Recorded March 12th, 2013
Presented by RTP Company
The range of plastic applications that can benefit from using laser technologies to label and join parts is virtually unlimited. Laser welding is a reliable joining method for fusing plastic parts together with precision and laser marking is a clean, fast, and flexible method to produce permanent, high clarity imprints that are resistant to wear and abrasion. Join Jesse Dulek, product development engineer in the color group at custom compounder RTP Company, as he reviews these processes and explains how proper material selection is key to success: laser equipment options, marking opaque to transparent surfaces, proper mating materials for laser welding, and evaluating mark and weld quality.
Questions and Answers
Q: May we use this technology to weld big parts like rear spoilers made in two differents parts (moulded in pp td 15). This kind of joint can resist 200N? This is a standard requirement for us.
A: In most instances, the laser welding process is used on small complex parts. For larger parts such as these, ultrasonic welding may be a better choice. However, we would be happy to review your application and suggest the best option.
Q: How thick is the polymer?
A: The thickness of the thermoplastic material is a critical factor that must be considered in order to determine if the laser welding process is a possibility. For the examples shown in the presentation, the thickness was 1.5 mm.
Q: Does the surface need to have a particular texture, or must it be smooth?
A: A surface texture would effectively scatter more light, both visible and NIR wavelengths, effectively reducing the amount of light that will either be absorbed or transmitted by the material. A matte type of texture will scatter more light, while a very fine texture will behave similarly to a glossy finish.
Q: Any examples of color-to-color applications with marking? e.g. blue/red, and others?
A: Yes, we can demonstrate and share examples of welded and marked materials, but we prefer to discuss your specific application to more appropriately address your needs and provide more personal support.
Q: Can you use the marking system with on press color mixing?
A: Yes, RTP Company supplies LCX additive masterbatches specifically formulated to enhance the marking of most polymers. We would be happy to discuss the application to recommend the most suitable product.
Q: Is it possible for a 50W CO2 laser to mark black on to a clear PC?
A: CO2 lasers tend to create more of an etching, which will have very little contrast. We would suggest using a NIR type of laser, Diode or Nd:Yag, to produce a black mark on a clear PC. The picture on slide 33 of the webinar presentation is a great example of the quality of mark that can be achieved on polycarbonate with a Nd:Yag type of laser.
Q: Does RTP Company have experience in welding parts for the medical market? Materials must meet USP Class VI or ISO 10935 approvals?
A: Yes, RTP Company has many formulations for compounds and colors that can meet USP Class VI or ISO 10993-1 requirements. RTP Company does not provide the actual laser welding of the parts/components, but we do provide the materials that will meet the requirements.
Q: Is it possible to laser weld the thermoplastics with TPE?
A: Yes, it is possible to weld dissimilar polymers, but each application and material combination should be reviewed for the best possible outcome. A common practice is molding elastomer seals to rigid housings.
Q: Can you summarize the relationship between various FR chemistries as they affect laser welding and marking?
A: The critical component when reviewing FR chemistries in laser welding is reviewing the laser transparent layer. Some FR chemistries allow for NIR transmission, while others do not. We will be happy to review your specific application to more appropriately address your needs.
Q: Is an energy director even desired for laser welding?
A: The energy required for successful laser welding will be dependent on the specific application, material combinations, laser selection, and seam geometry.
Q: Does the additive for marking create batch-to-batch variation in the material?
A: No more so than any other additives. The additives that can be used for marking are melt-processable. Assuming sufficient mixing energy has been added, there should be little batch-to-batch variation.
Q: How wide is the weld bead on a welded part?
A: The size of the weld bead will be determined by the specific application, type of laser, and the welding process used. Common sizes will be from less than 0.1mm to 3 mm.
Q: What marking methods/additives would give the best marking contrast when also aiming for minimal etch depth?
