Abstract Reconfigurable manufacturing systems (RMS) address challenges in modern manufacturing systems arising from product variety and from rapid changes in product demand。 This paper considers an arch-type reconfigurable machine tool (RMT) that has been built to demonstrate the basic concepts of RMT design。 The arch-type RMT was designed to achieve customized flexibility and includes a passive degree-of-freedom, which allows it to be reconfigured to machine a family of parts。 The kinematic and dynamic capabilities of the machine are presented, including the experimental frequency response functions (FRFs) and computed stability lobes of the machine in different configurations。 A comparison of FRFs and stability lobes of the arch-type RMT reveals almost similar dynamic characteristics at different reconfiguration positions。 These similar characteristics arise because the dominant mode where chatter occurs is due to the spindle–tool–tool holder assembly。 Consequently, to ensure consistent dynamic behavior regardless of reconfiguration, a desirable dynamic design feature for RMTs is that the machine’s structural frequencies are less dominant than the structural frequencies of the spindle,  tool  and tool holder。76168

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Keywords: Dynamics; Stability lobes; Customization;  Reconfiguration

1。 Introduction

Traditional manufacturing systems can be classified    as:

(a) dedicated manufacturing systems (DMS)—designed to produce a specific part or (b) flexible manufacturing systems (FMS)—designed to accommodate a large variety of parts even though parts are not specified at the design stage。 While DMS is economical when the output volumes are high for a manufactured product over a long period of time, FMS is more suited if the production volume is low and a large variety of parts are produced。  Changing product demands in current markets makes DMS less desirable, but FMS lacks the efficiency and robustness of DMS, making it uneconomical for many production situations。

Reconfigurable manufacturing systems (RMSs), which aim to achieve ‘exactly the capacity and functionality needed, exactly when needed,’ have garnered considerable attention in recent years [1–5]。 Research has been done   on

✕Corresponding author。 Tel。: +1 734 276 8010; fax: +1 734 615 0312。

E-mail address: jdhupia@umich。edu (J。  Dhupia)。

design and operation of RMSs; lead-time; and  ramp-up time reduction and open architecture controllers at various research centers in US, Europe and Japan [6–12]。 Industry is also beginning to adopt and implement various aspects of RMS [13,14]。 Indeed, it is becoming clear that reconfiguration will be an important aspect of many future manufacturing systems。 Key characteristics of an RMS include: (1) modularity, (2) integrability, (3) convertibility,

(4) customization, (5) scalability, and (6) diagnosibility。 The more of these characteristics a manufacturing system possesses, the more reconfigurable it  becomes。

An important issue is the appropriate ‘granularity’ of the modules in an RMS。 For many manufacturing systems the basic module for reconfiguration will be a 3-axis CNC machine tool—a commodity product whose cost has significantly fallen in recent years, while accuracy and reliability have improved。 However, in research one must consider a variety of alternatives。 Consequently, this paper will discuss the concept of a reconfigurable machine tool (RMT), which brings the ‘granularity’ of reconfiguration down from the machine level to the component level。 Reconfiguration at the component level, as in RMTs, raises

0890-6955/$ - see front matter r 2006 Elsevier Ltd。 All rights reserved。 doi:10。1016/j。ijmachtools。2006。03。017