Kittyhawk Products Inc.

Design engineers will benefit from learning about and taking advantage of the benefits of the Hot Isostatic Processing. (HIPing) process to keep up to the increasing demands on quality design and costs in the industry. Education is a priority at Kittyhawk Products. We have a technical expert available for consultation and we provide free HIPing services for test parts so that we can acquaint engineers and purchasers with what HIP will do for them. HIP must not be seen as a crutch to make good castings but as an integral step to providing quality castings to their customers. Engineers should see HIP as a process to improve yields rather than a last resort salvage operation.

Originally, the casting industry thought HIPing was a means to salvage castings and reduce its scrap rates. Prior to HIPing, no other non-destructive technique was available for the economic repair of castings containing internal porosity. The emphasis is now, however, changing towards the exploitation of improved properties as design engineers realize that cast parts which have been HIPed can develop properties similar to those of forged components.

The Hot Isostatic Process was initially developed as a means of diffusion bonding nuclear reactor components and for the removal of internal porosity in hard materials. However, the major commercial activity now centers on consolidation of powder metals and the densification of high performance castings. HIPing is utilized in a wide range of industries including aerospace, power generation, automotive, medical, defense, metalworking and recreation.

The origins of porosity in castings include shrinkage as the material cools through the liquid to solid transition, trapped gases, and the generation of gases by reaction. The effects of HIPing on the mechanical properties are higher strength, higher toughness, longer fatigue resistance and longer creep life. The most beneficial effect of HIPing is the reduction of the scatter in the mechanical properties of castings.

When Hot Isostatic Processing was first developed, the high cost limited the application to expensive materials. A significant reduction in the costs has occured in recent years. HIPing can now be an integral part in saving costs down the production line. If a casting is rejected after the machining process then it is the manufacturer that loses the most because he cannot recover valuable scheduling time and the costs of the machining step.

HIP is buying insurance for your casting. You don't want to be insurance poor but there are instances when insurance makes sense.

· Cast alloys are subject to defects that generally result in their having lower and more variable mechanical properties than their wrought counterparts. These defects include shrinkage, inclusions and alloy segregation. Reasonable control is possible by proper mold design and good foundry practice. However, the complete elimination of all defects from cast shapes is not possible without applying some external force to accomplish the deformation necessary to close voids and porosity. HIP provides the ideal mechanism for the application of this force. The simultaneous application of heat and isostatic gas pressure combine to collapse voids and porosity by creep mechanisms and to "heal" the material by diffusion bonding the material together. The isostatic nature of the applied pressure is well suited to healing the defects in castings. Void closure is accomplished with a minimum, usually not measurable, dimensional distortion. Pieces of extremely complex geometry can be treated without the use of expensive tooling.
· The many investigations conducted on several classes of cast material show that HIP results in startling improvements in mechanical properties, as well as significantly reducing scrap losses and rework. The casting reliability is improved due to the closing of defects in the casting.
· The greatest significance of the HIP process is the marked reduction in the statistical spread or scatter usually associated with the cast material. The net result is improved efficiency of the material utilization in the casting and the abiltiy to use castings for applications formerly requiring more expensive forged or wrought and machined materials to meet specifications.
· Increased resistance to thermal fatigue and wear.

One of the reasons for using HIP is to get the competitive edge in your field. Quality is always highly regarded among buyers. As manufacturers' standards increase, HIP will become a necessary tool for foundries to deliver the required product. HIP can be used to reduce rework and machining costs and as labor costs escalate, any process that can reduce direct labor is an asset. Expensive retooling can be avoided. When the requirements for castings increase, HIP can be used to increase the grade of your particular casting. Although HIP is not a substitute for poor casting practices, the integration of castings and HIP can reduce material and processing costs.

In the end, everything comes back to the cost of a part and for this reason the treatment of this topic is at the beginning and end of all discussions of HIP castings. It is very important to realize that HIP, whether used in routine processing or in reclamation and salvaging, does not merely involve the replacement cost of a rejected part. By the time the part is found to be unacceptable due to flaws or to low mechanical properties, one has spent a considerable amount of manufacturing costs, which often far exceed the original costs of the casting.


