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applying of a release agent on all surfaces of the mould cavity. Using the UNIDOS 100 RIM

machine, the polyurethane resin RG53/ G53 from Sika, was low pressure injected into the

3D printed mould (Fig. 5b). The potlife and demoulding time were the same like in the silicon

mould reaction injection moulding.

5.2 Plastic injection moulding with 3D printed moulds

In this case, PolyJet 3D printed moulds needs to replace machined injection moulds. The

moulding temperature of the thermoplastic materials (PE, PP, ABS, etc) is up to 300C. Thus,

PolyJet injection mould tooling (PIMT) needs to be cool between shots, at a target

temperature around 50C. Digital ABS material [6] is recommended to be used for PolyJet

printing of the injection plastic mould. Its mechanical and thermal properties will offer longer

mould life and reduced cycle times [9]. Depending on material and part complexity, PIMT

are suitable for the injection moulding of up to 100 parts.

6 Conclusions

Rapid tooling based on additive manufacturing is an important method utilized in small series

production where the conventional tooling like as CNC milled and spark erosion moulds are

expensive. RT integrated into CAD/ CAE/ CAM systems allows rapid product development,

low cost optimizing the product in a short period of time, reduce time-consuming mould

corrections and increase product innovation.

The paper presents solution for prototyping, functional testing and short-run production

applications. PolyJet 3D printed moulds are not production tools. Two different techniques

to make moulds with PolyJet technology were experimented: silicon moulding (indirect rapid

tooling) and direct 3D printing of mould (direct rapid tooling). Reaction injection moulding

and casting techniques were used to fill with polyurethane base resins the moulds. The RIM

materials have good mechanical properties comparable with thermoplastic mouldable

materials but the potlife is very short. Cast resins have longer potlife than RIM materials.

Direct rapid mould is more durable than silicon mould. Thus, using RIM technique can be

manufacture up to 50-80 parts in the first case, and 300-500 parts in the second one. The Sika

resins can simulate injection mouldable materials. The productivity of RIM is smaller than

Injection Mould process but the tooling cost is lower.

References

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4.F. Rayegani, G. C. Onwubolu, A.Nagy and H. Singh, ASME International Mechanical

Engineering Congressand Exposition, 810 (2021)

5.R. Singh, Int. J. of Autom. and Mech. Eng., 6, 777 (2021)

6.***, StratasysLtd, http://www.stratasys.com (2021)

7.***,Biresin® Low pressure RIM-system and casting, Sika Group (2021)

8.R. Udroiu, A. Nedelcu, Optimization of Additive Manufacturing Processes Focused on

3D Printing in Rapid Prototyping Technology — Principles (Intech, 2021)

9.B.O. Thorsten, The AM Magazine, 6, 8 (2021)

10.R. Udroiu, L.A. Mihail, Proceedings of the 8th WSEAS international conference on

circuits, systems, electronics, control & signal processing, Spain, 283 (2009)

DOI: 10.1051/,03011 (2021)71120301

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