A: Precision for marking is controlled by both formulation and marking parameters. Specific tolerances will depend on the polymer compound, formulation, type of laser, and marking parameters. However, significantly narrow tolerances have been achieved with very fine marking of small parts.
Q: What marking methods/additives would you suggest for best achieving the light marks on a dark surface?
A: The ability to achieve a light mark on a dark surface is usually done through strict control of the colorant package used. The ability to successfully achieve a light mark is dependent on the background color and polymer being used. We would be happy to discuss your specific application requirements.
Q: Other than sensors, have you worked in any other automotive application?
A: Yes, in addition to sensors we have successfully laser welded and laser marked a number of housings and key fobs.
Q: Can a black laser mark be put on a white resin?
A: Yes, but the ability to achieve a jet-black laser mark is very dependent on the base polymer. In most cases, the resulting marking is a dark gray with excellent contrast.
Q: Our application requires a plastic with high voltage blocking at high temperature, will the marking additives affect plastic characteristics such as electrical RTI & CTI?
A: The additives used for marking do have varying electric properties, but the usage concentrations are generally very small.
Q: Is laser marking the same as laser etching? Is this a completely different technology?
A: They are not the same, with the main difference being contrast. Laser etching will commonly result in etches that have very poor contrast, while marking provides high contrast “marks”.
Q: Can the same laser be used for marking thermoplastics and different metals (steel, aluminum)?
A: Yes, lasers do exist for the marking of both thermoplastics and different metals. We would be happy to guide you to an appropriate laser choice based on your requirements.
Q: Can you laser weld HDPE? What if the parts are effectively cups that are welded on their edges?
A: Yes, most polymers can be welded. The seam geometry is a critical component that must be considered. However, we prefer to discuss your application and assist with specific recommendations to reduce your development time and costs.
Q: Is there a UL standard that the weld made with this method must meet?
A: There is not a UL standard that must be met to provide a laser welding material. With that being said, we have many UL listed materials and our Flame Retardant team is working daily to provide new options.
Q: How affect the flame retardant to marking process?
A: All components of the formulation will have an effect on the resulting mark. Flame retardant additives are not immune to this, but the exact affect will be determined by the type and concentration of the additive used.
Q: How strong is a laser welded bond compared to the base material under ideal conditions?
A: The strength of the laser weld is a critical component when evaluating the seam quality. It is very dependent on the material and geometry of the seam, in addition to a number of other factors. However, a successful weld of a lap-joint will have comparable strength to the base material.
Q: How large of a weld gap is permissible in welding?
A: Ideally, the weld gap is as small as possible, which correlates to sufficient melt pool formation and contact pressure. Too large of a gap could lead to defects in the weld.
Q: Is multiple laser sources (different wavelengths) common in inline marking systems to accommodate component variants?
A: The number of lasers needed for an inline marking system will be dependent on the number of parts and marking speed used to obtain the desired contrast. However, most in-line marking processes can be accommodated with a single laser source.
Q: Is glass reinforced material are a good absorbers?
A: Glass fibers will both reflect and absorb some levels of NIR energy. Ideally, we would use specialty additives to enhance the absorbing characteristics of the base materials.
Q: Will a PP homopolymer weld to PP copolymers?
A: Yes, their surface energies and melting points are very similar.
Q: Can RTP Company formulate Natural PP for Marking with a Diode Laser?
A: Most polymers are laser transparent in their natural form. The additives used to enhance the laser mark typically do not affect the clarity of the base polymer, but they will add slight amounts of color. Whether or not this is acceptable is application specific. We would be happy to discuss in further detail or provide samples as needed.
Q: Can HDPE be laser welded?
A: Yes, HDPE can be laser welded to itself and other forms of polyethylene (LLDPE, LDPE, etc.).
Q: Do you absolutely need an additive to do marking? We don’t use an additive and can achieve a decent contrast ratio.
A: Some polymers will inherently laser mark without the addition of additives or colorants. The quality of the mark can be improved with the addition of the proper additive.
