Hybrid manufacturing essentials: Design & Engineering
There are cutting tool considerations when machining molds and other complex components using hybrid manufacturing technology.
Hybrid additive manufacturing is a process in which selective laser melting in a powder bed is combined with subtractive three-axis milling in a single hybrid machine tool. Although selective laser melting is the most frequently used AM technology, other appropriate technologies include laser metal deposition, direct metal deposition and metal powder application.
On one hand, hybrid AM achieves significantly higher part accuracies and surface qualities than are possible with conventional laser melting in a powder bed. On the other hand, zero-point definition through machine-integrated spindle coordinate systems makes it possible to generate precise reference and clamping surfaces for the downstream process chain. This capability minimizes the downstream process chain, especially with toolmaking, moldmaking, rapid prototyping and small series production, as well as providing new possibilities in terms of designs, structures and material properties.
One of the main advantages with hybrid AM is saving costs by reducing machining waste and scrap. Consider a block of 45-kg (100-lb.) steel placed in a CNC machine. If the finished part weighs only 11 kg (25 lbs.), this means that 34 kg (75 lbs.) of scrap is tossed in the chip bed. It is therefore prudent to consider hybrid AM.
Tool Trends
Cutting tools have evolved to support the subtractive part of the AM process and offer geometric shapes and coatings relative to the layering process with abrasive properties and toughness characteristics of the tool sintering procedure.
A selection of endmills is available from Emuge for hybrid manufacturing applications. Image courtesy of Emuge
For optimal results, select endmills specially designed with the right geometries, tool substrates and coatings for machining molds and other components that have been additively manufactured. The selection of workpiece materials includes titanium and aluminum alloys; nickel-chrome-iron; and tool, stainless and cobalt-chrome steel. For example, ballnose and radius endmills should have a special neck design optimized to minimize deflection and enhance stability. This design imparts a fine surface finish while extending tool life.
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