HRS

Best Practice: FLEXflow Weld Lines Management

01/09/2016

THE NEW FLEXflow TECHNOLOGY
The new FLEXflow is a servo-driven valve gate that assures accurate, easy and flexible control of pressures and flow rates during the injection process. This new system allows the indipendent control of each valve pin by precisely adjusting position, acceleration, velocity and stroke. Among the main benefits: the improvement of the part quality and the realization of challenging applications. Let's see a concrete case study.
 
GENERAL INFORMATION
Application field: automotive interior
Molded part: instrument panel
Part size: 1440 x 474 mm
Nominal weight: 1160 g
Nominal thickness: 1.8 mm
Material: PP - TPO
 
HOT RUNNER SYSTEM LAYOUT
The hot runner system is composed by n. 6 nozzles Ga series with conical valve gate. Two of them are angled, injecting directly on the part. Each nozzle is managed by a FLEXflow electric motor in its on plate configuration.
 
CUSTOMER’S EXPECTATIONS
This mold was specifically conceived as a prototype tool. Here the customer’s aim was to exhibit how it is possible to manage the shape and the position of the weld lines using FLEXflow, in particular in order to obtain straight weld lines.
 
PROCESS PARAMETERS
Injection time: 10.3 s
Holding time: 7.7 s
Hot runner temperature: 230 °C
Mold temperature: 40 °C
 
SOLUTION
The molding method to inject the part during this trial expected to create two flow fronts (one from M3-M6-M4 and the other from M5) and to handle the resulting shape and position of the consequent weld line.
 
The starting point was the traditional standard sequential in which, as it is visible from the picture (Fig. 1), the two flow fronts generate an irregular weld line shape. Afterwards, switching to FLEXflow settings, with fine tuning of the opening and closing profiles for valve pin M6 was instead possible to make that weld lines perfectly straight (Fig. 2). In case of need, FLEXflow versatility offers also the possibility to reposition the weld line keeping it always straight (Fig. 3), simply shifting the opening of valve pin M5.
 
ADVANTAGES
 
• weld lines shape management
• weld lines repositioning