Washington Softwares Ltd. has developed a unique software package for design of centrifugal fans. With this software package the complex design is generated by software at fastest speed with highest accuracy. Washington Softwares Ltd. Is worlds leading company in providing design solutions for the mechanical industry in order to make design process simple and highly accurate.Mechanical springs are used almost in all machines and equipments .Now design engineer can design optimum spring with the aid of WSL's design package. A spring is a mechanical device that is used for efficient storage and release of energy. Strength and flexibility are the two essential requirements of spring design. Strength is taken into consideration by load stress equation and Flexibility by load deflection. All Standards are used throughout this module.