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How to Spec an EV Module or Frame Seal: What to Send H-O for a Quote
A seal RFQ that says "EPDM gasket, 3 mm, see DXF" reads like a finished spec, but it is actually a stack of unstated assumptions: that the joint is static, that the class is IP67, that the closure force suits EPDM's firmness, that nothing hot or oily touches the line. When any of those assumptions is wrong, the revision loop starts after tooling instead of before it.
This article is the checklist the H-O applications team works from for module and frame seals: the eleven things to send, why each one changes the answer, how the drawing itself should dimension the seal, 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 joint (module perimeter, frame face, coolant face, vent) | Whether the part is a seal at all, and which of the page's three jobs it does. A coolant-face joint and a vent location route to different materials than a perimeter seal. |
| 2. Static or dynamic, and service frequency | The first fork in the whole spec: a factory-sealed joint prioritizes conformability and set resistance; a repeatedly opened cover prioritizes low stress relaxation, fatigue, and a thicker section. |
| 3. Target IP class (IP67 / IP68 / IP6K9K) | The duty the assembly must pass, per IEC 60529 or ISO 20653. It tunes section, compression plan, and the venting conversation; the rating itself belongs to your tested enclosure. |
| 4. Operating temperature range | The first material filter: silicone's wide span versus EPDM's and neoprene's narrower ranges. |
| 5. Media / chemistry (coolant, fuel, road fluids) | The second filter: petroleum exposure pushes the joint from silicone toward fluorosilicone or neoprene; coolant chemistry is named, not assumed. |
| 6. Available closure force and the gap to close | Whether a soft sponge or a firmer closed-cell section is even feasible. A low-force latched joint and a high-force bolted frame want different firmness. |
| 7. Groove / land width and seal footprint drawing | The geometry review: land width versus thickness, corner radii, fastener positions relative to the seal line. |
| 8. Flame requirement (e.g. UL 94 V-0) | Whether the family must carry a listing; V-0 is available on closed-cell silicone and dedicated sponge grades, always verified per grade and gauge on the TDS. |
| 9. Thermal-cycle and vibration environment | The aging accelerants. Heat and vibration drive both compression set and stress relaxation, so the duty cycle shapes the family and section margin. |
| 10. Adhesive / liner needs and presentation | PSA on one side or none, kiss-cut on rolls or sheets, pull-tabs: how the part installs without stretching on a long perimeter. |
| 11. Prototype and annual volume | Converting method and price structure. Prototype quantities through full production runs are equally accepted; the method may differ. |
How to dimension the seal on the drawing
The geometry rules from the parent page translate directly into drawing practice. Give the seal a sealing-surface width at least equal to its thickness, and ideally about one and a half times, so it compresses against a stable land instead of rolling or extruding. Draw radiused corners rather than sharp ones; sharp corners are stress risers that tear and compress unevenly.
Keep fasteners outside the seal path and note the bolt pattern, because an alternating pattern compresses the perimeter evenly. Prefer a continuous one-piece gasket where the footprint allows, and where the frame is too large for the sheet, say so: a jointed puzzle or collapsible-joint gasket is an engineered solution we can quote, an improvised butt splice is not.
Finally, note the venting plan; a pressure-equalization membrane such as Gore ePTFE is part of the sealing system and is usually die-cut alongside the gaskets.
What engineering does with the list
The review runs the same sequence the application page teaches.
Items 1 and 2 fix the duty; item 3 fixes the class; items 4 and 5 filter the family, with closed-cell BISCO HT/BF silicone the common lead for low set, wide temperature, and the V-0 line, the V-0 silicone sponge where closure force must stay low with a flame listing, closed-cell EPDM as the cost-down secondary, SCE-series neoprene in legacy and oil-adjacent zones, and fluorosilicone sponge where fuel or oil contacts the line.
Items 6 and 7 size the section against the force and the land; items 8 and 9 check the listings and the aging margins (set per the ASTM D1056 procedure for cellular grades, relaxation per ISO 3384); items 10 and 11 set the converting and presentation plan. The output is a family and grade direction with the TDS attached, a section and footprint proposal, and a quote.
What happens after you send it
- Drawing review. Typically opened the same business day; the response is either a material direction or the specific missing items.
- Material direction and quote. Family, grade direction, section, and 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, so the joint can be compression-checked on real hardware.
- 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 stock, and the enclosure's IP result and the pack's UN 38.3 standing belong to your tested assembly.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Duty undeclared | Static material on a dynamic cover; leaks after service cycles | Item 2 |
| Class quoted from the wrong standard | IP67 thinking on an underbody joint that needed IP6K9K (ISO 20653) | Item 3 |
| Firmness beyond the closure force | Under-compressed seal; the assembly fails its ingress test with a "good" material | Item 6 |
| Seal line through the bolts | Pierced sealing line; corner leaks | Item 7 |
| Flame listing assumed family-wide | UL 94 classes are grade- and thickness-specific | Item 8 plus the TDS check |
| No venting plan | Pressure cycling stresses the seals; slow moisture ingress over years | The venting note in the geometry review |
Frequently asked questions
Can H-O tell me what IP class my pack needs?
No, that target comes from your program requirements and the vehicle exposure, and the rating is earned by your tested enclosure. What we do is downstream: once you name the class (IP67, IP68, or IP6K9K per ISO 20653) and the joint geometry, we set the family, section, and compression plan so the seal supports the test, and we say plainly that the rating belongs to the assembly, not the gasket.
What if the joint sees coolant on one face and weather on the other?
Describe both exposures in item 5. Mixed-media joints are common at coolant faces and frame transitions, and the answer may be a different family than either exposure alone would suggest, or a two-part sealing plan. The chemistry list (coolant type, road fluids, any fuel or oil) lets engineering check each medium against the candidate family's data sheet rather than guessing.
Do you need a finished CAD model, or is a marked-up sketch enough to start?
A dimensioned sketch with the land width, gap, corner radii, and fastener positions is enough to open the review and the geometry check. The production die ultimately wants a clean DXF or STEP outline, but the material direction and most of the engineering feedback do not wait for it. Send what exists; the response will list what the final drawing still needs.
How do samples work for a long perimeter gasket?
Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand. For a large frame footprint, the sample may be a representative section or a jointed version while the one-piece production die is decided, which is usually enough to validate compression, corner behavior, and installation handling before tooling.
Send the checklist, get a module-seal quote
Attach the 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 module & frame 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); ISO 3384 (stress relaxation under compression).
- UL 94 (flammability listings); UN 38.3 (pack-level transport context).
- Manufacturer technical data sheets: BISCO HT/BF closed-cell silicone, V-0 silicone sponge, RE-series closed-cell EPDM, SCE-series neoprene, fluorosilicone sponge, 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.