Tech Knowledge Base

When engineers specify a custom silicone part, shore hardness is often treated as an afterthought — chosen by intuition rather than engineering logic. Yet hardness directly governs compression set, dynamic fatigue life, contact sealing force, and even the acoustic signature of a keypad click. Getting it wrong typically means expensive mold rework or, worse, a field failure. This guide demystifies Shore A durometer for silicone rubber, giving you a practical framework to specify the right hardness the first time.

1. What Is Shore A Durometer and How Is It Measured?

Shore A durometer is the standardized measurement of indentation hardness for soft elastomers, defined by ASTM D2240 and ISO 868. The test presses a truncated cone indenter (1.79 mm tip diameter) into the material surface under a 822 g spring load for 15 seconds. The penetration depth is converted to a 0–100 scale — higher numbers mean harder material. For silicone rubber, the useful engineering range spans roughly Shore A 10° to Shore A 80°; anything softer than 10° is gel-like, and materials harder than 80° typically transition into rigid thermosets.

Key measurement conditions that can shift your readings by 3–5 Shore A points: specimen thickness must be ≥6 mm (stack thin sheets if needed), ambient temperature should be 23 ± 2°C, and readings should be taken at least 12 mm from any edge. Always specify tolerances — ±5 Shore A is typical for compression-molded silicone; ±3 Shore A is achievable with tight process control.

2. Hardness Range Reference Table

The table below maps Shore A ranges to common silicone product families. Use it as a starting framework — consult your material engineer to verify suitability for your specific load, chemical environment, and temperature range.

3. Key Factors Affecting Hardness Selection

Sealing Pressure: A softer compound (Shore A 30°–50°) requires less clamping force to achieve a gas-tight seal, reducing bolt loading on thin-walled housings. However, higher system pressure demands higher hardness (Shore A 60°–70°) to resist extrusion under the pressure differential. Match hardness to your working pressure and groove geometry using the O-ring extrusion chart from Parker or Apple Rubber.

Dynamic vs. Static Applications: Static seals can use softer compounds that maximize contact area. Dynamic reciprocating or rotating seals must balance friction, wear resistance and compliance — typically Shore A 50°–65° for reciprocating, and Shore A 60°–75° for rotary shaft applications where abrasion is a concern.

Mating Part Clearance and Surface Finish: For over-molded or press-fit seals, the harder the silicone, the greater the interference force required for assembly. Ultra-soft compounds (Shore A 10°–20°) are extremely sensitive to surface scratches and irregular clearances. Verify your mating plastic or metal Ra surface finish against the silicone hardness spec.

Operating Temperature: Silicone rubber retains flexibility across –60°C to +230°C, but hardness shifts with temperature. A Shore A 50° compound at 23°C may read effectively Shore A 35° at 150°C and Shore A 65° at –30°C. For extreme-temperature applications, model the expected hardness shift to ensure your seal will still engage at both ends of the thermal cycle.

4. Jun-Hsiang's Available Hardness Range & Customization

Jun-Hsiang Enterprise stocks and compounds silicone rubber across the full Shore A 10° to 80° spectrum. Our in-house mixing lab can formulate custom Shore A targets in 5-degree increments with tolerances as tight as ±3 Shore A. We support:

• Standard HTV (High-Temperature Vulcanization) silicone in all common hardnesses
• LSR (Liquid Silicone Rubber) two-part formulations for Shore A 20°–60° range
• Specialty compounds: medical-grade, food-grade, electrically conductive, and low-compression-set grades
• Dual-hardness co-molding for products that need a hard structural core bonded to a soft sealing lip

Before finalizing your drawing, our engineering team will review your application parameters — sealing pressure, dynamic cycle count, temperature range, and mating material — and recommend the optimal hardness grade with supporting data.

Ready to specify your silicone hardness? Contact our engineering team with your application details for a free technical consultation and quotation.

Walk into any kitchenware trade show and you will see hundreds of booths claiming their silicone baking mats, spatulas, and baby bottle nipples are "FDA certified" or "LFGB approved." In reality, these certifications are far more nuanced than a simple pass/fail stamp — and the difference matters enormously if you are a brand manager, product engineer, or procurement specialist responsible for market access in North America, Europe, or Asia. This guide gives you the technical grounding to distinguish genuine food-contact compliance from marketing noise.

1. FDA 21 CFR 177.2600 — The US Standard

The US Food and Drug Administration regulates food-contact materials under the Code of Federal Regulations Title 21. For silicone rubber, the critical regulation is 21 CFR 177.2600, which covers "Rubber articles intended for repeated use" in contact with food. To comply, the silicone compound must:

• Be composed only from FDA-listed ingredients (base polymers, crosslinkers, fillers, catalysts, colorants)
• Pass total extractable limits for chloroform-soluble, n-hexane-soluble, and aqueous-phase extractables
• Pass a color additive test if pigments are used

Note that FDA compliance is self-declared — the FDA does not issue certificates. A supplier claiming "FDA certified" is technically using imprecise language. The correct statement is "formulated to comply with FDA 21 CFR 177.2600," backed by third-party extractables testing from an accredited laboratory.

