Contract and Spot Naphtha Spread behind a Thirty Day Quote
Contract and spot naphtha spreads undermine fixed thirty-day resin quotes, requiring indexation formulas and dock MFR testing to prevent margin erosion.
Tool Nozzle Erosion
Meaning
Wear mechanism where high-velocity polymer melt gradually enlarges the diameter of the tool gate or nozzle entry. This tool nozzle erosion occurs primarily when processing resins filled with abrasive glass fibres or ceramic additives. It changes the pressure drop across the runner system and alters the flow rate into the cavity.
Flow Control
Diameter changes caused by the friction of passing solids lead to unpredictable filling times and part weights. Once tool nozzle erosion becomes advanced, the cycle parameters set at the start of the project are no longer valid. This leads to flash defects or under-filled parts as the resistance to flow decreases.
Material Influence
Selection of low-viscosity resins can sometimes speed up the wearing process because the lower resistance allows for higher melt speeds. When tool nozzle erosion is detected, the surface must be repaired or the component replaced with a harder alloy like tungsten carbide. This cycle of wear and repair must be tracked in the factory maintenance log.
Dimensional Stability
Variations in the injection point size impact how well the plastic packs out the furthest edges of the part. If left unchecked, tool nozzle erosion will create visible discrepancies in part dimensions across multiple production months. Constant monitoring of nozzle tips ensures that precision parts stay within their design tolerances.