Multiple clamping with SINUMERIK Operate
Definition of multiple clamping
Multiple clamping means the possibility of clamping several different or identical parts or components in the machining space of a machine tool. Multiple clamping systems are primarily used for milling machines.
Better use of the machining space
CNC workpiece programs are usually programmed in relation to the clamping of a workpiece. Single clamping of a workpiece may lead to the machining space not being used sufficiently, or the number of pieces to be produced requires the production of several workpieces simultaneously on one machine.
The clamping of multiple workpieces uses the machining space of the machine better, but the advantage gained is quickly lost by the number of tool changes, caused by the individual programming of workpieces and the longer programming time.
Process several workpieces, save tool changes
Using the "Multiple clamping" feature in SINUMERIK Operate (828D and 840D sl), the user has the option of optimizing the same or different workpiece programs for multiple clamping by just pressing a button. The image above shows an example of three workpieces clamped onto a machine table. ShopMill was used to program each individual workpiece.
Without the use of the multiple clamping feature, the control would machine these three workpiece programs sequentially, i.e. the same tools would be used and loaded several times, thus leading to a loss of time.
The multiple clamping feature automatically generates a new "Multiple clamping program" from multiple programs – this is only possible in ShopMill. In this program, the sequence of all tools used is rearranged for all workpieces, i.e. The number of tool changes will be reduced significantly, thus increasing the productivity. The workflow is repeated for all of the tools used for all of the workpieces.
In practice, multiple clamping is used for medium-sized series production in the Job Shop domain. A significant increase in productivity by using multiple clamping systems starts from 100 workpieces and above.
Advantages and disadvantages of multiple clamping
Multiple clamping on a machine generally requires higher equipping time and costs, which only pays off for higher batch quantities. However, the high level of convenience offered by the SINUMERIK multiple clamping function significantly reduces programming costs. If you were to allocate the tools to several clamping operations manually, you would need a very experienced CNC programmer and the resulting workpiece would be rather confusing and diagnostics would not be user-friendly.
Multiple clamping types
The SINUMERIK multiple clamping function supports both simple linear clamping systems as well as those with clamping blocks, reversible clamping devices, clamping towers, etc. When using reversible clamping devices, clamping towers etc., the maximum number of clamping operations is limited to 99 (number of work offsets).
Each workpiece clamping must be assigned a work to offset. When using reversible clamping devices etc., the switch condition of the rotary axis must also be specified. This is realized in a pre-configured CUST_CLAMP cycle (see standard cycles in the system data area).