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Highlight: Excellent in interchangeable cores molds design & making. Molds can be interchangeable on molding machines.
Mold Steel: Buderus, Assab, AISI & JIS(including preharden steel and fully harden steel).
P20(=1.2311),S136(=1.2344), Starvax 420(=stainless steel).
Mold Base: Hasco standard, European standard, world standard Surface Finish: Texture(MT standard), high gloss polishing .
Engraving: Date stamps(year and month), logotype, etc .
Mold sampling-Mold trial: Trial molding machine available: from 50~2500T.
The mouth of edible oil bottle is 28MM, 30MM, 45MM. 28MM capacity is usually 500ml, 1L, 1.5L, 2L. 2.5L. The cap has a combination of upper and lower caps. The upper cap can be divided into two types: tear off anti-theft and non anti-theft. The lower cap is mostly opened by the middle pull ring. There are pull rings in some flap cap of 28MM and 30MM, it is more convenient to open and close them directly without unscrewing the threads.
Thickness of the pull-ring connecting bridge: The connecting part (i.e., the tear-off bridge) between the pull ring and the lower cap must be precisely controlled by the mold, typically designed to be 0.15-0.25mm. Excessive thickness makes pulling difficult, while insufficient thickness may cause accidental breakage during transportation. The mold must use slow wire cutting to process the tear-off bridge cavity, ensuring a tolerance within ±0.01mm, so that the pull-off force of each batch remains stable at 8-15N (easily pullable by adults with one hand, yet not easily opened by children).
Filleted edges of the pull ring: The edges of the pull ring in the mold cavity must be designed with a radius of R0.1-R0.2mm to avoid sharp right angles after molding. The surface roughness of the pull-ring edges after molding must reach Ra ≤ 0.8μm, ensuring no cutting sensation when touched by users' fingers and no skin scratches during pulling.
Concentricity of the pull ring and the cap: The concentricity error between the center of the pull ring and the center of the lower cap must be ≤ 0.1mm, guaranteed by the precise fit of the mold's locating pins and guide pillars (with a clearance ≤ 0.005mm). Excessive concentricity deviation may cause uneven force during pulling, leading to partial residue or pull-ring breakage.
The pull ring and its surrounding cavity require multi-stage polishing: from rough grinding (800# sandpaper) to fine polishing (W3.5 diamond paste), achieving a final surface roughness of Ra ≤ 0.02μm to ensure the molded pull ring has a smooth, flawless surface. Additionally, the cavity must undergo chrome plating (plating thickness 5-8μm) with a hardness ≥ HV800, which not only enhances wear resistance (preventing burrs caused by cavity wear during long-term production) but also facilitates the cleaning of oil stains during demolding (meeting food-grade hygiene requirements).
The area around the pull ring is the end of melt flow, where bubbles or shrink marks are likely to form due to poor venting, leading to burrs during pulling. The mold must have invisible venting grooves 0.01-0.02mm wide at the root of the pull ring, with a length of 5-8mm, ensuring smooth gas discharge during melt filling while preventing melt overflow that would form flash.
The mold design for the pull-ring lower cap of edible oil bottles focuses on ensuring the pull ring is "easily pullable, burr-free, and non-polluting" through precise structural parameters (connecting bridge thickness, fillets, concentricity), high-gloss cavity processing, and matched injection molding processes. Every detail—from the width of venting grooves to the control of cooling water temperature—must revolve around the safety and user experience of food-grade packaging, ultimately achieving the household scenario requirements.
