The texture and molding stability of lipstick shells largely depend on the material properties and processing precision of the upstream aluminum slugs. As a core substrate in the cosmetic packaging industry, the alloy system, surface condition, and dimensional tolerances of aluminum slugs directly affect the downstream stamping yield and final appearance. Haomei Aluminum’s aluminum slugs for lipstick shells have served over twenty well-known cosmetic packaging manufacturers worldwide, covering markets in Europe, America, Southeast Asia, and the Middle East.
Alloy Selection Directly Determines Molding Method and Surface Finish
Common aluminum alloys for lipstick shells fall within the 1xxx series pure aluminum category. Different alloys correspond to different molding processes and appearance requirements. 1070 alloy aluminum purity ≥99.7%, elongation ≥45% after O-state annealing, excellent plasticity, suitable for deep-drawn straight-tube lipstick cases, high surface finish after molding, and no risk of orange peel texture. 1100 alloy, reinforced with trace amounts of copper, boasts a tensile strength of 110-135 MPa in the H14 state, exhibiting higher hardness and suitability for screw-on lipstick cases with internal threads and snap-fit structures. Both alloys undergo strict control of Fe and Si impurity content to ensure uniform anodizing and prevent streaks or color variations.
Dimensional Accuracy and Surface Quality are Core Thresholds
Lipstick cases are classified as Grade A appearance parts, and dimensional deviations in slugs directly amplify in the finished case. Professional-grade lipstick shells use slugs with diameter tolerances typically controlled within ±0.03 mm and thickness deviations ≤±0.015 mm, ensuring stable feeding and consistent forming height during multi-station continuous stamping. Surface finishing requires double-sided precision grinding, achieving a roughness Ra ≤ 0.15 μm, with no burrs, oxide spots, or scratches on the end faces. Aluminum slugs achieving this level of precision can achieve a 6-8 percentage point higher overall yield in downstream stamping processes compared to ordinary industrial-grade slugs, resulting in a significant cost advantage for long-term large-scale production.
Grain Size and Microstructure Uniformity Affect Surface Treatment Limits
High-end alloy casings generally require secondary surface treatments such as anodizing, sandblasting, electrophoresis, or spraying. The uniformity of the aluminum’s internal microstructure determines the upper limit of these processes. High-quality aluminum slugs undergo homogenization annealing during the casting stage to control the grain size within the first-level range, resulting in a fine and consistent metal microstructure. After anodizing, the film thickness is uniform, with high color saturation and no color difference; after sandblasting, the surface is smooth, without bright or dark spots caused by localized coarse grains. For special appearance requirements such as metallic matte finishes and gradient colors, custom-made slugs with refined grains can also be produced, breaking through the surface performance boundaries of conventional aluminum materials.
Material Balance Between Lightweight and Structural Rigidity
Compared to zinc alloy die-casting and plastic electroplating, aluminum lipstick shells achieve a better balance between weight and rigidity. Pure 1070 aluminum slugs, after stamping and stretching, can have a wall thickness as low as 0.25mm while maintaining sufficient resistance to deformation. The overall weight is more than 35% lighter than zinc alloy cases of the same specifications, resulting in a lighter feel in the hand. At the same time, aluminum has good toughness, making it less prone to breakage from drops and extending its lifespan compared to plastic cases. Furthermore, aluminum is 100% recyclable, complying with EU Packaging and Waste Directives and aligning with the current sustainability trends of beauty brands.
Supply Chain Stability and Customization Capabilities
Lipstick shells come in a wide variety of specifications, with significant differences in diameter, height, and structure between different brands. This places high demands on the customization response speed of aluminum slug suppliers. Established suppliers typically have molds covering a full range of diameters from 12mm to 45mm and thicknesses from 0.6mm to 3.0mm, enabling rapid mold creation and customization of special specifications. Haomei Aluminum have two dedicated cosmetic slug production lines with a monthly capacity exceeding 200 tons. We maintain safety stock of standard sizes, and our FOB Qingdao Port delivery time is consistently between 10 and 15 days. Each batch of products comes with a material certificate and surface testing report, supporting SGS and FDA food contact grade certification for traceability.
For new clients, we offer free sampling and technical support services. We can assist clients in adjusting alloy conditions and surface precision until stamping trial production meets standards. If you are evaluating aluminum slug for lipstick shells, or have special specifications or surface requirements, please feel free to contact us for samples.