2. LFGB §30/§31 — The German/EU Standard

The German Food and Feed Code (Lebensmittel- und Futtermittelgesetzbuch, LFGB) Sections 30 and 31 govern food-contact articles sold in Germany and, by extension, are widely adopted across the European Union as a de facto premium standard. LFGB testing is significantly more stringent than FDA in several respects:

• Sensory testing: The silicone part must not impart odor or taste to food simulants (water, 3% acetic acid, 15% ethanol, olive oil) at elevated temperatures.
• Migration limits: Primary aromatic amines (PAA), heavy metals, and specific volatile siloxanes (especially D4 and D5 cyclic siloxanes) are tested against strict migration limits.
• Peroxide crosslinker residuals: Products crosslinked with peroxide must pass additional extractables tests for decomposition residues.

LFGB certification IS issued by accredited test institutes (e.g., SGS, TÜV, Intertek), making it a verifiable, third-party document — a meaningful differentiator for European market access.

3. EC Regulation 1935/2004 — The EU Framework

EC 1935/2004 is the overarching European Union regulation for all food-contact materials. It establishes the general safety principle: materials must not transfer their constituents to food in quantities that could endanger human health, bring about unacceptable changes in composition, or impair flavor/odor. Unlike LFGB, EC 1935/2004 does not specify test methods for silicone — it relies on implementing measures (such as the plastic regulation EU 10/2011) or, for silicone specifically, member-state regulations like LFGB. Demonstrating EC 1935/2004 compliance typically requires a Declaration of Compliance (DoC) supported by appropriate migration testing.

4. SGS and Third-Party Testing — What to Ask For

SGS, Bureau Veritas, Intertek, and TÜV Rheinland are the major accredited laboratories that issue food-contact test reports. When evaluating a silicone supplier, ask for:

• Full test report (not just the summary page) issued by an accredited lab — verify the accreditation number
• Scope of testing: which food simulants were used, at what temperature and duration
• Compound identification: the test should reference the exact compound formulation/batch, not a generic material family
• Date of testing: food-contact reports are typically valid for 2–3 years; request a re-test for older compounds

5. How to Identify Genuine Food-Grade Silicone

A simple field test: perform the "pinch test" — stretch and twist the silicone sharply. If white filler (typically calcium carbonate or titanium dioxide, common in low-cost non-silicone TPE knockoffs) appears through the stretched area, the material is likely not pure silicone. Genuine food-grade silicone should remain translucent or maintain its original color throughout. However, the only reliable verification method is laboratory chemical analysis and a traceable Certificate of Conformance from the compounder.

6. Jun-Hsiang's Food-Grade Silicone Capabilities

Jun-Hsiang maintains food-grade HTV silicone compounds that are formulated to comply with both FDA 21 CFR 177.2600 and LFGB §30/§31. Our compounds are manufactured under segregated processing conditions to prevent cross-contamination with non-food-grade materials. We can provide:

• Third-party test reports from SGS or equivalent accredited laboratory upon request
• Declaration of Compliance for EC 1935/2004 as required for EU market access
• Food-grade colorants in a full palette — all pigments selected from FDA/LFGB-compliant approved lists
• Production in Shore A 20°–70° to cover baking molds, seals, bottle nipples, and kitchenware components

Sourcing food-contact silicone components? Contact Jun-Hsiang with your product specifications and target market to receive compliance documentation and a competitive quotation.

Engineers frequently underestimate the engineering depth behind a silicone O-ring. A simple circular cross-section part must maintain a leak-free interface across tens of thousands of pressure cycles, survive aggressive cleaning agents, and fit precisely within a groove machined to ±0.01 mm. When a standard off-the-shelf O-ring doesn't meet your dimensional, material, or hardness requirements, the path to a reliable seal runs through custom tooling and controlled manufacturing. Here is exactly how that process works.

1. When to Go Custom vs. Standard

Standard O-ring sizes (AS568 in the USA; JIS B2401 in Japan; ISO 3601 internationally) cover a wide range of cross-section diameters and inner diameters. Choose custom tooling when:

• Your groove dimensions fall between standard sizes, requiring a non-standard inner diameter or cross-section (e.g., 2.2 mm cross-section instead of the standard 1.78 mm or 2.62 mm)
• You need a material not available in standard O-ring stock (e.g., high-purity VMQ for semiconductor, FVMQ for low-temperature + fuel resistance, or electrically conductive silicone)
• Hardness tolerance is tighter than standard supply (±3 Shore A vs. typical ±5)
• You need a non-circular cross-section (D-ring, X-ring/quad ring, or custom profile seal)
• Your annual volume justifies tooling cost through per-unit savings and guaranteed material traceability

2. Five-Step Custom O-Ring Process

Step 1 — Design Review & DFM Analysis (1–3 business days): Submit your 2D drawing or 3D model. Our engineering team verifies groove geometry per ISO 3601-3 (housing/groove design standard), checks compression ratio (typically 15%–30% for static face seals; 10%–20% for radial seals), and flags any risk of extrusion, excessive squeeze, or installation damage. We return a DFM (Design for Manufacturability) report with any recommended modifications before committing to tooling.

