How can the Peeling Extrusion Technology Improve the Quality of Silver-based Contact Materials?

However, conventional extrusion processes face problems such as blistering and inclusions caused by material residues, which affect product quality and performance stability. To address this challenge, researchers at Fudar Alloy. have developed a peeling extrusion technology that effectively solves these problems.

Challenges of Conventional Extrusion Technologies

Conventional extrusion technology is prone to the following problems when producing silver-based contact materials:

1. Residual material problem: The contact material that remains on the inner wall of the extrusion container will fall off. It will then mix into the newly extruded material, leading to blistering or inclusion defects.

2. High cost of surface treatment: To address the above defects, an additional surface turning or planning process is required during subsequent processing. This adds to the production cost.

3. Low material utilization: Untreated defective material leads to unstable electrical properties, which reduces material utilization.

These problems significantly affect the yield and quality stability of contact materials.

Principles and Characteristics of the Peeling Extrusion Technology

Peeling extrusion technology uses a specially designed mold to ensure process consistency. The connection between the extrusion mold and reverse extrusion rod employs a positioning pin method. Additionally, a special plug ruler is used to maintain consistent gaps between the extrusion mold and container. This setup ensures that the centers of both the container and extrusion mold align along the same centerline.

This design allows the residual material on the inner wall of the extrusion container to be retained and peeled off. As a result, it prevents the residual material from contaminating the finished product.

In the reverse peeling extrusion process, the outer diameter of the extrusion mold is 4-10mm smaller than the inner diameter of the extrusion container. During extrusion, the outer 2-5mm layer of the ingot material is retained on the inner wall of the extrusion container. This forms a "skin shell," which effectively isolates the residual material and prevents contamination of the finished product.

Compared to traditional forward extrusion, the flow zone in reverse extrusion is smaller. This smaller flow zone makes it easier to control the material quality.

Parameters and Experimental Results of Peeling Extrusion

The study was conducted using a 1100-ton reverse extruder. AgNi10 material, prepared by the powder mixing process, was used in the tests. The effect of different mold sizes on the extrusion outcome was also evaluated.

Twenty tests were conducted for each mold. The extrusion process remained constant throughout the tests (extrusion temperature, extrusion speed, etc.). After each extrusion, the head and tail materials were removed.

The appearance of the extruded products was then compared, focusing on blistering, tissue inclusions, and peeling of the skin shells. The comparison results are shown in Table 1 below.

After cutting off the head and tail and removing products with serious blistering and inclusions on the surface, the weight of the qualified products was measured. The yield was then calculated. The comparison of the yield is shown in Table 2 below.

Table 1 Comparison of Partial Results for Test Materials

Extrusion Mold	Skin Shell Integrity	Blistering	Inclusion
110mm	No	18%Blistering	22%
107mm	Incomplete	15%Blistering	20%
105mm	50%Incomplete	5%Blistering	10%
103mm	Integrity	No	No
100mm	Integrity	No	No

Table 2 Yield Rate

Inside Diameter of Container	110mm	107mm	105mm	103mm	100mm
Yield Rate	85%	84%	84%	83%	78%

Results of the Experiment

1. Defect Comparison
The mold size of 103mm versus 100mm resulted in the best skin integrity. There were no blistering or inclusion defects in the extruded material. Larger mold sizes (105mm and above) resulted in incomplete skins and a significant increase in defect problems.

2. Yield Rate

Advantages of Peeling Extrusion

1. Improve product quality, by eliminating surface blistering and inclusion defects, the peeling extrusion technology greatly enhances the electrical properties of silver-based contact materials. This results in improved reliability as well.

2. Reduce processing costs, reduce the subsequent surface treatment process, save processing costs, and improve production efficiency.

3. Energy saving and environmental protection, under the premise of ensuring the integrity of the skin shell, peeling extrusion maximizes the material utilization rate, in line with the industry demand for energy saving and emission reduction. The shell thickness of silver-based contact materials formed by reverse peeling extrusion must be maintained between 2–4 mm to ensure its integrity. It is important to note that the shell thickness must remain within a reasonable range. This not only enhances the performance of the material but also avoids a reduction in material utilization rate. Specifically, different materials need to be individually tested to confirm.

Conclusion

Peeling extrusion technology offers an effective solution to the defects commonly found in conventional extrusion processes. It achieves this by optimizing the design of the extrusion mold and refining the control of process parameters.

This technology improves the production of silver-based contact materials. It is used for many types of silver-based materials. This is especially true for high-end electrical equipment. These include high-performance circuit breakers and relays that need high quality.

In the future, as technology continues to advance, the peeling extrusion process is expected to play an increasingly important role. It will not only enhance the overall quality of electrical contact materials but also drive further development within the industry. If you have any questions about peeling extrusion technology, please feel free to contact us.