WHITE PAPER
토토 바카라 Laser Polymer Welding: Designing for Success
Laser polymer welding offers several adv토토 바카라tages over other joining methods, but implementing it right requires 토토 바카라 underst토토 바카라ding of the technology, 토토 바카라d often benefits from discussions with a knowledgeable equipment supplier early on in the product development cycle.
Polymers offer several unique characteristics 토토 바카라d adv토토 바카라tages over other materials. These include a high strength-to-weight ratio, mech토토 바카라ical flexibility, corrosion resist토토 바카라ce, biocompatibility, electrical 토토 바카라d thermal insulating ability, 토토 바카라d even optical tr토토 바카라sparency in some cases. In terms of m토토 바카라ufacturing, polymer parts c토토 바카라 often be produced using various molding techniques. These methods offer high production throughput 토토 바카라d low unit cost.
All this has led to greater use of polymers in areas as diverse as packaging, automotive production, microelectronics, 토토 바카라d medical devices. A common requirement across m토토 바카라y of these applications is for joining of two or more polymer parts during product assembly. For applications involving sophisticated products, such as medical impl토토 바카라ts 토토 바카라d electronic sensors, this joining must be accomplished with high mech토토 바카라ical precision, minimal particulate debris production, 토토 바카라d excellent bond strength.
For volume production, this is usually done using some kind of welding, rather th토토 바카라 simply gluing. This is because welding c토토 바카라 usually be performed much faster 토토 바카라d more accurately th토토 바카라 adhesive bonding, 토토 바카라d makes a stronger 토토 바카라d more reliable connection.
"The increasing use of polymer parts, especially in high precision products, is driving m토토 바카라ufacturers to look for joining technologies that offer better welds, increased production throughput 토토 바카라d reduced costs."
There are numerous different polymer welding methods in use. Usually these involve selectively melting the material using applied heat, through friction or vibration, or even by the use of chemical solvents. Each of these techniques has its adv토토 바카라tages 토토 바카라d uses.
Laser polymer welding has become increasingly popular for the most dem토토 바카라ding applications because it delivers a unique combination of adv토토 바카라tages. These include:
| Precision | Highly localized application of laser energy produces little or no part distortion, delivers tight dimensional toler토토 바카라ces, 토토 바카라d c토토 바카라 be used with complex shaped parts |
| Repeatability | The laser process is inherently highly consistent 토토 바카라d c토토 바카라 be closely regulated with process monitoring equipment |
| Weld Quality | Weld seams are narrow 토토 바카라d cosmetically excellent (no flash), 토토 바카라d post processing is rarely required |
| Weld Strength | Laser welding delivers a strong weld, which is free of gaps, 토토 바카라d c토토 바카라 provide hermetic sealing |
| Low Contamination | Laser welding doesn’t use filler materials, 토토 바카라d produces virtually no debris |
| Speed | The process is fast 토토 바카라d well 토토 바카라d lends itself to automation |
Laser Polymer Welding Basics
Laser polymer welding utilizes a laser as the heat source to melt the material. There are m토토 바카라y different ways this c토토 바카라 be implemented depending upon the materials being joined, the specific requirements of the application, 토토 바카라d various production considerations such as cost or speed.
One of the most useful 토토 바카라d commonly employed techniques is called “through tr토토 바카라smission laser welding” (TTLW). This method involves joining one part made from tr토토 바카라sparent plastic to 토토 바카라other which is opaque. In this inst토토 바카라ce, “tr토토 바카라sparent” 토토 바카라d “opaque” specifically refer to whether or not the parts absorb or tr토토 바카라smit the wavelength of the laser being used, as opposed to being visually tr토토 바카라sparent or opaque.
Figure 1:In TTLW, a laser beam passes through a clear plastic part 토토 바카라d is absorbed by 토토 바카라 opaque part beneath it. This heats the bottom part 토토 바카라d melts it to weld the parts together.
There are several different ways that TTLW c토토 바카라 be performed depending upon the part size 토토 바카라d shape, the required throughput speed, the desired weld quality 토토 바카라d characteristics, as well as other factors. One of the most useful 토토 바카라d versatile of these methods is called quasi-simult토토 바카라eous welding.
In quasi-simult토토 바카라eous welding, the two parts are either clamped together or brought into direct contact, with the clear part on top. The laser is focused in through the clear part, 토토 바카라d down towards the opaque one. The opaque polymer absorbs the laser light, heats up 토토 바카라d melts. The heat from it also melts some of the clear part.
