Custom Vibration Isolation & Acoustic-Control Parts for Electronics
H-O Products die-cuts and converts microcellular polyurethane, silicone foam, vinyl-nitrile foam, felt, and acoustic-mesh gasket stacks into the isolation pads, damping patches, and sealing rings that quiet fans, motors, hard-disk drives, speakers, and microphones inside consumer and industrial electronics, built to your drawing.
Built for: fan and small-motor isolation pads, hard-disk-drive (HDD) and sensitive-module grommets, speaker sealing gaskets, microphone acoustic-mesh-plus-gasket stacks, buzz-squeak-rattle (BSR) interface strips, and panel damping patches, on your footprint drawing.
To control vibration and acoustics inside an electronic device, decide which of three jobs you have. Isolation: a compliant pad or grommet of PORON® microcellular polyurethane, silicone foam, or vinyl-nitrile foam between the source (fan, motor, speaker) and the chassis, sized so the isolator’s natural frequency is roughly a third of the source frequency — isolation only occurs above a forcing-to-natural ratio of √2, and too stiff amplifies.
Damping: a viscoelastic patch (constrained-layer for the most damping per unit mass) on a ringing panel. Sealing / venting: a speaker gasket stops the acoustic short-circuit that kills bass; an acoustic mesh / ePTFE vent over a mic port passes sound but blocks water and dust. All three are mapped in the When-to-spec list. Values are per the TDS on file; see the material reference below for ordering details.
Material-level, per the maker TDS: ASTM D3574 (flexible cellular urethane methods, CFD and compression set) · ASTM D1056 (cellular rubber classification) · ASTM D2240 (durometer) · ASTM E756 (vibration-damping loss factor and modulus) · UL 94 (flammability classes incl. V-0 on the rated grades) · SAE J314 (wool and part-wool felt).
Assembly-level, by designation (the rating belongs to the finished device): IEC 60068-2-6 (sinusoidal vibration) · IEC 60068-2-27 (shock) · IEC 60068-2-64 (random vibration) · MIL-STD-810 (Method 514 vibration, 516 shock) · IEC 60529 / ISO 20653 (IP ingress ratings).
Isolation theory cited to a named engineering reference; VDA 230-206 governs stick-slip material pairing.
- Fan / motor isolation pad: PORON® 4701 series
- High-temp / flame isolation: silicone foam (BISCO® HT)
- Cost / oil-resistant isolation: vinyl-nitrile / Ensolite®
- HDD / module grommet: PORON® or neoprene foam
- Speaker sealing gasket: BISCO® HT/BF silicone
- Microphone vent / mesh: ePTFE acoustic mesh
- Anti-squeak decoupler: SAE felt
- Panel damping patch: viscoelastic / acrylic-foam tape construction
- Heavy equipment base pad: rebonded neoprene
- Weather-exposed isolation seal: EPDM foam
This guide is for acoustic, mechanical, and NPI engineers specifying vibration isolation pads, damping patches, speaker sealing gaskets, and microphone acoustic-mesh stacks for consumer devices, IoT hardware, and industrial-electronics enclosures, and for the sourcing buyers qualifying those made-to-order parts. If you own a buzz-squeak-rattle complaint, a fan or HDD that transmits noise into the chassis, or a speaker/mic port that has to seal or vent, start here.
Noise / vibration problem → isolate-damp-or-seal decision → material selection → converted part → production supply.
- 1Name the sourceFan, motor, HDD, speaker, mic, or a squeaking/rattling joint, with its dominant frequency or RPM.
- 2Isolate, damp, or sealDecide the physics: decouple the mass, dissipate the ring, or seal/vent the acoustic path.
- 3Select the material familyMatch temperature, flame, chemical, and compression-set duty to PU, silicone, vinyl-nitrile, felt, or mesh.
- 4Tune the padPick the CFD and thickness so the isolator's natural frequency lands below the source frequency.
- 5Die-cut to drawingAdd adhesive, liner, mesh laminations, and pull tabs; or kiss-cut the pad, ring, or stack.
- 6Quote prototype or productionSend the drawing and volumes; review comes back with a manufacturable option and the TDS.
Where are you in the spec process?
This page serves engineers who already know the pad, gasket, or mesh stack they want and engineers still deciding whether the problem is isolation, damping, or sealing. Pick the path that matches where you are.
Send a drawing, get a quote
A PORON® isolation pad, a silicone-foam gasket, a vinyl-nitrile washer, a felt anti-squeak strip, or a mesh-plus-gasket microphone stack on your drawing.
Skip to the quote form →Decide the physics, then the material
Six selection factors (isolate vs damp vs seal, natural frequency, compression set, material family, acoustic path, squeak-rattle), a checklist-driven part builder, and seven material families with TDS-cited data.
Start with selection factors →
-
1Send drawingUpload a DXF, STEP, or PDF, or describe the fan, speaker, mic, or joint. A sample part works too.
-
2Material reviewEngineering reviews the isolation, damping, or sealing job against the maker TDSs, sizes the pad by natural frequency, and frames the standards language honestly: material classes (UL 94, ASTM) by TDS; IP ratings belong to the finished enclosure.
