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The battery compartment of an electric nasal irrigator is a wet-adjacent environment with electrical contacts in it, which is a combination worth engineering around. The sleeve shown here holds two cells side by side in a moulded enclosure whose figure-eight cross-section is dictated by the batteries it carries, with contact openings at one end and insulation everywhere the cells touch plastic.
Five views cover the sleeve from its open end, its contact end and its sides. The form looks simple; the mould that makes it is not, because two parallel cylinders joined along their length is a deep-draw core problem in both directions.
The figure-eight section is the moulding challenge. Each bore needs a core, and the cores run parallel down the full length of the part. Where the two cylinders join, the cores nearly touch, and the web between them is a thin bridge the melt has to reach from both sides. Get the cores slightly out of register and the web thins on one side, which shows up later as a weak point exactly where the two cells press against each other.
Draft on long parallel cores is a balance: too little and the cells gall on ejection, too much and the battery fit loosens. The draw is tuned with the actual cells, not a nominal diameter, because a slip fit that is half a percent off either way turns into rattling batteries or sleeves that split at the open end during assembly.
The closed end carries the openings where the electrical contacts pass through. These apertures are doing three jobs at once: locating the contacts so they land on the cell terminals every time, insulating them from each other and from the housing, and sealing against the splashes that a device used in a bathroom inevitably receives. Their positions come from the contact assembly drawing, and the walls between adjacent contacts are held wide enough to keep the insulation honest under the device’s working voltage.
The contact openings are also the smallest features on the part, which makes them the last to fill and the first to short. Gating is arranged so the melt arrives there with pressure to spare, and first-article inspection looks specifically at those corners.
The resin is chosen so the part does its insulation job without a second thought: high resistivity, stable in humidity, and dimensionally steady across the temperature range of a device that gets charged and used warm. Because the sleeve also mechanically fixes the cells, its wall has to survive the insertion and removal loads of battery changes without cracking at the contact apertures, which is where the section is thinnest.
Bore diameter and slip fit with the actual cells. Web thickness between the bores, since that is the structural weak point. Contact aperture positions against the contact assembly, and the insulation walls between them. Dielectric check on samples where the customer specification calls for it, and clip retention on the mounting features.
Kunshan Maifeng Precision Industry Co., Ltd. reviews medical device component designs before quoting, builds the injection molds in house, and molds single-color and dual-color parts on 36 machines from 90 to 700 tons. Send us the cell and contact drawings, and we will come back with a feasibility comment and a tooling proposal.
Kunshan Maifeng Precision Industry Co., Ltd. (MIF) has an investment of RMB 35 million and an independent factory of more than 5,000 m². The company operates 36 single- and dual-color injection molding machines from 90 to 700 tons, together with more than 50 sets of mold manufacturing and processing equipment. Our service, management and production team includes over 100 people.
Our parent company was established in 2008. We provide product design, mold design and manufacturing, injection molding and product assembly services for custom plastic parts, supporting both domestic and international customers.
1. Product Design
Product structure design and optimization based on customer drawings and samples.
2. Mold Design
Mold design developed around product geometry, material and production requirements.
3. Mold Manufacturing
Machining, polishing, fitting and assembly for custom injection molds.
4. Injection Molding
Single- and dual-color injection molding for project and order requirements.
5. Product Assembly
Supporting assembly services for molded plastic components.
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