What are the different fastening and sealing methods for an enclosure

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This article will give an insight to the different fastening methods of plastic and they depend on many factors like, Tooling method, Productivity, Ease of Manufacturability, Ease of Assembly, Cost and many other. The selection also depends upon the design outcome, IP Rating, Aesthetics and Durability.


Assembly of enclosure

There are a lot of ways to join the assembly condition of the enclosure with a reliable method and equipment. A few of the strategies are given below.

These are commonly numerous sorts of screws standard & custom screw

  • Screw Fit
  • Snap-Fit
  • Adhesive Bonding
  • Ultrasonic Welding

Screw fit

Mechanical Screws are used to keep 2 Plastics together. These are commonly used method and hasslefree although are not the most aesthetically appealing design. These are commonly used in Industrial type of enclosures. There are 2 types of Screws used, Screw which Self Taps onto the plastic which has atmost 10 Life Cycles. And another is having a Brass Insert Female threads which are either overmolded or Heat Stacked into the plastic. One can open and close the device multiple times without any deviation in bonding quality. Plastic Tooling for Screw method is the most economical method.

There are numerous type of screws which are available in the market based on the application of the product. This method is slightly costlier since the cost of the screws add up to the BOM.

Snap fit

Snap fits are most popular and low-cost method. These are used when the product needs a seamless finish Like Mobile Phones and they are the most cost efficient method in Large volume manufacturing despite the complications involved in the Tooling side. There are numerous Pros of using this method like these reduce the usage of Screws and thereby light on the BOM Cost. The assembly of the product is much simpler as one have to throw the hardware in and push 2 plastics together to snap ON. Although these don’t work efficiently for IP67 rating and additionally glues are sometimes required to properly seal them. There are different types of Snap Design like Cantilever Snap, Tapered Beam, Cylinder Snap On to name few and these are optimized based on the design, material and production volume.

Adhesive bonding

Adhesives are commonly utilized in conjunction with gaskets and seals. This will be utilized depending upon execution and natural factor. Generally, adhesives deliver more consistent and predictable results in joints requiring strength and durability than other joining methods. It progresses the fixing execution of a sporadic surface. These are indeed most traditional method of keeping 2 parts together.

Ultrasonic Welding

The Most Critical part of this method is the Part Design. The Butt design needs be carefully calculated based on the energy director. During the ultrasonic welding the Ridge melts and bonds with the mating part and thereby providing the complete sealing. This is a Permanent Joint and therefore we need to break the part apart in order to open the deivce. The Method is known for foolproof water proofing.