"But the performance of plastic injection molding technology, grasp the process performance and characteristics of all kinds of plastic, is the basic professional knowledge of every worker must understand the plastic injection molding, the performance is set" injection molding conditions "basis, one of the most important factors is the quality problems and the abnormal phenomenon in the process of injection molding analysis.

PP commonly known as polypropylene, because of its good resistance to fracture, also known as "100 fold gum."". PP is a semi crystalline and semi crystalline thermoplastic. It has high strength, good insulation, low water absorption, high thermal deformation temperature, small density and high crystallinity. Modified fillers are usually made of fiberglass, mineral fillers, thermoplastic rubber, etc..

Different uses of PP, its mobility difference is big, generally used PP flow rate between ABS and PC.

1. plastic processing

Pure PP is a translucent ivory color that can be dyed in various colors. PP dyeing in general injection molding machine can only use color masterbatch. In some machines, separate plasticizing elements with enhanced mixing can also be dyed with toner. Outdoor products are usually filled with UV stabilizers and carbon black. The proportion of recycled materials should not exceed 15%, otherwise it will lead to lower strength and decomposition of color. PP does not require special drying treatment prior to injection molding.

2. selection of injection molding machine

There are no special requirements for the selection of injection molding machines. Because PP has high crystallinity. A computer injection molding machine with high injection pressure and multi stage control is needed. Clamping force is generally determined by 3800t/m2, injection amount of 20%-85% can be.

3. mold and gate design

Mold temperature 50-90 degrees, for higher size requirements, with high mold temperature. The core temperature of the cavity than the low temperature above 5 DEG C, channel diameter 4-7mm, needle gate length 1-1.5mm, diameter up to 0.7mm. The shorter the gate length, the better is about 0.7mm, the depth is half of the wall thickness, the width is two times of the wall thickness, and increases with the length of the molten cavity in the cavity. The mold must be of air exhaust hole depth is 0.025mm-0.038mm, thickness of 1.5mm, in order to avoid shrinkage marks, it is necessary to use the large and round injection port and circular runner, the thickness of the stiffener is smaller (such as the wall thickness of 50-60%). Homopolymer PP products, the thickness can not exceed 3mm, otherwise there will be bubbles (thick wall products can only use copolymerization PP).

4. melt temperature

The melting point of PP is 160-175 DEG C, the decomposition temperature is 350 DEG C, but the temperature can not exceed 275 DEG C during injection processing, and the melting temperature is best at 240 DEG C.

5. injection rate

In order to reduce internal stress and deformation, high speed injection should be selected, but some grades of PP and mould are not suitable (bubbles and air streaks). If the surface of the pattern appears to be diffused and diffused by the gate, slow injection and higher mold temperature should be used.

6. adhesive back pressure

5bar melt back pressure can be used, toner material back pressure can be appropriately increased.

7. injection and hold pressure

Higher injection pressure (1500-1800bar) and packing pressure (about 80% of injection pressure) were adopted. About 95% of the total trip time, keep the pressure, and use a longer dwell time.

After treatment of 8. products

In order to prevent the shrinkage deformation after crystallization, the product usually needs to be soaked by hot water.

Shenzhen Tengfei plastic products Co., Ltd. - professional mold design and manufacturing, injection molding manufacturers, vacuum electroplating manufacturers.

Tengfei Huang was founded in 2008, is located in Shenzhen city of Baoan District Shu Donghua third industrial zone, professional mold design and manufacturing, injection molding processing, automatic painting. Vacuum plating, as well as various types of silk screen, UV silk screen, printing, water transfer, laser engraving, bronzing in one of the industrial companies. Welcome customers both at home and abroad to visit our company and negotiate business. We look forward to working with you to create value! Tel: 0755-2908-2001 m.tj51.cn