Introduction to the Practical Trials
The driving factor for the use of a new technology was the increasing order intake and thus the need to shorten the production cycle. It was agreed that ŠEBESTA would supply the complete technological equipment for the test, as well as provide an application technologist to commission the micro spray technology together with AS-CASTING personnel.
The test was first carried out on a Bühler 84D casting workstation with a Wollin PSM3 die spraying machine with SD13 standard spray nozzles and then on a new Colosio 2P 1000 L die casting machine and a Wollin ESM3 die spraying machine with Wollin DD4 dosing nozzles. Chem-Trend® SL 8801 (HERATM) was chosen as the release agent.
Step-by-Step Development of Practical Tests and Transfer to Series Production
Micro Spraying on a Quad Mould; First Tests; 2016
The first test was conducted with an existing quad mould, designed for standard spraying. This involved spraying 1.25 liters of release agent per cycle. The gross weight of the casting was 1.8 kg and the mould was at the end of its service life (approximately 85 000 shots). The cooling of the mould was not changed for the test. The first test reduced the cycle time from 58.1 seconds to 50.3 seconds. In addition to the increase in productivity, the press-in speed was reduced from 3.3 m/s to 2.6 m/s and the pressure in third phase was reduced from 480 to 300 bars. The mould surface temperatures were stabilized in the range of 190-350 °C.
The first application used an older micro-spray technique with a continuous micro spray. The consumption of Chem-Trend® SL-8801 concentrate per spray cycle was still 9 ml.
The result of the first test was thus a confirmation of the applicability and stability of micro spraying and a clear advantage for the production itself.
When monitoring long-term production, the process proved to be more stable than standard spraying. There was no more sticking of the release agent to the mould surface, the process was controlled more precisely and reproducibly, and the occasional internal porosity of the castings no longer occurred.
Micro Spraying on the Second Quad Mould; 2017
Based on practical experience and actual temperature values, a new mould with optimized, internal mould cooling was developed. At the same time, Wollin developed a newer technology for applying the release agent using dosing nozzles. The use of dosing nozzles is much more precise, more targeted, better controllable and thus ensures higher production stability. This has further stabilized the production process and reduced the consumption of the concentrate to 4 ml.
In this constellation, 193,000 shots were cast at AS-CASTING.