-
3PrototypeSamples typically ship in 3–5 business days for common configurations on materials we keep on hand. Made-to-order; MOQ varies by material and part.
-
4ProductionStandard production runs ship about 2 weeks after drawing approval, on flatbed die-cutting, CNC knife cutting for kiss-cut pad sets, and kitting for mesh-plus-gasket stacks. Ongoing parts run with material traceability and lot-code TDS records.
Which problem are you solving?
Application Zones
Six material problems define vibration and acoustic control inside electronics: isolating a fan or small motor from the chassis; decoupling a hard-disk drive or a vibration-sensitive module; damping thin panels and covers so they stop ringing; sealing a speaker and venting a microphone; killing buzz, squeak, and rattle at the joints; and, in industrial cabinets, isolating a heavier fan or drive assembly on a base pad. Click a tab to see the part, the controlling property, and the families H-O converts for that zone.
Fan & small-motor isolation: keep the source off the chassis
A cooling fan, blower, or small motor is a rotating imbalance and a set of bearing tones; bolt it hard to the enclosure and every one of those tones becomes audible structure-borne noise. A compliant pad or grommet between the fan frame and the chassis decouples the source.
The engineering is tuning, not thickness: the pad is a spring whose natural frequency follows from the static deflection under the mounted load, and isolation only begins once the fan's dominant frequency is above √2 times that natural frequency, so a pad chosen too stiff can amplify rather than isolate.
PORON® microcellular polyurethane is the precision default because its compression-force-deflection (CFD) can be tuned across a wide range and its compression set is low, so the tuning holds over years; the 4701 series spans soft through very firm (4701-60 lists a compression set of 10% or less at 70 °C on its TDS). Silicone foam steps in where temperature or a flame class rules; vinyl-nitrile is the cost-and-oil-resistant option.
Hard-disk-drive & sensitive-module isolation
A spinning hard-disk drive is both a source and a victim: its actuator and platters radiate, and external shock or chassis vibration can reach the heads. Grommets and pads decouple it in both directions. The same duty covers vibration-sensitive modules, optical assemblies, MEMS sensors, and imaging stages that must be shielded from the enclosure's vibration. Because the mounted mass is small, the isolators are low-load and the tuning is delicate: a grommet that is too stiff pushes the natural frequency up into the very band it should reject.
PORON® and soft neoprene foams supply the low-load compliance; the qualification these assemblies face (sinusoidal, random, and shock per the IEC 60068-2 series or MIL-STD-810 methods 514 and 516) belongs to the finished device, and the isolator is one material inside that evaluation.
Panel & cover damping: stop the ring, don't just move it
Damping is a different job from isolation. Where isolation decouples a mass, damping dissipates vibrational energy as low-grade heat, cutting the resonant amplitude and the ring of a thin panel or cover. Two constructions do the work. A free-layer treatment applies a viscoelastic layer to one face of the panel and dissipates energy as the layer stretches and compresses.
A constrained-layer construction sandwiches the viscoelastic between the panel and a stiff top skin, so the layer works in shear and dissipates more energy per unit mass; ASTM E756 formalizes both, using free-layer beam specimens for stiff materials and sandwich specimens for soft viscoelastics, and reports the loss factor and modulus.
A useful threshold: a loss factor of about 0.1 is generally considered the minimum for significant damping. H-O the viscoelastic and adhesive layers of these patches to the panel footprint.
Speaker sealing & microphone venting: two opposite acoustic jobs
The acoustic port is where sealing and venting split. A speaker needs its front and rear radiation kept apart: without a continuous, correctly compressed sealing gasket between the driver and the baffle, rear-radiated sound wraps around and cancels the front output, an acoustic short-circuit that most damages low frequencies. A silicone-foam or PORON® ring seals that path.
A microphone port needs the opposite: the acoustic inlet must be sealed to the MEMS mic so no unwanted sound couples in, yet the outer opening must pass sound while blocking water and dust, which is the job of an acoustic mesh or ePTFE vent that stays acoustically transparent (dust and splash grades add well under a decibel of insertion loss; immersion-rated grades a little more).
The common microphone stack is exactly that: an outer acoustic mesh, a PSA gasket ring that seals the inlet, and a foam layer, and laminated as one part. The IP rating those parts help achieve belongs to the finished enclosure, not the gasket.
Buzz, squeak & rattle: decouple the pair, fill the gap
Buzz, squeak, and rattle (BSR) is the mature discipline the automotive industry built, and it transfers directly to device assemblies. The three noises have three mechanisms. Squeak is friction-induced stick-slip: where two hard parts rub, static friction builds until it suddenly yields to sliding friction, releasing energy as an audible creak, and it worsens with temperature and humidity for many polymer pairs.
Rattle is impact noise across a clearance. Buzz is vibration-induced noise in a panel. The fixes are interfaces. For squeak, separate the dissimilar pair with a low-friction film or a felt strip so stick-slip cannot build; stick-slip material pairing is what VDA 230-206 tests and the SAE material-pair database screens. For rattle, take up the clearance with a compressible pad so the parts cannot impact.
For buzz, add a damping patch or a compliant mass to the panel.