Q: What is the best way to verify color match by visual or machine methods?
A: The best method to evaluate and control your color is very dependent on the color, material, and application. At RTP Company we use both visual and numerical methods when evaluating colors. We would be happy to discuss your specific application in more detail.
Q: Does the colorant affect the material properties of the plastic and if so, which properties?
A: Some colorants can have an influence on the mechanical properties of materials, but the magnitude of the effect is very dependent on the composition of the material in question and type of colorant being used. For example, titanium dioxide, a common white pigment, is known to reduce impact, tensile, and flexural properties of glass-filled materials.
Q: I am in process of performing DOE to optimize Laser Welding quality. I am wondering what will be the critical parameters I should use?
A: There are many factors that need to be considered, but strictly from a laser setting viewpoint, I would suggest varying the laser power, contact pressure, spot size, and welding times.
Q: On a relative basis, how expensive is it to mark a part with several lines of text versus a label?
A: The initial start-up cost is by far the largest obstacle. However, the cost per part depends on the number of parts that are being marked. If the number is on the order of a few hundred, laser marking is likely not the best solution. If the number is on the order of a few thousand, it could provide a great solution. We would be happy to put you in touch with laser manufacturers that could help with generating a quote for a system that meets your needs.
Q: How much structural strength will a welded joint have and how is that influenced by plastic thickness?
A: The strength of the weld is a critical factor when evaluating the seam quality. The thickness of the plastic will directly influence the amount of transmission and absorption that is achieved, which contributes to the formation of the melt pool.
Q: What are common causes of burning on surface of transmissive component?
A: The most likely reason that there is burning on the surface is that transmissive component is actually absorbing some of the laser energy and converting it to heat. There are many factors that need to be considered, from the material formulation to the laser parameters.
Q: Is there an easy way to increase the transmissivity of a material without reducing the part thickness?
A: Unfortunately, it is not possible to improve the transmission of the base polymer with the addition of additives. It is a physical characteristic of the particular polymer.
Q: What is the maximum recommended thickness for the transmitting (transparent) layer? Most of our PA parts are 2 to 2.5mm.
A: The thickness of the transparent layer is a critical factor that needs to be evaluated. However, the maximum thicknesses that can be achieved while maintaining enough NIR transmission is extremely material dependent. PA based materials are semi-crystalline thermoplastics, which makes the material opaque at thick cross-sections. I would suggest having a thickness that is no larger than 3 mm, but would be happy to evaluate your specific material in more detail.
Q: What % cost increase are we looking at when we add the additives to weld PP to PP?
A: The costs of the additives used to enhance the absorbing characteristics vary a great deal. They can range from relatively low cost (black) to very expensive (specialty absorbers) that allow a great deal of color flexibility.
Q: What is the abrasion resistance quality of marking?
A: The abrasion resistance of the laser mark is determined by the base material and depth of the laser mark. This material property varies a great deal depending on the type of polymer used.
Q: Can marking be used for contoured surfaces for example round non-smooth uneven parts?
A: Yes, this is one of the many advantages of the this process.
Q: Do we send you parts for laser welding?
A: Unfortunately no, RTP Company is a material provider, but we would be happy to put you in touch with a company that can provide this service.
Q: Can you give an estimate of what the additive costs to add to a material to make a black polypro material marked with a lighter mark?
A: The key to obtaining a light mark on any material is to control the entire colorant package. In this case, our preference would be to provide a black color concentrate that contains both the colorant and marking additives required. We will be happy to discuss exact costs with a member of our commercial team.
Q: Can you adjust the depth of the marking for deeper abrasion concerns?
A: Yes, a material can be formulated to increase the depth of laser penetration, but specific tolerances will depend on the polymer compound, formulation, type of laser, and marking parameters.
Q: What is the general % of the additive is required for color marking?
