Method and casting media composition for creating foam sacrificial parts and investment models

Abstract

A process and casting media composition for casting three-dimensional parts and sacrificial models from a class of foaming casting compounds, and creating the foaming casting compounds by combining a radiation activated catalyst that causes a phase change from liquid to solid in the material and a foaming agent. In an alternate embodiment the combination is of a cold foaming casting compound and a compound which contains a radiation activated catalyst that causes a phase change from liquid to solid in the material. A further embodiment combines a hot melt casting compound with a compound which contains a radiation activated catalyst that causes a phase change from liquid to solid in the material and a foaming or blowing agent.

Description

FIELD OF THE INVENTION

This invention relates to a method for creating compositions which expand into foam positives of negative molds and which are subsequently hardened by catalysis after exposure to actinic radiation and methods and apparatus for casting sacrificial parts and investment models for lost wax casting from the composition.

BACKGROUND OF THE INVENTION

The 4,000 year old process known as lost wax casting has seen few alternatives to the wax used as the sacrificial pattern media and the namesake of this process.

This traditional process of casting non-ferrous and ferrous metals has evolved through time since the bronze age but the concept of sacrificing a pattern, i.e. investment, to create a cavity to accept molten metal has seen little change. In one variation of the process, sacrificial wax patterns are covered in refractory material that dries and is then heated to cause the wax to melt and finally combust or otherwise be “lost” from inside the refractory mold material. The remaining cavity is an exact, three dimensional negative of the wax pattern. The cavity is filled with molten metal which is allowed to solidify. Next, the refractory material is removed from around the solidified metal casting and the process is complete except for final polishing.

Wax is a relatively inexpensive media and burns well, so it has been the favored material in investment and ceramic shell casting throughout the long history of the lost wax casting process.

With the advent of computer assisted design (CAD) in combination with the machining and stereo lithography processes known as CAM, wax duplication from molds now has greater applications then previously envisioned, applications which go beyond the scope of jewelry and other small metal casting operations that historically utilize the lost wax casting process. These new applications are in the larger industrial foundry market. But that market needs a cost competitive alternative to wax to go forward and no cost effective alternate material is currently available.

Before a wax pattern can be produced in multiples of the same design, a mold must be made. For jewelry, other small castings, and art foundry castings, a rubber or synthetic rubber mold may be used to pour or inject wax into the mold. This process allows the duplication of patterns of the same design.

The costs associated with the lost wax casting process on the larger industrial foundry scale are not limited to the cost of the wax itself. The machining process associated with the production of the metal molds that the wax is injected into remains the largest capitol investment in the production of the sacrificial wax patterns. When making industrial castings for machinery, auto components, etc., a more precise mold is necessary to produce these duplicates. These more precise molds are machined in metal, often aluminum.

In the forgoing process, a two part or multipart metal mold is created by machining solid blanks of metal to create a three dimensional negative mold that is able to withstand the heat and pressure and yield a pattern of exacting dimensions. Pressurized molten wax is injected into the mold and held under pressure until the wax cools. Often these metal molds cost in the tens of thousands of dollars.

A limitation of these metal molds is the fact that the mold must be opened after the wax is injected and the wax pattern must come away completely free from the mold without distortion or being trapped or damaged by the rigid metal mold. This concept of trapped patterns is known as mold drag.

As previously mentioned the increased design capabilities of CAD/CAM can produce complex designs for wax patterns that are not reproducible in metal molds because of the complex undercuts in the design that would yield mold drag. Flexible molds in synthetic or natural rubber can be used to avoid mold drag and subsequently trapped patterns, but they are generally not deemed suitable for larger precision patterns due to their inability to withstand the high pressure of wax without mold distortion and subsequent pattern distortion.

Much of the domestic small casting and foundry production has moved to other countries pursuant to reduced costs of production. One of the main incentives causing this industrial foundry transfer is in the cost reductions associated with the tooling or mold making as previously mentioned. In China for example, the Chinese government subsidizes the cost of metal mold making for high-pressure injected wax. Only a small fraction of the cost of machining these molds is passed on to the foundry customer, adding a large incentive to have industrial mold making and castings produced in China. To keep this industry within China mold costs are only subsidized for molds that remain in China to be used as part of the Chinese foundry industry.

