Jefferson Rubber Works, Inc. specializes in custom rubber injection molding, liquid silicone molding, and rubber-to-metal bonding. We support OEMs during early-stage design, helping evaluate material performance, molding tolerances, and regulatory requirements before tooling is finalized.
Tooling represents a significant upfront investment. Identifying material or performance issues after initial trials can require costly revisions and delay production. Understanding elastomer options early in the design process helps reduce this risk.
Material Performance & Environmental Compatibility
Material selection is typically driven by environmental exposure, chemical compatibility, and mechanical performance requirements.
When should I specify EPDM vs. Nitrile?
EPDM provides strong resistance to weathering, ozone, and polar fluids such as water and coolant, making it suitable for outdoor and thermal cycling applications. However, it is not compatible with petroleum-based fluids.
Nitrile (NBR), in contrast, is commonly used in fuel systems and hydraulic applications due to its resistance to oils and hydrocarbons, but it degrades under prolonged UV exposure.
What dictates LSR vs. traditional silicone selection?
Liquid Silicone Rubber (LSR) uses automated injection molding for rapid 30- to 90-second cure cycles. While upfront tooling costs more, LSR drives down per-unit labor costs and holds tight ±0.005″ tolerances. It becomes the most economical choice when annual volumes cross 10,000 units. Traditional High Consistency Rubber (HCR) suits lower volumes, where keeping tooling expenses low matters more than cycle-time speed.
How does chemical compatibility dictate selection?
Chemical exposure is a primary driver of rubber material selection. Polymer compatibility must match the operating environment:
- Acids: Fluoroelastomers (FKM) withstand concentrated acids; EPDM handles dilute variants.
- Bases: EPDM and butyl rubber withstand alkaline solutions; Nitrile degrades.
- Solvents: FKM resists aromatic hydrocarbons; EPDM swells in aliphatic solvents.
- Steam: EPDM and silicone maintain physical properties during steam sterilization.
Achieving Precision Tolerances in Rubber Molding
Achievable molding tolerances depend on material properties, part geometry, and molding process.
What tolerances are achievable?
Standard commercial tolerances follow ASTM D3767 guidelines. Tighter tolerances can be achieved through controlled molding processes such as LSR injection or transfer molding.
Higher durometer materials tend to hold tighter tolerances, while softer compounds are more prone to deformation during curing. Mold design accounts for shrinkage, filler content, and cross-section thickness.
The Rubber-to-Metal Bonding Process
How does the bonding process work?
During molding, the elastomer cures onto the prepared insert under controlled heat and pressure conditions.
- Substrate Prep: Grit blasting or chemical etching creates mechanical anchor points.
- Adhesive Application: Operators apply a primer matched specifically to the elastomer’s chemistry.
- Cure Bonding: The rubber cures onto the insert under immense heat and pressure.
We validate this chemical bond through destructive 180° peel testing per ASTM D429, confirming the rubber tears before the adhesive layer fails. Automotive applications generally demand peel strengths exceeding 15 lb/in.
Regulatory Compliance & Certification Standards
What makes rubber FDA-compliant?
FDA-compliant rubber must meet requirements outlined in 21 CFR 177.2600 for food contact applications. This includes using approved base polymers, verifying extractables, and maintaining material traceability.
Jefferson Rubber Works maintains ISO 9001 and ISO 13485 certifications, supporting quality control and traceability in regulated applications.
Do military applications require specific callouts?
Defense contractors specify exact material callouts, such as MIL-R-83248 for general elastomers or AMS-R-83485 for aircraft-grade silicone. We stock compounds meeting common military specifications and formulate custom blends for extreme environments.
Design Rubber Components with Manufacturing in Mind
Rubber material selection and process decisions directly impact part performance, durability, and cost at the production scale.
Jefferson Rubber Works reviews part geometry, material compatibility, and regulatory requirements early in the design process to identify potential issues before tooling is committed.
Request a material selection consultation to discuss your application, or view our Engineering Design Guide for detailed material comparisons and design considerations.