Direct method for Rapid Tool Production
Lew Kok Fah RPTCU Lew Kok Fah, Lin Liutong, Seah Kwee Teck, Mohd Harun Shah Bin Rahim Shah R & D in the area of Speech and Hearing |  |
1. Introduction
Rapid Prototyping Technologies have many advantages, like for example: form & fit checking, functional test, facilitate in mould discussion etc.
But due to the limitation of the material used, it still cannot be used as a production part. This posts as a problem to manufacturer who wants to perform a trial run of his new product before commit to heavy investment in tools making.
2. Rapid Tooling
To fabricate 50 prototypes with a particular RP machine is costly, furthermore, property of the final prototype may not serve the purpose. This is where the idea of Rapid Tooling comes into the picture.
Rapid Tooling is the process where the mould inserts (core/cavity) are being built by a RP machine, and only minor machining work is required at the end of the RP process. Because no CNC is involved in the whole process, the lead-time to come out with an injection mould is relatively short. This will allow the designer to test out the parts while the toolmakers are still drafting the mould drawings. This again will provide ample time for the designer to identify problematic area, and feedback to the mould maker accordingly.
3. Process In this project, RapidSteel 2.0 from SLS is used. These metal powder are made up of low-carbon steel particles which diameter is merely 55um. The model of the part is first modelled by Pro/Engineer, and subsequently, the CAD files of the core and cavity of the part are generated using Pro/Mould module. Both STL files of the core and cavity are sent to the SLS machine, ready for the Rapid Tooling process. Green part manufacture (SLS process) |  |
With the help of the laser, the mould insert is temporary formed by the RapidSteel material layer by layer through fusion of the binder. Brown part manufacture (Furnace debinding & sintering cycle) Part infiltration (Furnace bronze infiltration cycle) Finally, the inserts are mounted to a standard mould base ready for testing. The result is satisfactory. The testing is carried out with a 100-ton injection-moulding machine, and besides with a slight warpage, the moulded parts are in good condition without much moulding imperfections. |
4. Summary
The process is proved to be successful. It can provide meaningful parts with industrial grade polymer, which can be used in actual production process to verify design concept, as well as full functional test.
The other advantages are the relatively short lead-time, and low cost, these make this process even more attractive for product manufacturers to consider it as an option in this product development cycle.
