In response to concerns about global warming and depletion of subterranean resources such as petroleum oil, the automobile industry is rapidly shifting from gasoline-based cars to hybrid and electric cars. As a CO₂ emissions-reduction measure, many countries are competing to make solar power or wind power generation fit for practical use as a source of energy.

Weight-reduction techniques are one of the most important technological innovations in the midst of this competition. This section explains weight-reduction techniques.

(1) Purpose of weight-reduction techniques

• The purpose of adopting weight-reduction techniques is to save energy consumption by reducing the weight of a moving body.

Examples:
(1)Substitute an automobile body made of steel with one made of aluminum alloy to reduce weight ([Fig.1])
(2)Reduce the weight of bullet train cars by adopting aluminum alloy materials
(3)Reduce the weight of an airplane by increasing the ratio of CFRP composite materials

• Adopting weight-reduction technologies is becoming more important in the field of automation devices and mechanical devices for the same purpose.

Examples:
(4)Substitute the metal stock with resin material to reduce the weight of a movable body
(5)Substitute the steel material of the device column portion with resin composite, concrete composite, or ceramic materials
(6)Adopt a slim or hollow design for the component parts, such as linear slide guides, or reduce the weight by material substitution

(2)Overview and agenda of weight-reduction techniques