Industrial cabinet fans & drive assemblies: heavier base isolation
Inside an industrial-electronics cabinet the same isolation logic applies at higher loads and longer service. A cabinet cooling fan, a blower assembly, or a drive/controller module carries more mass than a consumer fan, so its isolation pad is a static-stress calculation first: size the pad so its bearing stress sits inside its working range, then confirm the natural frequency lands below the fan or drive's dominant frequency.
Rebonded neoprene handles the heavier equipment pads; solid neoprene and EPDM cover general and weather-exposed sealing-plus-isolation duty; and where the cabinet runs hot, silicone foam keeps its properties. Durometer (ASTM D2240) and the cellular-rubber class (ASTM D1056) are the spec handles on these grades.
Six decisions that drive your isolation & acoustic material spec
A vibration or acoustic part is a single-purpose layer, and each has one controlling property. Miss it and the failure is quiet: a pad amplifies instead of isolates, a preload relaxes, a gasket leaks bass, or a mesh is the wrong grade.
Isolation and damping are different physics. Isolation decouples a mass with a compliant element and only works above a frequency ratio of √2 relative to the isolator's natural frequency. Damping dissipates energy as heat and cuts the resonant peak. Sealing and venting are opposites at the acoustic port. Decide which job you have first; the material follows.
Below a source-to-natural frequency ratio of √2 (≈1.414), an isolator amplifies. A common rule of thumb sizes the mount so its natural frequency is about one third of the frequency of concern, which puts the source comfortably in the isolation region. The natural frequency follows from the static deflection under the mounted load, so the load and the pad's CFD, not its gauge, set the tuning. [10]
Read the six factors below in order. The first two decide the physics and the tuning; the next two pick the material and hold the preload; the last two cover the acoustic port and the squeak-rattle joints. Every factor names its test method, because in this application the documentation is part of the part.
Show all 6 selection factors tap to expand
Decide the job: isolate, damp, or seal
Rule — name the physics before the material. Isolation decouples a source from the chassis with a compliant element; damping dissipates a panel's resonant energy as heat; sealing and venting handle the acoustic port. A pad and a damping patch look alike and solve different problems, and the wrong one quietly fails: an isolation pad does nothing for a ringing panel, and a damping layer does not decouple a fan. State which of the three jobs the part does, then read the factor that matches. [10]
Tune the isolator by natural frequency, not thickness
Rule — size the pad so its natural frequency sits well below the source frequency. The isolator is a spring; its natural frequency follows from the static deflection under the mounted load (fn = (1/2π)√(g/d) for the undamped case, which reduces to the familiar deflection form). Isolation begins only above a frequency ratio of √2, so a pad tuned too stiff lands in the amplification region and makes the noise worse.
Get the mounted mass, the bearing area, and the source's dominant frequency or RPM onto the drawing; the CFD grade and thickness fall out of those. [10]
Pick the material by temperature, flame, and chemical duty
Rule — once the tuning is set, the material is a duty decision. Microcellular PU (PORON®) is the precision default for consumer isolation. Silicone foam (BISCO® HT) steps up where the part sees -55 to +200 °C or needs a UL 94 V-0 flame class (the HT-800 TDS lists both). Vinyl-nitrile is the cost-and-oil-resistant closed-cell option. Felt is the anti-squeak decoupler, not a spring. Name the temperature range, any flame class, and any oil/fluid exposure; those three route you to the family. [12]
Hold the preload: specify compression set, not just CFD
Rule — a pad that relaxes is a tuning that expired. Compression-force-deflection sets the day-one spring; compression set decides whether it survives. PORON® 4701-60 lists a compression set of 10% or less at 70 °C and BISCO® HT-800 a set of 2.4% at 100 °C, which is why both hold their preload over years while a high-set commodity foam drifts. State a compression-set limit at the service temperature alongside the CFD window, and let it pick between the families before cost does. [1]
The acoustic port: seal the speaker, vent the microphone
Rule — they are opposite jobs, so specify them separately. A speaker needs a continuous, correctly compressed sealing gasket so rear radiation cannot cancel front output (the acoustic short-circuit that kills bass). A microphone needs the inlet sealed to the MEMS port but the outer opening vented through an acoustically transparent mesh or ePTFE membrane that blocks water and dust.
Call out the seal continuity and closure force for the speaker gasket, and the IP target and acoustic budget for the mic vent; the IP rating belongs to the finished device, not the part. [13]
Kill squeak by decoupling, rattle by filling the gap
Rule — match the fix to the mechanism. Squeak is friction stick-slip between a dissimilar pair, so separate them with a low-friction film or a felt strip; stick-slip material pairing is exactly what VDA 230-206 tests and the SAE material-pair work screens. Rattle is impact across a clearance, so take up the gap with a compressible pad. Buzz is a vibrating panel, so add a damping patch. Tell us which of the three you hear and where the contact or clearance is; the interface follows. [7]
Specification Tools
Two tools to take you from "we have a noise problem" to here's the material checklist for the drawing set: a requirement-driven part builder that assembles the layer list with its citations, and a side-by-side comparison of every family on this page.
1. Isolation & acoustic part checklist builder
Check the problems your design has. The builder assembles the corresponding parts into a checklist with the family, what to send with the drawing, and the honest citation language (material classes per TDS; isolation theory and IP ratings by reference/designation). The default selection is a typical consumer device with a cooling fan and a speaker; every part is also printed in the material reference section, so nothing here exists only behind a script.
