PEEK PEI Parts Injection Molding Processing Analysis

October 13, 2024

Special high-temperature plastics: PEEK, PEI parts injection molding processing analysis

Injection molding uses high-performance engineering plastics such as PEEK and Ultem® PEI to create high-temperature parts with enhanced physical properties. Heat transfer channels and thermal pins optimize mold temperature control, and high-strength steels and aluminum are suitable materials for molds.

Injection molding is a fast and cost-effective process that is ideally suited for the high-volume production of accurate, repeatable parts. Previously, injection molded parts were made from more common plastics. However, over the years, various industry teams have begun to explore the possibilities of injection molding using high-performance engineering plastics. These specialty engineering plastics give parts enhanced physical and mechanical properties and offer improved thermal performance due to their high melting points.

Common High-Temperature Plastics

High-temperature plastics - engineering plastics with melting points between 216°C and 382°C - are beginning to replace metals as industries such as the automotive industry strive to improve energy and fuel efficiency. These plastics are not only lightweight but also corrosion-resistant, improving design flexibility and dimensional stability.

With its ordered crystal structure and narrow melting range, polyether ether ketone (PEEK) is a popular high-temperature plastic that absorbs large amounts of heat. In addition, PEEK molding emits only low levels of fumes and gases.PEEK's high melting point of 343°C allows for faster feeds and speeds, and its UL 94 V-0 flammability means that burning of vertical parts will stop in less than 10 seconds.PEEK is lightweight and resistant to creep, heat, electricity, abrasion, corrosion, and fatigue, making it ideally suited for use in harsh or high-temperature environments.

ULTEM® (a brand name for PEI) is an amorphous plastic resin that is easy to thermoform or bond with adhesives and is another popular high-temperature thermoplastic. ULTEM® PEI has an atactic molecular structure, a wide softening range, a melting point of 218°C, a V-0 flame-retardant rating, and the ability to maintain its mechanical integrity and electrical properties at high temperatures. Durable PEI produces minimal fumes, is flame retardant and chemically resistant, making it an ideal material for the aerospace industry and circuit boards.

1. Includes heat transfer channels

During the injection molding process, your manufacturer will spend a considerable amount of time cooling your parts before demolding and heating your molds before injection. These processes can be accelerated by including isometric heat transfer channels in your mold design. These channels should expose each cavity to the same amount of heating or cooling fluid at the same time. This will allow your manufacturer to quickly and uniformly raise or lower the temperature of the mold.

2. Use Thermal Pins

If it is not possible to include heat transfer channels in certain parts of the mold due to extensions or protrusions, thermal pins can be used. With their high thermal conductivity, these pins can quickly transfer heat from any previously inaccessible areas to the heat transfer channels of the mold. Hot pins will optimize the internal temperature of the mold without disrupting coolant pressure.

Thermal pins contain fluid that is sealed inside the cylinder. As the fluid absorbs heat from the mold, it evaporates and condenses as it releases heat to the coolant. With heat transfer efficiencies nearly 10 times greater than copper and copper alloy steel inserts, hot pins are an excellent choice when you have complex molds. Just be sure to avoid any air gaps between the hot pins and the mold, or fill them with a highly conductive sealant.

3. Choose the right mold material

The material of the mold affects the final product and also the design of the mold. You need to find a high-temperature mold material that strikes a balance between processability, cost, and wear resistance. After all, you want the mold to last for several runs, but you don't want it to take too much time or money to create. If you're planning on high-volume production, consider using a high-strength steel like H-13, S-7, or P20. If you're making prototypes, aluminum is a cost-effective material for tooling.

Special engineering plastic parts processing_Focus on shaped non-standard parts mold injection molding

Compared with traditional metal materials, special engineering plastics have good dimensional stability, its excellent processing technology, not only can more quickly change the appearance of the product structure, to avoid secondary processing of the product, but also to meet the dimensional tolerances of the product parts and appearance requirements.

Processable special engineering plastics such as: PEEK, PPS, PEI, PSU, PPSU, etc., generally have high temperature resistance, corrosion resistance, high strength and other characteristics.

Polyether ether ketone (PEEK) injection molding process and its applications:

Because PEEK high temperature resistance, excellent wear resistance, good mechanical properties, the earliest was used in the field of aviation, instead of metal materials to manufacture the internal structure of the aircraft. After also be used as automotive bearings and other parts: valve seats, valves, pumps, piston rings; excellent electrical properties also allow PEEK can be applied to love wafer carrier; and PEEK's excellent chemical stability and corrosion resistance can be used in the field of medical equipment.

Typically, PEEK molding temperature of 300 ℃ ~ 340 ℃, mold design, you can use the high light and polishing and other ways, over again in the molding process next time to affect the quality of the product, the injection molding machine molding pressure needs to be adjusted to the ratio of pressure and speed to ensure that the size and quality of the product to meet the requirements.

Polyphenylene Sulfide (PPS) injection molding process and its applications:

PPS has excellent heat resistance, flame retardancy, excellent electrical properties, melt flow and other characteristics, PPS is suitable for automotive injection molding parts: automotive three electric system motor module parts, electronic control module parts, battery module parts. In response to the trend of automobile lightweighting, hundreds of parts are applied from the exterior functional parts to the interior structural parts of automobiles.

In order to obtain good product appearance, PPS injection molding process should be high-speed injection, in order to maintain stable metering, it is recommended that the back pressure is set to 2 ~ 5MPa, metering instability can be set to 8 ~ 10MPa, strict control of the processing temperature and time, to avoid excessive high or low temperature negative impact on the performance of the PPS material.

Author:

Ms. Tina

E-mail:

sales@honyplastic.com

Phone/WhatsApp:

+86 18680371609