The modular tool system (see Fig. 8-27) is to separate the tool handle and the working part, make serialized modules respectively, and then assemble a set of modular tools with different purposes and specifications through the intermediate module.
In this way, it is not only convenient for manufacturing, but also convenient for use and storage, greatly reducing the user’s tool reserves.
（1） Introduction to TMG Tool System
Fig. 8-27 Modular Tool System
Fig. 8-28 shows the composition of TMG tool system.
Fig. 8-28 TMG Tool System Composition
At present, there are dozens of modular tool systems in the world.
The difference between them is mainly due to the different centering and locking modes of module connection.
However, any modular tool system is composed of the following three parts:
(1) Main handle module – tool module directly connected with the machine tool spindle.
(2) Intermediate module – the tool module for lengthening the axial dimension of the tool and replacing the connection diameter.
(3) Working module – module for clamping various cutting tools.
The main difference between various modular tool systems lies in the different centering and locking modes of module connection.
Fig. 8-29 shows the module composition of the TMG21 modular tool system.
Fig. 8-29 Module Composition of TMG21 Module Tool System
（2） Type of TMG NC Tool System
The common modular tool systems for boring and milling in China include TMG10, TMG21 and TMG28.
The first digit of these models indicates the centering mode of module connection;
The last digit indicates the locking mode of module connection.
(1) TMG10 – short taper centering, axially tensioned with central screw, mainly used for infrequent disassembly after tool combination or when machining parts have a certain batch.
(2) TMG21 – single cylindrical surface centering, radial pin locking. It is mainly used in heavy machinery, machine tools and other industries.
(3) TMG28 – single cylindrical surface centering.
It has good interchangeability, high repeatability of connection, convenient assembly/disassembly, firm and reliable connection, good combination rigidity and good cutting performance, and is mainly used for efficient cutting.
（3） Representation of TMG module model
(1) The expression contents are in order: module interface form, module type, purpose or relevant characteristic parameters.
(2) Centering mode of module connection – ten digits (0~5) of TMG type code.
(3) Locking mode of module connection – single digit of TMG type code (0~6, TMG28 is 8).
(4) Category of module – module category identification, there are 5 types in total.
(5) Handle form code – indicates the taper handle form.
(6) Taper specification represents the shank size (taper number).
(7) Diameter at module interface – indicates the outer diameter of the interface between the master handle module and the tool module.
(8) Overhanging length installed on the spindle – the diameter of the big end of the taper of the main handle refers to the distance between the front end of the intermediate module or the distance from the front end of the intermediate module to the interface of the intermediate module.