Frequently Asked Questions

Dongguan, Guangdong, China (523000). Manufacturing and tooling are at the same site.

Zhengao Electronics was founded in 2017.

Yes. We manufacture to your drawing under OEM/ODM arrangements; every part is made to order rather than taken from a catalogue.

We are a custom moulding manufacturer. We do not hold stock of generic parts and we do not resell other factories catalogues.

We hold ISO 9001:2015. We do not claim IATF 16949, medical device registration, aerospace approval or automotive OEM approval, because we cannot evidence them.

Yes - ours or yours. We do not share drawings or tooling records with third parties.

We maintain the tool and it is not shared with other customers. Where tooling transfer is required, the terms are agreed in writing before the project starts.

Yes. Packaging can be specified for your line - bulk, trayed, bagged or kitted - and the shipping method is agreed at order confirmation.

Yes. Kitting, orientation, trays and bagged quantities can all be arranged at order stage.

No. We do not hold stock of generic parts. Every part is moulded to order, so the drawing and the annual volume define what we make.

A custom moulded silicone gasket seals the interface between two mating surfaces - an enclosure lid, a housing joint, a control panel or a cable entry - so that water, dust and contaminants cannot cross it. It is specified by the sealing gap, the compression available and the service environment, not by a catalogue size.

Silicone (HTV and LSR), EPDM, NBR, FKM (Viton), NR, SBR and CR. The compound is chosen from the service environment, not from preference.

Yes. Every part is made to your drawing, including a physical sample as the starting point where no drawing exists.

Yes, against a physical sample rather than a screen image. Colour matching is verified on a moulded part, not on a colour chip alone.

Certain silicone grades are available for these applications. Tell us the specific requirement at RFQ stage - we will confirm what is available and what evidence we can provide.

We mould to drawing rather than stocking a range. Where a joint articulates, a standard O-ring is usually the wrong geometry because it cannot follow the motion - a custom moulded profile designed for the movement is the correct answer. If a standard geometry genuinely fits your gland, we will say so.

Yes - conductive silicone keypads for switching and tactile interfaces, moulded to drawing with the actuation force and travel defined by the tool.

Yes - silicone vibration dampers and isolators, treated as their own component family rather than as a soft version of another part.

Yes - protective sleeves, boots and covers moulded to the geometry of the part they protect.

Yes - silicone and rubber feet, pads and bumpers, including Shore-A and geometry combinations chosen for grip versus damping.

For an existing part, yes - if the photograph is clear and you can supply key dimensions. For a new part we need a drawing or 3D file, because a photograph does not define the geometry.

Yes - sealing, protection, vibration damping and cable-sealing components for robotics, including articulating joints where the seal is worked in service.

Yes - keypads, conductive keypads, gaskets, seals and protective components, including sealing an electronic enclosure and tactile actuation life.

Yes - protection, waterproofing, vibration and cable-protection components, including camera payload vibration.

Start with temperature and then with the contact fluid. Above 150 C sustained, silicone or FKM. Water, steam and weather, EPDM or silicone. Hydrocarbon oils and fuels, NBR or FKM. Send the service conditions and we will make a recommendation with the reasoning.

Lower hardness seals at lower compression and feels softer; higher hardness resists extrusion and compression set. The correct value depends on the load and the sealing geometry. We work across 20-80 Shore A.

As a working reference we hold +/-0.05 mm on critical moulded dimensions under controlled conditions. For non-critical features a wider band is usually correct and cheaper. We will tell you which of your dimensions are realistically tight before tooling.

The published working range is -60 C to +230 C, and the usable band depends on the compound selected. Give us the continuous temperature and the peak, because they are not the same requirement.

The most common cause is compression set: the elastomer stops springing back and the sealing force disappears. It is a compound and gland-design problem, and replacing the seal with an identical one will reproduce the same failure.

If the joint articulation works the seal, a standard O-ring is usually the wrong geometry - it cannot follow the motion. A custom moulded profile designed for the movement typically lasts far longer.

Yes. Friction raises motor current and heat and accelerates wear on both the seal and the bearing surface. On a continuously articulating joint it is often the limiting factor rather than the sealing performance itself.

Yes. Send the failed part and the exposure details. We will identify the failure mechanism and propose a compound and geometry change, then produce samples to verify.

With dedicated sealing at the pass-through rather than relying on the main gasket to cover it. Corners and holes are where industrial seals leak first.

The joint motion, the cycle rate, the temperature range, the coolant or chemical exposure, and the dimensions of the current sealing gland. A photograph of the failed part helps considerably.

Compression set is the permanent deformation an elastomer keeps after the load is removed. Once it sets, the seal stops pushing back against the gland and the sealing force disappears - which is why a joint seal can pass a leak test on day one and fail months later.

In an articulating joint the seal is worked continuously. Friction raises motor current and heat and wears the counterface, so it can be the limiting factor even when the hardness is correct for the static gland.

Yes. First-article samples for fit, function and life testing are produced before mass production, shipped with inspection data. Sample cost is quoted separately from tooling.

Incoming material verification, in-process parameter checks, dimensional inspection of critical characteristics, hardness testing and visual inspection against the approved reference sample.

Dimensional and hardness inspection records. Material sheets are available on request.

The silicone molding page documents the work we decline. Read it before you send a requirement that sits outside moulding, tooling and finishing - we would rather decline early than quote something we cannot evidence.

A drawing or 3D file (STEP, IGES, PDF, DWG) or a physical sample, plus the application, the service environment (temperature, chemicals, motion), expected annual volume and any documentation requirement. The more you provide upfront, the fewer quotation rounds are needed.

Simple enquiries with a clear drawing come back quickly. Enquiries where we need to clarify material or geometry take longer because we would rather ask than guess. We will tell you if we need something from you.

MOQ is quoted per project rather than published as a blanket figure. It depends on part size, tooling and compound. Because tooling cost is refundable against volume production, a pilot order is usually workable.

It depends on part size, geometry, number of cavities and process. It is quoted per project and stated separately from the part price so you can see what you are buying.

The tooling cost is credited back against production once cumulative volume passes the threshold stated in your quotation. The terms are written into the quote, not implied.

It depends on mould complexity and capacity. It is quoted per project with a dated commitment rather than an open-ended estimate.

Material sheets and batch records are available. Where a specific third-party certification is required, raise it at RFQ stage and we will confirm honestly whether we can provide it.

Yes. First-article samples for fit, function and life testing are produced before mass production and shipped with inspection data. Sample cost is quoted separately from tooling.

Yes. Quotations return material options, tooling scope and pricing by volume band, so you can see how the unit price behaves as the annual quantity changes.

No. Tooling is stated separately from the part price, with the refund-against-volume terms written into the quotation.

Eleven third-party SGS reports on the silicone compound: EU RoHS (EU) 2015/863, REACH SVHC, seventeen phthalates to EN 14372, eighteen PAH parameters to AfPS GS 2019:01 PAK, halogen to EN 14582, US FDA 21 CFR 177.2600, LFGB Section 30 and 31, LFGB bisphenols and GB 4806.16-2025. All Pass. The report numbers are listed on the material compliance page.

Yes, at compound level, and we will show you the evidence rather than a label. The compound carries SGS reports to US FDA 21 CFR 177.2600, LFGB Section 30 and 31 with BfR recommendation, and GB 4806.16-2025 - all Pass. Compliance of a finished part depends on the grade, the colour and the process, so tell us the standard your market requires and we will match the grade.

Yes, for a named project. The reports were issued to the compound manufacturer, so we cite the report numbers and the standards publicly and send the documents that apply to your grade and application on request. Tell us which standard your customer or your market requires.