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Our Manufacturing department is made up of two primary processes. The first is Machining and the second is Assembly. Between these two functions, we also perform secondary operations such as silk screening, RFI/EMI shielding, sonic welding, and other types of processes that may go into the manufacturing of enclosures. While not every enclosure will require these additional processes, most will need some level of secondary operation in order to meet our customers' specifications. For a typical project that would require all of our manufacturing operations, the following is a general guideline of the sequence of events.
Please keep in mind that the sequence of the steps presented above can be changed based on the overall project. As an example, depending on the level of RFI/EMI shielding required, we may have the plastic sheets shielded before or after CNC routing. Or, the silk screening may be required to go on the panels after the entire enclosure has been assembled due to painting requirements. The key point here is that our process is extremely flexible and as long as the laws of physics are not an issue, we will do whatever it takes to produce the enclosures that our customers want. Finally, as with most manufacturing companies, we perform regular and routine inspections throughout the entire production process. Because our products and our process are geared for customization, each project is evaluated as to what, when and how the inspections are performed. For that reason, it is not possible to list standard procedures for which dimensions or the product functionality are checked. What we can state is that each time a job is released to the production floor, every panel, manufacturing process, and subassembly will undergo a thorough first article inspection including sign-offs on a fresh set of manufacturing drawings. Furthermore, for quantities that justify in-process inspections, timelines are established and ongoing inspections of key attributes or dimensions are performed. The end result is a cost effective process for ensuring high quality enclosures for low quantity volumes. |
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There are two types of bends that we typically perform in order to produce aesthetically and structurally sound enclosures. The one used on nearly every enclosure assembly is what we call the 'Point Bend.' This type of bend involves scoring/cutting one of the surfaces of the plastic material, applying a directed, concentrated heat source at that bend point/line, and then physically bending the panel to the proper angle. This type of bend is usually done to create a change in angles between two adjacent surfaces. The second type of bend is better described as a sweep, arc, or curve. For these bends, we do not apply heat, but rather perform a cold-rolling process on the specific curvature area. The reason for this cold-roll approach is that experience has shown adding heat to an 'uncontrolled surface' reduces the process tolerance window to the point that warpage, shrinkage, and surface deformation (such as gloss) becomes difficult to control. Typically, such variables would be controlled with fixtures, jigs, or other hard tooling...which defeats the benefits of our 'No Tooling' process! As such, we leave the heat forming process to injection molding or thermoforming and, instead, concentrate our capabilities on providing true alternatives to those capital investment types of processes. A key element of our cold-rolling process has to do with preparing the panel for the bend. In order to incorporate such features in our designs, we have developed unique, yet subtle cut profiles for those bend areas. As such, it should be stated here that the first step in providing arcs and curves involves the surface preparation by the CNC routing process, which means that these types of features are programmed into our process long before the panels are physically bent in assembly. Finally, we should note the limitations of our process with regard to bends and curves. While we can incorporate many of the surface shapes that most enclosure customers require, we cannot produce domes or spherical features. Because we do not use tooling in our process, there is no way to change the geometry of the material to produce these types of shapes. To do so would require that the dimensional surface area of the plastic panel(s) be altered, which involves plasticizing and re-forming the plastic material. At that point, we would be using an injection molding or thermoforming process that requires hard tooling, longer lead-times, etc. etc. etc.! |
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The final phase of the manufacturing process involves the assembling of panels and components into a finished product. For the most part, this is where the product starts to look like an enclosure with the appearance and functionality the customer requires. There are many techniques PEI employs for assembling enclosures including sonic welding, solvent bonding, epoxy gluing, threaded insert fastening, as well as our customized tongue and groove 'snap fitting.' It should be noted here that any of these assembly processes can be used either alone or in combination. As with most of our customization features, deciding which method is best depends on the specific enclosure design as well as the function of the device. Additionally, the operating environment plays a significant role in determining the design of the enclosure and the assembly process used, therefore, it would be very difficult to try to present a detailed list of when a particular method should be used over another. Rather, our engineers select the assembly procedure and bonding mediums based on broader attributes such as the size, function, and operating environment of the enclosure. Before finalizing the assembly process, the customer will be consulted on the basic design such that their input or confirmation of our recommendation is discussed. Usually, this is done during the quotation phase so that pricing and lead-times correspond to what will ultimately be produced. Please note that while we do not share with the customer those design elements that are part of our proprietary process, we will communicate on those issues that will affect the form, fit, or function of the enclosure. |
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SHIELDING - Manufacturing Process Shielding of plastic parts typically involves applying a paint specially formulated with suspended metal (copper or zinc) particles. From a processing stand point, the most important issues involve even dispersion of the copper shavings and adequate coverage of the paint to ensure adhesion and cohesion to the substrate. On that note, we at PEI hold UL certification for the application of the copper shielding paint for the two UL rated substrate materials we use (Royalite R59 and Kydex T). As such, we can provide a completely UL approved product with regard to the materials and application of the shielding. As for the process itself, we can have the shielding applied at three different manufacturing points. Pre-Shielding In-Process
Shielding This method, while potentially more effective than the pre-shielding method, is both more costly and will add time to the overall manufacturing process. In particular, the cost comes from the added labor of masking some areas and then (typically) setting up the CNC machines a second time for final cutting after shielding. As for the additional manufacturing time required, it is due to having to break into the CNC and assembly operations to perform a consecutive process as opposed to doing it during pre-release or while another process is being performed. Post
Shielding While we
are not experts in the field of electronics, we do have extensive experience
in the application of shielding coatings used for controlling RFI/EMI
as well as providing grounding and continuity throughout a plastic housing.
