Masking cap
Masking caps are cylindrical rubber products that are fitted over bolts, screws, pins, holes, and contacts during painting or plating to prevent coating or plating from adhering to them. The elasticity of the cap holds it in place on the target part, and after processing, removing it leaves threads and conductive areas ready for use. Silicone, which offers excellent heat resistance, is the main material, and EPDM is also used depending on the application. Shapes include straight, flanged, and ribbed types that resist slipping off. In addition to powder coating and baking finish processes, they are used to prevent paint intrusion into paint line hanger sockets and unused contacts.
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Masking cap
Socket Cap for BHL
A silicone cap that prevents paint from entering the socket of the hanger and protects the contacts. For BHL, available in two types: G10 and G10X.
Iwata Seisakusho Co., Ltd.
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Masking cap
Socket Cap for BH R65
Silicone socket cap for BH R65. Available in red and orange, it prevents paint from entering the socket.
Iwata Seisakusho Co., Ltd.
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Masking cap
Socket Cap for BH R58
Model: BHG20
Silicone socket cap for BH R58. Green, available in both box and pack packaging.
Iwata Seisakusho Co., Ltd.
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Masking cap
Rib-Equipped Cap GAQM6X30
Model: GAQM6X30
Silicone masking cap for frames, used for masking unused contacts.
Iwata Seisakusho Co., Ltd.
How to choose Masking cap
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1. Check the relationship between fitting diameter and inner diameter
The basic principle is to make the cap's inner diameter slightly smaller than the diameter of the bolt or pin, relying on rubber stretch to hold it. If the inner diameter is too large, the cap may come off during baking or transport; if too small, it becomes difficult to fit and may tear. Verify the fitting diameter specification against the actual dimensions of the target.
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2. Assess fit using the inner diameter dimension
Even with the same fitting diameter, the inner diameter setting changes the tightness of the grip. For threaded parts, base the selection on the outer diameter of the thread crest. In processes such as powder coating, where paint tends to wrap around, choose a dimension with enough interference to prevent gaps.
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3. Secure the required length with overall length
The overall length determines the protected range. Measure the thread engagement length or the exposed length of the contact and select a length that fully covers it. If the cap is too long, it will mask surfaces that should be painted, so also confirm the boundary position for the color division.
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4. Select a material that withstands the baking temperature
Powder coating and baking finishes expose parts to high temperatures in the oven, so choose a product whose heat resistance exceeds the process baking temperature and holding time. Silicone is generally preferred where heat resistance is important. If heat resistance is insufficient, the cap may soften or deform, allowing paint to penetrate.
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5. Confirm the material suits the process and chemicals
Silicone offers excellent heat resistance, while EPDM is used for weather resistance and resistance to certain chemicals. If the cap contacts plating or pretreatment chemicals, verify its resistance to those chemicals. For repeated use, ease of peeling off the coating is also a factor in material selection.
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6. Choose a shape that suits the mounting target
Straight types suit bolts and pins in general, and flanged types suit locations where the bearing surface also needs covering. Ribbed types resist slipping off and are used for masking contacts. Model-specific products exist for paint hanger sockets, and attention must be paid to differences in insertion direction (horizontal, or vertical and horizontal).
This guide was written by AI based on the listed products' documents and specification items. Check each manufacturer's documents before adopting.