Composite Plunger Tip
Conventional ring-fitted plunger tips exhibit gaps inherent to their mechanical assembly. These gaps permit the infiltration of molten aluminum, leading to adhesion and corrosion that foster hard-particle formation, severe adhesion renders the removal of these rings labor-intensive and inefficient.
The wear mechanism of the assembled structure involves the superposition and mutual promotion of multiple wear forms, it’s not a simple "1+1" effect, but a further amplification of the deterioration process. More importantly, the failure mode of such assembled plunger tips is highly concealed, and its service life attenuation curve shows virtually no obvious warning phase.
The composite plunger tip features multifunctional coating that combines the high thermal conductivity of copper alloy, it achieves metallurgical bonding without any assembly gaps, delivering excellent high-temperature resistance, wear resistance and corrosion resistance as well as outstanding resistance to molten aluminum adhesion. This composite plunger tip with copper‑alloy coating is beryllium‑free.
Due to the significant difference in the coefficient of thermal expansion between beryllium copper rings and steel substrates (or steel rings and beryllium copper substrates), slight relative sliding occurs on their mating surfaces during operation. This fretting wear generates abundant wear debris on the substrate mating surfaces.
During the injection process, these wear debris also enter the fit clearance between the ring and the substrate, further widening the gap and reducing the positioning accuracy of the ring. This aggravates the eccentric wear of the ring and produces more wear debris. More critically, the wear rate of the mating surfaces between the ring and the substrate is dramatically amplified in this process: since the hardness of beryllium copper is lower than that of steel, the substrate mating surface wears faster during their relative sliding, resulting in rapid expansion of the fit clearance within a short period and further accelerating the failure process of the steel ring or beryllium copper ring.
The wear mechanism of the assembled structure involves the superposition and mutual promotion of multiple wear forms. It is not a simple "1+1" effect, but a further amplification of the deterioration process. More importantly, the failure mode of such assembled plunger tips is highly concealed, and its service life attenuation curve shows virtually no obvious warning phase.