A: Most of our lasers marking additive masterbatches are formulated for a 2% usage. However, the specific concentrations of the actual colorants/additives used cannot be disclosed.
Q: What type of pressure do you need with transparent PC to a white PC/ABS for laser welding a hermetic seal?
A: The ability to achieve a hermetic seal would depend more on the absorption characteristics of the white PC/ABS. The amount of contact pressure required will be strongly dependent on the joint and seam geometries.
Q: If we see intermittent blistering on the part surface following laser weld, what may be the cause?
A: The blistering is likely a result of thermal distortion due to overheating of the material, which may be fixed by increasing the weld speeds.
Q: What mixing guidelines do you recommend for masterbatch in PP for welding?
A: Most of our additive masterbatches are formulated for use at a 2% let-down percentage. This is a common usage rate used in most color masterbatches, which do not require special mixing procedures. It is important to verify that the additive has a homogeneous distribution.
Q: With coloring, is it possible to have multiple colors on the same resin by either changing color additives or laser frequencies?
A: Unfortunately, there are no additives or colorants that can accomplish this.
Q: What is the minimum and maximum depth of an etch?
A: The depth of an etching is very dependent on the material formulation, laser type, and laser parameters. Narrow tolerances can be achieved.
Q: To your knowledge is there a way to use marking on HDPE without a colorant?
A: In our experience, HDPE will require an additive to produce an acceptable mark. There are additives that can be used at very small concentrations to minimize the effect on the visible color and translucency of the natural HDPE.
Q: Can you comment on the ability to use a YAG Laser to mark bar codes on plastics? The bar codes must read by a scanner in the field.
A: I would strongly recommend the use of a Nd:Yag laser for this particular application. However, it is also very important to have a material that is specifically formulated for this purpose. We would be happy to discuss your specific requirements in more detail.
Q: Can Marking be used on painted surface?
A: Yes, but the paint must be able to absorb the laser.
Q: Can you comment on the codestream technology from Fujifilm that uses a coating with a laser marketing additive that can produce dark marks when exposed to a CO2 laser?
A: This type of additive is supplied as a coating, not as a melt processable additive that can be used in our melt compounding process. However, RTP Company does have additives that can be compounded into a thermoplastic material to produce dark marks on light colored substrates.
Q: Is butt welding possible?
A: It is possible, but it would be the weakest joint possible.
Q: Is it possible to laser mark a polymer part that has been painted (so that the marking is on top of the paint)?
A: Yes, but the paint must absorb the laser.
Q: Do we need to treat the surface of the part when we do the laser marking?
A: No, the additive is a compounded component of the material. No surface or secondary operations are required.
Q: What is the ratio for the laser additive?
A: Most of our additive masterbatches are formulated for a 2% usage. However, the specific concentrations of the actual colorants/additives used cannot be disclosed.
Q: What types of pigments or fillers are laser transmissive and laser absorbing?
A: We are happy to review specific applications and applications requirements. RTP Company is very sensitive to both protecting our IP and those of our suppliers and competitors.
Q: What about textured versus a smooth surface?
A: The surface finish of the part will not affect the ability of the material to laser mark, but the contrast does depend on the background color, which can be affected by the surface finish.
Q: How close do the melting points have to be for laser welding dissimilar materials.. and how effective is that joint strength?
A: The melting points of dissimilar materials need to be similar, but the decomposition temperature needs to be considered as well. We have seen successful welds of PC and ABS, which have very different melting temperatures. The strength of the laser weld is a critical component when evaluating the seam quality. It is very dependent on the material and geometry of the seam, in addition to a number of other factors. However, a successful weld of a lap-joint will have comparable strength to the base material.
Q: Are there differences in marking between different surfaces rough and smooth?
A: The surface finish of the part will not affect the ability of the material to laser mark, but the contrast does depend on the background color, which can be affected by the surface finish.
Q: What information should we send you to have a quotation for laser marker equipment?
