Five factors to consider in PEEK injection molding

Five factors to consider in PEEK injection molding

1) Equipment: Standard injection molding machine

The first is equipment for PEEK injection molding: PEEK can be molded on standard injection molding machines from most well-known machine suppliers. According to what you want to shape

PEEK grades, the processing temperature of the injection molding machine barrel will be between 350-400⁰C. Most standard injection molding machines can reach these temperatures without retooling. If necessary, if a heating system modification is required, it is usually necessary to modify the heating coil or thermocouple/controller of the injection molding system. We recommend that you use a ceramic heating coil because of its higher heating consistency. In addition, the use of high-temperature-resistant insulation materials to insulate the barrel can also be considered, thereby saving energy costs. Universal screw suitable for PEEK injection molding. Copper and copper alloy materials (in contact with the melt) should be avoided. All metal parts should be smooth and highly polished to well avoid material degradation due to prolonged local residence in the barrel.

2) Importance of drying PEEK polymer

The second point pertains to dry PEEK polymers: PEEK pellets should generally be dry, but absorb moisture from the atmosphere. In our data sheet and injection molding guide, we provide some dry guidance. In short, we recommend placing the pellets on the tray in a conventional oven and drying at 150-160°C for 2-3 hours, optionally continuous drying. See our guide for more information. The aim is/should be to reduce the residual moisture content to <0.02%. A dehumidifier or hot air dryer can also be used and must be able to maintain a dew point or saturation temperature of -40°C.

3) Cleanliness is key

The third point is an important requirement: keep it clean! Avoid any contamination when handling PEEK. As you will learn, most other polymers degrade at the processing temperatures of PEEK, necessitating the use of a clean oven and feed system. Before starting injection molding of PEEK, it is important to clean the screw and barrel properly and efficiently to ensure that the equipment is clean and free of other material residues. Return material may be the main source of contamination, we recommend that you use special equipment and do its cleaning well to ensure that PEEK material is not contaminated by other materials during its operation. Remember: any contamination that is inadvertently involved in the entire injection molding process can cause black spots in the final PEEK injection molded part.

4) The product should use large-sized gate design as much as possible. Fourth point: The large gate design is suitable for PEEK injection molding. Gate size depends on part maximum wall thickness, number of cavities and part geometry. PEEK is a semi-crystalline polymer with higher shrinkage compared to amorphous thermoplastics. Furthermore, higher processing temperature cooling gradients tend to result in greater shrinkage than lower temperature processing polymers. Use as large a gate design as possible to achieve better packing. At Victrex, there is a general rule that the gate is 2/3 the thickness of the maximum section thickness of the injection molded component. Depending on the PEEK grade you are molding, the minimum gate size is 1mm for unfilled PEEK and 2mm minimum for filled reinforced PEEK. The general injection gate design types are generally applicable to PEEK injection products. Submersible gates can be considered for thin-walled or small-part product designs, but such gates are not suitable for injection molding of parts with larger wall thicknesses, because such gates are more likely to occur in advance of the gate Freeze, thereby affecting the subsequent feeding effect of thick-walled products.

5) Good temperature control The fifth point is very important: good temperature control of the mold. Victrex Chief Scientist John Grasmeder has stated that mold temperature is critical to obtaining semi-crystalline parts that take advantage of PEEK's unique properties. Let's take a look at the color comparison of the appearance of some PEEK molded parts that are fully crystallized and those that have not achieved reasonable crystallinity.

• Contact Us

B Block,No 21,Nan Xing Three Street,Nan Fang Industrial Park,

Bei Ce,Humen,Dong Guan,Guang Dong,China.

info@deepmould.com

Skype: Deepmould

Tel/Wechat: 86-15024107707