Step 2 — Tooling Design & Fabrication (7–14 business days): We design a cavity mold in S45C or P20 steel (hardened H13 for long-run precision tooling). Cavity count is optimized for your volume — typically 2+2 to 16+16 cavities. Flash-less mold technology minimizes post-mold trimming, which is critical for clean-room and food-contact applications. Tooling drawings are submitted to you for approval before machining begins.

Step 3 — First Article Sampling & Measurement (3–5 business days post-tooling): We produce a pilot run of 20–50 pieces and perform full dimensional inspection per your drawing: inner diameter (ID), cross-section diameter (CS), and surface finish (Rz). We also perform compression set testing (ASTM D395 Method B at your specified temperature) and hardness verification. A First Article Inspection Report (FAIR) is submitted for your approval.

Step 4 — Customer Approval & Process Lock (2–5 business days): You test the samples in your actual assembly and environment. Upon approval, we lock the process parameters — compound batch, curing time/temperature, press tonnage, and inspection criteria — into a Control Plan. Any future change requires a formal Engineering Change Notice (ECN).

Step 5 — Mass Production & Delivery (lead time per volume): Typical lead times: 10,000–50,000 pcs in 7–10 business days; 100,000–500,000 pcs in 14–21 business days. We ship with a Certificate of Conformance (CoC) and, for traceability-critical customers, individual batch QC data.

3. Required Drawing Parameters

To generate an accurate quotation and tooling design, provide the following on your drawing:

• Inner Diameter (ID) with tolerance (e.g., Ø25.00 ±0.13 mm)
• Cross-Section Diameter (CS) with tolerance (e.g., Ø3.00 ±0.10 mm)
• Material: compound family, any certifications required (FDA, LFGB, USP Class VI)
• Hardness: Shore A target ± tolerance
• Surface finish: any requirements for smooth bore, post-cure, or PTFE coating
• Annual volume and target unit price (helps us optimize cavity count)

4. Material Comparison: Silicone vs. Alternative Elastomers

5. Jun-Hsiang Custom O-Ring Capabilities

Jun-Hsiang has produced custom silicone O-rings and profile seals for customers across semiconductor equipment, food processing, medical device, and aerospace connector applications. Our capabilities include:

• Inner diameter range: Ø2 mm to Ø1,500 mm (very large seals via splice-join process)
• Cross-section diameter: 0.8 mm to 20 mm
• Hardness: Shore A 20°–80°, tolerance ±3 Shore A
• Material options: Standard VMQ, high-purity VMQ (semiconductor grade), FVMQ, EPDM, FKM — all compound options available
• Certifications available: FDA, LFGB, USP Class VI, RoHS
• Flash-free, post-cured, PTFE-coated options available

Have a custom sealing requirement? Send us your drawing or inquiry and receive a tooling cost estimate and DFM feedback within 2 business days.

Every piece of production machinery — from CNC machining centers and injection molding presses to precision measurement instruments and semiconductor wafer handlers — generates or experiences vibration that must be managed. Unchecked vibration cascades into thermal growth, positional errors, bearing wear, and structural fatigue. The anti-vibration foot (or leveling mount) is the last line of defense between the machine and the floor. Choosing the wrong one degrades the machine's performance; choosing the right one can extend its service life by years. This guide gives engineers and procurement specialists the technical framework to make that choice correctly.

1. Vibration and Damping Fundamentals — Why Silicone Outperforms Metal Springs

A vibration isolation system works by ensuring the mount's natural frequency (fn) is significantly lower than the disturbing frequency (fd) of the machine. The isolation efficiency improves as the ratio fd/fn increases. Metal coil springs achieve very low natural frequencies (2–5 Hz) but have nearly zero internal damping — they transmit resonant surges and high-frequency structure-borne noise freely. Silicone and natural rubber mounts, by contrast, exhibit:

• Internal damping (loss factor δ = 0.05–0.15 for silicone): Energy is dissipated as heat within the polymer matrix rather than transmitted to the structure.
• Broad frequency response: Silicone mounts attenuate both low-frequency displacement (10–30 Hz machine harmonics) and high-frequency acoustic noise (100–2000 Hz).
• Temperature stability: Silicone maintains consistent stiffness from –50°C to +200°C, unlike natural rubber (which hardens below 0°C) or EPDM (limited at high temperature).
• Chemical resistance: Silicone resists cutting oils, coolants, and cleaning solvents common in machine shop environments.