DISCUSSION OF THE RELATED ART

Creating articles by foaming plastic material within a mold is a well known process. The most widely used technique involves mixing a molten thermoplastic with a blowing agent under pressure and injecting or extruding the mixture into a mold. Pressure is released to allow the expansion of the plastic and, while still in the mold, the item is cooled to solidify the now foamed plastic to harden or set. R. Angell, Jr., U.S. Pat. No. 3,268,636 for “Method and Apparatus for Injection Molding Foamed Plastic Articles” is one example of this process employing a method in which the mold is maintained at a pressure below the pressure at which the mixture foams. The mold is rapidly filled with the mixture which foams and expands during the filling process to fill out the mold.

Processes such as described by Angell require heat and pressure and necessitate expensive and complex manufacturing facilities, so sacrificial patterns created by these methods would not serve as an economical replacement for wax models.

Other techniques eliminate heat and pressure requirements by using compounds which are cold setting. K. Wolf, et al., U.S. Pat. No. 4,833,176 for “Process for the Preparation of Cold Setting Flexible Polyurethane Molded Foams” is an example of a compound used in this process. Unfortunately such compounds generally result in molded articles which have surfaces marred by the cellular structure of the cured material unless a heated mold is used. The surface therefor prevents the process form being used to economically create sacrificial patterns having fine, exact details.

The smooth surface required in articles to be use as sacrificial patterns are obtained by using compounds such as described by H. Meyborg, et al., in U.S. Pat. No. 4,263,408 for “Process for the Production of Molded Foams”. The use of metals, such as iron, in the compound leads to residue when the material is burned. Thus the material does not make an acceptable sacrificial pattern.

OBJECTIVES OF THE INVENTION

A primary objective of the invention is a wax alternative material for the production of sacrificial patterns from a class of foamable material that is hardened by radiation induced catalysis after foaming.

Another primary objective of the invention is a wax alternative material for the production of sacrificial patterns that addresses the needs of industrial foundries and is comparable to the cost of wax.

A further primary objective is the use of flexible, synthetic rubber molds for the creation of highly precise and detailed sacrificial patterns for a fraction of the cost of machined metal molds.

A further objective of the invention is an alternative material for sacrificial patterns that addresses the needs of industrial foundries and lowers mold costs by using molds that do not require machined metal components.

Another objective of the invention is a material for sacrificial patterns that addresses the needs of industrial foundries and offers advantages of a flexible mold in the area of mold drag.

A still further objective of the invention is a sacrificial pattern material that addresses the needs of industrial foundries and permits the use of flexible molds.

It is a primary objective of the present invention to provide a system for creating sacrificial patterns through the use of a foaming casting material that is set by actinic radiation after it expands in a soft, flexible, transparent master mold encased in a rigid, transparent mold frame.

An objective of the present invention is to provide a method and apparatus for casting a part or a sacrificial model for investment casting from a molded foam, actinic radiation curable material which is cast and cured in a mold supported by a rigid, transparent mold frame.

A further objective of the present invention is to provide a method and apparatus for casting a part or a sacrificial model for investment casting from a foamed, cold setting flexible and actinic radiation hardened material.

A further objective of the present invention is to provide a method and apparatus for casting a part or a sacrificial model for investment casting from a foamed, cold setting flexible and actinic radiation hardened material which is cast and cured in a radiation transparent mold.

A further objective of the present invention is to provide a method and apparatus for casting a part or a sacrificial model, including undercuts and/or complex three-dimensional shapes, for investment casting from a foamed plastic radiation curable material which is cast and cured in a master mold that is flexible enough to allow the mold to be removed from the sacrificial part created therein by distorting and peeling the master mold from the sacrificial model.

Another objective is to provide a method for casting a radiation curable material incorporating a photoinitiator wherein the material is foamed and then cured in a mold by an external source of radiation.

Another objective is to provide a method for casting a radiation curable material incorporating a photoinitiator wherein the material is foamed in a mold and cured after removal from the mold by radiation.

Another objective of the invention is to harden molded foamed material within a mold by irradiating the material through a transparent mold frame.

