Personal Care Molds Application Case: Design and Manufacturing of Special Molds for Shampoo Pump Head Housings-News

Personal care molds are key equipment for the large-scale production of personal care product packaging and core components. Their forming precision, appearance reproduction ability, and hygienic safety directly determine the product's user experience, brand texture, and market competitiveness. As a frequently used personal care packaging component, the shampoo pump head housing not only functions to protect the pump core, control liquid output, and transmit pressing force but also needs to have excellent appearance texture, chemical corrosion resistance, hygienic safety, and assembly stability to meet the mass production needs of different specifications of shampoo packaging. Traditional molds struggle to balance the forming of precision buckle structures, high-gloss appearance consistency, and low-cost mass production, while special personal care molds can achieve triple compliance of product performance, appearance, and production efficiency through optimized structural design and precision manufacturing. Taking the 500ml shampoo pump head housing as the target product, this article elaborates on the application details, technical points, and practical value of personal care molds, providing a reference for the development of similar molds.

I. Product Characteristics and Core Mold Requirements

The shampoo pump head housing focused on in this case has a stepped cylindrical structure with an overall size of Φ32mm×65mm and a main wall thickness of 1.3mm. It integrates an arc-shaped pressing platform on the top, a pump core installation cavity, a snap-fit fixing structure, and a leak-proof groove inside, with a threaded interface reserved at the bottom for matching with the bottle body. The appearance surface needs to present a high-gloss mirror effect without shrinkage marks, flash, scratches, or color difference, and the surface glossiness is ≥90GU. The product is made of food-grade ABS resin, complying with GB 4806.7-2016 and FDA 21 CFR §177.1500 food contact material standards. It has excellent corrosion resistance to shampoo components (surfactants, fragrances), impact resistance, and no fracture, deformation, or liquid leakage after more than 2,000 pressing cycles.

The core requirements for the corresponding personal care mold are clear: cavity dimensional tolerance of ±0.01mm to ensure precise adaptation of buckles, threaded interfaces to the pump core and bottle body, with assembly gap controlled within 0.05mm and leak-proof groove sealing precision up to standard; the appearance cavity requires high-gloss polishing (Ra≤0.1μm) to ensure appearance consistency of mass-produced products, with color difference ΔE≤0.8; a 16-cavity symmetrical layout is adopted to balance mass production efficiency and forming quality; a precise gating and cooling system is equipped to avoid high-gloss surface defects and structural deformation; the mold material must be easy to polish, wear-resistant, and free of impurity precipitation, adapting to the forming characteristics of ABS material, with a service life of not less than 600,000 cycles to meet the large-scale mass production needs of the personal care industry.

II. Key Design Points of Personal Care Molds for Pump Head Housings

The mold adopts an overall two-plate structure suitable for horizontal injection molding machines, optimized for the high-gloss and precision characteristics of the pump head housing. The mold material is S136 medical-grade stainless steel, subjected to solution treatment, nitriding treatment, and surface polishing treatment to improve wear resistance, corrosion resistance, and high-gloss reproduction ability. The core design points are as follows:

Parting surface and cavity design: The parting surface is arranged in an arc along the maximum contour line of the housing, avoiding key areas such as the pressing platform and threaded interface. An angle pin parting structure is adopted to reduce the impact of parting line marks on the high-gloss appearance. The cavity is precisely processed according to the curved surface of the pump head housing, and the internal core is integrally formed corresponding to the buckle and leak-proof groove structures. A 0.03mm pre-deformation compensation is reserved at the buckle part to adapt to the shrinkage characteristics of ABS material, avoiding assembly jamming and liquid leakage. The inner wall of the cavity achieves a high-gloss mirror effect through multiple polishing processes, with a 0.06mm draft angle reserved, combined with a built-in release agent channel, to ensure smooth demolding of the product without scratching the high-gloss surface.

Gating and cooling system: A hot runner + submarine gate gating system is adopted, with a main sprue diameter of 9mm and symmetrically distributed branch runners. Each cavity is equipped with an independent hot runner nozzle, with a temperature control accuracy of ±0.5℃. The gate is set at the bottom of the non-appearance surface of the housing to reduce gate residue and marks, ensuring uniform filling of the thin-walled structure with molten plastic, and avoiding local material shortage and shrinkage marks. The cooling system adopts an annular conformal water channel design, fitting the arc-shaped outer wall of the cavity and the inside of the core, with a water channel spacing of 7-9mm. The mold temperature is controlled at 50℃ and precisely regulated by a constant temperature cooling machine to ensure uniform temperature in all cavities, shorten the forming cycle to 18s, and effectively prevent high-gloss surface defects and structural deformation.