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		Design Engineers Design engineers will benefit from learning about and taking advantage of the benefits of the *Hot Isostatic Processing. (HIPing) process to keep up to the increasing demands on quality design and costs in the industry. Education is a priority at Kittyhawk Products. We have a technical expert available for consultation and we provide free HIPing services for test parts so that we can acquaint engineers and purchasers with what HIP will do for them. HIP must not be seen as a crutch to make good castings but as an integral step to providing quality castings to their customers. Engineers should see HIP as a process to improve yields rather than a last resort salvage operation. Originally, the casting industry thought HIPing was a means to salvage castings and reduce its scrap rates. Prior to HIPing, no other non-destructive technique was available for the economic repair of castings containing internal porosity. The emphasis is now, however, changing towards the exploitation of improved properties as design engineers realize that cast parts which have been HIPed can develop properties similar to those of forged components. The Hot Isostatic Process* was initially developed as a means of diffusion bonding nuclear reactor components and for the removal of internal porosity in hard materials. However, the major commercial activity now centers on consolidation of powder metals and the densification of high performance castings. HIPing is utilized in a wide range of industries including aerospace, power generation, automotive, medical, defense, metalworking and recreation. The origins of porosity in castings include shrinkage as the material cools through the liquid to solid transition, trapped gases, and the generation of gases by reaction. The effects of HIPing on the mechanical properties are higher strength, higher toughness, longer fatigue resistance and longer creep life. The most beneficial effect of HIPing is the reduction of the scatter in the mechanical properties of castings. When *Hot Isostatic Processing* was first developed, the high cost limited the application to expensive materials. A significant reduction in the costs has occured in recent years. HIPing can now be an integral part in saving costs down the production line. If a casting is rejected after the machining process then it is the manufacturer that loses the most because he cannot recover valuable scheduling time and the costs of the machining step. HIP is buying insurance for your casting. You don't want to be insurance poor but there are instances when insurance makes sense. · Cast alloys are subject to defects that generally result in their having lower and more variable mechanical properties than their wrought counterparts. These defects include shrinkage, inclusions and alloy segregation. Reasonable control is possible by proper mold design and good foundry practice. However, the complete elimination of all defects from cast shapes is not possible without applying some external force to accomplish the deformation necessary to close voids and porosity. HIP provides the ideal mechanism for the application of this force. The simultaneous application of heat and isostatic gas pressure combine to collapse voids and porosity by creep mechanisms and to "heal" the material by diffusion bonding the material together. The isostatic nature of the applied pressure is well suited to healing the defects in castings. Void closure is accomplished with a minimum, usually not measurable, dimensional distortion. Pieces of extremely complex geometry can be treated without the use of expensive tooling. · The many investigations conducted on several classes of cast material show that HIP results in startling improvements in mechanical properties, as well as significantly reducing scrap losses and rework. The casting reliability is improved due to the closing of defects in the casting. · The greatest significance of the HIP process is the marked reduction in the statistical spread or scatter usually associated with the cast material. The net result is improved efficiency of the material utilization in the casting and the abiltiy to use castings for applications formerly requiring more expensive forged or wrought and machined materials to meet specifications. · Increased resistance to thermal fatigue and wear. One of the reasons for using HIP is to get the competitive edge in your field. Quality is always highly regarded among buyers. As manufacturers' standards increase, HIP will become a necessary tool for foundries to deliver the required product. HIP can be used to reduce rework and machining costs and as labor costs escalate, any process that can reduce direct labor is an asset. Expensive retooling can be avoided. When the requirements for castings increase, HIP can be used to increase the grade of your particular casting. Although HIP is not a substitute for poor casting practices, the integration of castings and HIP can reduce material and processing costs. In the end, everything comes back to the cost of a part and for this reason the treatment of this topic is at the beginning and end of all discussions of HIP castings. It is very important to realize that HIP, whether used in routine processing or in reclamation and salvaging, does not merely involve the replacement cost of a rejected part. By the time the part is found to be unacceptable due to flaws or to low mechanical properties, one has spent a considerable amount of manufacturing costs, which often far exceed the original costs of the casting.