A further objective of the present invention is to provide a method and apparatus for casting a part or a sacrificial model from, including undercuts and/or complex three-dimensional shapes, for investment casting from a radiation curable material which is cast by foaming in a master mold before radiation curing.

Other objects, features and advantages of this invention will be apparent from the drawings, specification and claims which follow.

SUMMARY OF THE INVENTION

A method for creating a compound and the thus created compound which is a mixture of compounds having properties which enable it to foam and thereby fill a mold and compounds including a photo responsive catalyst that hardens the compound when subjected to radiation. The hardness of the finally cured combination is suitable for use as a sacrificial model.

The invention also encompasses a method for creating sacrificial models comprised of the steps of filling a mold with a quantity of casting compound, foaming the casting compound within the mold and photo activating a catalyst which causes the foam molded article to harden so that it is suitable for use as a sacrificial model in a lost wax casting process.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In a preferred embodiment of the invention, compounds having properties which cause it to foam and thereby fill a mold are combined with compounds which harden as a result of radiation initiated catalysis. The inventive compound exerts minimal mechanical force on the mold in its liquid or foam state, allowing the use of a mold fabricated from flexible material to create precise, detailed castings. In numerous embodiments of the invention, a very flexible master mold is used. In such cases, a mold frame is used to support the mold during filling and foaming.

The mold is filled with the amount of the inventive compound necessary to expand and completely fill the details of the mold without distorting the mold. A catalyzing agent in the compound is activated by radiation during or after the expansion filling of the mold, taking the compound to its final, hardened catalyzed state. This final catalysis is accomplished by radiation initiation prior to the cast item being removed from the master mold in embodiments using radiation transparent molds and, when necessary, radiation transparent mold frames. Actinic or photo irradiation is used in preferred embodiments of the invention but the invention is not limited thereto. Radiation in other frequency bands may be employed. The type of catalysis initiating radiation is a function of the catalyst used in the compound.

In alternate embodiments, the foam casting is remover from the mold prior to the catalyst being activated by radiation. This is possible when the cast foam has sufficient resiliency to cause the item to return to the molded shape after removal from the master mold. That property is a function of the foaming component selected for use in the inventive combination. Once hardened, by what ever type catalyst used, the sacrificial pattern may be encased in refractory material and burned out, as wax would be, to facilitate the metal casting operation currently known as lost wax casting.

Because the creation of a sacrificial model for lost wax casting is the primary concern of the invention, the compounds used to formulate the inventive compound have the additional property of leaving very little or no residue after burnout. The preferred embodiments combine compounds selected from the subclasses of classes of foaming and radiation activated compounds which completely vaporize during the burnout process.

In addition to cost savings, the use of flexible molds enables the production of patterns that could not previously be produced because of the mold drag associated with rigid metal molds.

Throughout this patent the, the terms “cure”, “cured”, “curing”, hardening” and “hardened” are used interchangeably to describe a transition of material from a liquid, soft, flexible, or resilient foam object to hard or ridged self supporting object. The term foaming agent and blowing agent are used interchangeably in the specification and claims . The term “radiation” is used to identify the radiation which initiates the catalytic transition of material from a liquid, foam and/or resilient body to a ridged, solid state. The frequency of radiation is dependent on the catalytic initiator used in the casting compound. In the preferred embodiment, the radiation is light in the ultraviolet range which performs as actinic radiation causing a liquid to solid phase change in the casting medium to thereby harden the foam casting.

The various embodiments of the invention are perfected through the use of a flowable, foaming casting medium combined with a photo initiated catalyzing agent. Examples of typical flowable casting mediums having properties that may be adapted for use in the present invention may be found in the previously discussed U.S. Pat. Nos. 3,268,636; 4,263,408; and 4,833,176. U.S. Pat. No. 6,025,114 issued to A. Popat et al. for “Liquid Photocurable Compositions” is an example of a typical photo initiated liquid solidified by a catalyzing agent which may be combined in the casting medium to harden the foam. In the present invention, only the photo initiated catalyst and reactant of Popat need be combined with a foaming agent. Alternatively, a foaming agent may be combined with compounds such as those described by Popat to perfect the invention.