With that in mind, we are always available to share our wealth of knowledge
with customers who are struggling with this subject of determining the
need for applying a barrier treatment. If you find yourself questioning
whether to include shielding or which application method to use, please
feel free to use PEI as an added source of information in your decision
process. |
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The first step in our manufacturing process (excluding material preparation such as pre-shielding) is CNC routing of the panels. This process involves cutting three-dimensional details into the plastic sheets such that either downstream operations can be performed and/or to accommodate the final enclosure configuration. Examples of the two types would be the cutting of an opening for a DB9 connector that the customer requested versus cutting a PEI 'snap fit' feature that is used solely for the assembly of the enclosure. In addition to CNC routing, we have secondary cutting machines that can perform specific tasks or cut profiles. For the most part, we rely on our CNC machines to do the cutting, however, there are projects for which using our secondary routing machines is either more cost effective or more convenient than developing the geometry in CAD/CAM and then laying down the associated CNC tool paths. As with most of our manufacturing operations, the decision as to which machines to use for a particular enclosure design is made by the engineer during the CAM process. As with many operations performed by PEI, it would be difficult to try to list all of the cut configurations that go into manufacturing an enclosure. Furthermore, many of these cuts, including their associated tolerances, are proprietary and not for publication. As such, we do not list individual cuts, methods, or specifications unless that information is pertinent to the topic and does not infringe on our trade secrets. We trust you will understand our disclosure policy on this subject, however, if you have questions on this subject, please do not hesitate to call customer service and we will be happy to address your inquiry. |
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DECORATING - Manufacturing Process Decorating refers to those features that add aesthetic appeal and/or provide information for the user to read. More specifically, decorating for PEI manufactured enclosures includes silk screening, painting, engraving, and pocketing for labels, overlays, and membrane switches. Other processes employed by higher volume enclosure manufacturers are not offered by PEI simply because they either require tooling to be made and/or they extend lead-times beyond our business model. As such, at this time we do not offer pad printing or hot stamping. Should those processes evolve to where the tooling and lead-times fall within our operating parameters, we will certainly look into adding them to our repertoire. Please note that there is more detailed information available for each of these processes on our Silk Screen and Painting pages. The information presented here is only meant to provide a guideline for how decorating fits into our manufacturing process. Silk
Screening Typically, we apply the silk screening image on flat panels and not on bent subassemblies or finished product. This means that the silk screening process takes place between the CNC routing and assembly operations. As such, silk screening may extend the lead-time of the final product's ship date by a day or more. However, depending on the complexity of the project, we may be able to concurrently perform silk screening and other processes such that the final delivery is not affected by this operation. Usually, this is achievable for the more complex projects where we can begin production of the silk screened panels first and then have them printed while other panels and/or operations are being performed. Unfortunately, for very simple enclosure styles, lead-times and process steps are so short that silk screening may delay the shipment by a day or so. Painting However, to accomplish this high quality paint application involves a somewhat longer lead-time for supplying the finished product. Depending on the specific enclosure design, we may have to assemble and mask each panel before applying the paint. Then once the paint has dried, we would have to unmask and clean (masking tape glue, over-spray, etc.) the units before final inspection and packaging. As such, the painting process is not typically done concurrently with other process steps, but rather after final assembly, which ultimately extends the delivery lead-time. Also, if silk screening is required on a painted part, those two processes will have to be performed sequentially, which will further add to the lead-time projection. Engraving As for the actual machining process, again our experience is that compared to the other processes this can sometimes be a better alternative to silk screening, depending on the quantity and final application. However, we also find that the majority of the decorating that is done with silk screening would not be a good candidate for engraving due to the amount, size, and legibility of text as required by the customer. For logos and simple labeling, engraving is an ideal candidate, especially if no other silk screening is involved. If you have any questions on any of our decorating processes, please do not hesitate to run it by us for input or direction. With our years of experience in designing enclosures, we can provide guidance on which would be the best method for your specific application. |
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