Views: 0 Author: Site Editor Publish Time: 2026-07-23 Origin: Site
In cosmetic, paint, DIY art supply, and daily chemical packaging industries, CT continuous thread finishes (400, 410, 415, 425 series) are the most universal global standards. For injection mold manufacturers and packaging product buyers, understanding thread differences is critical for stable mass production, perfect sealing performance, and long mold service life.
Many customers only focus on thread size but ignore mold release structure, steel hardness, thread compensation, and gate layout — these factors directly determine whether the cap can be assembled smoothly, leak-free, and produced consistently for 200,000+ shots.
All standard neck finishes follow the same rule:
First number = outer neck diameter (mm)
Last three digits = thread height, pitch, and engagement turns
For example: 18/410 means 18mm neck diameter with standard 410 thread profile.
Features: Shallow thread, short engagement, simple structure, easy release.
Common sizes: 10/400, 13/400, 15/400, 18/400, 20/400, 24/400
Applications: Ordinary flip-top caps, simple packaging, low-viscosity liquid bottles with basic sealing requirements.
Injection Molding Analysis
Suitable for forced demolding for soft PP material, low mold cost
ABS / PC hard plastic cannot use forced ejection — thread teeth will crack and scratch
Low precision requirement, friendly for small-batch production
Mold steel: P20HH is enough for short-run production
Features: Balanced thread depth, perfect sealing, smooth twisting feeling, universal compatibility.
Common sizes: 18/410, 20/410, 24/410, 28/410
Applications: Art paint bottles, pigment squeeze caps, essential oil bottles, spray nozzles, daily chemical packaging — exactly your customer’s 18/410 nozzle cap project.
Injection Molding Analysis
Best choice for rotary thread core mold structure
Guarantees zero thread scratch, uniform tolerance after tens of thousands of shots
Thread tip is thin and easy to wear — requires pre-hardened high-grade steel
718H / 2083BSH is highly recommended for 200,000–250,000 shots long-life production
Strict shrinkage compensation required for ABS / PP materials to avoid loose or tight assembly
Customer Case Match: The 18/410 thread with a 1.2mm top front nozzle hole fully belongs to high-precision 410-series molding, requiring stable mold structure and high-hardness steel for consistent batch quality.
Features: Longer thread engagement, stronger locking force, excellent leak-proof performance.
Common sizes: 18/415, 20/415, 24/415
Applications: High-viscosity paint, texture paste, glue, pressure-resistant packaging that requires no leakage during long-term storage and transportation.
Injection Molding Analysis
Must use rotary thread demolding — forced ejection is impossible
Long thread core easily causes deflection during high-pressure injection
Higher requirement for cooling balance and venting design
Mold cost is 15–25% higher than 410 molds due to complex mechanical structure
Features: Coarse thread, large pitch, high structural strength.
Common sizes: 28/425, 33/425, 38/425
Applications: Large-capacity chemical cans, thick lotion containers, heavy-duty packaging.
Injection Molding Analysis
Thick plastic wall leads to longer cooling cycle
Easy to have air traps and thread burning — needs optimized venting system
Recommended steel: S136H / 2083BSH for anti-rust and high polishing
≤100,000 shots: P20HH — cost-effective for simple thread caps
200,000–250,000 shots long-term mass production: 718H / 2083BSH
White ABS / transparent PC cosmetic parts: 2083BSH with corrosion resistance, no yellowing, no rust spots
Thread scratching / whitening: Hard plastic must use rotary demolding; lower ejection speed; mirror polishing for thread inserts
Loose assembly & leakage: Inaccurate shrinkage compensation; optimize mold temperature and cooling balance
Incomplete thread filling: Avoid gate directly facing thread area; improve local venting
Short-term thread wear: Upgrade mold steel from ordinary P20 to pre-hardened steel
For daily chemical and art paint packaging caps, 410 series (especially 18/410) remains the most balanced and reliable thread standard for overseas long-term orders. With professional rotary thread structure + 718H / 2083BSH high-hardness steel, molds can maintain excellent dimensional consistency and zero-leakage performance for 200,000–250,000 shots, perfectly matching automated factory mass production for European and American customers.
We provide custom precision injection molds for all 400/410/415/425 thread closure caps, including custom top nozzle hole sizes (1.0mm, 1.2mm, 1.5mm), hidden submarine gate design, full DFM analysis, and long-life mold solutions for overseas bulk production.
