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Case Study: TRIZ Solves a Hard Drive Reliability Problem

| On 14, Nov 1998

Zinovy Royzen, President
TRIZ Consulting, Inc.
12013 C 12 Ave N.W., Seattle, Washington
Tel: (206) 364-3116, E-mail:Zroyzen@aol.com
Web site: http://members.aol.com/zroyzen/triz.html

This paper was presented at The Tenth Symposium on Quality Function Deployment,
June 14-16, 1998, Novi, Michigan

Introduction

TRIZ is the Russian acronym for The Theory of Inventive Problem Solving. TRIZ is a unique knowledge-based technology for accelerated development of design concepts. The power of TRIZ is based on the understanding of the evolution of successful products, ways to overcome psychological barriers, and generalization of the ways used to solve problems in the most innovative inventions. TRIZ can guide you in analyzing your product’s or process’s functions in order to best use its resources and identify the best opportunities for its development.

Accelerated product development has become increasingly important. You need to develop successful new generations of products while shortening development cycles and reducing project spending. Implementing the TRIZ methodology from the beginning of your project can save you much time and effort in your search for the ideal solutions. In problem-solving, TRIZ systematically analyzes the problem as an innovative situation and applies a series of guidelines to generate solution alternatives.

Contradictions, or conflicts, represent the most difficult type of problem during product development. In many cases a desired improvement can cause a deterioration in another area. For example, very often an attempt to increase productivity causes deterioration in quality. As a result, a trade-off situation is created.

The TRIZ methodology includes algorithms for resolving conflicts between product parameters while minimizing product changes and costs, leading to breakthrough solutions. As an example, consider the following case study of a difficult problem.

Initial Situation

A hard drive has an actuator arm, which can move relative to a magnetic disk that is rotated by an electric motor. At the end of the arm is a read/write head, which can magnetize or sense the magnetic field of the disk. The head is separated from the surface of the disk by airflow generated by the rotating disk. The gap between the head and the disk is very small. Any contact between the head and the magnetic disk may cause loss of data.

The disk has a landing zone, where the head is positioned when the disk is not spinning. The landing zone is an area of the disk where no data is stored. When the computer is switched on, the disk starts spinning, creating an airflow, which lifts the arm, creating the required gap. Then the arm is moved away from the landing zone to read and write data. When the computer is turned off, the arm is returned to the landing zone. Slowing of the spinning disk decreases the airflow supporting the arm. As a result, the arm rests on the landing zone.

Applying an external force to the drive (such as moving or knocking the computer), can move the head away from the landing zone and destroy data on the disk. A latching mechanism is used to prevent the arm from moving when the computer is not in use. A permanent magnet holds the arm when the head is in the landing zone. When the computer is turned on, the arm has to overcome the latch magnet in order to move.


Hard drive

Problem

The drive needs to be protected against stronger external force. This could be achieved by replacing the current latch magnet with a stronger one. But the arm would not be able to overcome the force of any magnet stronger then the current one. Thus an attempt to improve the reliability of the hard drive causes deterioration of its performance.

A breakthrough solution is needed to improve the reliability of the drive without any deterioration of its performance, while minimizing any increase in production costs.

Summary of Application of TRIZ

Functional Analysis

The latching mechanism includes the latch magnet, a plastic holder for the latching magnet, and a screw.

The function of the latch magnet is to hold the arm.

The performance of the latch magnet is insufficient according to the requirements for a new design.

A stronger latch magnet will hold the arm adequately, but the arm will not be released.

The Model of the conflict:

Application of Ideal Ways

Ideal Ways is an analytical TRIZ method developed by Zinovy Royzen. The method is an advanced development of Altshuller’s concept of Ideal System Ideal Ways comprise the best directions for improvement of a product.

Ideal Way 1. Eliminate the need for holding the arm.

The arm has to be held in order to prevent it from moving while the computer is not in use. If the arm cannot be moved by the external force, there is no need for holding the arm. This statement requires a description of the chain of unwanted actions that causes the unwanted motion of the arm.

Unwanted action: The arm is moved by its pin.

Problem: The motion of the pin caused by an external force has to be eliminated.

Unwanted action: The pin is moved by the drive case.

Problem: The motion of the case caused by an external force has to be eliminated.

Unwanted action: The drive case is moved by the computer chassis.

Problem: The motion of the chassis caused by an external force has to be eliminated.

TRIZ Standard Technique (direct ways to eliminate an unwanted action) was applied to solve some of the formulated problems.

Ideal Way 2. Substitute the latch magnet.

The list of resources includes resources of the latching mechanism, the drive, and the surroundings. Analysis of the resources revealed the possibility of substituting for the latch magnet.

