# Statistical Tolerance Analysis--A Survey on Awareness, Use and Need in German Industry
## 2 What Led Us to Today?--A Brief Historical Review on Tolerance Engineering  
The history of tolerance engineering is closely linked to progress in the manufacturing and assembly of products and in particular the manufacturing of tools and weapons. The idea of interchangeability in the production of bows and arrows was born in ancient Egypt (3000 BC) [5]. However, it was only in the 18 th century in France that the interchangeability of weapon components was promoted by [PERSON] and [PERSON] as well as in the USA by [PERSON][6,7]. The interchangeability for the first time allowed the quality of products to be guaranteed even if certain deviations were accepted. At the beginning of the 20 th century, the standardization of products and processes was implemented massively worldwide. Beginning in Great Britain (1901), another 24 organizations for standardization were founded within the following 31 years [5]. Among the first results published in 1922 by the German Standards Committee (DIN) was the DIN system of fits [8], which still exists today in a modified form [9]. As standardization progressed, the need for a uniform specification of tolerances in technical drawings and sketches, which was first regulated at the beginning of the 20 th century, also increased [10]. At the beginning of the 20 th century, statistics and probability theories found their way into almost every science, including mechanical engineering [5]. The rapidly growing automotive industry in particular demanded new methods to improve the production and thus the quality of vehicles. [PERSON] explained in [11] as early as 1925 that the quality of each product during use was a function of the qualities of the single parts used [12]. In [12], he explained the necessity to analyze the effects of individual part deviations on the quality of the product, taking into account the associated probability distributions and permissible reject rates. With this requirement, [PERSON] explained the statistical tolerance analysis in its currently known form, although he did not explicitly use this term. During World War II, research activities decreased enormously [13]. However, in the following years, the newly flourishing automobile production (especially in the USA) and the rapidly increasing economic and thus purchasing performance in Europe spurred the spread of statistical tolerance calculations in research and industrial mass production [14]. With the increasing availability of mainframes in the 1960s, research and development on tolerance engineering probably experienced the greatest impetus to date. Existing and established methods and approaches [15; 16; 17] could be implemented on the fly and then applied quickly and easily. In addition to tolerance analysis, however, tolerance synthesis in particular benefited from the almost unlimited possibilities of computer support. This is illustrated by the multitude of research work in the 1970s in the field of statistical tolerance optimization (e.g., [18; 19; 20; 21; 22]) as well as tolerance-cost models (e.g., [23; 24; 25]). This decade can, therefore, be regarded as the decade of tolerance-cost models [26]. With the introduction of the personal computer 30 years ago, the development of software tools for tolerance analysis increased in importance [27]. A large number of software tools [28; 29; 30] were developed [31; 32; 33; 34], which have since established themselves in few companies worldwide [35; 36]. Due to the variety of methods and tools developed, there was an increasing need to revise existing standards. The revision of the Geometric Product Specification (GPS) by expert committees [37; 38] deserves special mention and is still in full progress.