# US 4,398,407 A · Sizing of powder metal parts

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- Number: US 4,398,407 A
- Document ID: US4398407A
- Status: Granted
- Kind: A
- Application number: 06/228,300
- Filed: 1981-01-26
- Granted: 1983-08-16
- Earliest claimed: 1981-01-26
- Assignees: AMSTED Industries Incorporated
- Inventors: Paul T. DeFay, Jr.
- Web page: https://patentgrep.com/patent/US4398407A

## CPC

- B22F 3/24: After-treatment of workpieces or articles {(B22F3/1146 takes precedence)}
- B22F 5/10: of articles with cavities or holes, not otherwise provided for in the preceding subgroups
- Y10T 29/47: Burnishing
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Powder metal first pressed into a green briquette having an inner cavity is then sintered to form a rigid part. The inner cavity of the part is next sized in a lap-like operation by a spherical-shaped tool. The tool is rotated in an orbital pattern comprising a series of elliptically-shaped cycles. As the tool rotates, small successive portions of a surface of the cavity are contacted by the tool. This lap-like interaction between the tool and cavity surface not only sizes the cavity to an exact dimension but improves the wear quality of the cavity surface by increasing the density of a wall of the cavity as well as providing an improved surface finish.

## Claims

### Claim 1

A method of sizing a generally spherical surface formed in the base of a cavity having raised areas provided in a powder metal part, said method comprising
(a) applying a deforming pressure against the base of said cavity with a member having a substantially spherical surface, and
(b) uninterruptedly rotating said member in a series of overlapping and different substantially elliptical orbital paths to cause deformation of said raised areas in said cavity spherical surface and displacement of raised portions of metal into depressions until said cavity base is smooth.

### Claim 2 (depends on 1)

The method as defined in claim 1 including the step of compacting said cavity spherical surface with said member spherical surface to increase the density of said cavity base.

### Claim 3 (depends on 2)

The method as defined in claim 2 including the step of lapping said spherical surface.