Laser Polymer Welding is the right choice for your design!