US 12,251,759 B2Granted

Powder metal parts with improved machinability

AssigneeKeystone Powdered Metal Company

InventorPeter G. Imbrogno

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Abstract

It has been unexpected found that the machinability and corrosion resistance of powder metal parts can be greatly improved by incorporating calcium aluminoferrite powder, such as naturally occurring brownmillerite powder (Ca2(Al,Fe)2O5), into the part. Improved machinability is of enormous value in manufacturing countless parts where it is necessary or desirable to machine the part after it has been sintered, such as is frequently the case with gears, rotors and sprockets. In the practice of this invention, calcium aluminoferrite powder can also be incorporated into parts which will not necessarily be machined for the sole purpose of attaining better corrosion resistance. Surprisingly, the incorporation of the calcium aluminoferrite powder into such parts does not significantly compromise the strength, durability, or wear characteristics of the part and generally improves the service life of the part by providing better corrosion resistance.

Claims19

Dependent claims

A method for manufacturing a powder metal part having good machinability and good corrosion resistance which comprises the steps of:

placing a metal powder composition into a mold having the desired shape of the part, wherein the metal powder composition is comprised of iron and a machinability enhancing agent which is comprised of calcium aluminoferrite powder, wherein the calcium aluminoferrite powder is present in the metal powder composition at a level which is within the range of 0.08 weight percent to 3 weight percent, wherein the calcium aluminoferrite powder is a brownmillerite powder of the general formula Ca2(Al,Fe)2O5 which is comprised of 30 weight percent to 50 weight percent Al2O3, 30 weight percent to 50 weight percent CaO, and 10 weight percent to 30 weight percent Fe2O3, basis upon the total weight of the machinability enhancing agent;
compressing the metal powder in the mold into the shape of the part under a pressure of 20 tons per square inch to 70 tons per square inch to produce a metal green part;
removing the green metal part from the mold;
sintering the green metal part at an elevated temperature within the range of about 60% to about 90% of the melting point of the metal composition to produce the sintered metal part;
and machining the sintered metal part by drilling, grinding, or cutting.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/312,678Filed 5 May 2023 · division
Priority: 22 Jul 2019
Published: US 2023/0302536 A128 Sep 2023
Granted: 18 Mar 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

B22F 3/162
In successive or repeated steps: machining, working after consolidation
C22C 33/0228
Using a mixture of pre-alloyed powders or a master alloy: comprising other non-metallic compounds or more than 5% of graphite
B22F 2301/35
Metallic composition of the powder or its coating: iron
B22F 2302/45
Metal Compound, non-Metallic compound or non-metal composition of the powder or its coating: others, including non-metals

Family

Application62/877,035Us provisional application · filed 22 Jul 2019
Application16/934,691Parent of this division · filed 21 Jul 2020
US 2023/0302536 A1Pre-grant publication · published 28 Sep 2023
US 11,707,785 B1Parent of this division
US 12,251,759 B2This patent

From the US filing history. Foreign family members aren’t listed.