Advanced Series hot runner - DME

Casting Resins &Mold DesignChemical ProductsGate AccessInfoThe ability to remove the cavity plate in the press is a mold design feature which adds little upfront mold cost, but cansignificantly reduce the molder’s maintenance cost. The procedure is to provide a latch which can fasten the cavityplate to the moving half, so as to access the gate area and nozzle tip without removing the tool from the press. This isalways a good design practice, but it is essential to utilize this technique with Hot Tip systems.Gate / Land relationshipGate and land tolerances are generally very tight. Adherence to a specific nominal gate diameter and land, althoughimportant, is in no way as critical as maintaining uniformity among all gates and lands. DME strongly recommends thatthe total variation between all gates and lands in your system does not exceed 0.05mm.Gate CoolingSufficient gate area cooling is necessary for the properoperation of any hot runner system. Insufficient cooling slowsthe gate solidification (for non-valved systems ), detracts froma quality gate appearance, and with some gating methodsactually prevents proper functioning of the system. Hence, eachgate should ideally have dedicated water cooling with exactlythe same conditions as every other gate in the system.For this reason, placing each gate cooling circuit in seriesshould be avoided, as each subsequent gate will run slightlywarmer than the previous one.Turbulent water cooling mustbe positioned in close gate proximity. It is especially critical tohave good gate cooling for the amorphous and semi-crystallineapplications.Design for cavity plate removal22/12/2010www.dmeeu.com - 9