Hot micro-embossing: effect of pressure on 316L metal parts

Abstract

The use of replicative processes has become strategic and critical in industry to produce precise, microscopically detailed metallic parts and devices via low cost manufacturing routes. Metal powder hot embossing is an emerging process that brings some advantages associated with the reduction of production costs relative to powder injection moulding (PIM). The technology involves four distinct steps: preparation of the selected feedstock material (powder and binder); hot embossing; debinding; and sintering. The effect of continuous pressure during the hot embossing step as a means of replicating microdetails in 316L stainless steel parts is examined. Dimensional accuracy, microstructure and mechanical properties of the parts produced were evaluated. For the configuration tested, the most promising results were achieved when processing at 180°C for 30 min at a pressure of 14 MPa.

Development of Metal Powder Hot Embossing: A New Method for Micromanufacturing

“…This is called secondary debinding and sintering approach. However, a sequential debinding and sintering steps can be applied [20], or these treatments can be carried out separately in two different stages [13,29].…”

“…The four feedstock revealed torque values < 2N [30] Gradual addition procedure during mixing torque CPVC = 62% PL = 60% [8,13,24,27] Gradual addition procedure during mixing torque 16,29] Gradual addition procedure during mixing torque CPVC = 62% PL = 60% [34] The value of the powder and binder content in feedstock (determined as PL) also affects the performance of debinding and sintering. An excess binder does not retain the shape after debinding [32].…”

“…In studies where powder hot embossing was analyzed, it was reported that replicability (shape retention and surface roughness) is affected by critical embossing parameters: pressure [8,13,14,27,30], temperature [6,8,14,20,[22][23][24]30] and holding time [6,8,9,20,24]. The temperature should be high enough to promote pseudoplastic behavior in the mixture; the embossing temperature range is predicted by TGA analysis [8,14,16,24], as already mentioned.…”

“…In fact, the release stage can be improved using these softer molds, as reported in [27], where different geometries and materials were tested. The use of release agents, which enhances the release stage, has been reported [13,34] even when elastomeric molds are used. These agents have the purpose of controlling or eliminating the adherence between the green parts and the mold.…”

“…The final products obtained by powder hot embossing technology are, until now, microengineering applications, such as micromold inserts or micromedical components [13][14][15]. The studies concerning the developments of powder hot embossing are summarized in this revision.…”