The spring actuated machine needle shut-off nozzles type SHP are used in processing of thermoplastics, principally with low viscosity materials such as: PA, PPS, PE, POM, PP.
Finds application in: Packaging, automobile and leisure industries, medicinal and electronic equipment.
Operation: The nozzle is opened directly from the injection pressure and closed again with spring power. A needle which moves axially in the needle shut-off nozzle is held in the closed position by the force of the spring. The nozzle orifice is normally closed. With the increasing melt pressure exerted against the spring through a ring of exposed surface area on the needle, the nozzle opens at 200 bar. If the melt pressure drops (‹ 45bar), the nozzle closes.
• If the standard opening pressure is not appropriate, the needle must be modified to the requirements (modification of the spring is not possible).
• The nozzle size required depends on the injection rate per second (cm3/s).
• Air pockets during screw retraction
• Material leakage when dosing with a withdrawn injection unit
• Material leakage while vertically injecting
• Controlled, clean shut-off of the melt stream
• Shorter cycle times - increase in productivity
• Increased process reliability and repeatability
• Usability with increased back pressure - improved homogenization
• Quick machine installation
• Add-on capability (on tool side)
• Filter module