Part checklist: 2 parts selected
Each checked problem adds its part below. The list is the starting bill of materials for the engineering review, not a certification: material classes (UL 94, ASTM) come from the grade TDS, isolation tuning follows the cited theory, and IP ratings belong to the finished enclosure.
- Fan / motor isolation pad: PORON® 4701 series (silicone foam if hot)Send: mounted mass, bearing area, fan RPM / dominant frequency, temperature. Cite: CFD and set per ASTM D3574; tune below √2 crossover.
- Speaker sealing gasket: BISCO® HT/BF silicone or PORON® ringSend: driver footprint, closure force, gap, flame class. Cite: continuous seal stops the acoustic short-circuit; UL 94 per grade TDS.
2. Side-by-side: material family comparison matrix
Every family called out on this page, with construction, the property that drives its selection, the methods its TDS cites, and the job it serves. Click a column header to sort. Click any material name to jump to its accordion entry.
| Material | Construction | Selection driver | Methods on the TDS | Job | |
|---|---|---|---|---|---|
| Isolation & cushioning | |||||
| PORON® Industrial (4701 Series)Microcellular urethane | Microcellular PU foam | CFD window + low set | ASTM D3574; D2240 | Fan / HDD isolation | |
| Silicone Foam (BISCO® HT / BF)Closed-cell silicone | Closed-cell silicone foam | Temp range + flame class | UL 94 V-0; -55/+200 C (TDS) | Hot isolation / speaker seal | |
| Vinyl-Nitrile Foam (Ensolite®)PVC/NBR closed-cell | Closed-cell PVC/NBR foam | Cost + oil resistance | ASTM D1056; UL 94 HBF/HF-1 | Cost isolation / anti-rattle | |
| Neoprene / EPDM / Rebonded NeopreneRubber foam set | Closed-cell / rebonded foam | Static load / weather | ASTM D1056; D2240 | Economical / heavy base pads | |
| Acoustic port, damping & BSR | |||||
| ePTFE Acoustic Mesh / VentMembrane / woven mesh | ePTFE membrane / woven mesh | Insertion loss + IP target | Insertion loss per vent TDS | Mic / speaker venting | |
| Viscoelastic Damping ConstructionsCLD / FLD patch | Viscoelastic + skin laminate | Loss factor (η ≥ 0.1) | ASTM E756 | Panel / cover damping | |
| SAE Felt & Cork InterfacesWool felt / cork | Pressed felt / rubberized cork | Friction decoupling | SAE J314; VDA 230-206 (ref) | Anti-squeak / shim | |
Skip ahead and request your engineering review now
If your drawing set already calls out a PORON® grade, a silicone-foam gasket, a felt strip, or a mesh-plus-gasket stack, send it over for engineering review against the TDSs and the isolation tuning.
Vibration & acoustic failures you can prevent at spec
These parts fail quietly: a pad tuned into amplification, a preload that relaxed, a squeak nobody predicted, a speaker that lost its bass, a mesh that clogged. Five patterns cover most of it, and each is a specification decision made before the first part is cut.
An isolator you did not tune can amplify. The most common mistake on this page is treating an isolation pad as a spacer and selecting it by thickness. If its natural frequency lands within √2 of the source frequency, transmissibility rises above 1 and the pad makes the noise worse. Tune by natural frequency; state the mounted mass and source frequency.
Show all 5 failure modes tap to expand
1. The isolation pad that amplified instead of isolating
Fix — tune by natural frequency, not gauge, and keep the source above the √2 crossover. A fan pad was chosen for gap fill: the right thickness, the wrong spring. Its natural frequency landed near the fan's dominant frequency, transmissibility climbed above 1, and the "isolator" made the cabinet louder. Isolation only occurs above a source-to-natural frequency ratio of √2, and a common rule sizes the mount's natural frequency at about a third of the frequency of concern.
Get the mounted mass, the bearing area, and the source frequency onto the drawing, and let the PORON® CFD grade and thickness fall out of the tuning. [10]
2. The preload that quietly expired (compression set)
Fix — specify a compression-set limit at the service temperature, not just a day-one CFD. A pad or gasket chosen only by its as-installed force relaxes over service life: the isolation tuning drifts, or a speaker seal loses closure force and starts to leak. Low-compression-set families hold the spec, PORON® 4701-60 at 10% or less (70 °C) and BISCO® HT-800 at 2.4% (100 °C) per their TDSs, while a high-set commodity foam drifts.
Name the set limit at the temperature the part actually sees, alongside the CFD window, so the part is still doing its job in year three. [1]
3. The squeak nobody predicted (stick-slip)
Fix — decouple the dissimilar friction pair with felt or a low-friction film. Two hard parts were allowed to rub; static friction built until it suddenly yielded to sliding friction, and the joint creaked, worse in heat and humidity for many polymer pairs. Adding a felt strip or a sliding-optimized film between them is the named stick-slip prevention measure: it separates the pair so the stick-slip cannot build.
