HRS MultiTech Knowledge in Caps Field
HRSMultitech, a division of HRSflow, is the solution specifically developed for high volumes and low weight production in closures, medical, cosmetics and in general any technical application where fast cycle and peak quality performance are at the highest expectation.
In Caps & Closure sector, hot runner must adopt specific technical solutions such as thin wall injection to allow lighter container weight to combine different mechanical and chemical properties of plastics.
In order to meet customers' needs to achieve greater quality control, minimal scrap and cut down on energy consumption, HRSFlow proposes the use of Selective Laser Melting Technology, or SLM, to optimize mold cooling and to improve aesthetic finish of the product thanks to a more uniform temperature of the cavity surface. SLM provides total geometric freedom to implement cooling circuits that closely follow the parts shape, eliminating barriers to obtaining a uniform mold temperature for critical areas, in particular for caps applications where a perfect cooling was unthinkable.
Case study of a spirit cap, uncompromising balance
Our client's basic requirements for the creation of this piece were the good functionality of the cap, excellent aesthetic qualities, the ability to make a fast colour change, low maintenance and, finally, a high performing cycle.
Given the high production request, the toolmaker choice was a 32 cavity mold, with thermal cut injection.
The toolmaker PPF-Stamplanet(Italy), after seeing the project complexity, asked for HRS MultiTech cooperation, in order to be advised on the most suitable solution, considering that:
- the material to be processed is ABS medium viscosity(MFI19);
- the average thickness is 1mm, 0.8mm minimum;
- the tamper evident is linked to the main body by 5 hinges - 0.5 x 0.5mm;
- the core cavity is provided in 3 inclined slides to disengage the cap thread.
A dedicated team involving engineers with great expertise and skill has carried out extensive field tests to provide PPF-Stamplanet with a reliable and productive system, a key factor in a no-stop production environment. Special attention was paid to the "energy saving" aspect, considering also the scrap reduction during system restart. These technical solutions have allowed the customer to obtain an excellent thermal stability, thanks to reduced thermal dissipation between system and hot half, combined with an optimal channels definition.
After analyzing carefully the points listed above, HRS Multitech, division of HRSflow, decided to use a robust nozzle with a generous flow channel and its rheologically and thermally balanced hot runner on multiple levels, dimensioned as to create a low pressure drop, but at the same time able to ensure a quick cleaning of the channels themselves, avoiding any sharp edges or stagnation.
Stretched tips, made from a material utilized in the aeronautics industry, have instead allowed the control of the gate area with tip point accuracy independently of the other moulding parts keeping the vestige injection as invisible as possible, but at the same time ensuring an efficient holding phase, necessary to avoid sink-marks near the areas with varying thicknesses.
This result was obtained thanks to the repeatability of the cycle equal to 8.8 sec, the exceptional consistency of the part content of 1 .5%, the absence of sink-marks and to the color change average of 60 cycles, also thanks to the use of insulating polymer rings which are closely linked with tips / end-rings and installed between them and the cavity bushings.
There is no rule without an exception: balance and spirit can get along!