Envision Plastics Expert Announces Part Four in the Series: How to Design Plastic Enclosures Using NMR Technology

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NMR Technology (No Molds Required) is a technology Envision Plastics and Design uses to manufacture custom plastic electronic enclosures with no tooling or molds. Since it’s a unique plastic fabrication process, some forethought goes into the design criteria to make an economical plastic enclosure.

Common materials used are ABS, HIPS, polycarbonate, PETG and acrylic.

In the last segment of the NMR Technology design series, the internal considerations of the plastic enclosure were discussed –such as PCB’s, connectors, and LEDs. Another critical component of the design concept and applying NMR is the material required and what NMR can provide for these materials.

Material Criteria:

The NMR Technology utilizes extruded sheet plastic in varying sheet gauges. The material must have the following characteristics:

1. The material must be available in extruded sheet form. Some materials are only available in resin form for molding purposes.
2. The material must be able to be solvent welded.
3. Materials must be able to be bent with minimal heat. We cannot use thermo set materials.

Material Thickness:

Everything starts with a stock material thickness. It is not required to use the same material thickness for each part of the assembly, but it is recommended to use a common thickness if you are considering a custom plastic extrusion. The thinnest material we can use to form plastic enclosures is 3mm and the maximum wall thickness is 6mm (.236”) or 6.35mm (.250”) due to bending constraints. Typical plastic enclosures use a wall thickness of 3mm or 4mm. Flat parts can be milled from material as thin as 1.5mm (.060”) and as thick as 1”, but not bent and welded to create a complete plastic housing.

Material Types:

Once material thickness has been determined, a choice must then be made in material type. Common materials used are ABS, HIPS, polycarbonate, PETG and Acrylic. Each material has its own characteristics. ABS and HIPS are opaque, and polycarbonate, PETG, and Acrylic are transparent. ABS and HIPS require the same processing times and procedures at Envision, but the transparent materials require extra attention. Polycarbonates take longer to bend, are more susceptible to scratches and are more costly than other choices, but it offers a transparent high impact fire-rated material option. Acrylics have a higher tolerance range in thickness, which can affect tongue and groove depths.

Materials such as Nylon, Teflon, polypropylene, Ultem, etc. have different tolerance ranges and are difficult or impossible to bend using NMR and cannot be solvent welded. However, all of these materials may be CNC routed.

After four installments you should be more familiar with what NMR Technology is, the types of design concepts it can produce, how your electronics fit inside the enclosure, and the types of materials available to the NMR Technology manufacturing process.

The next segment of this series will offer a more in-depth depiction of the actual manufacturing process used in NMR Technology.

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Brian DuFresne
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