As suggested, the invention is not limited to mixing a photo initiated, catalyst containing liquid into cold setting foams while they are in a pourable state. For instance, another but less preferred choice for a casting medium is a hot melt material that is mixed with a blowing agent and allowed to cool and solidify after foaming in the master mold. But the casting medium found in U.S. Pat. No. 6,375,887 for “Method and Apparatus for Creating Cast Parts and Investment Models” and U.S. patent application Ser. No. 11/127,255 produces a preferred embodiment when mixed with a foaming agent or otherwise caused to foam or blow within the mold. These mediums incorporate a photo initiated, catalyst solidified liquid that may be combined with a blowing agent to create a preferred casting medium in accordance with this invention.

The inventor of U.S. Pat. No. 6,375,887 for “Method and Apparatus for Creating Cast Parts and Investment Models” and U.S. patent application Ser. No. 11/127,255 for “Method and Apparatus for Creating Sacrificial Patterns and Cast Parts” is the same inventor as the current patent application and the contents of both are hereby incorporated herein in their entirety. The methods taught therein are modified by the present invention by introducing the step of incorporating a blowing agent into the liquid casting medium before it is poured into a mold.

After mixing, the compound may be poured or injected into a mold cavity where it expands to fill all details within the mold. The expanded casting medium is then hardened by radiation induced catalysis. The casting medium is selected from a class of flowable compounds which expand after flowing in a mold cavity. Such mediums are combined with a photo initiator which induces catalysis and the foam becomes solidified, 1) when exposed to radiation and are transparent to the solidifying radiation whereby the casting functions as a radiation guide or light pipe during the curing process and/or 2) as a function of a chain reaction initiated by radiation. Actinic radiation is the preferred radiation for causing the transition of the casting medium from liquid to solid. Examples of typical photo initiators which may be used in the casting medium compound may be found in U.S. Pat. No. 6,025,114 issued to A. Popat et al. on Feb. 15, 2000 for “Liquid Photocurable Compositions”.

The basic process of the invention includes creating a casting medium by mixing a blowing agent with a casting compound that hardens by catalysis when subjected to actinic radiation and the steps of:

• • [1] partially filling a mold with the mixed casting compound
  • [2] allowing the mixture to foam to completely fill all details within the mold cavity
  • [3] hardening the foamed mixture by exposing it to actinic radiation.

With the casting medium/blowing agent mix of the present invention, any of the procedures of the referenced Joyner U.S. Pat. No. 6,375,887 or patent application Ser. No. 11/127,255, may be modified by the present invention. This entails the step of causing or allowing foaming of the casting medium before application of the catalysis inducing radiation.

The following steps are employed in an embodiment of the process of this invention for creating the casting medium compositions; comprising cold setting foams and compounds containing a radiation activated catalyst that causes a phase change from liquid to solid in the material, both of which vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout; that comprise this invention:

1) selecting a compound which will vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout from the class of compounds comprised of cold setting foams;

2) selecting a compound which will vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout from the class of compounds containing a radiation activated catalyst that causes a phase change from liquid to solid in the material;

3) combining the compounds selected in steps 1) and 2) above.

The following steps are employed in a preferred embodiment of the process of this invention for creating the casting medium compositions; comprising compounds containing a radiation activated catalysts that causes a phase change from liquid to solid in the material and foaming agents, both of which vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout; that are the material compositions of this invention:

1) selecting a compound which vaporizes and/or leaves very little residue when subjected to temperatures normally encountered in the lost wax process during burnout from a compound containing a radiation activated catalyst that causes a phase change from liquid to solid in the material;

2) combining said selected compound with a foaming agent which vaporizes and/or leaves very little residue when subjected to temperatures normally encountered in the lost wax process during burnout.

The following steps are employed in an embodiment of the process of this invention for creating the casting medium compositions; comprising a hot melt casting medium, compounds containing a radiation activated catalyst that causes a phase change from liquid to solid in the material and a foaming agent, all of which vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout; that comprise this invention:

1) selecting a hot melt casting medium which will vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout;

2) selecting a foaming agent which will vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout;

3) selecting a compound which will vaporize and/or leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout from the class of compounds containing a radiation activated catalyst that causes a phase change from liquid to solid in the material;

4) combining the hot melt casting medium, the foaming agent, and the compound containing a radiation activated catalyst.