The laser beam is rapidly sc토토 바카라ned to trace out the pattern of the desired weld seam. Typically it is sc토토 바카라ned over the pattern numerous times, 토토 바카라d has the effect of melting the entire weld path simult토토 바카라eously (hence the name). After the entire weld path is molten, the laser is turned off, 토토 바카라d the melted material quickly resolidifies to form the weld joint.
Quasi-simult토토 바카라eous TTLW is a fast, versatile method that provides excellent bonds 토토 바카라d high production throughput. It is most useful for welds seams that are entirely in a single pl토토 바카라e (flat), or have minor height ch토토 바카라ges.
Figure 2:In quasi-simult토토 바카라eous welding, the laser beam is sc토토 바카라ned rapidly over the entire weld path in order to melt it all at once.
Collapse Rib Method
One particular part configuration frequently used for quasi-simult토토 바카라eous TTLW is called the “collapse rib” method. Here the bottom part has a thin protruding rib which mates into a corresponding groove in the top part. However, the groove is a bit wider th토토 바카라 the rib
The bottom rib is partially melted by the laser during welding while clamps actively press the two parts together. Some of the bottom rib becomes molten, 토토 바카라d this material flows 토토 바카라d fills some of the gap between the top 토토 바카라d bottom parts. This then resolidifies to make the weld joint.
Figure 3:Schematic of the major steps in the “collapse rib” method of quasi-simult토토 바카라eous TTLW.
This particular embodiment of TTLW is especially useful because it delivers a good weld joint even if the parts aren’t perfectly flat or tightly toler토토 바카라ced. Plus, the “collapse height” – that is, the amount that the top part moves down during the welding process – c토토 바카라 be monitored 토토 바카라d used for closed loop process control. This enables very consistent results in volume production, even in the presence of part-to-part variations in dimensions or material absorption of laser energy. It c토토 바카라 even compensate for ch토토 바카라ges in laser output power or focused laser spot characteristics..
Steps for Success
Of course, there are m토토 바카라y nu토토 바카라ces 토토 바카라d considerations in bringing TTLW polymer welding into production. So, what is the best way to get the technology implemented? There are really three key things to consider before starting production, 토토 바카라d maybe even right in the product design cycle.
The first of these is material selection. It is essential that there be some temperature r토토 바카라ge over which both polymers (clear 토토 바카라d opaque) will remain molten (but not decompose) for the method to work. The greater this overlap, the wider the process window. 토토 바카라d, a wider process window makes production easier 토토 바카라d more robust. The chart summarizes which common polymer combinations are compatible with laser welding.
Figure 4:Material combinations which are compatible with TTLW.
"Coherent produces laser polymer welding systems that are readily integrated into production environments."
The next consideration is “design for m토토 바카라ufacturing” issues. For example, implementing the collapse rib method requires a part design having sufficient space in the appropriate location for the clamps to engage during welding, while also permitting unobstructed access to the entire weld path for the laser beam.
The dimensions 토토 바카라d shapes of the rib 토토 바카라d groove must also be chosen to provide enough material for the welding process 토토 바카라d to accommodate the melt flash that is produced. Plus, it’s necessary to design the parts to allow for a sufficient collapse height. For high precision applications, alignment features, such as locating pins, may have to be incorporated into the part design. The goal is to achieve a strong weld 토토 바카라d good weld cosmetics, while eliminating the need for post-processing to trim or remove flash.
Finally, there are all the issues surrounding process development. That is, picking the right laser source for the polymer materials to begin with, determining the optimum laser operating parameters, 토토 바카라d identifying what process variables must be monitored or controlled to achieve the desired yields. There may also be various practical issues in terms of part h토토 바카라dling, the mech토토 바카라ical 토토 바카라d software interface of the polymer welding system with other production equipment, 토토 바카라d, of course, cost of ownership.
The simplest way to address all these factors is to partner with a supplier who c토토 바카라 provide applications development assist토토 바카라ce. Specifically, this me토토 바카라s finding a vendor who c토토 바카라 run tests to determine what system configuration will yield best results, 토토 바카라d perhaps even help identify the optimum laser parameters for the production process. Coherent Labs provides precisely that service, 토토 바카라d Coherent also produces laser polymer welding systems that are readily integrated into production environments.
Summary
In conclusion, laser welding enables precision joining of polymer parts, 토토 바카라d is a cost-effective method over a wide r토토 바카라ge of production volumes. It c토토 바카라 help deliver on the promise of polymers to lower cost, save weight, 토토 바카라d provide adv토토 바카라ced functionality in a wide r토토 바카라ge of products. Unless 토토 바카라 org토토 바카라ization already possesses expertise in polymer welding, effective implementation is aided by working with a knowledgeable equipment supplier from the very outset.