Stick-slip material pairing is testable (VDA 230-206) and screenable against the SAE material-pair database, so the pairing can be designed rather than discovered on the line. [7]
4. The speaker that lost its bass (acoustic short-circuit)
Fix — seal the driver to the baffle with a continuous, correctly compressed gasket. An unsealed or poorly gasketed speaker lets rear-radiated sound wrap around and cancel the front output, an acoustic short-circuit that most damages low frequencies, so the device sounds thin. A silicone-foam or PORON® sealing ring, compressed to its working range with no gaps, keeps front and rear apart.
Call out the seal continuity and the closure force, and pick the material by temperature and flame class; a gasket that is the right shape but under-compressed still leaks. [15]
5. The microphone that muffled or lost its IP rating
Fix — match the mesh grade to the acoustic budget and the IP target, and seal the inlet separately. A mic port failed two ways: the inlet was not sealed to the MEMS port, so stray sound and vibration coupled in; or the outer mesh was the wrong grade, clogged, or torn, shifting the acoustic response or losing the ingress rating.
The fix is the stack done right: an acoustically transparent mesh or ePTFE vent sized to the insertion-loss budget on the outside, a PSA gasket ring sealing the inlet, and foam as needed, and laminated as one part. The IP rating belongs to the finished enclosure; the stack is one contributor to it. [13]
Material reference
Detailed specs for the seven families referenced on this page: the isolation foams (PORON® microcellular PU, silicone foam, vinyl-nitrile, and the neoprene/EPDM set), the acoustic-port materials (ePTFE mesh/vent and the sealing rings), the damping constructions, and the squeak-rattle interfaces (felt and cork). Values are per the maker TDS on file for each grade with the method named; isolation theory and IP ratings are cited by reference/designation. H-O die-cuts, kiss-cuts, slits, laminates, and kits every family to drawing.
PORON® Industrial Microcellular Urethane (4701 Series, 4701-60)Fan / HDD isolation pads & sealing rings · ASTM D3574 methods · low compression set
Specify the CFD window (kPa) and a compression-set limit at the service temperature, plus the mounted mass and source frequency, not just thickness. Values per the Rogers PORON® 4701-60 TDS on file.
Silicone Foam (BISCO® HT Series, HT-800; BF Series)Hot isolation & speaker seals · -55 to +200 °C · UL 94 V-0 per TDS
Match the compression class to the real closure force, and let any flame-class requirement pick the silicone track before cost does. UL 94 classes are per the individual grade TDS; H-O cites them by designation and does not certify the class.
Vinyl-Nitrile & PVC-Nitrile Foam (Ensolite® family)Cost-effective isolation & anti-rattle · closed-cell · oil resistant
Cite the specific grade: density, temperature, and class vary across the Ensolite® family. Values per the individual grade TDS on file.
Neoprene, EPDM & Rebonded Neoprene FoamEconomical & heavy-load isolation pads · ASTM D1056 classes
Size a base pad so its bearing stress sits inside its working range, then confirm the natural frequency lands below the source frequency. Class per ASTM D1056 on the grade TDS.
Acoustic Mesh / ePTFE Vent MembraneMic & speaker venting · acoustically transparent · blocks water & dust
Specify the insertion-loss budget at the acoustic frequency of interest and the IP target; the mesh grade follows. Values per the vent maker TDS; the IP rating is earned at the assembled device.
Viscoelastic Damping Constructions (CLD / FLD)Panel & cover damping · ASTM E756 loss factor & modulus
Provide the panel material and thickness, the resonant frequency band, and the temperature; the construction and layer stack follow. Loss factor and modulus per ASTM E756.
SAE Felt & Rubberized Cork InterfacesAnti-squeak & tolerance shims · SAE J314 felt grades
Name the two materials in the rubbing pair and the contact geometry; the felt grade or film choice follows the stick-slip prevention approach. Felt grades per SAE J314.
Crosslinked / Expanded Polyethylene (PE) FoamEconomical closed-cell pipe wrap, collars & spacers · ASTM D1056 / maker TDS
The economical closed-cell option for wrap, spacer, and collar duty; where the design calls for a specified permeance or a fire class, the elastomeric and glass-fibre tracks take over.
Foam MaterialsConverted Foam & Film Layers
Electronics vibration & acoustic materials: engineer-grade FAQ
Ten of the questions we hear most from acoustic, mechanical, and NPI teams. If your question isn't here, send a drawing or call, engineering picks up.
What is the difference between vibration isolation and damping?
They are different physics. Isolation reduces the transmission of energy from one body to another by inserting a resilient element, so a compliant pad decouples a fan or drive from the chassis. Damping dissipates vibrational energy, usually as low-grade heat, which lowers the resonant peak and stops a panel ringing. An isolation pad does nothing for a buzzing cover, and a damping patch does not decouple a fan.
Most devices need both, in different places, and you specify them differently: isolation by compression-force-deflection and natural frequency, damping by loss factor. [10]
Why would an isolation pad make the noise worse instead of better?
Because isolation only occurs above a source-to-natural frequency ratio of √2 (about 1.414). If the pad's natural frequency is too close to the source frequency, the system runs in the amplification region, where transmissibility rises above 1 and the pad transmits more than it blocks, worst at resonance where the ratio is 1. The fix is to tune the pad so its natural frequency sits well below the source, often around a third of it.