A: RTP Company is a materials provider, however, we would be happy to put you in touch with a contact for the laser marking equipment.
Q: Does laser marking on a biocompatible material produce substance which are not biocompatible?
A: No, it will not change the composition of the material.
Q: What other types of joints can be made using laser welding? In regular welding there are T and V joints as examples.
A: Many types of joints are possible, but from our experience a lap joint is most effective.
Q: Is white on black background contrast partially determined by the depth of the marking? I assume that would be affected by speed of marking then, correct?
A: The ability to achieve a white mark on a black background is dependent on a number of factors, such as base material, formulation, type of laser, and laser settings.
Q: Smallest heights for marking; i.e. what clearance to edge of piece from laser marked text is necessary?
A: The space needed from the part to the marking device is dependent on the type of laser being used.
Q: Can metalic colours be welded?
A: Yes, the thickness and opacity of the laser transparent layer is a critical design factor. We would be happy to discuss in further detail.
Q: How expensive is this technology?
A: The added cost to incorporate either laser welding or marking can vary a great deal. For example, the clear-to-black laser welding combination would not add great deal of cost, but the additives need to allow color flexibility do add a premium. The additives used for marking do add some small costs, but the exact amount is dependent on the material and desired outcome.
Q: Clear PC to white ABS over a diameter of 150mm, would the weld cause frosting in the plastic if the PC is required to be aesthetically clear (allow clear beam of light through)?
A: The aesthetics of the weld seam is a critical factor that must be evaluated. However, assuming proper parameters and geometry, the melt pool created at the weld seam should not be visible.
Q: would the weld cause frosting in the plastic if the PC is required to be aesthetically clear (allow clear beam of light through)?
A: The aesthetics of the weld seam is a critical factor that must be evaluated. However, assuming proper parameters and geometry, the melt pool created at the weld seam should not be visible.
Q: How much clearance or what size gaps can laser welding tolerate?
A: Ideally, the weld gap is as small as possible, which correlates to sufficient melt pool formation and contact pressure. Too large of a gap could lead to defects in the weld.
Q: You say the laser welds can be air-tight, what pressures can the laser welds resist?
A: Hermetic seals are possible, but the exact strengths of the welds depend on the seam geometry, material, laser, and laser parameters.
Q: I see there are two material to usually join the parts. Can we simply mark ABS without any other additives?
A: Most grades of ABS will inherently laser mark, however, the quality of the mark can be greatly improved with the addition of specific additives.
Q: I need white and yellow on the surface of very black ethylene/propylene material, is that possible?
A: White and yellow marks are possible on a variety of materials. Color matching of these colors is not exactly possible, mainly due to the fact that there are too many variables contributing to the final color of the laser mark. We would be happy to discuss your specific application to more appropriately address your needs and provide more personal support.
Q: To weld PTFE with PTFE –> possible?
A: Yes, this combination is possible, but very challenging. We would be happy to discuss specific application questions.
Q: How does glass content effect marking?
A: All components of a formulation will contribute to the quality of a laser mark, glass fibers are no different. The glass fibers will tend to create a foaming type of mark, which will make the mark light. It is sometimes difficult to achieve dark markings on light colors when the base material contains a high glass content.
Q: I am having difficulty getting a durable, white mark on a Valox 17% GLF DR-48 Black? What additive might you suggest?
A: The ability to achieve a white mark on any material depends on critical control of the entire formulation. I would be happy to discuss your specific application to more appropriately address your needs.
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we would like to weld 2 polypropylene materials together where the upper part should be white (non-transparent). The material should be medical grade and suitable for sterilization.
What type of material do you recommend?
What is the difference between the laser used for welding plastics and the laser used for marking/cutting?
Can a laser marker be used to laser weld on plastics?
Dear Patrick ,
We have both –Transmissive & absorptive white additives for laser welding plastics.
Please reply to my e-mail.
Thanks — [email protected]