0
Research Papers

Direct Sinter Bonding of Metal Injection-Molded Parts to Solid Substrate Through Use of Deformable Surface Microfeatures

[+] Author and Article Information
Thomas Martens

JTEKT Corporation,
Greenville, SC 29607
e-mail: thomas.martens@jtekt.com

M. Laine Mears

Clemson University—International Center
for Automotive Research (CU-ICAR),
Greenville, SC 29607
e-mail: mears@clemson.edu

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF Micro AND Nano-Manufacturing. Manuscript received June 20, 2012; final manuscript received January 23, 2013; published online March 22, 2013. Assoc. Editor: Jian Cao.

J. Micro Nano-Manuf 1(1), 011008 (Mar 22, 2013) (9 pages) Paper No: JMNM-12-1034; doi: 10.1115/1.4023532 History: Received June 20, 2012; Revised January 23, 2013

In the metal injection molding (MIM) process, fine metal powders are mixed with a binder and injected into molds, similar to plastic injection molding. After molding, the binder is removed from the part, and the compact is sintered to almost full density. Though able to create high-density parts of excellent dimensional control and surface finish, the MIM process is restricted in the size of part that can be produced, due to gravitational deformation during high-temperature sintering and maximum thickness requirements to remove the binding agents in the green state. Larger parts could be made by bonding the green parts to a substrate during sintering; however, a primary obstacle to this approach lies in the sinter shrinkage of the MIM part, which can be up to 20%, meaning that the MIM part shrinks during sintering, while the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. In this work, we present a structure of micro features molded onto the surface of the MIM part, which bonds, deforms, and allows for shrinkage while bonding to the substrate. The micro features tolerate plastic deformation to permit the shrinkage without causing cracks after the initial bonds are established. In a first series of tests, bond strengths of up to 80% of that of resistance welds have been achieved. This paper describes how the authors developed their proposed method of sinter bonding and how they accomplished effective sinter bonds between MIM parts and solid substrates.

Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Schematic of some limitations in MIM

Grahic Jump Location
Fig. 2

Effect of gravity during sintering

Grahic Jump Location
Fig. 3

Ideal sinter shrinkage [6]

Grahic Jump Location
Fig. 8

Etched micrograph detail of bonded area

Grahic Jump Location
Fig. 7

Sinter bond between powder compact (top) and solid metal part (below)

Grahic Jump Location
Fig. 6

Cross cut of a flat MIM compact bonded to a flat, 2 mm thick solid substrate

Grahic Jump Location
Fig. 5

Green MIM part on solid part (left) and sinter bonded composite part (right), substrate size: 25 mm × 25 mm

Grahic Jump Location
Fig. 15

Sinter bonding using micro surface features

Grahic Jump Location
Fig. 20

Determining the point of bonding

Grahic Jump Location
Fig. 14

Sintering on a substrate with friction

Grahic Jump Location
Fig. 13

MIM compact on substrate with high surface roughness

Grahic Jump Location
Fig. 12

Point contact on V-slot composite part (detail right side of separation)

Grahic Jump Location
Fig. 11

Point contact on V-slot composite part

Grahic Jump Location
Fig. 9

Hypothesized cause of deformation

Grahic Jump Location
Fig. 16

MIM compacts with surface features

Grahic Jump Location
Fig. 17

MIM compact (top) bonded to solid metal (below)

Grahic Jump Location
Fig. 18

Micro features bonding powder compact and solid substrate

Grahic Jump Location
Fig. 19

Part of the evaluated area of sinter bonded parts showing grain structure in micro features

Grahic Jump Location
Fig. 23

Shear test fixture installed on INSTRON testing system

Grahic Jump Location
Fig. 24

Shear diagram of sample with 100 μm feature size

Grahic Jump Location
Fig. 25

Bonding surface after shear test

Grahic Jump Location
Fig. 22

Cross section of shear test fixture

Grahic Jump Location
Fig. 21

Substrate expansion/powder shrinkage versus time and temperature

Grahic Jump Location
Fig. 26

Shear strength of different joining processes

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In