INNOVATION | CAPS & CLOSURES
Right:
Mold-Masters’ Sprint hot
runner systems are optimised for high-speed moulding and are capable of fast colour changes
intended to improve productivity. These include front mounted cavities and freely moving slides. The former enable quick and easy gate unblocking while the mould is still installed in the machine. This is said to allow for an 80% reduction in gate-cleaning downtime over standard closure moulds. Freely moving slides reduce cycle time: the low-mass slides move at the last possible moment, permitting the use of maximum closing speed for almost the entire mould stroke. Mould opening and closing strokes can also be reduced.
White also points to various
engineered features developed by the company to enhance the performance of the specific closure design. One of these focuses on tilt prevention during capping. “Tilted or cocked caps are the single most common capping defect, particularly with multi-start closures,” White says, noting that the patented design features lead-in geometry that significantly limits the tilting tenden- cy, resulting in a 75% reduction of cocked caps. Another feature, the Bionic Cam, is intended to help preserve part aesthetics by minimising preferential shrinkage within specific tamper-evi- dent band zones.
Stacks and cubes Athena Automation, the injection moulding equipment producer set up a few years ago by Robert Schad (who also founded Husky), continues to expand its offering for packaging applications. It recently introduced Niigon 350 Stack and Cube machines, building on the concept it introduced last year with the Niigon 150 Stack/Cube. (Niigon is a Canadian aboriginal word meaning “for the
future.”) This is a flexible platform capable of regular, stack, and cube moulding. “The word ‘stack’ conjures up conventional stack moulds with their balance and drool issues,” says Marketing Manager Aron Szasz Gabor. “Our approach is to ‘stack up’ two single-face moulds. Two on-centre injection units feed two single-face moulds mounted on a centre platen (with ejection).” He says the system provides output-per-footprint the same as that of a regular stack mould, without the issues associated with stack moulds. Stack machines can run
different colours, materials, or
closures, as long as the moulds have similar cycle time and clamp tonnage. “Additionally the stack approach allows a (lower-cost) single-face spare mould as compared with a spare stack mould for production assurance,” says Gabor. “And should the need arise, the moulds can run in a standard machine for back-up.” Athena has already supplied several 3,500 kN stack machines to run family moulds for packaging applications. On cube machines, the centre platen is replaced
by a rotating element with four faces to hold four core mould halves. This option can be retrofitted to a Niigon stack machine, providing a cycle reduc- tion with two extra core cooling stations and off-line part removal. The cube concept is well- suited to multi-piece, multi-colour, and multi-mate- rial closures.
Gabor says an early Niigon 150 cube machine has been running a 4x8 flip-top system for over one million cycles, without the need for mould refurbishment. A new 350 cube system is being installed this summer and a 550 cube is scheduled for installation late this year.
Athena’s Stack machine 20 INJECTION WORLD | July/August 2018
Hot runners for efficiency Milacron points to innovative products and technologies within its Mold-Masters hot runner portfolio for caps and closures. Top of the list is the Sprint hot runner. Sprint hot runner systems are optimised for reliable high-speed moulding and are capable of fast colour changes, ensuring maximum productivity and efficiency. Cycle times of under 2.4s are possible, thanks to the high injection velocities the system enables, and there are low pressure drops with minimal gate vestiges and no stringing on the moulded part. New colour
www.injectionworld.com
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