Liquid Silicon Rubber_Shenzhen ZhenXiong Hot Runner Technology co. LTD

Application case

Advantages of liquid silicone

application

1. Non-toxic to human body, safe and sanitary, odorless and tasteless;

2. Good transparency and can be disinfected;

3. No pollution to the environment and be degradable

performance

1. Good tactility, elasticity and aging resistance;

2. Good resistance to high temperature properties, thermal stability (continuous working temperature
can up to 180 ° C).

3. Excellent low temperature performance (-50 ° C still with softness);

4 excellent electrical insulation, when burning no harmful substances will be produced.

Electrical and mechanical engineering, mobile phone protecting brush, sealing element and spacer etc.

Sports and smart device , moto mobile ,watch ,toys etc.

》Properties of liquid silicone

Characteristics difference between liquid silicone molding and ordinary injection molding products:

1) liquid silicone is a kind of thermosetting material;

2) rheological behavior: low viscosity, rapid curing, shear thinning, high thermal expansion coefficient;

3) good fluidity, low requirements for mold locking force and injection pressure, but high requirements
for injection accuracy;

4) exhaust design is relatively difficult. Some products need to be designed with sealed and vacuum-
pumped structure, which requires high precision of the mold.

5) design the cooling structure of the cylinder and the casting system, and design the heating system
of the mold.

》Design essentials of liquid silicone mold heating

Mould temperature control.

Liquid silicone injection mold under the mold temperature 120 ~ 150 ℃ cause the curing reaction,the key point is to control mold temperature

1) the mold surface temperature shall be stable.

If the surface temperature is too high, which will produce products burning, parting line cracking, brittle products and other phenomena.

If the surface temperature is too low and the glue curing speed is slow which will cause the product can not demoulding and other quality problems;

2) the temperature of the mold shall be heated evenly.

Mould heating is not uniform, the temperature difference is large,which will make the plastic flow not stable, easy to appear air, injection dissatisfaction and other phenomena;

3) position the heater

Sufficient distance should be kept between the heater and the parting line to prevent the formwork from warping and deforming, leading to the formation of flash edges of finished products;

》Comparison of mold temperature control heating mode:

Key points of pouring design of liquid silicone mold

Runner pouring system design.

Cold runner molding is one of the important processing characteristics of liquid silicone rubber

1) cooling system shall be designed inside the cooling nozzle:

There is a big difference between cold runner molding and hot runner system. Water line should be designed inside the cold nozzle, and an effective heat insulation layer should be set between the mold cavity and cold runner to isolate temperature transfer.

If the sub-runner is too hot, the material will begin to solidify before injection, and the product is prone to cracking and no injection products will be produced.

2) the cooling nozzles shall be designed with a closed system for automatic production with a shorter cycle:

Cold nozzle design needs to use valve gate closed system, the gate design is between 0.5-0.8mm, the valve system needs to design a highly adjustable structure, which is easily to fine tune the flow through the valve.

3) the cold nozzle needs to be designed with the injection amount control system

When injection molding silicone seals of micro products, and the product weight is less than 1 g, the amount of precision control system need to be designed to ensure that the amount of plastic flow can be controlled and be adjustable.

》For micro products,the amount of precision control system need to be designed to ensure that the amount of plastic flow can be controlled and be adjustable.

Application of liquid silicone in waterproof mobile phone

The innovative application of liquid silicone in waterproof structural parts of mobile phones solves the problem of water damage of mobile phones. The injection molding methods of metal + silica gel, plastic + silica gel, glass + silica gel and other secondary forms will become the new trend of mobile phone waterproof.

》Advantages of two-color silicone injection molding waterproof over traditional mobile phone waterproof:

Traditional mobile phone waterproof adopts coating adhesion , ultrasonic welding, due to the need for manual operation in the middle, its assembly accuracy, stability can not be guaranteed, which means easily damaged and the waterproof effect is poor.

The waterproof structure of liquid silicone injection molding is simplified, the overall structure is compact, the assembly precision and repeat precision are high, the waterproof effect is improved, and the waterproof grade is above grade 5.

The secondary molding bond strength is high of liquid silicone injection molding and metal, plastic and other materials , which can be repeatedly disassembled and easy to be replaced and waterproof stability.