2. Load Calculation Method

Before selecting a mount, calculate the load per foot using this formula:

Load per foot = (Machine weight × Dynamic load factor) / Number of mounting feet

Typical dynamic load factors: 1.5× for smoothly running motors and fans; 2.0× for reciprocating compressors and presses; 2.5–3.0× for impact machinery such as punch presses or drop hammers. Always round up to the next available rated capacity — operating at 80–90% of rated load is best practice to avoid premature creep and compression set.

Example: A 2,000 kg CNC machining center on 4 anti-vibration feet with a dynamic factor of 2.0 requires: (2,000 × 2.0) / 4 = 1,000 kg per foot minimum rated load. Select a mount rated at ≥1,200 kg to maintain the 80% margin.

3. Hardness Selection for Vibration Frequency

Mount hardness governs the stiffness and therefore the system natural frequency. As a general rule:

• Low-frequency disturbances (10–30 Hz): Use softer mounts, Shore A 30°–45°. Lower stiffness gives a lower fn, improving isolation at the machine's fundamental frequency and its harmonics.
• High-frequency structure-borne noise (100–2000 Hz): Use medium-hardness mounts, Shore A 50°–65°. Higher stiffness provides better load support and prevents excessive deflection that could introduce secondary resonances.
• Impact and shock isolation: Shore A 40°–55° with a higher damping formulation; the mount must absorb kinetic energy rapidly without bouncing.
• Mixed applications (most production equipment): Shore A 50°–60° is the most common specification, balancing isolation efficiency, load capacity, and service life.

4. Material Comparison for Anti-Vibration Applications

5. Mounting Styles

Anti-vibration mounts come in several mechanical configurations:

• Compression (sandwich) type: Rubber pad bonded between two metal plates. Best for pure vertical loads. Easy installation, lowest cost.
• Shear type: Rubber in shear mode; provides lower natural frequency for the same hardness. Used where horizontal isolation is also needed.
• Leveling feet (conical/cylindrical): Combined leveling bolt and rubber element. Standard for CNC machines; allows height adjustment ±20 mm without removing the machine.
• Metal-bonded anti-vibration pad: Silicone rubber vulcanized to a steel insert with threaded studs top and bottom. Highest load capacity; used in heavy presses and generators.

6. Jun-Hsiang Custom Anti-Vibration Pad Capabilities

Jun-Hsiang manufactures custom silicone-to-metal bonded anti-vibration components. Our experience includes pads for semiconductor wafer handling robots, medical imaging tables, precision laser systems, and heavy industrial presses. We offer:

• Load range: 50 kg to 5,000 kg per mount
• Rubber hardness: Shore A 30°–70°, custom formulations for specific damping ratio targets
• Metal insert materials: carbon steel, stainless steel (SUS304/SUS316), aluminum alloy
• Surface treatment: zinc plating, powder coating, anodizing
• Testing: compression set, pull-out force, stiffness characterization per ASTM or DIN standards

Need a custom anti-vibration solution? Contact our engineering team with your equipment weight, operating frequency, and environmental conditions for a tailored recommendation.

A single contamination particle measuring 0.1 µm on a 300 mm silicon wafer can cause a die failure worth hundreds of dollars. In a leading-edge fab producing advanced logic chips at 3 nm nodes, the economic impact of a yield excursion traced to a contaminating seal can reach millions of dollars per day. This is not an exaggeration — it is the environment in which semiconductor equipment engineers specify their materials. Silicone seals used in this context face a standard of cleanliness and chemical stability that dwarfs any other industry. This article maps those requirements systematically by process area.

1. Fab Process Requirements by Station

Dry Etch (RIE/ICP/CCP) — HF, Cl₂, CF₄, SF₆, O₂ plasma: Seal materials face direct plasma bombardment on exposed surfaces and corrosive gas permeation through the seal body. Standard silicone (VMQ) is attacked by fluorine plasma, losing surface material in a process called "erosion." For fluorine-dominated chemistries, FFKM (perfluoroelastomer, e.g., Kalrez or Perlast) is the benchmark. For chambers with mixed chemistries including oxygen plasma, high-purity VMQ may suffice for secondary seals not directly plasma-exposed.

CVD/ALD (Chemical Vapor Deposition) — SiH₄, NH₃, TiCl₄, TEOS at 200–450°C: The dominant requirement here is high-temperature stability and near-zero outgassing. Seals must not release volatile siloxanes (D3–D6 cyclic oligomers), residual catalysts, or processing aids that could deposit on the wafer surface. High-purity VMQ with post-bake (secondary curing at 200°C for 4+ hours) dramatically reduces volatile extractables.

CMP (Chemical Mechanical Planarization) — Acidic or alkaline slurry + DI water: Seals in CMP equipment face abrasive slurry, pH ranges of 2–12, and continuous wafer-level mechanical action. High tensile strength silicone with good acid/alkali resistance; EPDM can substitute for CMP where temperatures are moderate.

