PEEK gear injection molding: perfect integration of high precision and high efficiency

In modern manufacturing, PEEK gears are widely used in various fields due to their excellent performance. As an efficient and precise molding method, injection molding plays a crucial role in manufacturing high-quality PEEK gears.

1,PEEK Injection molding process

Mold design and manufacturing:

This is the primary step in injection molding processing. Due to the high precision requirements of PEEK gears, the design of molds must accurately consider parameters such as gear profile, module, and number of teeth. 

Adopting advanced CAD/CAM technology for design, ensuring that the mold cavity can accurately replicate the shape of the gear. 

When manufacturing molds, high-strength and wear-resistant mold steel materials such as SKD11 are selected. Through precision machining and heat treatment processes, the mold has sufficient hardness and accuracy to ensure that it can withstand high pressure during injection molding and maintain the dimensional accuracy of the mold cavity after multiple uses.

Material preparation: 

Select high-quality PEEK plastic particles, whose purity and molecular weight distribution have a significant impact on gear performance. 

Before injection molding, PEEK particles need to be dried to remove moisture. Due to the presence of moisture, defects such as bubbles and silver wires may occur during the injection molding process, which can affect the quality of the gears. Usually, a vacuum drying oven is used to dry at a temperature of 150 ℃ -180 ℃ for 4-6 hours, reducing the moisture content to below 0.02%.

Injection molding:

 Add dried PEEK particles into the injection molding machine barrel. Injection molding machines need to have sufficient injection pressure and stable temperature control capabilities. The temperature of the material barrel is generally set in three stages, increasing sequentially from the hopper end to the nozzle. 

The temperature of the front stage is controlled at 380 ℃ -400 ℃, the middle stage at 400 ℃ -420 ℃, and the rear stage at 420 ℃ -450 ℃ to ensure that the PEEK material is fully melted and uniformly plasticized. 

The injection pressure depends on the structure and size of the gear, generally between 100-150MPa. The holding pressure is 60% -80% of the injection pressure, and the holding time is about 10-20 seconds to ensure the molding quality and dimensional accuracy of the gear.

Cooling demolding: 

After injection molding is completed, the mold needs to be rapidly cooled to solidify the PEEK gear into shape. Adopting a circulating water cooling system, the mold temperature is controlled between 80 ℃ and 120 ℃, and the cooling time depends on the thickness and complexity of the gear, generally ranging from 20 to 60 seconds. After the gear has cooled to a certain degree, it is removed from the mold through an ejector device.

2, Precautions for injection molding processing

Temperature control: The processing temperature range of PEEK is relatively narrow, and high temperatures can easily cause material decomposition and discoloration, affecting gear performance; If the temperature is too low, it will cause poor melt flowability and incomplete filling of the mold cavity. Therefore, it is necessary to accurately control the temperature of the barrel, mold, and nozzle, and continuously monitor and adjust them during the production process.

Pressure regulation: The magnitude of injection pressure and holding pressure directly affects the quality of gear molding. Excessive pressure may cause gear burrs and deformation; If the pressure is too low, defects such as material shortage and bubbles may occur. The optimal pressure parameters need to be determined through debugging based on the actual situation.

Mold maintenance: Regularly clean, lubricate, and maintain the mold, promptly clean the residual plastic and dirt on the surface of the mold, check the wear of the mold, repair or replace the worn parts to ensure the accuracy and service life of the mold.

3, Advantages of Injection Molding

High precision:

 Injection molding can achieve extremely high dimensional accuracy, and the dimensional tolerance of PEEK gears can be controlled within ± 0.05mm, meeting the requirements of high-precision transmission.

High efficiency: 

Compared with traditional mechanical processing methods, injection molding can achieve rapid molding, short production cycles, significantly improve production efficiency, and reduce production costs.

Complex shape manufacturing: 

PEEK gears with complex shapes can be manufactured, such as gears with internal teeth, irregular teeth, and other structures, which are often difficult or costly to process using traditional processing methods.

4, The impact on the quality of PEEK gears

The quality of PEEK gears is directly determined by the advantages and disadvantages of injection molding processing technology. A good injection molding process can make the internal structure of PEEK gears dense, free of defects such as bubbles and cracks, with high surface smoothness and tooth profile accuracy that meets design requirements, thereby ensuring stable performance of the gears under harsh working conditions such as high load and high-speed operation, and extending their service life.

In short, injection molding is the core process for manufacturing PEEK gears. By precisely controlling each link, high-quality and high-performance PEEK gears can be produced, providing strong support for the development of many industries.