Inside EICF
ECHA (European Chemical Agency) to Prepare a Restriction Proposal for the Use of Microplastics
The European Commission asked ECHA (European Chemical Agency) to prepare a restriction proposal for microplastics in 2017. ECHA will answer in January of 2019 and launched a public consultation in the shape of a call for comments and evidence. The deadline to answer this call
was established on the 11th of May, 2018. Subsequent to that, ECHA is collecting and analysing all the received contributions from individuals and associations and is preparing a report to be included in the Annex XV of the REACH regulation.
EICF Contribution EICF stands for European Investment Casters’ Federation. It was born in 1954 as a forum to bring together the representatives of the European investment casting foundries to discuss developments and advances in the industry. Today it is composed of 117 members from 24 countries that represent foundries, suppliers and research institutions working in the field of investment casting. A summary of the report presented
to the ECHA, in the impact to the European Investment Casting industry from this potential ban on microplastics is presented here: Investment Casting, also known
as precision casting or lost wax, is a foundry casting process where the metal is cast into expendable refractory ceramic moulds. These moulds are produced using slurries based on alumino-silicates, alumina, silica or zircon bonded with an air-dried silica sol. A series of coats are applied over a wax pattern using slurry dips and refractory stuccoes. After the drying, dewaxing and sintering steps, the moulds are ready for the casting. Wax patterns are produced with mixtures of natural and synthetic waxes, which are produced by injecting the wax into aluminium or steel dies. The use of
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expendable ceramic moulds provides some outstanding features to investment casting: Intricate castings that cannot be produced with conventional process, almost near net shape components with tight dimensional tolerances, possibility of casting any metal alloys, exceptional surface finish and accuracy and large flexibility in the geometry and size of the castings. The main markets for this process in Europe are aerospace, energy, defence biomedical and automotive and Europe has a share of around 25% of the total world market of $14,000 M.
Use of Microplastics in IC The production of the wax pattern is an essential step in the entire complex investment casting process as it guar- antees the geometry requirements and surface conditions of the final compo- nent. Investment casting wax is a mix- ture or natural and artificial waxes, res- ins and different additives. One of the latter is a microplastic called XLPS or Crosslinked Polystyrene. It is presented as XLPS beads with a size range of 0 – 400 microns. XLPS can be present with- in engineered waxes up to 45% weight volume. XLPS is used to create dimen- sionally robust wax parts. All other wax components are deemed not to fall into the category of a microplastic. Cross-Linked Polystyrene (XLPS)
is supplied as hard opaque spherical beads with a particle distribution nor- mally of the order of 0 – 400 microns, with an average mean of 70 microns. XLPS is non-biodegradable and has a melting point of 270 degrees Celsius and has a CAS Number of 9003-70-7. The usage of XLPS filler enables
the Investment Casting foundries to economically produce tight tolerances metal parts for the aerospace, energy, automotive, medical and general industry. The main function of XLPS is to provide dimensional stability to the patterns and contribute to a correct
dewaxing step. It is used in more than 95% of the waxes for investment casting due to is unique properties and there are not real alternatives to it. Other products that have been used to try to provide the same performance to the wax in the past also contain microplastic, there is no real alternative for the product and furthermore the impact of the elimination of XLPS for investment casting usage would be hugely negative in economic and technical terms for European foundries. It is deemed that as the XLPS
particles are encapsulated by wax and resin there is no risk of flushing out into the aqueous systems/drainage. The investment casting waxes are recycled, disposed of in landfill or burnt at the end of the life cycle. The current intentionally broad
definition of “microplastic” in ECHA’s Call for Evidence would include some important investment casting wax ad- ditives. It is also useful to note that ECHA’s Q&A recognises that uses that do not result in release microplastics into the environment should not be subject to a Restriction (answer A.10 of ECHA’s Q&A from the online informa- tion session 12 March 2018). The use of polymer additives in the lost-wax in- vestment casting process does not con- tribute to release of the polymer addi- tives into the environment because the particles are embedded into a matrix of wax during use. Therefore, EICF re- quests not to include XLPS in the list of microplastics to be restricted in its use, at least in the investment casting sector.
Specific Information Request XLPS stands for crosslinked polystyrene and is used as an additive in the for- mulations of the waxes used to produce the wax patterns in the investment cast- ing process. It is a unique material that provides dimensional stability, reduc- tion of shrinkage of the wax models, prevention of cavitation shrink holes in
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