Process for removing loose powder particles from interior passages of a body

• US 5,490,882 A
• Filed: 11/30/1992
• Issued: 02/13/1996
• Est. Priority Date: 11/30/1992
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Bredt, James F., Cima, Michael J., Sachs, Emanuel M., Khanuja, Satbir
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): CHAUDHRY, SAEED T
• Application Number:
  US07/983,156
• Time in Patent Office: 1,170 Days
• Field of Search: 134/1, 134/42, 134/22.1, 134/35
• US Class Current: 134/1
• CPC Class Codes: B08B 3/10 with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
• CPC Class Codes: B08B 3/12 by sonic or ultrasonic vibrations washing or rinsing machines for crockery or tableware using sonic or ultrasonic waves A47L15/13; of natural teeth, of prostheses using ultrasonic techniques similar to those used for natural teeth A61C17/20; application of ultrasonic vibrations to chemical, physical or physico-chemical processes in general B01J19/10
• CPC Class Codes: B08B 5/04 Cleaning by suction, with or without auxiliary action B08B9/035 takes precedence; suction cleaners A47L
• CPC Class Codes: B08B 7/00 Cleaning by methods not provided for in a single other subclass or a single group in this subclass
• CPC Class Codes: B08B 9/00 Cleaning hollow articles by methods or apparatus specially adapted thereto B08B6/00 takes precedence
• CPC Class Codes: B22C 9/18 Finishing
• CPC Class Codes: B22F 10/10 Formation of a green body
• CPC Class Codes: B22F 10/20 Direct sintering or melting
• CPC Class Codes: B22F 10/68 Cleaning or washing
• CPC Class Codes: B24B 1/04 subjecting the grinding or polishing tools, the abrading or polishing medium or work to vibration, e.g. grinding with ultrasonic frequency polishing or abrading surfaces on work by means of tumbling apparatus B24B31/00, involving oscillating or vibrating containers B24B31/06; superfinishing surfaces on work, e.g. by means of abrading blocks reciprocating with high frequency, B24B35/00
• CPC Class Codes: B29C 33/56 Coatings , e.g. enameled or galvanised; Releasing, lubricating or separating agents in-mould coating B29C37/0028; using or applying separating agents B29C37/0067
• CPC Class Codes: B33Y 40/20 Post-treatment, e.g. curing, coating or polishing
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A technique for removing loose powder from the interior surfaces of ceramic molds made using layer manufacturing processes, such as three dimensional printing processes. The interior of a mold can be filled with liquid, such as water, which is boiled by applying microwave energy of a frequency selected to heat the liquid. The particles are entrained in the flow caused by the boiling liquid. Alternatively, fine particles are introduced into the mold and the mold is agitated to dislodge the particles and the powder so that they can be poured out of the mold. Such technique tends also to remove the surface finish of the mold. Any of the particles which remain can be dissolved in a liquid and removed in the liquid from the mold. Further, the surface finish of the mold can be improved by casting a slip of fine particles onto the surface to form a generally level, and preferably non-conformal, coating on the surfaces.

Claims

1. A process for removing loose powder particles from interior passages of a body made by a layer manufacturing technique comprising the steps of

placing the body within a bath of liquid;

and

applying, to the liquid and the body, microwave energy of a frequency selected to heat the liquid throughout its volume so as to cause the liquid to boil throughout said volume, whereby fluid motion is produced within the interior passages of said body, said motion producing an expulsion of the loose powder particles from substantially all regions within said passages.

2. A process in accordance with claim 1 wherein the liquid is water.

3. A process in accordance with claim 2 wherein the frequency of said microwave energy is selected to be about 2450 MHz.

4. A process in accordance with claim 1 wherein the body is ceramic.

5. A process in accordance with claim 4 wherein the ceramic body is a mold to be used for metal casting.

6. A process in accordance with claim 1 wherein the body is made by a three dimensional printing layer technique.