Rapid tooling for diecasting can be
created through the application of di- rect metal deposition technology, which is similar to fused deposition modeling. It uses a laser to melt injected powder metal and deposit it in a precise loca- tion. For die inserts, more methods have been developed, including direct metal laser sintering (DMLS), electron beam melting (EBM) and laser engi- neered net shaping (LENS). DMLS machines create a die
insert by sintering thin layers of powdered metal. EBM is similar to SLS or DMLS,
except it uses an electron beam to melt the powder. It can only be used on iron. With LENS technology, a laser
creates a molten pool of metal on an existing metal substrate. T en, metal powder is added as the work piece is moved through a programmed path, building layers to create the fi nal piece. Laser-based RP methods for die
inserts allow for more complex designs but are limited in size and the life of the tooling, seldom exceeding 10,000 shots. CNC machining also can be used to
create individual dies, as well as metal parts and tooling. And rapid solidifi ca- tion process tooling (RSP) begins with an RP part or machined prototype, which is used to create a ceramic nega- tive of the die. Molten H13 or a similar steel is sprayed onto it, then the die is cut to fi t and polished.
Lost Foam Inroads Rapid lost foam casting options
include cut foam patterns as well as machined and assembled aluminum prototypes. Equipment makers have adapted
CNC machinery to cut foam patterns accurately and quickly. T ey employ special cutting tools designed for the properties of the foam material, and incorporate supports to prevent fl aws and breakage. T ese patterns can be
used to produce molds immediately, without any post-processing steps. Another option for lost foam casting
is to produce the tooling by machined aluminum rapid prototyping. T is often is used during development to cast test samples of a part. T e pattern can be made in sections and glued together, and good CAD data is critical to ensuring the prototype is a match with the fi nal production tooling. T e benefi ts to using rapid manu-
facturing techniques and technology include greater design fl exibility and the ability to test casting designs at a low cost, as well as quick-turn proto- types that closely resemble production product. T e possibility of using RP methods for an entire production run presents a signifi cant savings opportuni- ty in tooling costs as well as turnaround times. T e casting supplier is a valuable resource for purchasers and designers exploring this rapidly evolving area of metalcasting technology.
30 | METAL CASTING DESIGN & PURCHASING | Nov/Dec 2012
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