How to Chose the Correct Size for Silicone Pull Plugs

How to Chose the Correct Size for Silicone Pull Plugs

When masking through holes, silicone pull plugs, washer pull plugs, and chamfer pull plugs are your best options to ensure a clean and effective masking process. Proper sizing is crucial to guarantee the quality of your powder coating, E-coating, or plating processes. Here's a straightforward guide on selecting the correct silicone pull plug size to achieve optimal masking results.

 

Step 1: Determine the Internal Diameter (ID)

Firstly, you need to know the internal diameter (ID) of the threaded hole you're masking. There are two easy ways to determine this:

  • Thread Chart: Consult a thread chart to find the internal minor diameter for threaded holes of common Standard and Metric threads. You can check out our metric thread size chart here.

  • Digital Caliper: Measure the internal minor diameter of the hole directly using a digital caliper.


Step 2: Selecting the Correct Pull Plug Size

Once you have the internal diameter, select a silicone pull plug that's slightly larger to ensure a tight seal. Recommended oversize percentages differ for E-coating, anodizing and powder coating:

  • For E-Coating and Anodizing: Choose a plug approximately 15% larger than the hole's ID to ensure a robust seal and prevent leaks.

  • For Powder Coating: Choose a plug approximately 10% larger than the hole's ID for ease of installation and removal.


Example Calculations:

E-Coating and Anodizing Example:

  • Hole ID: 0.200" (5.08 mm)

  • Recommended plug size: 0.200" × 1.15 = 0.230" (5.84 mm)

Powder Coating Example:

  • Hole ID: 0.200" (5.08 mm)

  • Recommended plug size: 0.200" × 1.10 = 0.220" (5.59 mm)

 

Masking Chamfered Holes and Leading Threads

If protecting the chamfered area (countersink) and leading threads is essential, chamfer pull plugs are ideal. These plugs are designed with softer rubber to provide enhanced sealing around the chamfer and leading threads, ensuring both areas are effectively masked.

 

Masking Contact Areas Around Holes

When masking the contact area around a hole is necessary, washer pull plugs are an excellent choice. These plugs effectively protect the area surrounding the hole from coating, ensuring clean and uncoated contact surfaces essential for grounding or mechanical assembly. > Shop our washer pull plugs.


Conclusion

Choosing the correct silicone pull plug size is straightforward when you follow these steps. Accurate measurement and selecting the appropriate oversize ensures you achieve the perfect seal for your finishing processes. If you need additional help determining the best masking solutions for your applications, don't hesitate to contact our experts at MaskingSupply.com—we're here to help!

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