Universal Rights and Wrongs

This paper argues for the important role of customers as a source of competitive advantage and firm growth, an issue which has been largely neglected in the resource-based view of the firm. It conceptualizes Penrose’s (1959) notion of an ‘inside track’ and illustrates how in-depth knowledge about established customers combines with joint problem-solving activities and the rapid assimilation of new and previously unexploited skills and resources. It is suggested that the inside track represents a distinct and perhaps underestimated way of generating rents and securing long-term growth. This also implies that the sources of sustainable competitive advantage in important respects can be sought in idiosyncratic interfirm relationships rather than within the firm itself

Applications of Powder Densification Maps to Direct Metal SLS/HIP Processing

Recent investigations have shown that Direct Selective Laser Sintering in conjunction with Hot Isostatic Pressing (HIP) is capable of producing fully dense, near net shape, high performance metal components. A key aspect of this combined processing method is the selection of appropriate HIP process parameters to obtain full density parts. Powder Densification Maps provide a powerful tool for predicting the effect of time, temperature, pressure, and material properties on part density. This paper summarizes developments in Powder Densification Map production for Ti-6Al-4V and Inconel 625 materials. A comparison of theoretically predicted and experimentally determined densities for a variety of processing conditions is presented.Mechanical Engineerin

Processing of Titanium Net Shapes by SLS/HIP

SLS/HIP is a hybrid direct laser fabrication method that combines the strengths of selective laser sintering (SLS) and hot isostatic pressing (HIP). SLS can produce complex shaped metal components with an integral, gas impermeable skin. These components can then be directly post-processed to full density by containerless HIP. SLS/HIP is envisioned as a rapid, low cost replacement for conventional metal can HIP processing. The advantages of freeform fabrication combined with in-situ HIP encapsulation include ability to perform containerless HIP, no adverse container-powder interactions, reduced pre-processing time, and fewer postprocessing steps compared to conventional HIP of canned parts. SLS/HIP is currently being developed for Inconel 625 superalloyand Ti-6AI-4V. This paper focuses on microstructure and mechanical properties of SLS processed and HIP post-processed Ti-6AI-4V. SLS/HIP technology for Ti-6Al-4V was demonstrated by fabricating a subscale AIM-9 missile guidance section housing to specification. This work is funded jointly by DARPA and ONR under contract N00014-95-C-0139 titled "Low Cost Metal Processing Using SLS/HIP."Mechanical Engineerin

Direct Laser Fabrication of High Performance Metal Components Via SLS/HIP

Recent research in the area of direct freeform fabrication of components via selective laser sintering/hot isostatic pressing (SLS/HIP) has focused on the processing of Alloy 625. Alloy 625 is a nickel-based superalloy which provides high temperature strength and corrosion resistance. Alloy 625 test specimens were successfully SLS processed with an integral gas impenneable skin or "can". These samples were subsequently HIPed to high density (>99.5%). Characterization of the test specimens indicated that microstructures similar to conventionally processed P/M materials are achieved in the HIP consolidated "core" region ofthe parts, while structures similar to those found in cast materials are present in the SLS processed "can" regions. Mechanical analysis of Alloy 625 SLS/HIP parts and production of complex structures will commence shortly.Mechanical Engineerin

Direct Selective Laser Sintering and Containerless Hot Isostatic Pressing for High Performance Metal Components

A novel net shape manufacturing method known as SLSIHIP that combines the strengths ofselective laser sintering (SLS) and hot isostatic pressing (HIP) is presented. Direct selective laser sintering is a rapid manufacturing technique that can produce high density metal components of complex geometry with an integral, gas impermeable skin. These components can then be directly post-processed to full density by containerless HIP. The advantages of in-situ HIP encapsulation include elimination of a secondary container material and associated container-powder interaction, reduced pre-processing time, a short HIP cycle and reduction in post-processing steps compared to HIP of canned parts. Results of research conducted on Inconel 625 superalloy, Ti-6AI-4V and Monel are presented. This research is funded by DARPAlONR contract N00014-95-C0139 titled "Low Cost Metal Processing Using SLSIHIP".Mechanical Engineerin

Non-exchanging hydroxyl groups on the surface of cellulose fibrils : The role of interaction with water

The interaction of water with cellulose stages many unresolved questions. Here2H MAS NMR and IR spectra recorded under carefully selected conditions in1H-2H exchanged, and re-exchanged, cellulose samples are presented. It is shown here, by a quantitative and robust approach, that only two of the three available hydroxyl groups on the surface of cellulose fibrils are exchanging their hydrogen with the surrounding water molecules. This finding is additionally verified and explained by MD simulations which demonstrate that the1HO(2) and1HO(6) hydroxyl groups of the constituting glucose units act as hydrogen-bond donors to water, while the1HO(3) groups behave exclusively as hydrogen-bond acceptors from water and donate hydrogen to their intra-chain neighbors O(5). We conclude that such a behavior makes the latter hydroxyl group unreactive to hydrogen exchange with water