Snap Joint: An Essential Mechanism for Prototype Plastic Parts(how to remove a broken tap Daniel)

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In the world of manufacturing, prototypes play a vital role in bringing ideas to life. They serve as a visual aid and functional representation of the final product. To create these prototypes, various techniques and mechanisms are employed, and one such mechanism is the snap joint. This article will explore the concept of snap joints and how they are used in the production of prototype plastic parts.

What is a Snap Joint?

A snap joint is an innovative fastening technique that involves interlocking two or more components without the need for additional hardware like screws or adhesives. It allows for easy assembly and disassembly of parts, making it ideal for rapid prototyping and iterative design processes. The simplicity of snap joints makes them cost-effective and time-efficient, thereby reducing overall production expenses.

Components and Types of Snap Joints:

Snap joints typically consist of two essential components - a male part and a female part. The male part has protrusions or extensions called snaps, while the female part features corresponding recesses or indentations. These complementary features create a locking effect when the two parts are pressed or snapped together.

There are several types of snap joints, each with its unique advantages and applications:

1. Cantilever Snap Joint:
- One of the simplest forms of snap joints.
- Involves a thin beam-like extension on the male component that flexes during assembly.
- Commonly seen in lids, covers, closures, and other similar applications.

2. Torsion Hinge Snap Joint:
- Uses a torsional or rotational motion to join the male and female components.
- Provides a secure connection while allowing flexibility for opening and closing movements.
- Widely used in enclosures, clamshells, and cases requiring repeated access.

3. Annular Snap Joint:
- Utilizes a circular snap feature, also known as a snap ring or retaining ring.
- Provides a 360-degree engagement, ensuring a strong connection between the components.
- Often employed in bottle caps, containers, and other sealing applications.

4. Living Hinge:
- Involves a thin, flexible web-like hinge that connects the two parts together.
- Enables repeated bending without deformations or failure.
- Frequently found in foldable designs like boxes, packaging, and folding chairs.

Advantages of Snap Joints for Prototype Plastic Parts:

Snap joints offer several advantages when used in the production of prototype plastic parts:

1. Cost-effectiveness: Snap joints eliminate the need for additional fasteners or assembly hardware, reducing overall material costs.

2. Easy Assembly and Disassembly: Snap joints facilitate quick and simple assembly, enabling rapid prototyping iterations and adjustments. Disassembling parts is equally effortless, allowing easy repair or replacement if necessary.

3. Versatility: The different types of snap joints accommodate a wide range of design requirements, making them suitable for various applications across industries.

4. Aesthetics: Snap joints can be incorporated into the design seamlessly, preserving the visual appeal of the finished product.

Production of Prototype Plastic Parts with Snap Joints:

To produce prototype plastic parts using snap joints, manufacturers employ Computer Numerical Control (CNC) machining techniques along with injection molding technology. Here's a step-by-step overview of the production process:

1. Conceptualization and Design:
- Identify the purpose and specifications of the prototype part.
- Create a 3D model using CAD software, considering the type of snap joint suitable for the application.

2. Material Selection:
- Choose an appropriate plastic material compatible with CNC machining and injection molding processes.
- Consider factors such as durability, flexibility, temperature resistance, and cost.

3. CNC Machining Preparation:
- Convert the 3D model to machine-readable G-code instructions.
- Set up the CNC milling machine with the selected cutting tools and required parameters.

4. CNC Machining:
- Load the plastic material into the CNC machine, ensuring proper fixturing for stability during the machining process.
- Execute the programmed G-code instructions to accurately carve out the components' shapes and features.
- Pay close attention to precise tolerances and surface finishes so that the snap joints function optimally.

5. Injection Molding Preparation:
- Create a mold cavity that will give the desired shape to the prototype part.
- Consider factors like gate location, ejection system, and cooling channels.
- Ensure the mold can accommodate the snap joint geometry in both male and female parts.

6. Injection Molding:
- Heat the selected plastic resin until molten, then inject it into the prepared mold cavity under high pressure.
- Allow the molten plastic to cool and solidify within the mold.
- Open the mold to release the newly formed prototype part, including the snap joint feature.

7. Post-processing:
- Remove any excess material or remnants from the manufacturing process using methods such as trimming or sanding.
- Inspect the finished part for quality control, ensuring the snap joint functions correctly and fits securely with other components.


Snap joints provide an efficient and cost-effective solution for assembling prototype plastic parts. Their versatility, ease of use, and compatibility with various industrial applications make them invaluable in rapid prototyping processes. By understanding the different types of snap joints and incorporating them wisely in the design, manufacturers can produce functional and visually appealing prototype plastic parts efficiently through CNC machining and injection molding techniques. With snap joints, the possibilities for creating innovative products are limited only by imagination! CNC Milling CNC Machining