Wet Clean — HF, H₂O₂, SC-1, SC-2 chemistry: Seals must resist concentrated HF (up to 49%) and hydrogen peroxide mixtures. Standard VMQ degrades rapidly in concentrated HF. FFKM is the only fully HF-compatible elastomer. For dilute HF applications, high-purity VMQ with a fluorocarbon surface treatment may extend service life.

2. Low Outgassing and Cleanliness Requirements

Outgassing is measured by NASA ASTM E595 standard: Total Mass Loss (TML) must be <1.0% and Collected Volatile Condensable Materials (CVCM) must be <0.10% after 24 hours at 125°C in vacuum. For semiconductor-grade seals, even stricter internal specifications are common — some equipment OEMs require TML <0.3% and CVCM <0.02%.

Key techniques to reduce outgassing in silicone seals:

• Post-cure (secondary vulcanization): Baking at 200°C for 4–8 hours in a circulating-air oven drives off residual peroxide decomposition products, low-molecular-weight cyclic siloxanes, and processing aids. This single step can reduce volatile extractables by 90%.
• High-purity base polymer: Specify VMQ compounds produced from ultra-high-purity polydimethylsiloxane with ion content (Na+, K+, Cl–) <1 ppm to prevent ion migration in gate dielectric layers.
• Clean-room molding: Parts should be molded, post-cured, inspected, and packaged in a controlled environment (ISO Class 6 or better) to prevent particulate contamination before installation.

3. Standard Silicone vs. High-Purity VMQ vs. FFKM

4. FPD Applications (TFT-LCD / OLED Panel Manufacturing)

Flat panel display (FPD) fabs face similar contamination challenges to semiconductor fabs, but at much larger substrate scales (Gen 8+: 2,200 × 2,500 mm). Key silicone seal applications include:

• Vacuum chuck pads and edge exclusion seals: Hold large glass substrates flat during CVD and photolithography. Must be soft (Shore A 20°–35°) for intimate contact with glass without marking, and must outgas minimally under process vacuum (<10⁻³ Torr).
• Glass transfer robot arm seals: End-effector suction seals that cycle thousands of times per day. Must resist vacuum fatigue and maintain consistent suction without particulate generation.
• Gate valve and chamber door seals: Must seal against process gases (SiH₄, NH₃) at temperatures up to 250°C. High-purity VMQ post-baked to <0.3% TML is the standard specification.

5. Jun-Hsiang Semiconductor-Related Capabilities

Jun-Hsiang has supplied silicone sealing components to equipment manufacturers serving Taiwan's semiconductor and FPD industry. Our relevant capabilities include:

• High-purity VMQ compounds processed in clean-room adjacent environments
• Post-bake secondary vulcanization at 200°C/4–8 hr for low-outgassing compliance
• Precision molding of O-rings, custom profile seals, and flat gaskets
• Cleanroom packaging in anti-static bags with lot traceability
• Hardness range Shore A 20°–70° for chuck pads through chamber door seals

Sourcing seals for semiconductor or FPD equipment? Contact our technical team with your application details, operating chemistry, and cleanliness requirements for a material recommendation and quotation.

In industrial precision protection and sealing applications, a material's chemical inertness and thermal limit directly determine the lifespan of components. When common seal materials like nitrile rubber (NBR) or standard silicone fail due to swelling upon contact with strong solvents or fuels, specialty fluoroelastomers become the only viable solution. While both Fluorocarbon (Viton/FKM) and Fluorosilicone (FVMQ) contain fluorine atoms, their physical properties and application scenarios differ significantly due to different backbone structures. Below is an in-depth comparison of these two specialty materials:

1. Fluorocarbon Rubber (Viton / FKM): The Shielding Standard for High Temperatures and Strong Corrosives

Viton (FKM) is a saturated carbon-chain elastomer copolymerized from fluorinated monomers:

• Chemical & Oil Resistance: FKM exhibits exceptional chemical stability, withstanding most hydrocarbons, diester-based lubricants, strong acids, high-concentration fuels, and organic solvents. Its chemical resistance leads all common rubber materials.
• Temperature Limits: Continuous operating temperatures range from -15°C to 220°C (with short-term peaks up to 250°C). It retains high mechanical strength and low compression set at high temperatures.
• Limitations: FKM has poor low-temperature elasticity. Below -15°C, it gradually loses flexibility and hardens (brittleness point at -20°C to -30°C), making it unsuitable for extreme cold or high-altitude aerospace applications. Additionally, it has weak resistance to ketones (such as acetone) and low-molecular-weight esters.