The natural frequency follows from the static deflection under the mounted load, so the mounted mass and the pad's compression-force-deflection set the tuning, not the thickness. [10]
Microcellular PU vs silicone foam vs vinyl-nitrile: which do I pick for isolation?
Pick by duty once the tuning is set. Microcellular polyurethane (PORON®) is the precision default: a wide compression-force-deflection range and low compression set (4701-60 lists 10% or less at 70 °C) hold the tuning over years. Silicone foam (BISCO® HT-800) steps up where the part sees -55 to +200 °C or needs a UL 94 V-0 flame class, with a very low 2.4% compression set.
Vinyl-nitrile (Ensolite®) is the cost-and-oil-resistant closed-cell option with good sound-deadening, at higher compression set. Name your temperature, flame, and oil requirements plus the compression-set limit; those route you to the family. Values per the maker TDS. [11]
What does a speaker gasket actually do, and what happens without one?
A speaker sealing gasket keeps the driver's front and rear radiation apart. Without a continuous, correctly compressed seal between the driver and the baffle, rear-radiated sound wraps around and cancels the front output, an acoustic short-circuit that most damages low frequencies, so the device sounds thin. A silicone-foam or PORON® sealing ring, compressed into its working range with no gaps, provides that seal.
Specify the seal continuity and the closure force, not just the ring shape; a gasket that is the right outline but under-compressed still leaks. [15]
What is the difference between an acoustic mesh and a gasket for a microphone?
They do opposite jobs and a microphone stack usually needs both. The acoustic mesh (or ePTFE vent membrane) is the venting layer: it passes sound while blocking water and dust, staying acoustically transparent so it adds only a small insertion loss. The gasket is the sealing layer: a PSA-backed ring that seals the acoustic inlet to the MEMS microphone port so no stray sound or vibration couples in.
The common part laminates an outer mesh, a PSA gasket ring, and foam into one stack. The IP rating the stack helps achieve belongs to the finished enclosure, not the gasket. [13]
How do I isolate a hard-disk drive or a vibration-sensitive module?
With low-load grommets and pads that decouple the drive or module in both directions, so its own vibration does not radiate and external chassis vibration does not reach it. Because the mounted mass is small, the isolators are soft and the tuning is delicate: too stiff a grommet pushes the natural frequency up into the band you wanted to reject.
PORON® microcellular PU and soft neoprene foams supply the low-load compliance. The device-level qualification (sinusoidal, random, and shock per the IEC 60068-2 series or MIL-STD-810 methods 514 and 516) belongs to the finished product; the grommet is one material inside that evaluation. [5]
How do I stop a squeak between two plastic or metal parts?
Decouple the rubbing pair. Squeak is friction-induced stick-slip: static friction builds until it suddenly yields to sliding friction, releasing energy as an audible creak, and it worsens with temperature and humidity for many polymer pairs. The named prevention measure is to separate the pair with a sliding-optimized film or a felt strip, so stick-slip cannot build. Stick-slip material pairing is testable (VDA 230-206) and screenable against the SAE material-pair database, so a squeak-free pairing can be designed rather than discovered on the line.
Tell us the two materials and the contact geometry and the felt or film follows. [7]
Do these parts carry a UL 94 or an IP rating?
The UL 94 flammability class is a material-level property that belongs to the grade and is listed on its TDS (for example BISCO® HT-800 lists UL 94 V-0), and H-O cites it by designation; H-O does not certify the class. An IP ingress rating (IEC 60529 / ISO 20653) is different: it is earned by the finished, tested enclosure, not by a gasket or mesh.
The parts on this page help a device achieve its IP target, but the rating belongs to the assembled product. H-O supplies the converted layers, the maker TDSs, and lot-code traceability behind them. [12]
Constrained-layer or free-layer damping for a ringing cover?
Constrained-layer damping (CLD) is the more effective construction per unit mass. A free-layer treatment applies a viscoelastic layer to one face and dissipates energy as it stretches and compresses; a constrained-layer construction sandwiches the viscoelastic between the panel and a stiff top skin, so it works in shear and dissipates more. ASTM E756 formalizes both and reports the loss factor and modulus, and a loss factor of about 0.1 is generally the minimum for significant damping.
For a thin cover that rings, a constrained-layer patch is usually the answer; provide the panel material, thickness, resonant band, and temperature. [4]
What should I send H-O to get a quote?
By job: for isolation, the source (fan/motor/HDD/speaker) with its dominant frequency or RPM, the mounted mass and bearing area, and the temperature and flame requirements; for damping, the panel material and thickness and the resonant band; for a speaker gasket, the driver footprint, closure force, and gap; for a mic part, the IP target and acoustic budget; for squeak or rattle, the two materials and the clearance.
Plus a footprint drawing, adhesive and liner needs, and quantities for prototype and production. "Recommend the part" is a valid callout, that is what the engineering review is for.
Glossary: terms used on this page
Quick reference for the vibration, damping, and acoustic terminology used throughout. Each entry links to the relevant reference or test method where applicable.