One possibility: The arm carries a voice coil. Interaction between the magnetic field created by an electric current through the voice coil and the magnetic field of the voice coil magnets swings the arm around the pin. The latch arm could be substituted with a much stronger voice coil magnet. In this case, there would be no need for the latch magnet, its plastic holder, and the screw. In mass production of the hard drives, the solution could save a lot of money for the manufacturer.

Another possibility: The external force itself could be used to hold the arm instead of the latch magnet. The solution looks like a “safety belt” for the arm.

The requirement to consider alternative ways to hold the arm lead to analysis of a variety of locking mechanisms used in different industries.

Ideal Way 3. The arm held by a stronger magnet has to be released when necessary.

We already described the conflict caused by an attempt to make the latch magnet stronger. The Algorithm for Inventive Problem Solving (ARIZ), the main TRIZ method for solving conflicts, was applied to solve the formulated conflict.

Through the step-by-step application of ARIZ, the model of the problem was formulated, then the physical contradiction of the conflict, then the ideal final result.

After application of the Physical Contradiction Separation Techniques and utilization of the resources of the latching mechanism and the hard drive, a number of design concepts were developed. Any of the developed concepts allow significant increase of the holding force without any deterioration of the performance of the arm.

All developed design concepts were evaluated. The concepts are the set of mutually exclusive but collectively exhaustive best possible improvements. This set is the basis for both short-term and long-term planning of innovation.

Conclusion

TRIZ is a logical, knowledge-based technology for conceptual design. Guided by TRIZ, users not only overcome psychological inertia and preconceived notions, they also have the opportunity to analyze the best directions for improvement of products. TRIZ methods help TRIZ users to maximize utilization of the resources of a system to meet objectives of new product development projects with less cost and without any unwanted effects.

Engineers, researchers, and managers involved in product development can rely on TRIZ to avoid a failure and trade-off concept.

Application of TRIZ accelerates the search for breakthrough solutions and gives users the ability to reach far greater levels of product performance. TRIZ users have demonstrated a strategic advantage in new product development.

REFERENCES

  1. Altshuller, G. S., 1984, Creativity as an Exact Science. New York: Gordon and Breach.
  2. Altshuller, G. S., 1986, in Russian, To Catch an Idea. Introduction in the Theory of Inventive Problem Solving, Novosibirsk: Nauka.
  3. Royzen, Z. 1993, “Application TRIZ in Value Management and Quality Improvement.” The SAVE Proceedings, Vol. XXVIII, Society of American Value Engineers, International Conference, May 2-5, 1993, Fort Lauderdale, Florida, Pp. 94-101.
  4. Royzen, Z. 1995, “Product Improvement and Development of New Generation Products Using TRIZ.” The ASI Symposium, Total Product Development, November 1-3, 1995, Dearborn, Michigan, pp. 251-257.
  5. Royzen, Z. 1996, “Product Improvement and Development of New Generation Products Using TRIZ.” The ASI Symposium, Total Product Development, November 1-3, 1995, Dearborn, Michigan, pp. 251-257.
  6. Royzen, Z. 1996, “Solving Contradictions in Development of New Generation Products Using TRIZ.” The ASI 2nd Annual Total Product Development Symposium, November 6-8, 1996, Pomona, California, Pp. 799-805.
  7. Royzen, Z. 1998, “TRIZ Technology of Conceptual Design. Inventive Problem Solving Five-day Workshop“, Seattle: TRIZ Consulting, Inc.

About the Author

Zinovy Royzen is Founder and President of TRIZ Consulting, Inc., Seattle, Washington the first U.S. company to apply TRIZ; and Affiliate Associate Professor, University of Washington, Seattle. Mr. Royzen is a leading expert in TRIZ with fourteen year’s experience in the application of TRIZ to new product development, quality improvement. cost reduction, and problem solving. Previously, as a project manager at The Scientific and Technological Center, Kishinev, the former Soviet Union, he conducted many 192-hour TRIZ workshops and taught TRIZ to nearly 1,000 engineers and scientists.

Mr. Royzen has applied TRIZ to numerous projects in diverse industries for some of the largest companies in the former Soviet Union and since 1992, he has led workshops and/or provided consultation at numerous organizations in the United States, including Boeing, Eastman Kodak, Ford Motor Company, Gillette, Hewlett-Packard, Howmet Corporation, Illinois Tool Works, Kimberly-Clark, Lexmark International, NASA, Paccar, Western Digital Corporation, Weyerhaeuser Company and Xerox, among others.

He has published articles on creative problem solving and holds 26 patents.

Zinovy Royzen received his Master’s degree in Mechanical Engineering from Engineering University of Kaliningrad, Russia, in 1975.

Zinovy Royzen
TRIZ Consulting, Inc.
12013 C 12 Ave NW
Seattle, WA 98177
Tel: (206) 364-3116
Fax: (206) 364-8932
E-mail: Zroyzen@aol.com
Web site: http://members.aol.com/zroyzen/triz.html