2. Fluorosilicone Rubber (FVMQ): The All-Weather Performer Combining Wide Temperature Range and Fuel Resistance

Fluorosilicone (FVMQ) is a copolymer modified by introducing fluorinated alkyl groups into the polysiloxane backbone, combining the advantages of both silicone and FKM:

• Chemical & Oil Resistance: Thanks to the protection of the fluorinated side chains, FVMQ offers excellent resistance to non-polar solvents, aviation fuels, lubricants, methanol fuels, and hydraulic fluids, with very low swelling.
• Outstanding Temperature Range (-60°C to 200°C): This is the core advantage of FVMQ. It maintains excellent softness and sealing flexibility at extremely low temperatures down to -60°C, while retaining continuous heat resistance up to 200°C.
• Limitations: FVMQ has high raw material costs and lower mechanical strength (tensile, tear, and abrasion resistance) compared to Viton (FKM). Thus, it is primarily used in static seals or low-dynamic precision gaskets.

3. Property Comparison Table: EPDM Foam vs. Silicone Foam

4. Jun-Hsiang Enterprise — Your Custom Special Rubber and Molding Partner

Specialty rubbers like Viton and FVMQ have narrow processing windows and are significantly harder to mold than standard rubbers. Jun-Hsiang Enterprise Co., Ltd. possesses over 30 years of mold engineering and custom formulation experience, providing highly cost-effective manufacturing:

• Custom Formulations & Hardness: We support Shore A 50° to 90° hardness adjustments and can customize compounds for specific anti-static or chemical-resistant specs.
• Rubber-to-Metal Bonding: Our dedicated metal surface treatment and adhesive application line allows us to bond Viton or FVMQ to metal substrates (stainless steel, brass, aluminum alloys) during molding. The bond strength exceeds the rubber's tensile limit, preventing delamination.

Whether you require prototyping, technical evaluation, or mass production, we provide complete B2B manufacturing services. Share your STEP/IGS files or physical samples with our engineering team for in-depth consultation.

In UAV hardware architecture, flight controllers, camera gimbals, and power systems are highly sensitive to high-frequency vibration and moisture. Precision silicone and rubber components, though small, function as the "invisible mechanical shield" that stabilizes flight, prevents water intrusion, and cushions landings. Below is a detailed design guide for silicone and rubber components across three core UAV application areas:

1. Gimbal Camera Dampers & Motor Mount Cushions (Vibration Isolation)

Propellers and motors spinning at high speeds (50Hz–200Hz) cause high-frequency jitter, resulting in the "jello effect" in aerial video.

• Gimbal Damping Balls: Must be designed with low-hardness (Shore A 30°–45°) high-damping (tan δ) silicone rubber. Its viscoelastic properties absorb micro-vibrations, while the shear and compression rigidity must be mathematically calibrated based on camera payload.
• Motor Mount Dampers: We recommend rubber-to-metal bonding. Covalently bonding custom NBR or FKM rubber to aluminum alloy motor mounts eliminates secondary assembly, isolates motor resonance, and prevents gyroscope signal distortion.

▲ Custom high-damping gimbal balls and metal-bonded motor mount dampers by Jun-Hsiang

2. Flight Controller Sealing & Dynamic Joint Bellows (Airtight Weatherproofing)

Industrial and delivery drones require all-weather operation, requiring them to perform under high-altitude freezing temperatures (-40°C or below) and rain.

• Waterproof Sealing Rings: Traditional elastomers harden and crack in subzero temperatures. LSR (Liquid Silicone Rubber) injection-molded gaskets provide excellent compression set resistance (< 10%) and thermal stability (-60°C to 250°C), achieving IP67/IP68 ingress protection.
• Servo Dust Boots: For dynamic joints in VTOL tilt-rotor drones, ultra-thin (0.3mm–0.5mm) high-tear silicone bellows protect internal servo gearboxes from rain and dust without adding rotational drag.

3. Landing Gear Buffers & Battery Slip Pads (Physical Protection)

• Landing Gear Pads: Engineered from high-wear, tear-resistant NBR or Polyurethane (PU) to absorb high impact forces during hard landings, preventing micro-fractures in carbon fiber arms.
• Battery Anti-Slip Pads: EPDM rubber provides high weather/UV resistance and maintains a high coefficient of friction under high aerodynamic forces, preventing battery shifts.

UAV Precision Component Materials Comparison:

Four. Jun-Hsiang — Your Engineering Partner for High-Reliability UAV Parts

Most UAV dampers and sealing components are custom-engineered. With over 30 years of OEM expertise, Jun-Hsiang Enterprise is equipped with Liquid Silicone Rubber (LSR) injection machines and professional rubber-to-metal bonding lines. We provide an integrated solution—ranging from custom material compounding (low-temp flexibility, high tear strength) to high-precision tooling and rapid prototyping. Let us help your products withstand severe environmental tests and capture opportunities in the global drone market.

