2.  Tool magazines

Tool magazines are generally employed in CNC drilling and milling machines. Compared to tool turrets the tool magazines can hold more number of tools therefore proper management of tools is essential. Duplication of the tools is possible and a new tool of same type may be selected when a particular tool is worn off. The power required to move the tools in a tool magazine is more in comparison with that required in tool turrets. The following are some of the tool magazines used in automation.

                        2.1  Disc or drum type

                        2.2  Chain type

                        2.3  Disk or drum type

 

2.1 Disc type magazine

Fig. 4.6.2 Drum magazine

The disc type tool magazine rotates to get the desired tool in position with the tool change arm (Fig. 4.6.2). Larger the diameter of the disc/drum more the number of tools it can hold. It has pockets where tool can be inserted. In case of drum type magazine which can store large amount of tools, the pockets are on the surface along the length. It carries about 12 to 50 tools. If the number of tools are less the disc is mounted on top of the spindle to minimize the travel of tool between the spindle and the disc. If the tools are more then, the disc is wall mounted or mounted on the machining center column. If the disc is column mounted then, it needs an additional linear motion to move it to the loading station for tool change.

2.2 Chain type magazine

 

Fig. 4.6.3 Chain magazine

When the number of tools is more than 50, chain type of magazines are used (Fig. 4.6.3). The magazine is mounted overhead or as a separate column. In chain magazines the tools are identified either by their location in the tool holder or by means of some coding on the tool holder. These types of magazines can be duplicated. There can be two chain magazines: one is active for machining and the second magazine is used when the duplicate tool is needed since the active tool is worn out.

2.3  Rack type magazine

Fig. 4.6.4 Rack magazine

Rack magazines are cost-efficient alternative to usual tool magazine systems (Fig. 4.6.4). Set-up time can be optimized by utilizing the racks' capacity of up to 50 tools. The high storage capacity of up to 400 tools permits a large production capacity of varying work pieces without tool changes. They can also be used to store work pieces.