Chinese
Mandrel Head
General note
In PET bottle production, the stability of the process often depends on parts that are not visible in the finished bottle. The mandrel head is one of those components. It is installed inside the blow molding system and directly interacts with the preform during forming, blowing, and neck control stages.
The mandrel head with a size of Ø26.3 × 62 is used on PET bottle production lines where dimensional accuracy and repeatability are required over long production cycles. It is manufactured by Foshan Baijinyi Precise Technology Co., Ltd. (BJY), a Chinese manufacturer established in 2011 and specialized in PET molds and precision mechanical parts.
BJY mainly supplies PET preform molds, blow molds, cap molds, and functional components used on beverage and packaging production lines. Company background and related products are available at www.bjypetmold.com
Practical Function During Blow Molding
When a heated PET preform enters the mold, its position must remain stable before and during blowing. The mandrel head supports the preform from inside and helps keep it aligned with the mold cavity. Without proper support at this stage, the preform may shift slightly, which often leads to uneven wall thickness or shape deviation after blowing.
Material distribution inside the bottle is also affected by the mandrel head. Its diameter, surface profile, and relative position determine how the material stretches as air pressure increases. A well-machined mandrel head allows the material to expand in a controlled manner, reducing local thinning and improving overall bottle strength.
During the blowing phase, compressed air expands the preform against the mold wall. The mandrel head does not generate air itself, but its structure influences airflow behavior inside the preform. An optimized design helps avoid irregular expansion caused by uneven pressure or uncontrolled air movement.
On some production lines, especially blow–fill–cap integrated systems, the mandrel head continues to play a role after bottle forming. It may serve as a reference or guide for filling components and helps keep the neck area stable before sealing. This improves consistency in filling and reduces problems related to misalignment or poor sealing.
The upper section of the mandrel head is usually designed for neck control. Accurate machining in this area helps improve bottle mouth quality and reduces common defects such as deformation, burrs, or leakage after capping.
Material Selection and Manufacturing Process
Depending on operating conditions, the mandrel head can be produced from alloy steel or stainless steel. Material choice focuses on wear resistance, strength, and the ability to maintain dimensional accuracy during long-term operation.
All machining is completed using CNC equipment. Critical dimensions are controlled to ensure proper fit with the mold and machine system. Surface finishing and treatment can be adjusted according to production speed, temperature, and customer requirements.
Basic Technical Data
Outside diameter: Ø26.3 mm
Length: 62 mm
Machining method: CNC precision machining
Application: Continuous PET bottle production
Custom versions: Available based on drawings or samples
Application Range
This mandrel head is commonly used on:
PET stretch blow molding machines
Rotary and linear blow molding equipment
Blow–fill–cap integrated lines
Beverage, bottled water, edible oil, and general PET packaging lines
How It Works in Production
The mandrel head is positioned inside the mold cavity and supports the preform during heating and blowing. As compressed air expands the preform, the mandrel head helps stabilize the process and limits uncontrolled movement. After forming, it contributes to maintaining accurate neck dimensions, which is critical for downstream filling and capping operations.
About BJY
BJY has been manufacturing PET-related molds and precision components since 2011. The company’s designs are based on real production feedback rather than theoretical models alone. Attention is given to machining accuracy, material stability, and long-term performance under industrial conditions.
Compared with original equipment parts, BJY products offer reliable performance with more flexible cost control. Components are supplied to customers using various PET production systems and are intended for continuous operation.
For technical details or product inquiries, please visit www.bjypetmold.com
description2