Algor Software Helps Canadian Firm Earn Patent for Mandrel Design Used in Nickel Vapor Deposition

Algor Around the World: Canada

	Miro Milinkovic, Mirotech, Inc. founder and mandrel design engineer.

Miro Milinkovic couldn't be happier! His company, Mirotech, Inc., was recently awarded a U.S. Patent for his mandrel design used to support nickel molds during nickel vapor deposition (NVD).

Mirotech is based in Weston, Ontario, Canada and is the world's only developer of NVD technology. The company uses NVD process to manufacture nickel shapes and molds for scientific, commercial and industrial applications.

What is NVD?

NVD is a chemical metal forming process based on the growth of a metal from gaseous vapors. Gaseous nickel, which breaks down into a solid metal at a very high rate of decomposition at a relatively low temperature, is used. By heating an object to the temperature required and having the nickel carbonyl gas flow over the object within a sealed chamber, an exact nickel duplicate negative-mold of the object is obtained. NVD is widely recognized by the scientific and industrial community for its ability to reproduce the surface detail of a master object down to the finest texture and smoothness without the residual stresses and warpage found in other deposition processes such as aluminum or plastics.

Mandrel Design Requirements

The mandrel is a frame-like structure which is mounted in a chamber and supports the nickel shell during the NVD. Several criteria have to be met in order to assure the mandrel will withstand NVD processes:

• The material must be chemically inert and thermally stable at all process temperatures.
• The coefficient of thermal expansion (CTE) of the mandrel must closely match that of nickel.
• The thermal conductivity of the mandrel must be high enough to allow even heating of its working surface.
• The density, thermal inertia, and Young's modulus of the mold being created must be taken into consideration.
• The mandrel must be made of an isotropic, well-mixed material in order to maintain the homogeneity of the properties listed above.

Algor Model Analyzed to Meet Mandrel Criteria

Mr. Milinkovic used Algor software to create a computer model of his proposed design. He then performed both steady-state and transient analyses to determine the effects of heat and process conditions on the mandrel.

The mandrel design is a brand new concept in NVD technology. With Algor, Mr. Milinkovic was able to effectively optimize his design options to produce a geometry which would result in minimum deformation.

"Typically, a thermal analysis is performed to determine a temperature profile. If Algor told me that the temperature distribution was not applicable with the required NVD process, I moved the heating elements to other locations to get a more favorable temperature map," said Mr. Milinkovic.

According to Mr. Milinkovic, "The Algor analysis results of the mandrel design clearly showed the direction of the desired geometry so that the deformation due to thermal stresses could be minimized".

		The structure to the left is of a typical mandrel used in the NVD process. Mirotech's newly patented composite mandrel is pictured to the right.

Prototype Measurements Concur with Algor Analysis Results

Confident with the results obtained from his Algor analysis, Mr. Milinkovic then gave the go-ahead for Mirotech to fabricate an actual mandrel prototype model. The model was tested and the measurements obtained were compared to the Algor analysis results. "The agreement was almost perfect," stated Mr. Milinkovic.

Contracts in the Works Aided by Algor Analysis

Every new project at Mirotech is analyzed using Algor software. Recently, the firm was asked by the University of Washington to continue its NVD research on the Sudbury Neutrino Observatory (SNO) project. SNO is a joint United States, Canada and United Kingdom research effort focused on studying the amount of neutrinos emitted by the sun. Mirotech has been contracted to develop the sensitive tubular proportional counters needed to detect the products of neutrino interactions. These devices must be made of extremely pure materials in order to avoid false signals produced by the sun's natural radioactivity. Mirotech is the only company in the world that can produce nickel pure enough to address this need.

In addition to the SNO project, Mirotech has just concluded a technology transfer agreement with a premier nickel tooling company which is engineering a large scale NVD facility in Germany to service the European market.

"I found that Algor software was easy to learn, user-friendly and robust," said Mr. Milinkovic.