Custom Rubber Washers Gaskets

Material Selection and Compound Formulation
The performance of a rubber washer or gasket is fundamentally determined by its elastomer compound. We process a variety of base polymers, each selected for distinct environmental resistances:

Nitrile (NBR): Standard for petroleum-based oils, fuels, and hydraulic fluids.

EPDM: Preferred for outdoor applications, hot water, steam, and weathering due to its ozone and UV resistance.

Silicone (VMQ): Utilized for extreme temperature ranges (-60°C to +230°C) and food-grade or medical applications.

Neoprene (CR): Offers moderate oil resistance combined with good mechanical strength and flame retardancy.

Fluoroelastomer (FKM/Viton): Deployed in highly aggressive chemical environments and sustained high-heat conditions.

Compounding is performed in-house to ensure batch consistency. Raw polymers are mixed with specific ratios of carbon black, plasticizers, and curing agents. This internal control allows us to adjust Shore hardness, typically ranging from 40 to 90 Shore A, to match the compression requirements of the target gland design.

Manufacturing Methods: Die Cut vs. Molded
The production method is determined by part geometry, volume requirements, and tolerance needs.

Die-Cut Washers: For flat gaskets and simple washers, we utilize steel-rule dies or solid steel dies to punch components from vulcanized rubber sheets. This method is highly efficient for high-volume production of standard profiles. The rubber sheet is first cured in large platens, then precision-cut. Edge quality is maintained through regular die sharpening schedules.

Molded Gaskets: For complex geometries, non-standard thicknesses, or parts requiring molded-in features (such as ribs or lips), compression or transfer molding is utilized. Custom molds are machined to exact specifications. Molding allows for tighter control over the Z-axis (thickness) and can produce parts with integrated sealing lips that cannot be achieved through die cutting.

Dimensional Tolerances and Quality Control
Rubber is a compressible material, and its dimensions can be affected by curing shrinkage and post-cure relaxation. We apply industry-standard tolerance charts (such as ISO 3302-1 or RMA A-A-59601) based on the part's cross-sectional diameter and material hardness.

Quality assurance protocols include:

Visual Inspection: Checking for flash, parting line defects, porosity, and contamination.

Dimensional Verification: Using optical comparators, pin gauges, and durometers to verify inner diameter, outer diameter, thickness, and hardness.

Compression Set Testing: Periodically testing cured compounds to ensure the material will recover its shape after prolonged compression, which is critical for long-term sealing force.

Design for Manufacturability
While we can produce custom designs, certain geometric considerations improve both manufacturability and sealing performance. We recommend maintaining uniform cross-sections where possible to prevent uneven curing and internal stresses. Sharp internal corners should be radiused to prevent tearing during installation and to facilitate mold release. For die-cut washers, the minimum flange width should be sufficient to prevent tearing during the punching process.

When designing for compression, engineers must calculate the appropriate squeeze percentage. Typically, a 15% to 30% compression is optimal for static seals; exceeding this can lead to excessive stress and premature failure.

Secondary Processing and Finishing
Depending on the application, raw rubber parts may require secondary operations. We offer deflashing services, including cryogenic deflashing for complex molded gaskets, to remove parting line flash without damaging critical sealing surfaces. Surface treatments, such as PTFE coating or lubricant application, are available to reduce friction during assembly in dynamic applications.

Engineering Support and Documentation
Custom sealing is an application-specific discipline. Our engineering team reviews customer drawings to identify potential manufacturability issues or material mismatches before tooling is commissioned. Upon production, we provide comprehensive documentation, including First Article Inspection Reports (FAIR), material test certificates, and dimensional data, ensuring full traceability for regulated industries.

This technical overview reflects our standard operating procedures for custom rubber washers and gaskets. Specific project requirements should be submitted for a detailed engineering review and quotation.