》Comparison of mobile phone soft rubber jacket -- TPU and liquid silicone
silicone jacket
Advantages: non-toxic to human body, good buffering performance, high wear resistance, oil resistance, water resistance, good flexibility, comprehensive protection, and it will not turn yellow.
It can be used in double color gluing mould to make waterproof sheath.
Disadvantages: slightly poor fitting with the fuselage

TPU jacket
Advantages: high wear resistance, high strength, outstanding cold resistance, oil resistance, water resistance, mycete resistance, good flexibility
Deficiency: easy to deform and turn yellow

Zhenxiong provides customers with integrated solutions
For the silicone mold, zhenxiong provides more professional, more convenient solutions.
Zhenxiong can provide solutions according to customer requirements, including:
Front mold cold nozzle and front mold structure design
According to the hot -half structure to provide cold nozzle whole delivery (cold nozzles, front board and insulation board are delivered to the customer after zhenxiong processes and assembles them)
Provide installation technical guidance and trial mold technical services.

Solution

》Reasons for system leakage.
  ■ Zhenxiong manifold is inserts and polished by the runner polishing machine
Along with Hot fit application (interference fit) without leakage .

Leakage of nozzle sealing
  ■ Zhenxiong has strict testing training and requirements for all the installation
personnel. Only when all the dimensions are processed accurately according
to the drawings can they be installed to ensure no leakage.

Nozzle and manifold matching surface leakage.
  ■ zhenxiong design has avoided possible machining errors, as shown in the
right figure
  ■ Zhenxiong focuses on engineering materials and high glass fiber products
Imported steel, specially treated, more wear - resistant and corrosion - resistant
  ■ Zhenxiong nozzles are made of imported steel with special treatment,
effectively ensuring the life of products. The quality of hot runner products is
designed with 10 years' service life, and the design life of products with fiber
added within 15% is designed with 2 million times of mold.

》Zhenxiong focuses on engineering material and high fiber products
   Imported steel, specially treated, more wear - resistant and corrosion -resistant
Zhenxiong nozzles are made of imported steel with special treatment, effectively ensuring the life of products. The quality of hot runner
products is designed with 10 years' service life, and the design life of products with fiber added within 15% is designed with 2 million times of mold.

》Reasons for products yellowing ,black coating.
■ Dead angle existed in nozzle outlet .
Zhenxiong has professional MTO patent for molding transparent/color changing products nozzle.This type of nozzle
has no dead angle, fast color change  and small pressure loss.
■ There is a dead angle at the corner of the manifold. The plug at the
junction angle of the runner adopts smooth transition, and the special
position adopts mosaic structure to ensure the junction angle is smooth.
■ The plastic material stays in the runner too long.
See attached page for detailed calculation of plastic injection volume and
residence time

》Nozzle temperature difference accuracy
The internal temperature error of zhenxiong nozzle is no more than 10 degrees.

product standard
1. 90% of the products are standardized and 90% are in
sufficient inventory.
Standardized production ensures the consistency of quality.
2. Material import
Nozzles are made of ASSAB imported materials, and the
processing technology is strictly controlled to ensure the
interchangeability of
nozzles effectively.
3 .Process standard
The heating coil winding method has been tested strictly, the winding
process is standardized, and high quality is required to ensure stable
quality.

》Causes of wire drawing drooling of gate.
There is no reasonable cooling at the tip of the nozzle.
Reasonable cooling water line should be designed near the nozzle gate to increase
cooling Water line can avoid problems such as wire drawing and drooling caused by
heat accumulation at the gate
The nozzle selection is unreasonable
Zhenxiong nozzle is a special structure without nozzle core, without drawing and
drooling. Valve type nozzle is recommended for drawing caused by extreme injection
molding condition .
The temperature of nozzle is not stable and the long-term production stability is poor.
Zhenxiong heating accessories are imported , see the attached page

》Causes for valve needle stuck:
1. The valve needle is too long with the needle brush.
The matching length between the guide brush and the valve needle of zhenxiong
is shorter than other companies,which get less needle stuck.
2. Improper fitting tolerance between valve needle and needle brushing.
The matching tolerance between the guide brush and the valve needle of Zhenxiong
is customized according to the fiber adding material, and it has been tested and verified
repeatedly to ensure no leakage and needle stuck.
3. Processing error leads to unqualified or unstable quality.

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