Vibration isolation
Reducing the transmission of vibrational energy from one body to another by inserting a resilient (compliant) element, per [10]. A pad decouples a source (fan, motor, drive) from the chassis. Isolation only occurs above a frequency ratio of √2 relative to the isolator's natural frequency.
Damping
The dissipation of vibrational energy, usually as low-grade heat, which lowers the resonant amplitude and stops a panel ringing, per [10]. Different physics from isolation: damping removes energy, isolation redirects the transmission path.
Natural frequency (fn)
The frequency at which an isolator naturally oscillates: fn = (1/2π)√(K/M), or fn = 3.13√(K/W) in English units, or the static-deflection form fn = (1/2π)√(g/d), for the undamped case, per [10]. The tuning target: keep the source frequency well above it.
√2 crossover
The frequency ratio (≈1.414) at which transmissibility returns to 1. Below it is the amplification region (transmissibility > 1); above it is the isolation region (transmissibility < 1), per [10].
Transmissibility
The dimensionless ratio of energy out of an isolated system to energy in. It approaches infinity at resonance for an undamped system; damping lowers the resonant peak, per [10].
Compression force deflection (CFD)
The pressure a cellular material exerts at a given compression, the curve that turns a foam pad into a specifiable spring. Reported per ASTM D3574 [1] on the PORON® TDSs; isolation pads are specified by their CFD window and natural frequency, not thickness.
Compression set
The permanent thickness a material loses after sustained compression and release, per ASTM D3574 [1] / ASTM D1056 [2]. Low set (PORON®, silicone foam) keeps an isolation tuning or a seal's closure force alive over service life.
Loss factor (η)
A dimensionless measure of a material's damping (energy dissipated per cycle relative to energy stored), η ≈ 2ζ. A value of about 0.1 is generally the minimum for significant damping, per [10]; measured per ASTM E756 [4].
Stick-slip (squeak)
Friction-induced instability where static friction builds until it suddenly yields to sliding friction, releasing energy as an audible creak, the root of squeak. Screened by material-pair testing (SAE 972056 [7]; VDA 230-206) and prevented by decoupling the pair with felt or film.
Acoustic short-circuit
The cancellation that occurs when a speaker's rear-radiated sound wraps around and meets the front radiation out of phase, killing bass and efficiency, per [15]. Prevented by a continuous sealing gasket between the driver and the baffle.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, engineering references, and maker technical data sheets cited throughout this page. Isolation theory is cited to a named engineering reference; qualification standards and IP ratings are cited by designation and belong to the finished device, not a part. Standards editions current as of July 2026; verify against the publishing body before final spec. H-O materials are aligned to the standards cited through the source manufacturer's TDS, not independently certified by H-O unless explicitly stated on the quote.
[1] ASTM D3574
Standard Test Methods for Flexible Cellular Materials—Slab, Bonded, and Molded Urethane Foams. The methods behind compression-force-deflection (Test C) and compression set (Test D) on the PORON® TDSs. store.astm.org (ASTM D3574)
[2] ASTM D1056
Standard Specification for Flexible Cellular Materials—Sponge or Expanded Rubber. The Type/Class/Grade classification behind the neoprene, EPDM, and vinyl-nitrile cellular-rubber grades. store.astm.org (ASTM D1056)
[3] ASTM D2240
Standard Test Method for Rubber Property—Durometer Hardness. The durometer method for the solid rubber and foam grades on this page. store.astm.org (ASTM D2240)
[4] ASTM E756
Standard Test Method for Measuring Vibration-Damping Properties of Materials. Reports loss factor and modulus using free-layer and sandwich (constrained-layer) beam specimens; the method behind the damping-patch selection. astm.org (ASTM E756)
[5] IEC 60068-2 series (by designation)
Environmental testing—Part 2-6 Test Fc: Vibration (sinusoidal); Part 2-27 Test Ea: Shock; Part 2-64 Test Fh: Vibration, broadband random. The device-level vibration and shock qualification; the rating belongs to the tested product. webstore.iec.ch (IEC 60068-2)
[6] MIL-STD-810 (by designation)
Department of Defense Test Method Standard, Environmental Engineering Considerations and Laboratory Tests: Method 514 (Vibration) and Method 516 (Shock) for ruggedized electronics. Cited by designation; distributed via DLA ASSIST. quicksearch.dla.mil (MIL-STD-810)
[7] SAE 972056 / VDA 230-206 (stick-slip)
SAE Technical Paper 972056, "Frictional Behavior of Automotive Interior Polymeric Material Pairs," the material-pair friction/stick-slip database work; and VDA 230-206, "Testing of the stick-slip behaviour of material pairings" (VDA, 2005), the governing stick-slip test for squeak-free pairing. sae.org (SAE 972056)
[8] SAE J314
SAE J314, "Felts, Wool and Part Wool." Specifies chemical and mechanical properties, thickness, width, and mass for the wool and part-wool felt grades used as anti-squeak and interface materials. sae.org (SAE J314)
[9] Stick-slip prevention (Ziegler / VDA 230-206)
Ziegler Instruments, "Stick-Slip Effect / VDA 230-206," describing the stick-slip mechanism and prevention measures, including decoupling the contact with sliding-optimized films or felts. The basis for the anti-squeak film/felt approach on this page. zins-ziegler-instruments.com (stick-slip)