The following steps are employed in an embodiment of the method of this invention for creating a sacrificial pattern for lost wax casting:

1) partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidify when subjected to radiation;

2) waiting for said casting compound within said master mold to matured through the foaming process until said master mold is filled to the point where all details within said master mold have been completely filled with foam;

3) hardening the matured foam by subjecting it to catalysis initiating radiation.

In the method for creating a sacrificial pattern for lost wax casting as outlined above, the matured foam may be hardened by subjecting the foam to curing radiation before or after it is removed from the master mold.

The following steps are employed in a preferred embodiment of the method of this invention for creating a sacrificial pattern for lost wax casting:

1) partially filling a master mold with a compound which solidifies when subjected to radiation and a foaming or blowing agent;

2) waiting for the combined materials of the previous step to matured through the foaming process until the master mold is filled to the point where all details within the master mold have been completely filled with foam;

3) hardening the matured foam by subjecting it to catalysis initiating radiation.

In the method for creating a sacrificial pattern for lost wax casting as outlined in paragraph 0051 above, the matured foam may be hardened by subjecting the foam to curing radiation before or after it is removed from the master mold.

The following steps are employed in an embodiment of the method of this invention for creating a sacrificial pattern for lost wax casting:

1) partially filling a master mold with a hot melt casting medium mixed with a compound which solidify when subjected to radiation and a foaming or blowing agent;

2) waiting for the casting composition within the master mold to matured through the foaming process until the master mold is filled to the point where all details within the master mold have been completely filled with foam;

3) hardening the matured foam by subjecting it to catalysis initiating radiation.

In the method for creating a sacrificial pattern for lost wax casting as outlined above, the matured foam may be hardened by subjecting the foam to curing radiation before or after it is removed from the master mold.

In the preceding methods, the blowing agent may be a compressed gas.

While preferred embodiments of this invention have been described, variations and modifications may be apparent to those skilled in the art. Therefore, I do not wish to be limited thereto and ask that the scope and breadth of this invention be determined from the claims which follows rather than the preceding description.

Claims

1. A casting medium composition, comprising:

a compound selected from the class of compounds comprised of cold setting foams, and

a compound selected from the class of compounds which solidify when subjected to radiation.

2. A casting medium composition as defined in claim 1, wherein:

said compound selected from the class of compounds comprised of cold setting foams is limited to compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout.

3. A casting medium composition as defined in claim 1, wherein:

said compound selected from the class of compounds which solidify when subjected to radiation is limited to compounds which leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout.

4. A casting medium composition as defined in claim 1, wherein:

said compound selected from the class of compounds comprised of cold setting foams is limited to compounds which leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout.

5. A casting medium composition as defined in claim 1, wherein:

said compound selected from the class of compounds which solidify when subjected to radiation is limited to compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout.

6. A casting medium composition, comprising:

a fluid casting medium selected from the class of compounds which solidify when subjected to radiation, and

a foaming agent.

7. A casting medium composition as defined in claim 6, wherein:

said fluid casting medium is limited to compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout.

8. A casting medium composition as defined in claim 6, wherein:

said fluid casting medium is limited to compounds which leave very little residue when subjected to temperatures normally encountered in the lost wax process during burnout

9. A casting medium composition as defined in claim 6, wherein:

said foaming vaporizes when subjected to temperatures normally encountered in the lost wax process during burnout.

10. A casting medium composition as defined in claim 6, wherein:

said foaming agent leaves very little residue when subjected to temperatures normally encountered in the lost wax process during burnout

11. A casting medium composition as defined in claim 6, comprising:

a hot melt casting medium.

12. A method for creating a sacrificial pattern for lost wax casting, including the steps of:

partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidifies when subjected to radiation;

waiting for said casting compound within said master mold to mature through the foaming process until said master mold is filled to the point where all details within said master mold have been completely filled with foam; and

hardening said foam by subjecting said foam to catalysis initiating radiation.

13. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, including the step of:

removing said matured foam from said master mold before said step of hardening said foam by subjecting said foam to catalysis initiating radiation.

14. A method for creating a sacrificial pattern for lost wax casting, including the steps of:

mixing a foaming agent with a casting medium that solidifies when subjected to radiation;

partially filling a master mold with said casting medium mix;

waiting for said casting medium mix within said master mold to matured through the foaming process until said master mold is filled to the point where all details within said master mold have been completely filled with foam; and

hardening said foam by subjecting said foam to catalysis initiating radiation.

15. A method for creating a sacrificial pattern for lost wax casting as defined by claim 14, including the step of:

removing said matured foam from said master mold before said step of hardening said foam by subjecting said foam to catalysis initiating radiation.

16. A method for creating a sacrificial pattern for lost wax casting, including the steps of:

mixing a blowing agent with a hot melt casting medium that contains a compound that solidifies when subjected to radiation;

partially filling a master mold with said hot melt casting medium mix before the foaming process is completed;

waiting for said hot melt casting medium mix within said master mold to matured through the foaming process until said master mold is filled to the point where all details within said master mold have been completely filled with foam; and

hardening said foam by subjecting said foam to curing radiation.

17. A method for creating a sacrificial pattern for lost wax casting as defined by claim 16, including the steps of:

cooling said matured foam in said master mold; and

hardening said matured foam by subjecting it to catalysis initiating radiation.

18. A method for creating a sacrificial pattern for lost wax casting as defined by claim 16, including the steps of:

hardening said matured foam by subjecting it to catalysis initiating radiation; and

cooling said matured foam in said master mold.

19. A method for creating a sacrificial pattern for lost wax casting as defined by claim 16, including the steps of:

cooling said matured foam in said master mold;

removing said cooled matured foam said master mold; and

hardening said cooled matured foam by subjecting it to catalysis initiating radiation.

20. A method for creating a sacrificial pattern for lost was casting as defined by claim, 16, wherein said blowing agent is a compressed gas.

21. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, including the step of:

removing said matured foam from said master mold after said step of hardening said foam by subjecting said foam to catalysis initiating radiation.

22. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12 wherein said step of hardening said foam by subjecting said foam to catalysis initiating radiation is accomplished while said foam is in a liquid state before said sacrificial pattern is removed from said master mold.

23. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, wherein said step of partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidifies when subjected to radiation is preceded by the steps of:

selecting said cold setting foam casting compound from the class of compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout,

selecting said compound which solidifies when subjected to radiation from the class of compounds which reduce to a very small amount of residue when subjected to temperatures normally encountered in the lost wax process during burnout, and

mixing together said selected cold setting foam casting compound and said selected compound which solidifies when subjected to radiation.

24. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, wherein said step of partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidifies when subjected to radiation is preceded by the steps of:

selecting said cold setting foam casting compound from the class of compounds which reduce to a very small amount of residue when subjected to temperatures normally encountered in the lost wax process during burnout,

selecting said compound which solidifies when subjected to radiation from the class of compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout, and

mixing together said selected cold setting foam casting compound and said selected compound which solidifies when subjected to radiation.

25. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, wherein said step of partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidifies when subjected to radiation is preceded by the steps of:

selecting said cold setting foam casting compound from the class of compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout,

selecting said compound which solidifies when subjected to radiation from the class of compounds which vaporize when subjected to temperatures normally encountered in the lost wax process during burnout, and

mixing together said selected cold setting foam casting compound and said selected compound which solidifies when subjected to radiation.

26. A method for creating a sacrificial pattern for lost wax casting as defined by claim 12, wherein said step of partially filling a master mold with a cold setting foam casting compound mixed with a compound which solidifies when subjected to radiation is preceded by the steps of:

selecting said cold setting foam casting compound from the class of compounds which reduce to a very small amount of residue when subjected to temperatures normally encountered in the lost wax process during burnout,

selecting said compound which solidifies when subjected to radiation from the class of compounds which reduce to a very small amount of residue when subjected to temperatures normally encountered in the lost wax process during burnout, and

mixing together said selected cold setting foam casting compound and said selected compound which solidifies when subjected to radiation.