Method to form multi-material components

• US 6,660,225 B2
• Filed: 09/24/2001
• Issued: 12/09/2003
• Est. Priority Date: 12/11/2000
• Status: Expired due to Term

• Current Assignee: AMT Pte Ltd
• Original Assignee: Advanced Materials Technologies, Pte. Ltd. (Temasek Holdings Pte Ltd. (Investment Management))
• Inventors: Lim, Kay Leong, Tan, Eng-Seng, Baumgartner, Robin, Tan, Lye-King
• Primary Examiner(s): MAI, NGOCLAN THI
• Application Number:
  US09/960,908
• Publication Number:
  US 20020071781A1
• Time in Patent Office: 806 Days
• Field of Search: 419/6, 419/36
• US Class Current: 419/6
• CPC Class Codes: B21C 3/02 Dies; Selection of material therefor; Cleaning thereof
• CPC Class Codes: B22F 2207/20 Cooperating components
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B22F 3/22 for producing castings from a slip
• CPC Class Codes: B22F 3/225 by injection molding
• CPC Class Codes: B22F 5/00 Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
• CPC Class Codes: B22F 5/007 of moulds
• CPC Class Codes: B22F 5/10 of articles with cavities or holes, not otherwise provided for in the preceding subgroups
• CPC Class Codes: B22F 7/06 of composite workpieces or articles from parts, e.g. to form tipped tools B22F7/002 takes precedence
• CPC Class Codes: B22F 7/062 involving the connection or repairing of preformed parts
• CPC Class Codes: H01F 1/22 pressed, sintered, or bound together

Abstract

The invention shows how powder injection molding may be used to form a continuous body having multiple parts, each of which has different functional properties such as corrosion resistance or hardness, there being no connective materials such as solder or glue between the parts. This is accomplished through careful control of the relative shrinkage rates of these various parts. Although there is no limit to how many parts with different functional properties can make up an object, special attention is paid to certain pairs of functional properties that are difficult and/or expensive to combine in a single object when other manufacturing means are used.

Claims

1. A process for manufacturing a compound sintered article, comprising the sequential steps of:

(a) providing a group of mixtures of powdered materials, each member of said group having, after sintering, a functional property that is different from any functional property possessed, after sintering, by any other member of the group;

(b) adding lubricants and binders to all members of said mixtures group, thereby forming a group of feedstocks, all of whose members shrink, after sintering, by amounts that differ from one another by less than about 1%;

(c) in a mold, compression molding a feedstock from said feedstock group, to form a green part;

(d) transferring said green part to a different mold and then injecting into said different mold a quantity of a different feedstock, taken from said feedstock group;

(e) repeating steps (c) and (d), each time using a different mold and a different feedstock, until all members of said feedstock group have been molded, thereby forming a final compound green part;

(f) removing all lubricants and binders from the final compound green part to form a powder skeleton; and

(g) sintering the powder skeleton to form said compound sintered article.

2. The process described in claim 1 wherein said first and second functional properties are selected from the group consisting of magnetic, corrosion resistant, controlled porosity, high thermal conductivity, high density, high strength, low thermal expansion, wear resistant, high elastic modulus, high damping capacity, good machinability, fatigue resistance, high hardness, high toughness, high melting point, oxidation resistant, easy joinability, and low internal stress.

3. A process for manufacturing a compound sintered article, comprising:

providing a first mixture of powdered materials, said mixture having, after sintering, a first functional property;

providing a second mixture of powdered materials, said mixture having, after sintering, a second functional property;

adding lubricants and binders to said first and second mixtures to form first and second feedstocks such that the amount that said feedstocks will shrink after sintering differs one from the other by less than about 1%;

using a first mold, compression molding the first feedstock to form a first green part;

transferring said first green part to a second mold and then injecting into said second mold a quantity of the second feedstock sufficient to form a compound green part;

removing all lubricants and binders from the compound green part to form a powder skeleton; and

sintering the powder skeleton to form said compound sintered article, whereby said first and second functional properties constitute a pair of functional properties selected from the group of functional property pairs consisting of magnetic-corrosion resistant, controlled porosity-high thermal conductivity, high density-high strength, high thermal conductivity-low thermal expansion, wear resistant-high toughness, controlled porosity-high strength, high elastic modulus-high damping capacity, high strength-good machinability, controlled porosity-fatigue resistant, magnetic-non-magnetic, high hardness-high toughness, wear resistant-oxidation resistant, easy joinability-corrosion resistant, and low internal stress-controlled porosity.

4. A process for manufacturing a cutting tool, comprising:

providing a first mixture of powdered materials, said mixture being, after sintering, suitable for use as a handle;

providing a second mixture of powdered materials, said mixture being, after sintering, suitable for serving as a cutting edge;

adding lubricants and binders to said first and second mixtures to form first and second feedstocks such that the amount that said feedstocks will shrink after sintering differs one from the other by less than about 1%;

using a first mold, compression molding the first feedstock to form a first green part having the shape of a handle;

transferring said first green part to a second mold and then injecting into said second mold a quantity of the second feedstock having the shape of a cutting edge, thereby forming, together with the first green part, a second green part;

removing all lubricants and binders from the second green part to form a powder skeleton; and

sintering the powder skeleton thereby forming the cutting tool.

5. The process described in claim 4 wherein said first mixture of powdered materials is selected from the group consisting of iron, all iron-based alloys, carbon steels, low-alloyed steels, and stainless steels).

6. The process described in claim 4 wherein said second mixture of powdered materials is selected from the group consisting of all tool steels, water-hardening steels (Type W), shock-resisting steels (Type S), cold-work steels (Type O, A, D and H), hot-work steels (Type H), High speed steels (Type T and M), mold steels (Type P), and tungsten carbide.