In the era of rapid development of Artificial Intelligence (AI) and Unmanned Aerial Vehicles (UAV), hardware stability directly determines the performance of algorithms and control systems. Operating in environments characterized by high voltage, high heat, high-speed vibration, and highly variable outdoor weather, high-end precision silicone rubber components play the role of "unsung heroes." Below are the key applications and design trends in these two core areas:

1. Key Applications of Silicone Rubber in AI Servers & Hardware

AI computing chips (such as GPUs and ASICs) release massive amounts of heat under heavy loads, and high-speed cooling systems introduce micro-vibrations, placing strict requirements on hardware sealing and shock absorption:

A. Efficient Thermal Interface Materials (TIM)

Ultra-high thermal conductivity silicone sheets or thermal gels must be used between AI chips and heat dissipation modules. By adding ceramic powders such as alumina, boron nitride, or silicon carbide, silicone provides excellent heat transfer efficiency (3.0~8.0 W/m·K or higher) while maintaining electrical insulation and soft elasticity (Shore A 10°~25°).

B. Liquid/Water Cooling Leak-Proof Gaskets

To break through heat dissipation bottlenecks, AI cabinets are rapidly shifting to liquid cooling. Gaskets and water-way seals manufactured via LSR (Liquid Silicone Rubber) injection molding possess extremely low compression set (requiring < 10%) and high chemical degradation resistance. They maintain 100% leak-proofing over years of high-temperature cycling, protecting expensive boards from moisture damage.

▲ High-conductivity thermal sheets and high-sealing LSR gaskets produced by Jun-Hsiang

C. EMI Shielding Gaskets

AI servers host numerous high-frequency communication modules where electromagnetic interference (EMI) can severely degrade data rates. We mix conductive particles like nickel-graphite or silver-copper into silicone to produce co-extruded or molded EMI shielding gaskets. These shield high-frequency noise, keeping volume resistivity below 0.01 Ω·cm.

2. Technical Demand of Drones (UAVs) for Precision Silicone Rubber

Drones must withstand high-altitude freezing temperatures, rain wash, and high-speed motor rotation. They are highly sensitive to lightweight construction, shock absorption, and weather resistance:

▲ Drone gimbal dampening balls and metal-bonded motor mount dampers by Jun-Hsiang

A. Gimbal Camera High-Damping Balls

The high-speed rotation of drone propellers causes high-frequency jitter (jello effect). Gimbal dampening balls must utilize silicone rubber with excellent resilience and damping coefficients, with carefully calibrated hardness (typically between Shore A 30° to 45°), to perfectly absorb micro-vibrations and ensure stable aerial photography and inspection footage.

B. Motor Mount Dampers (Rubber-to-Metal Bonding)

A drone's motor mount is the origin of heat and vibration. Utilizing **rubber-to-metal bonding technology**, aluminum alloy inserts are covalently bonded with custom NBR rubber inside the mold. This eliminates secondary assembly, provides high pull-out strength, isolates motor heat, and prevents motor vibrations from interfering with the IMU/gyroscope sensors.

C. Landing Gear Shock Absorbers

Using high-wear, tear-resistant NBR or PU rubber buffers on landing gear feet dampens landing impact forces, preventing micro-fractures in the drone's carbon fiber arms over time.

D. Servo Dust Boots

On the tilt-rotor joints and servo linkages of VTOL drones, ultra-thin (0.3mm~0.5mm) bellows made of high-strength silicone are used. They protect servo gearboxes from agricultural chemical sprays, dust, and rain without adding rotation resistance.

E. IP67/IP68 Enclosure Seals via LSR Overmolding

For all-weather drones (e.g., patrolling in rain or marine rescue), battery bays and housing joints require robust seals. **LSR double-shot overmolding** direct-bonds liquid silicone onto rigid PC/PA plastic frames, offering zero assembly tolerances and preventing peel-off or leakage from -40°C to 85°C.

Material Specification Guide for AI & Drone Applications:

3. Jun-Hsiang — Your Trusted Partner for Next-Gen Hardware Manufacturing

Most precision silicone components for AI and drone projects require custom tooling. Jun-Hsiang Enterprise Co., Ltd. possesses over 30 years of mold engineering and material modification experience. At our plant in New Taipei City, we offer complete NRE services, from formulation adjustments to LSR injection molding. Bring your STEP/IGS files or physical samples to our technical team for custom prototypes and high-yield mass production.

When developing silicone rubber products, choosing the correct molding process not only affects product quality but also directly determines tooling budgets and long-term production costs. Below is an in-depth analysis of the differences between traditional solid compression molding and modern automated liquid silicone injection:

1. Solid Silicone Vacuum Compression Molding

This is a long-standing, mature molding method using pre-mixed solid silicone compound (clay-like texture).

• Production Process: The raw compound is cut and weighed, then manually placed into preheated steel mold cavities. A hydraulic press closes to apply high temperature and pressure, curing and vulcanizing the silicone within the mold.
• Advantages: The difficulty of mold development and precision requirements are relatively low, making initial tooling costs more economical. It is highly suitable for low-to-medium volume production, especially for larger, simpler silicone components (such as anti-vibration rubber pads, seals, and large protective covers).
• Disadvantages: Manual material weighing and placement limit production efficiency. It results in thicker flash, with dimensional tolerances depending on mold and part design, making it less suitable for ultra-intricate precision parts.

