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Ningbo Jinyi Precision Machinery Co., Ltd.
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Product (264)
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Screw Barrel
(242)
- Single Screw Barrel (137)
- Injection Screw Barrel (29)
- Extrusion Screw Barrel (13)
- Bimetallic Screw Barrel (13)
- Twin Screw Barrel (18)
- Screw Barrel Accessory (21)
- Plastics Screw Barrel (8)
- Recycling Screw Barrel (2)
- Blowing Film Screw Barrel (1)
- Tie Bar (4)
- Reduction Gearbox (4)
- Auxiliary Machinery (14)
Trade Show (15)
Equipment (13)
Certificate (5)
Develop & Customers (1)
Study Room (17)
Credit Report
Products Index
Company Info
Ningbo Jinyi Precision Machinery Co., Ltd. [China (Mainland)]
Business Type:Manufacturer
City: Ningbo
Province/State: Zhejiang
Country/Region: China (Mainland)
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Study Room
Where the blooming occurs will determine the cause the the solution. Issues to consider include the thermal stability of the pigment or resin as well as the colorant
Cause | Solution | ||
Blooming around the gate: pigment is not disperse well. | Raise the packing pressure and slow the injection speed. Use a mixing nozzle and mixing screw. | ||
Blooming all over the molded product: thermal stability is inadequate. | Lower the resin temperature and shorten the retention time. Widen the sprue, runner and gate. | ||
Blooming around the welds, gate: colorant is the cause. | Raise the temperatures of the mold and the resin. Slow the injection speed as much as possible. | ||
14) Deflection
"Deflection" occurs when the frame thickness is uneven. The problem usually stems from the mold structure.
Cause | Solution | ||
The mold is deformed by the injection pressure. | Deformation at the gate creates uneven resin flow. | ||
The product shape is uneven. | The side of the flow that is poor causes the gate to thicken. | ||
Deflection of the mold. | Raise the resin temperature. Lower the injection pressure | ||
15) Warping, Bending, Twisting
Warping of box-shaped products or ribbed products is the result of differences in shrinkage rate, which in turn are caused by differences in cooling time.
The molded product cools slowly in places where the mold temperature is high or the product is thick. The slower cooling creates larger crystals, which result in greater shrinkage than in places where cooling is more rapid. Therefore, a cooling line must be added to the places (where cooling is too slow).
Bending is a common problem when molding thin, long products. The problem can be solved by using resin with excellent flowability, under high resin temperature and low pressure. Use of a fan gate or submarine age is also helpful.
Twisting usually occurs when molding HDPE products that are flat around the gate. The problem stems from a difference in shrinkage rates between the flow direction and the direction perpendicular to the flow.
Polypropylene is strong, while LDPE is low in density and shrinks little, and back warping is not common with these resins. Overloading the mold often causes the problem, so minimize the load within the designated limit.
Cause | Solution | ||
Cooling is inadequate or uneven. | Increase the cooling time, and only remove the product from the mold after it has hardened completely. | ||
The injector pin causes a deformation. | Re-polish the mold to facilitate removal. Use a releasing agent. Increase the releasing slop. Increase the number of injector pins. | ||
The product shape is deformed. | Increase the temperatures of the mold and the resin. Reduce the injection pressure. | ||
The product design is flawed. | Use designs with as much symmetry as possible. | ||
The gate position is wrong. | Install several gates. Change the gate position. | ||
