1 Introduction

In the 21st century, individualization of customer demand, intensification of global market and uncertainty of product life are increasing day by day. Due to all these issues, the manufacturing companies are facing a lot of pressure to reconfigure machine structure in manufacturing system. Therefore traditional manufacturing system (i.e. Dedicated manufacturing system and flexible manufacturing system) are not enabled for solving these issues. Experts from different manufacturing industries have developed a new type of manufacturing system known as Reconfigurable Manufacturing System (RMS).Yomen Koren was the first scientist who developed this RMS in 1999 after that a lot of researcher has worked in this field. Dedicated Manufacturing System (DMS) is generally used for mass production in which, conventional machines are used with fixed tooling condition and automation. These machines have no flexibility, convertibility and scalability features of machine tool. Whereas Flexible Manufacturing Systems have a configuration with fixed hardware but programmable software to handle changes in work orders, production schedules, part-programs, and tooling for several types of parts. Therefore, a new generation machine tool and manufacturing system are required with better functionality, responsiveness and robustness. RMS is designed for cost- effective response in market oriented manufacturing environments at a low cost and rapid time. Reconfigurable Manufacturing System (RMS) combines both the advantages of DMS and FMS. The main components of RMS are reconfigurable material handling, reconfigurable inspection system and reconfigurable machine tool but RMT is the heart of RMS. The modularity, scalability, convertibility, flexibility, diognasability, integrability are the core features of RMT that helps to reconfiguration the machine structure as per requirement. To achieve this, many computer aided design (CAD) of machine tool have been proposed and developed. Virtual Arch type machine, machine with multi spindle, modular scalable machine tool and many more machines have been developed at University of Michigan. For example, arc type reconfigurable machine [1] and multi spindle machine [2] is shown below in the Fig. 1a, b.

Fig. 1
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a Arch type multi spindle reconfigurable machine tool, b multi spindle tool

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These machines are designed on the basis of modularity, scalability principles [3, 4]. In RMT, reconfiguration can be done on at any level (i.e. at machine hardware level, software level and system level) to reconfigure the existing modules parts for performing of new specific operation. By doing this, convertibility, modularity and scalability of machine tool increases. Abdi [5] discussed a fuzzy analytical hierarchical process (FAHP) mode to integrate machine reconfiguration and equipment selection. The life cycle cost of different modular parts of machine tool can be reduced with the help of concepts of reconfiguration [6]. Xu et al. [7] had implemented the reconfiguration concepts for developing MRMT with minimum number of modules. He also discussed the module components library and reconfigurability. Consequently, reconfigurability also plays a vital role in machine tool. As per Gumasta et al. [8] reconfigurability is defined as the ability to frequently change and rearrange the machine tool components (both hardware and software) in a cost effective way.

In this paper, a reconfigurable drill machine tool has been proposed, which is designed with the help of Solid works platform. Module library, which consists of basic and auxiliary parts are also explained. The second section briefly emphasis the literature review work related to reconfigurable machine (i.e. lathe, milling, shaper, slotter, CNC, NC etc.). In the third section, reconfigurable principles and RMT are explained. In forth section, different designing steps of RDMT is also explained and highlighting the operational achievement of RDMT. Finally, the last fifth section concludes the article and point up the constraint of the study.

2 Literature review

See Table 1.

Table 1 Research work carried out for developing Reconfigurable Machine Tool (RMT): core characteristics’ and design principles
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3 Reconfigurable machine tool

An innovative concept and development of reconfigurable machine tool had started at university of Michigan at 1999. Since then, various types of reconfigurable machine tool have been developed [22, 27,28,29,30]. The structures of this machine tool are modular in nature. Therefore, different machine configuration can be obtained to produce desired shape of any family of part. Machine hardware and software are the basic elements of RMT as shown in Fig. 2. Further, machine hardware parts consist of basic and auxiliary modules, which are further classified into three categories: Function operated modules, motion operated modules and accessory operated modules.

Fig. 2
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Different machine configuration through basic modules and auxiliary modules [31]

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Function modules are modules which can be changed to provide a new machining process. Each function enables one of the following machining processes: drilling, milling, tapping, boring, grinding, polishing, engraving, and turning. Motion modules are modules which through their integration enables some kind of motion, whether it be liner or angular. Thus, they help in positioning and feeding of the tool post. Accessory modules are those modules which are not necessary for the machining operation but are used to make machining easier and simpler, like work clamps and stabilizers. Bed, column, legs, work piece table, arbor are the basic module and tool post, spindle, carriage, tail stock etc. are the auxiliary parts of lathe machine [9]. Modularity, Convertibility, Integrability, Scalability etc. are the core characteristics of RMT [1, 17, 24, 32]. Modularity means that both hardware and software modules of RMT should be modular so that it can be easily added or replace as per requirements [2, 33, 34]. Gadalla and Xue [23] proposed a machine tool configuration on modularity and convertibility principal with minimum reconfiguration efforts to change from one machine configuration to another machine configuration. In his research, he implemented modular hardware parts to perform drilling, milling and turning operation on RMT, which is illustrated in the Fig. 3.

Fig. 3
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Two configurations of a RMT, a modules library, b milling/drilling configuration and c turning configuration [35]

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3.1 Module library to develop reconfigurable drill machine tool (RDMT)

Modules are the heart of machine tool which allows developing multiple set of machine configuration and variation on machining operation (such as milling, drilling, cutting etc.) on single platform. Therefore, the synthesis of module library (i.e. basic and auxiliary) is building blocks to develop any reconfigurable machine tool [36]. They are generally selected from module library to provide required machine configuration. Padayachee et al. [14] listed a set of mechanical modules library (such as tail stock, tool post, rotary 4 column, end effectors, rotary arm, rotary bed, lathe front, column, power back etc.) that were used to develop a machine configuration which provide a different machining process: drilling, milling, boring and tapping. Figure 3b, c illustrates this concept. In this paper, different basic and auxiliary modules are used. All of them have been designed on solid works designing platform, which are shown in Fig. 4. Basic modules are generally heavy in weight and the shape and size are large as compared to auxiliary modules. In RDMT base, vertical column and work piece table are basic modules and guide way, tool post, arch type plate, actuator are auxiliary modules. Table 2 outlines the characteristics of basic and auxiliary modules.