2. LSR Liquid Silicone Rubber Injection Molding

This is an automated injection process designed to meet the demands of precision polymer products, using two-part (Part A and Part B) low-viscosity liquid silicone.

• Production Process: Part A and Part B raw materials are mixed at a precise 1:1 ratio and injected directly into heated closed mold cavities via a precision runner system, curing rapidly in seconds to tens of seconds.
• Advantages: Production with extremely short cycle times. Thanks to the excellent flowability of liquid silicone, it can produce ultra-complex, thin-walled, micron-level parts, with with dimensional tolerances controlled to precision levels. The process generates minimal flash, and the fully enclosed piping prevents human/environmental contamination, making it ideal for medical-grade silicone parts and electronic-grade waterproof seals.
• Disadvantages: The mold design is highly sophisticated (requiring precise runner control and high vacuum venting), leading to expensive initial tooling costs. High-volume mass production is recommended to achieve optimal tooling depreciation.

▲ Comparison of solid silicone hot pressing and automated LSR injection molding processes

Process Selection Matrix:

In designs like waterproof electronic accessories, medical catheter connectors, and automotive dampers, silicone-to-plastic and silicone-to-metal bonding are highly common. This process eliminates post-molding manual assembly and achieves IP68 waterproof and dustproof capabilities. Below are the four core steps to ensure a perfect chemical bridge and prevent substrate separation:

▲ Custom silicone overmolded onto metal inserts and rigid plastics produced by Jun-Hsiang

1. Strict Selection of Substrate Temperature Limits

Silicone curing temperatures typically range between 130°C and 175°C. Therefore, when overmolding silicone onto plastic, the rigid plastic substrate must withstand high temperatures, such as PC (polycarbonate), PA+GF (glass-reinforced nylon), PBT, or PEEK. Substrates with lower heat resistance (like ABS or PE) will easily melt or deform inside the mold.

2. Physical Surface Treatment & Activation

A perfect bond relies on a clean surface that allows mechanical interlocking. Before metal inserts (such as stainless steel or copper) are placed in the mold, they must undergo degreasing and oxide removal. Depending on requirements, sandblasting or plasma treatment is applied to increase micro-roughness, allowing the silicone to interlock physically.

3. Uniform Primer Application

This is the key to chemical bonding. Primer molecules possess dual reactive functional groups: one end bonds with the metal (or plastic) surface via intermolecular forces or covalent bonds, while the other end participates in the cross-linking reaction of the silicone during high-temperature curing. The primer thickness and drying temperature must be strictly controlled; too thick creates a brittle layer, while too thin results in weak adhesion.

4. Precision Mold Positioning & High-Pressure Control

During high-pressure injection, flowing silicone exerts a strong force on the metal or plastic inserts. If the mold positioning is inaccurate, the insert can shift by micrometers, leading to uneven wall thickness or exposed substrates. Additionally, the mold must feature efficient vacuum venting to prevent residual air at the bonding interface, which can inhibit the primer's chemical cross-linking.

Jun-Hsiang Enterprise has over 30 years of custom manufacturing experience. In our New Taipei City factory, we feature dedicated surface treatment areas and precision pull-testing equipment, allowing us to deliver the most reliable bonding quality and waterproof guarantees for complex multi-material assemblies.

Silicone keypads get their springy, tactile feel from the internal webbing (web) design. A high-quality keypad design requires mastering the following three physical specifications:

1. Actuation Force & Tactile Ratio

The force required to press the key (F1). Consumer electronics (like TV remotes) range from 80g to 120g; industrial, medical, and automotive panels require higher forces (150g to 250g) to prevent accidental activation. The tactile ratio `(F1 - F2) / F1` should be controlled between 40% and 60% to deliver a crisp click; below 30%, it feels mushy.

2. Travel & Pre-travel

Standard keypads have a travel distance of 1.0mm to 2.0mm. Short travel distances respond quickly, but if too short (<0.8mm), feedback is hard to perceive; excessively long travel increases finger fatigue.

3. Material Options for Conductive Contacts

Carbon Pills (resistance 100-150 ohms) are the most cost-effective and durable solution; Metal Pills (Gold/Silver) (resistance <10 ohms) are used for low-latency, high-precision signals; Conductive Ink is ideal for low-profile keypad designs.

▲ Section diagram showing travel, pre-travel, webbing (web), and bottom contact of a silicone keypad

Jun-Hsiang Enterprise possesses over 30 years of precision mold development capability, offering one-stop tooling services to help you calibrate webbing thickness for the perfect tactile feedback. Our factory is located on Xinshu Road in Xinzhuang, and we welcome you to provide drawings for technical discussion.