TY - JOUR

T1 - Wear phenomenon in injection molding

AU - Zidar, David

AU - Friesenbichler, Walter

AU - Blutmager, Andreas

N1 - Publisher Copyright: © 2023 Author(s).

PY - 2023/5/23

Y1 - 2023/5/23

N2 - Wear is a well-known problem in injection molding, especially when dealing with fiber reinforced materials.Fiber-reinforced polymers allow for implementation of plastic materials in structural components. However, increasingglass-fiber content in polymer melts up to 50 wt% causes accelerated component wear in injection molding machines,sprues, hot runner systems and tools. In this contribution the focus will be on abrasive wear. While testing high grade steelsfor their wear behavior a phenomenon was discovered. By varying the injection rate in the platelet-wear tester up to highestpossible values (56 cm³/s up to 210 cm³/s) we measured for the first time that even powder metallurgical steels with aRockwell hardness of 62 HRc could be soft annealed over a series of 210 injection shots down to a hardness of 43 HRc.The hardness decrease was detectable down to 0.9 mm distance from the surface. The suspected cause for this decrease inhardness is a change in micro-structure due to strong viscous dissipation. To cause a loss of hardness, temperatures over550°C have to occur on the steel surface. To further test and understand this phenomenon, a new testing apparatus basedon the well-known platelet wear tester was invented and built. The new testing apparatus will be presented, and itsmeasuring capabilities will be disclosed. Furthermore, we will show first measurement results regarding the temperaturerise inside the steel platelets that prove temperatures above 550°C. In addition to that, machine data that was recordedduring testing, will be disclosed to put the results when the phenomenon was first measured into the right light.

AB - Wear is a well-known problem in injection molding, especially when dealing with fiber reinforced materials.Fiber-reinforced polymers allow for implementation of plastic materials in structural components. However, increasingglass-fiber content in polymer melts up to 50 wt% causes accelerated component wear in injection molding machines,sprues, hot runner systems and tools. In this contribution the focus will be on abrasive wear. While testing high grade steelsfor their wear behavior a phenomenon was discovered. By varying the injection rate in the platelet-wear tester up to highestpossible values (56 cm³/s up to 210 cm³/s) we measured for the first time that even powder metallurgical steels with aRockwell hardness of 62 HRc could be soft annealed over a series of 210 injection shots down to a hardness of 43 HRc.The hardness decrease was detectable down to 0.9 mm distance from the surface. The suspected cause for this decrease inhardness is a change in micro-structure due to strong viscous dissipation. To cause a loss of hardness, temperatures over550°C have to occur on the steel surface. To further test and understand this phenomenon, a new testing apparatus basedon the well-known platelet wear tester was invented and built. The new testing apparatus will be presented, and itsmeasuring capabilities will be disclosed. Furthermore, we will show first measurement results regarding the temperaturerise inside the steel platelets that prove temperatures above 550°C. In addition to that, machine data that was recordedduring testing, will be disclosed to put the results when the phenomenon was first measured into the right light.

KW - hardness loss

KW - plastic mold steel

KW - viscous dissipation

KW - Wear

UR - http://www.scopus.com/inward/record.url?scp=85161440267&partnerID=8YFLogxK

U2 - 10.1063/5.0135808

DO - 10.1063/5.0135808

M3 - Article

VL - 2607.2023

JO - AIP Conference Proceedings

JF - AIP Conference Proceedings

SN - 0094-243X

IS - 1

M1 - 040003

ER -