J. Software Engineering revised June 29th, 2009; accepted July 7th, 2009. ABSTRACT Maintainability is an important character which is given by product design process. The maintainability design criteria and measure index used in product maintainability analysis are summarized and discussed in this paper. A product maintainability design method is studied by integrating the product feature model, maintainability design criteria with measure index. Product feature model can be built on the basis of the product feature library quickly. Product feature library for steam turbine design is created by using SolidWorks design library origination structure. A methodology which supports the design and development of product maintainability design support tool (PMDSTs) is put forward. The function of PMDSTs is designed by using UML (Unified Modeling Language) use case diagram, it is developed by using VC+ 6.0. The maintainability analysis application case of steam turbine-generator system is given at last. Keywords: Maintainability Design, Product Design Process, Steam Turbine, Solidworks 1. Introduction If a product has poor maintainability, the maintenance activities which have to be performed on it during its life cycle are difficult, it will result in increasing the costs, and also more time is required to accomplish the main- tenance tasks. Designs for maintainability had played an important role in the complex product deign process. Maintainability is the probability that required mainte- nance will be successfully completed in a given time period. It is a design characteristic that affects accuracy, ease, and time requirements of maintenance actions. It may be measured by combining factors such as fre- quency of maintenance, maintenance costs, elapsed maintenance or repair times, and labor hours etc. Design for maintainability requires a product that is serviceable and supportablebetter yet if the design in- cludes a durability feature called reliability (absence of failures) then you can have the best of all worlds 1. Maintainability is an important character which is given by product design, it makes easy to be repaired for the mechanical system. It has a specific effect on the maintenance cost of mechanical systems 2. In order to realize product design for maintainability, some approaches and software tools have been studied and developed. A maintainability evaluation approach based on fuzzy logic is presented in 3, fuzzy linguistic variables are employed in order to represent and handle the design data available early in the design process. The measure tool of the product maintainability is developed. Maintainability and safety indicators at design stage for mechanical products are studied in 4. The assessment procedure uses product 3D (Dimension) CAD (Computer Aided Design) model and associated semantic matrix gathering information from the product components criticality and reliability. 2. Product Integration Maintenance Model Product CAD model doesnt include product mainte- nance feature information; it can not provide support for product maintenance. So it needs to build product inte- gration model by combining CAD model and mainte- nance feature information. Product integration model is composed of shape feature Fs, heat treatment feature Fh, management feature Fm and maintenance feature Fma. They can be united altogether to build a whole product feature model. The product feature classification is shown in the Figure 1. Maintenance feature is used for describing maintainability design and relevant informa- tion. It includes maintenance organization feature, main- tainability feature, maintenance resource, maintenance process, fault feature, using demand, maintenance pro- gram, maintainability qualitative demand, quantitative demand, maintainability design analysis result, person model info etc. Maintainability program includes objec- tives, organization, maintainability design criteria, poli-Product Maintainability Design Method and Support Tool Based on Feature Model 166 cies and procedures, organizational interfaces, program tasks, evaluation and subcontractor/supplier activity etc. 5. Product maintenance integration model is shown in Figure 2. Ci means ith component. It can be a part or a sib-assembly. R(i,j) represents the assembly relation be- tween ith component and jth component. It is marked in the link arc between ith component and jth component. Every component has an attribute table, all attribute ta- bles are saved in the attribute table. Every attribute table file saves all feature informations of component Ci. Some data files such as design parameter table (excel file), de- sign intent (word file), maintenance plan (Microsoft pro- ject file) are stored in design document data or mainte- nance data. They have a link in the Tag file. Tag file will look for the relevant file by the link 5. Figure 1. Product feature clas