Generally speaking, what is understood by the term 'LSR production' the is high-volume manufacturing of moulded parts made from liquid silicone, utilising the full available potential for cycle time reductions. With the production of O-rings, Arburg demonstrates a machine configuration which meets all these criteria to the maximum possible extent.
A total cycle time of 10.6 seconds for 128 O-rings is an achievement which stands up to any comparison. This is made possible through the combination of a fast, high-precision electric Allrounder 470 A with a clamping force of 1,000 kN and a size 170 injection unit, as well as a servo-electric demoulding device. The O-rings made from LSR have a part weight of 0.12 grams, an internal diameter of 8.5 millimetres and a thickness (= cord thickness) of 2 millimetres. Each ring is injected directly via cold runner nozzles in an optimised manner to reduce material waste. The servo-electric clamping unit of the Allrounder A enables fast, highly dynamic, as well as precise mould positioning in order move effectively to the vacuum and demoulding positions. This results in reduced cycle times.
Servo-electric demoulding device yields cycle time advantages
The servo-electric, directly driven demoulding device has been specially adapted for use during LSR injection moulding production. Because all the movements are driven via servo motors, the extension and retraction movements in particular are performed energy-efficiently, reproducibly, fast, highly-dynamically and with extremely short intervention times. Thanks to individual programming of start/stop conditions in conjunction with the mould movements, the intervention time and consequently the cycle time are additionally minimised.
In special application cases, servo-electrically driven, double-sided, rotating aluminium brushes are used, which can, for example, be driven to each travel position with changeable rotation speeds for gentle demoulding.
Owing to its emission-free drive system, which prevents air turbulence, the demoulding device is as well-suited to highly dynamic applications as it is to the production of medical technology items and clean room applications. Its compact design allows the demoulding system, which is mounted on the mould, to be readily customised. Depending on the requirements, it can be flexibly equipped with an ejection unit or application-specific grippers or suction modules.
Complete integration in the Selogica control system
The servo-electric demoulding device can be fully integrated in the Selogica machine control system. The three servo-axes of the device are treated as additional machine axes by the Selogica system. This allows the machine operator to program the entire system in the familiar manner via the central Selogica control system. Thanks to the synchronised movements and easy data entry for positions and speeds, the process can be flexibly optimised and cycle times reduced.
Short set-up times are ensured through the storage of all setting parameters for the demoulding device in the machine data record for the relevant application.
As the LSR application demonstrates, the electric Allrounder 470 A 1000-170 in conjunction with the servo-electric demoulding device is predestined for applications requiring high-precision operation with short cycle times, energy-efficiency and minimal emissions. A configuration of this type is perfectly suited, for example, to production for the medical technology sector or for clean room production.