How to choose caps and plugs

Choosing the right cap or plug to protect your application can be challenging. Our caps & plugs application guide provides an easy way to choose the perfect solution by thread or hole size. Start by determining whether you need a cap or a plug, identify your application’s thread or hole size, then use the charts to select the Essentra product that will work best for you.

Our application guide will provide multiple solutions for your needs, so if you’re not sure which one will work best, request free samples today to ensure proper fit and function.

Download Caps and Plugs Application Guide PDF

What plastics are used for caps and plugs?

There are two main types of thermoplastics used to make caps and plugs. Firstly, amorphous thermoplastics, which are flexible and can be joined onto other materials. And secondly, semi-crystalline thermoplastics which are suited to heavy duty usage, cope well with friction and are resistant to cracking and wear. Nylon and LDPE are both examples of semi-crystalline thermoplastics.

Both types of thermoplastic can be used for commodity, engineering and high-performance purposes.

How to choose the right cap or plug

Consider your environment

There are various environmental factors to consider when protecting your application:

• Contamination - Are dirt and dust present?
• Temperature - At what temperature range is your application operating?
• Vibration - Is your application exposed to vibration or movement?
• Pressure – Are there any type of air or fluid pressure testing requirements?

Understand your application

Working with multiple applications can bring different variables. First, think about whether you need to protect or mask:

• Protection – Consider what part requires protecting and how the cap or plugs needs to perform. For example, if you are protecting a profile with an interior thread, you may select a threaded plug or if the application requires shielding against entry or escape of liquids, then an o-ring could be applied.
• Masking – Consider the surface area and the complexities of the masking process, which can include painting, blasting or high-temperature drying. For example, if you are masking a number of holes in a high-temperature environment, you may select a high-temperature flangeless silicone plug that includes tapered rings to allow a variety of hole diameters to be masked.

Identify the right material

One of the most critical environmental factors to consider is whether or not your application is exposed to heat. If heat tolerance is required, consider a high temp vinyl, EPDM or silicone cap or plug which can operate safely from 425° F up to 600° F.

Another consideration is whether or not the cap or plug is required to withstand a high impact environment. Softer materials such as PVC and EPDM are more flexible to impact versus LDPE or HDPE.

Think about your production process

Understanding your production process allows you to consider how caps and plugs can be applied. These can vary from manual to tool-based processes.

A push fit cap or flanged plug can be applied to fit multiple profiles. This allows for fast hand application, which is essential if you are looking to save time. For tool based processes, a cross head threaded plug can be used.

Consider the removal process

Ease and speed of removal might be a factor for your production environment. Protection for threads or profiles must be carefully removed, which may take time. Using a push fit product versus a threaded one can save time on removal, which saves time in your production schedule. To increase ease of removal, consider a cap or plug with an ergonomic pull tab or flange, which can inject speed and efficiency of the removal process.
 

Do I need a cap or a plug?

• Caps fit snugly on the outside of a component to protect external threaded and non-threaded ends
• Plugs grip the inside of a component to protect internal threads or holes
• Both protect against dirt and dust from entering your component

Download Caps and Plugs Application Guide PDF

Caps and Plugs applications

Caps and plugs prevent dirt, dust, moisture, liquids and any other contaminants from entering the opening during manufacturing, masking, storage and transportation. Some can be used multiple times and many are versatile enough for different stages in processes. We recommend that you try before you buy – ask us for free samples.

Caps and Plugs for protection during storage and transportation

Caps and Plugs for protection against liquid ingress

Caps and Plugs for easy application and removal

Caps and Plugs for end use

Caps and Plugs for masking

Materials react differently to processes, so before you actually start masking, request a free sample of the plug or masking cap for painting or for any masking process that you’re interested in. This will allow you to test it. Find out more about masking materials in our guide, Masking Materials Selection Guide.

You’ll also find masking tape convenient for areas that caps or plugs can’t cover. Find out more in our guide, How to choose the right high-temperature masking tape.

Thermoplastics for Caps and Plugs

Thermoplastics are a popular material choice for caps and plugs due to their versatility, durability, and cost-effectiveness. These materials can be easily molded into various shapes and sizes, ensuring a precise fit for a wide range of applications. Common thermoplastics such as polyethylene (PE), polypropylene (PP), and PVC offer excellent resistance to chemicals, moisture, and temperature variations, making them ideal for industrial, automotive, and packaging needs. Their lightweight nature also reduces transportation costs without compromising on strength. Additionally, thermoplastics are recyclable, aligning with sustainability goals. Whether you require flexibility, rigidity, or a blend of both, thermoplastics provide the adaptability needed to meet diverse performance and aesthetic requirements for caps and plugs.

How resistant to temperature are thermoplastics?

In the applications above, the temperature that the plastic component will need to withstand will vary. There are three classifications for temperature resistance:

• Commodity products are temperature resistant up to 70°C
• Engineering quality plastic caps and plugs can withstand up to 150°C
• High performance are the strongest plastic components, being able to maintain solidity at over 150°C

Download free CADs and try before you buy

Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen exactly what you need. If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.

Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.com or speak to one of our experts for further information on the ideal solution for your application 800-847-0486.

Download Caps and Plugs Application Guide PDF