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How to Spec an EV Pack-Closure Seal: What to Send H-O for a Quote
The outermost seal on a battery pack collects every requirement the enclosure has: the IP class, the corrosion exposure, the closure force the latch or bolts can actually supply, the service plan, and the flame brief. A closure-seal RFQ that names all of them gets a material direction and a quote in the first reply; one that names only a footprint gets a list of questions.
This is the checklist the H-O applications team works from for pack lids, covers, service joints, and moisture barriers: the eleven things to send, what each decides, how the drawing should dimension the joint, and what happens after you hit send.
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The eleven things to send, and what each decides
| Send this | What it decides |
|---|---|
| 1. The closure (lid, cover, service joint, barrier) | The form of the part: a compressed perimeter gasket for a lid or cover, or a conforming no-cure barrier (butyl) at a lap, transition, or penetration. Gasket thinking and barrier thinking are different parts. |
| 2. Static or dynamic, and service frequency | A factory-sealed lid is static (conformability and set resistance lead); a repeatedly opened service cover is dynamic (low stress relaxation, fatigue resistance, thicker and lower-force section). |
| 3. Target IP class (IP67 / IP68 / IP6K9K) | The duty the assembly must pass per IEC 60529 or ISO 20653. It tunes section and compression; the rating belongs to your tested enclosure. |
| 4. Available closure force (latch or bolted flange) | The fork between a soft closed-cell gasket (low-to-moderate force) and solid silicone (heavy, even bolted clamp). Force decides form before material. |
| 5. Corrosion / moisture exposure | Weights the moisture-barrier properties (closed-cell absorption behavior, butyl at laps and penetrations) and flags coastal, splash, and wash duty. |
| 6. Operating temperature range | The silicone-versus-EPDM filter: silicone holds sealing properties across a wider span; EPDM costs less inside a narrower one. |
| 7. Gap to close and groove / land width | The geometry review: land width versus thickness (at least 1x, ideally ~1.5x), compression percentage, and whether the section fits the groove. |
| 8. Lid / closure footprint drawing | Outline, corner radii, fastener positions, and any splice constraints; decides die strategy and whether a one-piece or engineered jointed gasket is the plan. |
| 9. Flame requirement (if any) | Whether the family must carry a UL 94 listing; V-0 is available on closed-cell silicone lines, verified per grade and gauge on the TDS. |
| 10. Adhesive / liner needs and presentation | PSA sides, kiss-cut rolls or sheets, pull-tabs: how a long perimeter installs without stretching. |
| 11. Prototype and annual volume | Converting method and price structure; prototype through production runs are equally accepted. |
What engineering does with the list
Items 1 and 2 fix the form and the duty. Item 3 fixes the class the assembly must pass, and item 4 forks the form: low-to-moderate force points at closed-cell BISCO HT/BF silicone, a heavy bolted flange points at solid silicone rubber, and a lap or penetration barrier points at butyl sealing tape rather than a gasket at all. Items 5 and 6 run the exposure filters, with EPDM foam entering where the program costs down inside a milder duty.
Items 7 and 8 are the geometry review (land, corners, bolts, splice plan), item 9 checks the UL 94 listing per grade and gauge, and items 10 and 11 set presentation and converting method. Aging is checked against the right procedures: set per ASTM D1056 for the cellular grades and ASTM D395 for solid silicone, never compared across the two bases.
What happens after you send it
- Drawing review. Typically opened the same business day; the reply is a material direction or the specific missing items.
- Material direction and quote. Family, grade direction, section, geometry feedback, and the converting plan, with grade data cited to the manufacturer's TDS.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials on hand; large lids may sample as a representative section while the production die is decided.
- Production. Standard production runs about two weeks after drawing approval; special orders are quoted to the job. MOQ varies by material and part.
Documentation available on request: material technical data sheet, certificate of conformance, lot traceability, and first-article inspection, under our ISO 9001:2015 certified quality management system. H-O is a die-cut converter, not a raw-material producer; we do not extrude or mold the silicone, butyl, or membrane, and the IP result and UN 38.3 standing belong to your tested pack.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Gasket specified where a barrier belongs | A compressed gasket bridging an irregular lap that wanted conforming butyl | Item 1 |
| Solid silicone on a latched cover | Under-compressed seal; the cover cannot supply the clamp force | Item 4 |
| Class copied from an industrial catalog | "IP69K" on a road-vehicle drawing that wanted IP6K9K per ISO 20653 | Item 3 |
| Land narrower than the seal thickness | Rolling and extrusion off the land | Item 7 |
| No service-frequency note | Static material on a dynamic cover; leaks after repeated opening | Item 2 |
| No venting plan | Thermal breathing loads the lid seal and works moisture past it | The vent note above |
Frequently asked questions
What is the single most common gap in closure-seal RFQs?
The available closure force. Footprints and IP targets usually arrive; the latch or bolt force rarely does, and it is the number that forks the whole answer between a soft closed-cell gasket and a solid silicone section. If the force is not yet known, send the fastening concept (latch, bolt count and size) and engineering can work the fork from there.
Can H-O quote the butyl barriers and the ePTFE vent with the lid gasket?
Yes, and it is the normal pattern. The lid gasket, the butyl pieces for laps and penetrations, and the ePTFE vent disks are die-cut parts of one closure system and are commonly quoted and kitted together, so the assembly line receives the set rather than three loose part numbers.
Do you need the groove dimensions if the gasket is flat-die-cut?
Yes, or the land dimensions where there is no groove. The land or groove width against the seal thickness is the first geometry check (at least 1x, ideally about 1.5x), and the gap drives the compression percentage the section must deliver. A footprint without the land and gap can be die-quoted but not engineering-reviewed.
How fast can a closure-seal program get samples?
Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand. Tooling-free cutting covers first articles for most footprints, and first-article inspection is available on request; standard production after drawing approval runs about two weeks, with special orders quoted to the job.
Send the checklist, get a closure-seal quote
Attach the lid or joint drawing and as many of the eleven items as you have. Drawing review typically starts the same business day.
Samples typically 3 to 5 business days; production about two weeks; MOQ varies by material and part. Expedited service available.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
Related reading
Request a quote for your EV pack closure & environmental sealing part
Send H-O your drawing or describe the part—engineering reviews every RFQ and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- IEC 60529 (base IP code) and ISO 20653 (road-vehicle IP code, IP6K / IP9K variants).
- ASTM D1056 (cellular rubber, compression-set procedure); ASTM D395 (dense rubber set, different basis).
- UL 94 (flammability listings); UN 38.3 (pack-level transport context).
- Manufacturer technical data sheets: BISCO HT/BF closed-cell silicone, solid silicone rubber, EPDM foam, butyl sealing tape (Poly-Seal class), Gore ePTFE venting membrane.
This checklist supports a quotation workflow; it does not constitute design guidance for any specific pack. Grade-level values are confirmed on the manufacturer's current technical data sheet; IP and UN 38.3 outcomes belong to the tested assembly. All parts are custom manufactured to order; minimum production run quantities vary by material and part. H-O is a die-cut converter, not a raw-material producer.