Milacron has been carrying out testing of Nickel and Tungsten Carbide barrel linings. The company’s objective was to show the quality of bi-metallic barrel linings.
These G65A and G76 abrasion and erosion testings were carried out in a domestic laboratory to identify the loss by gas-entrained solid particle erosion on the nickel and tungsten carbide linings to simulate the production environments.
To perform these tests, 40” barrels were sliced in half and stripped each liner in 6” x 6”-sections to get a flat 2” x 2” flat testing surface. Each liner was tested in 6 intervals (the length of one barrel) to get an average value of the wear resistance.
These attempts have verified some global standards of industry-knowledge, like that the wear life of tungsten carbide liners is the overall best method. This lining is increasing popular among complex applications like processing glass-filled resins.
It was discovered that various liners that would be considered the same grade from leading suppliers have unique formulas. Those recipes can have an impact on the moulding process.
A wide variance in the way the lining behaved during these tests was found. There is a balance required in the amount of tungsten applied in the liner of the barrel. The wear resistance was measurably at a faster rate when testing liners with lower values of tungsten in the liner. An unexpected find was that there is also a limit to the amount of tungsten that should be in the liner. The testings revealed that too much tungsten would cause cracking during the process.
Milacron’s goal is to pass this knowledge onto their customers to advise them on the best investment for barrel lining for each unique application. Milacron plans to continue testing barrel linings from suppliers throughout the world, and comparing those results to the initial results of their testing.
As the use of re-engineered resins and regrind/scrap materials continue to gain momentum in the market, the investment for proper barrels, screws, barrel lining, and other components will continue to grow exponentially, ensuring a sustainable production. This study is helping to understand how the barrel lining purchase of any customer will impact the wear life, as well as their part quality.