Plastic Enclosure Design & DFM Considerations for Injection Molding

Manufacturing has proven to be a significant sector over the last century, and it continues to grow. Many manufactured products require packaging within a secondary product—an enclosure of sorts—for added protection and a finished appearance. This is where custom plastic enclosures play an essential role. These enclosures are specifically designed for the products they house, ensuring the items remain safe, intact, and protected from damage. Plastics and metals are the most commonly used materials for manufacturing such enclosures. While metal enclosures are still used in certain heavy-duty applications, industries increasingly prefer plastic enclosures because they are: • Lightweight • Cost-effective • Durable • Corrosion-resistant • Easy to mold into complex shapes • Available in aesthetic finishes Plastic Injection Molding is the most efficient process for manufacturing these enclosures at high-volume, low cost, with consistent dimensional accuracy.

Plastics are among the most widely used materials in the world. Every year, over 360 million metric tons of plastic are produced globally. Their easy availability and the relatively low cost of developing plastic products make them highly appealing to engineers and designers. Additionally, their durability, cost-effectiveness, lightweight nature, reusability, and corrosion resistance make plastics ideal for manufacturing high-quality enclosures. When buying plastic enclosures, key factors to consider include the quality of the polymer used, the rating standards of the enclosure, and RoHS compliance.

• Plastic polymer used Plastic enclosures can be manufactured from a variety of plastic polymers, such as Acrylonitrile-Butadiene-Styrene (ABS), Low-Density Polyethylene (LDPE), High-Density Polyethylene (HDPE), and Polycarbonate (PC), among others. When purchasing an enclosure, it is important to understand the properties of the plastic that best suit your application. Some plastics may release toxic fumes, while others are more environmentally friendly. Therefore, selecting the appropriate polymer is essential for both performance and safety.

• Ratings of the plastic enclosure When browsing different plastic enclosures, you will notice various letters and numbers printed on them. These markings represent the ratings assigned by international standards organizations, indicating the product’s performance limitations and capabilities. They help users understand how well the enclosure can withstand factors such as dust, moisture, impact, and environmental conditions.

● Restriction of Hazardous Substances (RoHS) compliance RoHS regulates the use of certain hazardous substances. A ROHS mark on a product indicates compliance i.e. it is free from hazardous substances such as lead and mercury.

Some examples of plastic enclosures are: ● Small desktop plastic enclosures ● Plastic instrument case with handle ● USB enclosure ● Power plug enclosure

● Cost-saving; plastic is cheaper than metal ● Less labor cost ● Multiple finishing ● Accurate working ● Enhanced strength ● Minimize plastic waste ● Ideal for mass production ● Efficient and resourceful ● High-quality plastic components ● Flexibility in material and color ● Smooth finishing of plastic parts ● Good speed and fast production ● Capable of using multiple plastic types

DFM in plastic injection molded products can determine up to 70% of the manufacturing cost of the product. Naturally, it is widely integrated into the manufacturing process.

Aspects to be considered for a DFM integrated system while manufacturing plastic enclosures: ● The manufacturing processes ● Technology to be used for manufacture ● Various design principles which can be applied ● The right manufacturing materials ● Properties of the polymer to be used ● The right investment and assembly cost for the process

Wall Thickness: The main wall in the plastic enclosures is called a nominal wall and its selection is an integral part of designing. The best design for an enclosure is where the walls have minimum thickness, just enough for mold flow and structural integrity. The walls must also be uniform ● Wall thickness determines cost of the material. Thicker the wall, heavier the plastic enclosure and higher the cost. ● Molding cost depends on the cooling time, which is directly proportional to the square of the thickness of the wall. Consequently, smaller products may cost more for molding than the resin. ● Walls that are too thick can weaken the final product. A good balance between compressive layers and tensile layers in the plastic is needed. Uniformly thick walls and light weight are optimum features of a plastic enclosure. Optimal wall thickness depending on materials is as follows:

Material Guidelines: Materials used for manufacturing plastic enclosures must be selected after considering following factors: ● The main function of the product ● Environmental conditions the product will be used in ● Strength of the material required based on the product’s usage ● Flexibility needed in the product Polymers used in manufacturing the product change the look, operation and feel. Radius Selection Guidelines: Products with sharp corners cause great stress, affecting the manufacturability of the the product. Products should be designed with corners that have a large radius. The radii must be with regard to the wall thickness of the product so as to reduce high stress concentration. A general guideline is to use 0.9-1.2 times the nominal wall thickness for the corner thickness.

Before mass manufacturing the product, designers are required to evaluate the design decisions. Producing the prototype with the traditional techniques is time-consuming and very expensive. With advancement in 3D printing technology, it is possible to create a prototype with high functionality within hours and at a fraction of cost of the traditional prototype. https://www.custiv.com/service/prototyping-services

**Telecommunication industry: ** Factors to consider for enclosures in the telecommunication industry are EMC Shielding, UV resistance, flame resistance, chemical resistance and dielectric strength. Enclosures: Transmitter casings, setup box enclosures, mobile enclosures, server parts, antenna fabrication Plastic Materials used: Acrylonitrile Butadiene Styrene (ABS), Acrylonitrile Styrene Acrylester and Polycarbonate (ASA+PC Blend), Polyamide (PA), Polybutylene Terephthalate (PBT), Polycarbonate (PC)

**Healthcare and medical equipment industry: ** Medical equipment is unique, complex, and requires high precision. Factors to consider for enclosures in the healthcare and medical equipment industry are tolerance level, reliability, biocompatibility, flexibility, ease in cleaning, and mechanical strength.

Plastic enclosures: Surgical tools and devices, medical knobs, vials, beakers, medical implants, ventilator parts Materials used: Polycarbonate (PC), Polypropylene (PP), Polyethylene (PE)

Automotive components

Factors to consider for enclosures in the automotive industry are heat, chemical and weather resistance. Enclosures: Engine components, casings, wheels uprights, suspensions parts Materials used: Polyethylene (PE), Polyamide (PA), Polyurethane (PU), PolyVinylChloride (PVC)

At Custiv, we provide high-quality injection molding services to manufacture a wide range of thermoplastic components, including ABS, LDPE, HDPE, and PA. We specialize in various injection molding techniques such as prototype molding, production-run molding, insert molding, and over-molding. We operate as a one-stop plastic injection molding service with over 50 injection molding facilities, unlimited production capacity, certified manufacturing processes, tolerances as precise as 5 microns, a proprietary software platform, and multiple finishing options. We deliver the best possible service at competitive pricing and offer a price-match guarantee. For your injection molding requirements, you can request a quote and receive DFM (Design for Manufacturability) feedback within 24 hours. 🔗 https://www.custiv.com/service/plastic-injection-molding-services