Page 102 - Modular design for machine tools

66 Modular Design Guide and Machine Tools Description

on the basis of market needs. In fact, the work spectrum is another
dominant factor for the principles of both separation and standardiza-
tion. Ito and Yoshida [3] later carried out a further similar activity to
establish a modular design guide for large-size machine tools. As can be
readily seen, the module may be rationally determined from these data.
Regarding this principle, a new subject that is concerned with the LCA
and remanufacturing of the product and that has actually been proposed
elsewhere is the concept of a platform [4]. A group of platforms is capa-
ble of manufacturing the individual product configuration with higher
reusability, where reusability means the applicability of each platform
up to several cycles within its life to other products after necessary
modifications have been made. In accordance with the proposal, the
platform appears to be a variant of a module; and if this is so, what is
the difference between the module and the platform? Importantly, the
final goal of the platform is that of modular design so far, where the plat-
form is a combination of several common modules defined in the man-
ufacture of the different kinds of machine tool from a group of modules.
In other words, the platform is an entity of higher level than the module,
which consists of a certain number of modules commonly used in the
manufacture of different kinds of machines. As a result, the platform
concept is a clue to sublimate the principle of separation to the design
guides. As can be seen from Fig. 2-2, the platform is of hierarchical type
for manufacturing the different kinds in full consideration of its avail-
ability for the variant of the machining complex.
This interpretation may be supported in referring to the case study
of Metternich and Würsching [4]. Gleason Pfauter Hurth has manu-
factured the hobbing machine, gear grinder, and gear shaping machine
for work up to 2400 mm in diameter using the common base and same
column since the beginning of the 1990s. In this case, the base is the plat-
form; in addition, the joints of the base to the column and the base to
the table are standardized. Actually, the candidate for the platform is a
group of such modules that are, in most cases, in the same combination
across the whole different kinds.

Principle of unification. The design flexibility increases with the increas-
ing number of modules predetermined mostly on the basis of the prin-
ciple of separation; however, to reduce, for instance, the asset tax, the
total number of modules should be minimized. This is a typical trade-
off or ill-defined problem, resulting in the most crucial issue when detail-
ing the principle of unification. Thus up to today the principle of
unification has not been defined with wide acceptance among machine
tool engineers. In retrospect, we have considerable experience in this
context through the design of the TL in the 1960s. At that time, the prin-
ciple of unification was more concerned with how to formulate a group