Ejection and exhaust system: A combined structure of ejector pins and ejector plates is adopted. Ejector pins are evenly distributed in the non-appearance area of the housing edge, and the ejector plate is attached to the inner side of the bottom threaded interface, realizing uniform distribution of ejection force and avoiding product deformation and surface damage caused by uneven force. Micro exhaust grooves (width 0.02mm, depth 0.01mm) are set at the root of the buckle, the highest point of the cavity, and the corner of the leak-proof groove, combined with exhaust pins for auxiliary exhaust, to quickly discharge air and molten plastic volatiles in the cavity, control the air hole and burning defect rate below 0.1%, and ensure the structural integrity and sealing performance of the product.

III. Mold Manufacturing Process and Quality Control

The manufacturing of personal care molds for pump head housings follows the principle of "high-precision machining + full-process hygienic control", with the process flow: material pretreatment → 5-axis CNC milling → EDM precision machining → high-gloss polishing → cavity cleaning → assembly and debugging → mold testing and optimization → finished product acceptance. The whole process is controlled around three core aspects: high-gloss appearance, structural precision, and hygienic safety.

High-precision machining link: After quenching and tempering treatment, S136 stainless steel is processed into cavity and core blanks by 5-axis CNC milling, with a machining accuracy of ±0.003mm, focusing on ensuring the precision of the threaded interface, buckle size, and flatness of the leak-proof groove; EDM (Electrical Discharge Machining) is used to process complex structures inside the buckles, using copper electrodes for discharge forming, reducing the surface roughness to Ra≤0.08μm; Wire cutting is used to process precision parts such as ejector pins and positioning pins to ensure uniform fit gaps of all components without assembly jamming, adapting to high-speed injection molding needs.

High-gloss treatment and assembly: The inner wall of the cavity undergoes three processes of rough polishing, fine polishing, and mirror polishing in sequence, finally achieving a high-gloss effect of Ra≤0.1μm. After polishing, absolute ethanol is used to thoroughly clean the cavity to remove residual impurities and ensure hygiene. During assembly, an optical projector is used to calibrate the coaxiality and parallelism of each component, ensuring the ejection mechanism moves smoothly without jamming. Food-grade silica gel is selected for seals to prevent hydraulic oil leakage and product contamination, meeting the hygienic requirements of personal care products. Meanwhile, dual sensors for mold temperature and pressure are installed to monitor molding parameters in real time.

Mold testing and optimization: A Haitian MA2000/600 injection molding machine is selected for mold testing, with the plasticizing temperature set at 215-235℃, injection pressure at 75-85MPa, holding pressure at 55-65MPa, and cooling time at 18s. After mold testing, a coordinate measuring machine is used to detect key dimensions, and a gloss meter and color difference meter are used to test appearance performance. The holding time and mold temperature are adjusted to solve slight shrinkage marks on the high-gloss surface, and the qualified rate of optimized products reaches 99.8%, with 100% compliance in assembly adaptability and sealing performance.

IV. Application Value and Practical Effects

After the personal care mold is put into production, the single-shift output reaches 57,600 shampoo pump head housings, adapting to the mass production demand of 12 million bottles of shampoo per year. Compared with traditional 8-cavity molds, the production efficiency is doubled, and the unit product mold sharing cost is reduced by 22%. The mold has excellent stability, with a service life of up to 650,000 cycles under normal production conditions, greatly reducing the frequency of mold replacement and downtime losses, and meeting the cost control demands of large-scale mass production in the personal care industry.

Practical application verification shows that the pump head housings formed by the mold have uniform high-gloss texture without obvious defects, fit closely with the pump core and bottle body, and have good sealing performance, with smooth pressing without jamming or liquid leakage. They show no discoloration or cracking after 72 hours of corrosion resistance testing against shampoo components. Meanwhile, the mold is suitable for the forming of food-grade ABS material, and the products can directly meet the hygienic standards for personal care product packaging without additional grinding or trimming, shortening the production chain and helping brands improve product appearance and market competitiveness.

Conclusion

The design and manufacturing of special personal care molds for shampoo pump head housings accurately meet the core requirements of the personal care industry for high-gloss product appearance, sealing reliability, hygienic safety, and large-scale mass production. Through scientific cavity structure design, efficient gating and cooling system configuration, and full-process quality control, the dual improvement of product performance and production efficiency is successfully achieved. With the upgrading of the personal care industry towards high-endization and refinement, personal care molds will further integrate digital design and intelligent monitoring technologies, optimize high-gloss reproduction and precision structure forming capabilities, adapt to more complex shapes and functional needs, and provide core technical support for improving the quality and efficiency of personal care product packaging.