Fig. 4
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An example of module library for modular reconfigurable machine tool

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Table 2 characteristics of basic and auxiliary modules of RDMT
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4 Mechanism to develop Reconfigurable Drilling Machine tool (RDMT)

Modular Reconfigurable Machines (MRM) is constructed using basic and auxiliary modules, which can be added or removed from the machine tool [37, 38] in order to enhance the required capacity, modularity, scalability and functionality. The proposed machine discussed in this paper consists of the Basic Structure (Fig. 5) to which the various modules are added and also supports the work table bench, Arch-Shaped Guideways etc. The Arch-Shaped Guideways (Fig. 6) are symmetrically located around the table and can be moved perpendicular to the surface of the table with help of Telescopic Lifts. On the Arch-Type Guideways, modules for the motion of tool in X- and Y- Direction (parallel to the plane of the work table) are placed. Each module has arrangement so that they can be attached to a fellow module or another module. This is done by making each module independent of extra accessories i.e. the module itself consist of motor or actuator which makes them less dependent and since they are similar in their build they can be integrated together with minimal extra accessories. Each additional DOF is added through the integration of a motion module. By adding a new motion module, a new degree of freedom is achieved which, by the use of multiple spindles increases the modularity. A 360° Rotating Module is attached on top of the Y-Axis Motion Module which can conveniently make fine angular variations to the direction of feed (Fig. 7). Tool changing is done by 180° rotation of The Multi-tool Spindle (Fig. 8) The Multi-Tool Spindle contains modular interface for attaching two different tools on either side (front and back) of the spindle. In this machine tool, twist drill bit can generally used for drilling in all type of work piece and the material of drill tool is high speed steel and typically have a length of 9–14 times its cutting diameter. The motor which drives the spindle can be accommodated within the spindle housing in such a way, that power is transferred across both the tools. Hence two different machining operations can be performed by the same spindle alternately as per the machining requirement. The modules or combination of modules and the multi-tool spindle can be arranged independently on each of the Arch-Shaped Guideways. Hence, two faces of a workpiece can be machined simultaneously on the single work table by doing this machine convertibility increased. The machining operations can be independently performed by each spindle so that asymmetric parts can be machined in a single pass. On the other hand, a symmetric part can be machined quickly by performing identical operations on both the spindles. A vertical column (Fig. 9), that can slide in only one direction, carries a third spindle for machining the top face of the workpiece. An Arch-Plate is attached to the column which enables angular placement of the spindle, by changing the plate we can also change the type of machining operations which can be achieve by using the vertical column. This Spindle can be used for drilling holes or milling cylinder bores on surfaces inclined to the horizontal.

Fig. 5
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Basic structure

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Fig. 6
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Arch-shaped guideways

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Fig. 7
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Mechanical motion modules on arch-shaped guideways

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Fig. 8
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Multi-spindle tool post

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Fig. 9
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Motion modules along with arch plate module

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When using the machine at its full potential it will have all the motion and function modules assembled together (Fig. 10). Multiple spindles will ensure speedy production and independent operations will ensure the fabrication of a complete part in one go, along with fabrication of another part of the same family. When using the machine at its full potential it will have all the motion and function modules assembled together (Fig. 10). Multiple spindles will ensure speedy production and independent operations will ensure the fabrication of a complete part in one go, along with fabrication of another part of the same family. We can use any of the four different configurations as shown in Fig. 11, which best matches the production requirement. If drilling on inclined surfaces is the only requirement, the First Configuration may be used. If only the lateral sides of the workpiece need to be machined, the Second Configuration may be used. If a product requires both side as well as top faces to be machined the Third Configuration may be used.

Fig. 10
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Complete assembly of all modules on the machine

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Fig. 11
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Various configurations of proposed machine

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5 Conclusion

This paper classified the features of traditional drilling machine and Reconfigurable Drilling Machine Tool (RDMT) and also discussed the concept of Reconfigurable Manufacturing System. Further, this research paper provides an overview of the literature work related to the design and development of reconfigurable machine tool (RMT) in manufacturing system. Based on these design principles, we have proposed a Reconfigurable Drilling machine (RDMT) in which mechanical modules library (consists of basic and auxiliary modules) has been implemented for filling the space between conventional machine and flexible machine. In this machine tool, more than four manufacturing operations (vertical drilling, horizontal drilling, inclined drilling and milling operations) can be performed on a single platform through just replacing or adding basic and auxiliary modules which are proposed in Fig. 4. By doing this, we can enhance the core characteristics of machine tool (i.e. scalability, convertibility, flexibility and modularity). This machine and different types of modules have been designed on solid works designing platform. The authors are of the view that the reconfigurabilitry of Reconfigurabile Machine Tool (RMT) are depend on several modules parts and mechanism [9]. Some of these might have been not mentioned in this work. Therefore,some auxiliary reconfigurable mechanism can be used to develop next generation machine tool i.e. Industry 4.0. Further research work can be extended to implement measurement of cutting forces through Finite Elementary Analysis (FEA) during operation and to deploy active vibration damping for the development of light based modular structure of Reconfigurable Drilling Machine Tool (RDMT). In future, reconfigurability value can be assessed which is associated with multi spindle tool, material handling tool, reliability of different auxiliary modules.