Near Net Shape (NNS)Production

Ankit kumar (13BME0072)Arjun singh (13BME224)Dhruv Saxena (13BME0072)Venkateshwar Rao (13BME0571)

Table of content

• Introduction

• Objectives

• Problem definition

• Literature

• Proposed methodology

• Summary

• References

Introduction

• Net-shape and near net-shape, subsequently referred to as just net-shape, manufacturing can be defined as ‘the manufacture of a component or section of a component by consolidating material with minimal loss or wastage’. Two types of net-shape manufacture are envisaged; Additive processes based on high energy sources to consolidate wire or powder, for example, shape metal deposition (SMD) and direct laser deposition (DLD); Temperature and pressure activated consolidation of powder or fabricated structures,

• for example, metal injection moulding (MIM), Forging Process,

Additive layer manufacturing (ALM)

Objectives:-

• To Reduce material cost:- Most of the material in the form of wire or powder is used to directly build the componentshape with little overstock or other wastages.

• To Reduce ‘Removal’ operations:- Heavy machining or roughing operations are eliminated and finish machining is kept to a minimum which results in less swarf, low energy consumption, and less work in progress (WIP) together with associated lower risk of scrapping and enhanced rapid prototyping capability.

• To Enhance Product Opportunities.

Problem Definition• Is using Near Net Shape (NNS) injection moulding a better way to

manufacture products.

• Potential Detractions

– Higher cost of manufacturing machines, i.e debinding ,sintering process

– Usage of materials at higher rate in MIM process than any other methods.

• Can Hardness and Fatigue properties of products manufactured with NNS

Moulding match with those of “traditionally” manufactured products?

Literature:-

• Metal powders for the MIM process are mixed with thermoplastic binders and plasticisers to obtain a homogeneous feedstock in the form of pellets.

• The spherical metallic particles are normally in the range of 5-15µm and represent around 70% by volume of the mixture which is fed as thermoplastic material into injection moulding machines working at temperatures of 100°C to 250°C.

• The resultant ‘green’ parts have the geometric features of the finished article, apart from being enlarged, and are rigid enough to be handled

• Debinding

During the debinding stage, the binder and plasticisers are mostly removed and remaining traces are purged during the subsequent sintering operation. Debinding is usually performed by thermal decomposition and evaporation, chemical decomposition, or extraction with liquid chemicals.

• Sintering

Sintering takes place in a vacuum or protected atmosphere furnace and causes a linear shrinkage to achieve 95-99% density in the part. This is normally the finished condition ready to be assembled or to undergo secondary operations such as surface hardening.

For aero-space components it may be necessary to HIP( Hot isostatic pressed) the sintered part to reach full densification, made possible because the fine residual porosity is not surface connected.

Proposed Methodology• By using MIM process gives better finishing products with minimal amount of

machining processes.

• A tolerance band of ±0.3% of the nominal dimension can be regarded as a good guideline for designing MIM parts to reduce costs in aero-engines.

• impart mechanical properties.

• MIM part shrinks by about 20 percent during the debinding and sintering processes.

• the MIM part becomes soft and responds to gravity during the sintering process

Summary

• Net-shape powder consolidation has a major role to playing reducing the cost and environmental impact in the manufacture of future military engines from small intricate to very large and complex components.

References:-

[1] Metal Injection Moulding of Aerospace Components. David Heck.

Proceedings of IMEC, Sheffield, UK. May 2005.

[2] http://www.custompartnet.com/wu/metal-injection-molding

[3] The Role of Net-Shape Manufacture Reducing LifeCycle Costs of Gas Turbine Components. D Rugg, D Fray. TMS Conference (The Minerals, Metals & Materials Society), 2004

[4] http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/1249/report/F