[10] Basics of Vibration Isolation (E-A-R / Aearo)
Masterson, P. A., "The Basics of Vibration Isolation Using Elastomeric Materials," E-A-R Specialty Composites / Aearo Company. The named engineering reference for the natural-frequency forms, the √2 crossover, transmissibility, loss factor, and the isolation-vs-damping distinction cited on this page (in turn citing Inman, and Lord/Gatley/Evensen). vibrationdata.com (Basics of Vibration Isolation, PDF)
[11] Rogers PORON® 4701-60 TDS
Rogers Corporation PORON® 4701-60 (Very Firm) industrial microcellular polyurethane data sheet: CFD@25% 249/428/643 kPa, compression set 10% or less at 70 °C, temperature and thickness ranges; listed uses include vibration management and shock absorption. rogerscorp.com (PORON 4701-60)
[12] Rogers BISCO® HT-800 TDS
Rogers Corporation BISCO® HT-800 silicone foam data sheet (Publication 180-070): -55 to +200 °C, density 352 kg/m³, CFD 67 kPa, compression set 2.4% (100 °C), UL 94 V-0 (File E83967), ASTM E162/E662, FMVSS 302. rogerscorp.com (BISCO HT-800)
[13] ePTFE acoustic vent data
Gore Acoustic Vents (portable electronics) technical data: ePTFE membrane, hydrophobic/oleophobic, acoustically transparent, with insertion loss stated by ingress class (well under 1 dB for dust/splash grades, more for immersion-rated grades, measured at 1 kHz). The venting-vs-sealing basis for the mic/speaker mesh. gore.com (acoustic vents)
[14] MEMS microphone gasket design
Cirrus Logic Application Note WAN0284, "General Design Considerations for MEMS Microphones," covering the sealing gasket around the acoustic inlet and the mesh/gasket stack for a mic port. The basis for the mic stack (mesh + PSA gasket ring + foam). mouser.com (Cirrus Logic WAN0284, PDF)
[15] Speaker gasket / acoustic short-circuit
Reference on the speaker sealing gasket and acoustic short-circuit: a driver sealed to its baffle prevents rear radiation from cancelling front output, the cancellation that most damages low frequencies. sweetwater.com (Speaker Gasket)
Updated . Standards editions and links current at publication; verify against the publishing body before final spec. H-O materials are “aligned to” the standards cited; H-O does not certify systems or IP ratings. Lot-specific qualification documentation available on request.
To review your isolation or acoustic part, send:
- The source and its frequency / RPM
- Mounted mass and bearing area
- Isolate / damp / seal / vent
- Temperature & flame requirement
- Closure force and gap (gaskets)
- IP target & acoustic budget (mic/speaker)
- Part footprint drawing
- Adhesive / liner / mesh needs
- Prototype and annual volume
Get a vibration & acoustic materials engineering quote
Send a drawing, BOM, or a description of the noise or vibration problem. We typically respond within one business day with a material and part recommendation, prototype lead time, and TDS verification against your isolation tuning, sealing, or damping requirement.
See also: related H-O application pages
Engineering content for the adjacent Electronics & IoT sub-applications and the parent hub. Each page covers material selection, failure modes, and converter-side process detail for its application family.
Sibling sub-application
Electronics thermal management
The heat side of the same enclosures: thermal interface pads, gap fillers, and insulators for device cooling.
Read the page
Sibling sub-application
Display & PCB shock protection
The impact-and-drop side: die-cut cushioning that protects displays, boards, and modules from shock, next door to isolation.
Read the page
Sibling sub-application
Enclosure sealing & IP protection
The gasket-sealing playbook this page's speaker and mic seals draw from: perimeter gaskets and IP-rated closures.
Read the page
Industry hub
Electronics & IoT
The full Electronics & IoT application family: sealing, thermal, EMI, insulation, shock, battery, and vibration/acoustic.
Read the page
Material data & standards. All compression, temperature, flame, insertion-loss, and durometer values on this page are taken from the source maker's technical data sheets with the method named (ASTM D3574, D1056, D2240, E756; UL 94 classes per the listed grade TDSs). Isolation theory (natural frequency, the √2 crossover, transmissibility, loss factor) is cited to a named engineering reference.
Qualification standards (IEC 60068-2-6/-27/-64, MIL-STD-810 Methods 514/516) and IP ingress ratings (IEC 60529 / ISO 20653) are cited by designation only: they evaluate the finished device, the rating belongs to the tested product, and the materials on this page support designs evaluated to them.
H-O converts materials; H-O does not design devices, run the vibration qualification, or certify IP ratings, and does not independently certify materials against the standards unless explicitly stated on the quote. Verify against the maker TDS and your device-level test plan.
Conversion scope. H-O and converts sheet, roll, and mesh stock to drawing in Winsted, Connecticut: die-cut and kiss-cut pads, grommets, gaskets, and rings, slit films and meshes, waterjet-cut thick sections, laminated mesh-plus-gasket stacks, and kitted sets, with material traceability and lot-code TDS records. H-O does not perform molding or profile extrusion in-house; those profiles are coordinated through a partner network. Lead-time and MOQ details are in the process strip and the quote form above.