Processing Viton® Using Digital Laser Material Processing (DLMP®) Technology
Viton® is a class of thermoset fluoroelastomers developed by DuPont Performance Elastomers. Viton resins are comprised of two or more fluoropolymers. In all, there are four basic families of Viton:
Viton A Copolymer of hexafluoropropylene (HFP) and vinylidene fluoride (VDF or VF2)
Viton B Terpolymer of HFP, VF2, and tetrafluoroethylene (TFE)
Viton F Terpolymer of HFP, VF2, and TFE
Specialty Grades, including GLT, ETP, and GFLT Typically includes some combination of ethylene, TFE, and perfluoromethylvinyl ether (PMVE) for enhanced chemical resistance
Viton is most noted for its resistance to elevated temperatures, chemicals, atmospheric oxidation and sun exposure. Due to these properties, Viton is suited for demanding uses in aerospace, automotive, chemical and hydraulic applications. Viton is available in sheet, tube and cord form and is black in color.
FKM, Viton®, Tecnoflon®, Fluoroelastomer
N/A: Chemistry depends on grade of FKM
Viton and DLMP® Technology
The material properties of Viton, primarily heat and oxidation resistance, make it highly compatible with Digital Laser Material Processing (DLMP®) technology. The influence of these properties on the results of DLMP is discussed in detail in the following sections.
The effects of laser energy interaction with Viton are material ablation and material modification. The diagram below illustrates the effects and processes possible based on the unique interactions between laser energy and Viton. In the case of Viton, the process of laser cutting, laser engraving, and laser marking can be applied. The laser energy can ablate material to cut, engrave, or mark the material or it can change the surface properties to create a visible mark. Each of these processes are discussed in their respective section below.
Material ablation is a physical process that removes material. Material is removed completely from the top to the bottom surface or partially from the top of the material down to a specified depth.
Viton is an excellent absorber of CO2 laser energy (wavelength=10.6 μm). When Viton absorbs laser energy, it rapidly converts optical energy into molecular vibrations (heat). With sufficient heat, Viton undergoes thermal degradation, where the molecular bonds are broken at various points in its molecular structure. Material directly in the laser path is ablated away, creating vapor and a fine black powder. CO2 lasers are used exclusively for laser ablation of Viton.
Laser cutting is the complete removal and separation of material from the top surface to the bottom surface along a designated path.
Due to its excellent temperature resistance Viton can be cut with a high degree of accuracy. The edges that result from laser cutting Viton are smooth and free from discoloration sometimes associated with thermal processes. Laser cutting Viton will produce a fine black powder that is easily cleaned with an aqueous detergent solution. The basic capability shown in the example can be extended to nearly any shape, even complex and closely-spaced cuts.
Laser engraving is the process by which material is removed from the top surface down to a specified depth. This is possible due to tight control over laser modulation. By continuously varying the laser power, laser engraving can be used for textures, photographs, and information such as text and numbers. The example shows how the laser energy can be controlled to removed material to a controlled depth. Viton can be engraved without discoloration or melting. As with cutting, laser engraving Viton will produce a fine black powder that can be cleaned with an aqueous detergent solution.
Laser Marking (Depth)
When the laser energy is used to produce a human and/or machine readable identification or information into a material, such as a barcode, date/lot code, serial number, or part number, the process is considered laser marking with depth or laser depth marking, although it is essentially engraving into the material.
As discussed, 10.6 μm CO2 lasers are very useful for material removal for the purposes of cutting and engraving. However, CO2 lasers are ineffective at creating contrast. Fiber lasers are better suited for this task. Viton will also absorb 1.06 μm fiber laser energy and convert it into heat. The power applied to the surface can be tightly controlled to create contrast without material removal. The resulting mark will be light brown. This process, sometimes referred to as bleaching or foaming, leaves no residue or powder.
Laser Marking (Surface)
Viton can be surface marked with a fiber laser to convey information, such as numbers, text, barcodes, and even photographs. The mark is permanent and exhibits good contrast making it an attractive alternative to inking methods. While not a particularly bright mark, this process is sufficient for creating human and machine readable information.
Multiple processes can be applied to Viton without having to move or re-fixture the material. The example demonstrates how processes can be combined to cut Viton from sheet stock, engrave a channel into the material ,and surface mark a serial number. Engraving and marking are typically done before cutting in a combined process.
Environmental, Health & Safety Considerations
Laser material interactions almost always create gaseous effluent and/or particulate. Due to its complex polymer chemistry, laser processing of Viton using a CO2 laser produces a wide array of fluorine containing gasses. Most notably, this effluent contains carbonyl fluoride and hydrogen fluoride. These gases and particulate should be routed to an exterior environment in accordance with government regulations. Alternatively, the effluent can be treated with a filtration system first and then routed to an exterior environment. Viton is resistant to high temperatures but can undergo exothermic reactions if provided with enough laser energy. Therefore, laser processing of Viton should always be supervised.