Nylon + Glass Fiber Compounding with Twin-Screw Extruder

Overview
A global automotive parts supplier successfully improved the mechanical properties and dimensional stability of its parts by compounding nylon (PA66) with glass fibers using a twin-screw extruder. This case highlights the process, challenges, and benefits of glass-reinforced nylon production.

Background
The customer, a Tier 1 supplier to the automotive industry, was looking for a high-strength material for under-the-hood parts that could withstand high temperatures, mechanical stress, and chemical corrosion. Unfilled nylon lacked the required rigidity, while pre-mixes were costly and lacked flexibility for product-specific adjustments.

Solution
The company invested in a high-torque twin-screw extruder with a customized screw configuration optimized for fiber dispersion and melt uniformity at Henglan Machinery Technology Co., Ltd. (the Company) in Nanjing, China. Nylon 66 base resin is fed into the main hopper, while chopped glass fibers (30% by weight) are fed from the downstream side feed port to prevent fiber breakage.

The extruder is equipped with a vacuum degassing system to remove moisture and volatiles, ensuring a stable and high-quality melt. Processing temperature was tightly controlled within the range of 270-290°C.

Challenges

Fiber breakage: Minimizing the shortening of glass fiber length during compounding is critical to maintaining mechanical strength.

Moisture sensitivity: Nylon is extremely hygroscopic. Pre-drying and degassing during processing are critical to prevent hydrolysis and voids.

Homogenous dispersion: Achieving uniform fiber distribution without agglomeration is critical for mechanical properties and surface quality.

Results

Mechanical properties: PA66 + 30% GF composites have tensile strengths exceeding 150 MPa and excellent dimensional stability.

Production efficiency: In-house compounding reduces raw material costs by 20% compared to purchasing pre-compounded materials.

Customization flexibility: Manufacturers can now fine-tune glass fiber content, additives (such as flame retardants or impact modifiers), and color to customer specifications.

Conclusions
This project demonstrates the value of in-house nylon + glass fiber compounding using a twin-screw extruder. It enables automotive suppliers to improve part performance, reduce material costs, and gain greater flexibility in product development.