FAQ (Frequently asked questions)
 - What is LTW?
 It means “laser transmission welding.” When referring to resin welding, it is also called “laser welding.” However, as this term also refers to welding using laser, to avoid confusion, the term “laser transmission welding” is used.
 - What is ACW?
 It means “absorbance control welding.” By using this method, laser welding of parts with the same material and same color is possible. It is also capable of abutting the welding of plastic as with metal welding. Thermoplastic resin with high transmittance is suitable for the ACW method. We are now applying for a patent for this technique and related welding method.
 - What are the advantages of laser transmission welding?
 Unlike hot plate welding, vibration welding, and ultrasonic wave welding, laser transmission welding is a type of non-contact welding, producing excellent appearance without burrs.
 As this method is almost free from distortion caused by heat and no vibration is produced, it can be used for welding of thin plastic bonding parts, which require high accuracy.
 - What are resins (plastics) that can be welded by laser transmission welding?
 Amorphous resins including PMMA (polymethyl methacrylate), PS (polystyrene) and PC (polycarbonate), crystalline resins including engineering plastics like PA (polyamide), PBT (polybutylene terephthalate) and PPS (Polyphenylene sulfide), and olefin-based materials including PP (polypropylene) and PE (polyethylene) can be laser-welded. With the latest technology, it is possible to weld resins including COP (Cyclo Olefin Polymer) and TPO and TPV (bridged thermoplastic elastomer).
 - What is eBIND LTW?
 It is a type of coloring material for the transmission layer in LTW. It appears black to our eyes, but it transmits a laser beam. Its product form is masterbatch. We offer a number of products, in particular for crystalline resin.
 - What is S-type coloring matter?
 S-type coloring matter is coloring matter for LTW that has been developed leveraging Orient Chemical Industries’ proprietary technologies.
 To produce it, a chemical treatment is conducted on an anion-based compound. This gives properties such as heat resistance, humidity resistance, and sublimation resistance. Conventional dye-based coloring materials are inferior in these properties. In addition, pigments have the problem of large energy loss.
 - What is YAG?
 YAG is an acronym for Yttrium Aluminium Garnet. YAG laser is excited by a special lamp with Yttrium Aluminium Garnet crystalline structure, and laser beam is oscillated. These days, LD-excited YAG laser, whose excitation source is a semiconductor laser, has appeared.
 - What is LD?
 LD is an acronym for Laser Diode and means a semiconductor laser. The semiconductor has an intermediate resistivity between resistivity of conductor likely to conduct electricity, and resistivity of insulator unlikely to conduct electricity. The semiconductor laser oscillates a laser beam by conducting electricity.
 - What is fiber laser?
 Fiber laser is a type of solid laser that uses optical fibers as the amplification medium. When excited light enters a core fiber added with rare earth, light of specific wavelength is amplified, and it can be extracted as laser light. As it is possible to amplify light in a very thin core fiber, laser light with high beam quality can be obtained.
 - What is the dilution ratio of eBIND LTW?
 For the standard grade of eBIND LTW series, we recommend a dilution ratio of 15 times. As the added amount of eBIND is designed in consideration of the optical characteristics, we recommend that you use eBIND LTW at the recommended concentration. For example, eBIND LTW-8XXXC will become usable when it is diluted by 25 to 30 times.
 - What colors can be used for laser transmission welding (LTW)?
 For eBIND, black is currently set as the standard color, but from the technical point of view, various colors can be used. Orient Chemical Industries, Ltd. introduced a white-color material that transmits laser at the Nagoya Plastic Industrial Fair held in November 2003. Orient Chemical Industries, Ltd. holds patents for the techniques regarding this laser-transmitting white-color material and its manufacturing method.
 - What is “master batch”?
 “Master batch” refers to a high-concentration coloring matter compound consisting of plastic (resin), a great amount of dye/pigment, and others. This master batch is designed to provide correct color density when a small amount of the master batch is added to uncolored plastic. Among the features of the master batch are that it allows accurate measuring and does not contaminate its surrounding area.
 - Can I conduct a welding test using the laser transmission welding?
 Please refer to the links to companies related to LTW. Laser welding machines, monitoring devices for resin welding, laser processing job shops, etc. are introduced.
 - What is “visible light (region)”?
 This term basically refers to light and its region that a person can visually recognize. The definition of visible light differs from document to document. This is because recognition capability differs from person to person. The color difference measurement region by a spectrophotometer is 380 nm to 780 nm.
 - What is “infrared ray (region)”?
 This term refers to a region of electromagnetic wave from around 750 nm to around 1 mm. For LTW, near-infrared ray laser is generally used. Semiconductor lasers and YAG lasers oscillate lights that have a wavelength in this region. In laser welding, laser diode (LD) in particular is used, and a long-wavelength laser of 940 nm or greater is excellent in black color transmissivity.
 - What is “transmittance”?
 In LTW, this term refers to the ratio between the incoming light (I0) and the outgoing light (I) when light passes through a plastic transmission layer (thickness). In other words, it is an index indicating how much light has transmitted through the layer. Transmittance is generally represented by “t” and obtained by t = I/I0 × 100.
 - What is “reflection”?
 In LTW, this term refers to the ratio between light radiated to the plastic interface area and reflected light. The higher the reflection is, the lower the transmittance is, requiring a higher laser output.
 What is “scattering”?
 In LTW, this term refers to a phenomenon in which laser light entering the inside of plastic hits molecules and particles in the medium, and its path changes to various directions. It has been confirmed that in fillers such as crystalline resin and glass fiber, laser light expands due to the influence of scattering.
 - What is “dye” or “solvent dye”?
 In the field of plastic, “dye” mainly refers to oil-soluble dye (solvent dye) and it is generally called organic solvent soluble dye. Solvent dye belongs to organic pigment and refers to a compound soluble (soluble at molecule level) in solvent, wax, etc. Solvent dyes are used for coloring  plastic such as PS (polystyrene), ABS (acrylonitrile-butadiene copolymer), PMMA (polymethyl methacrylate), PC (polycarbonate), and PET (polyethlene terephthalate). As these dyes show migration, their use is limited under thermally-influenced conditions.
 - What is “pigment”?
 It generally refers to a particulate solid that is insoluble in solvent (water, solvent) or other solutions, and chemically and physically stable. With pigment, reflection, transmission, interference, and diffraction of light occur due to its particulate structure and thus its color is felt. Pigments are divided into organic pigments and non-organic pigments.
 - What is “carbon black”?
 It refers to a common black pigment that is produced by putting a compound containing carbon hydride or carbon in a condition with insufficient air supply (incomplete combustion), and is used for coloring plastic. Its nomination or properties vary depending on the raw material or manufacturing method. Carbon black is generally known as a substance that absorbs all light.
 - What is “black”?
 When all visible light is absorbed, a person recognizes its color as black. It is commonly known that when the three colors yellow, magenta, and cyan are evenly mixed, black is produced. (Subtractive color mixture)
 - Same color
 In color quality control, when color difference is ΔE 0.3 to 0.5, it is generally treated and managed as the same color.
 - Color difference
 A difference of color from the standard color to compare with is expressed as color difference. A value calculated using the L*, a*, and b* values in CIElab spaces is expressed as color difference (ΔE). The National Bureau of Standards in the U.S. sets the color difference value evaluation criteria (NBS unit) as follows.

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