Tool changes are mostly oriented to the state amount. This leads to
frequent shutdowns and high availability losses. Optimized tool change
strategies, such as bundling and parallel increase of tool changes,
the economy.
Machined metal companies in the money is also at the cutting edge.
With the right strategy, the tool change machine downtime can be
minimized.
The machine tool reports a standstill. The first glance at the screen
reveals the controls: A tool has reached its life quantity. A second
look reveals a different tool has only a small amount of residual
stand. The employee starts with the change of the past die and decides
to move to the second tool also. Then run the installation again.
Wear-related changes reduce productivity tool
This situation is typical in many ways and also shows two potential
strategies of tool change:
The employee learns of the upcoming short-term tool changes.
The decision whether to switch to other tools, is intuitive.
In the area of mass production machining significant productivity
losses due to wear caused by changing tools. In the few years ago
mainly for large quantities procured transfer these roads are well
within the range of 20%. But even with the new machine tool concepts
such as transfer centers are changing a cause for high availability
losses.
The reason for this is that the tools often require the change of
employee engagement in the area of the machine, which necessarily
leads to a shutdown of the plant. While the race was in the context of
lean production, particularly through methods such as Single Minute
Exchange of Die (SMED) is considered intense, is the optimization of
tool changes due to wear a side issue. The approaches are technically
in the rule, for example, increasing the amount of state or chuck for
fast and reliable Wechsel.Anzeige
Until now, little organizational approaches for less downtime caused
by tool change
Organizational approaches are distributed only rudimentary. It lacks,
above all, strategies that allow an optimization of the
tool-change-related outages of the lines in terms of tooling costs,
line availability and personnel costs. Closing this gap is the goal of
the Institute of Production Management, Technology and Machine Tools
(PTW) at the TU Darmstadt.
Here are methods for determining the optimal sequence and frequency of
change of cutting tools (tool change strategies) developed and tested.
For the tool change strategy is the individual state amount of the
tools the most important determinant. The state level may be exceeded
by the tool change strategy at any time. But a very conscious level
below the maximum amount allowed, if thereby the availability of the
line is increased.
Two basic strategies for the tool change
Hence the two basic strategies arise for tool change:
Gallery
Click on a picture to open the photo gallery (7 Photos)
Strategy and tool life
Interval strategy.
In a purely volume-based strategy was every tool to achieve its
individual life quantity is changed, while for a purely
interval-related change strategy, the change in a defined interval in
conscious waiver of parts of the life are summarized. The strategies
have different strengths and weaknesses (Table 1 - see gallery).
Thus, the quantity-based strategy was purely just a large difference
in tool life with high downtime of the machine tool is connected. In
contrast, the interval-based tool change is leading to increased tool
costs by reducing the amount of unused state and thus to a larger
number of necessary tools.
Determine the optimal sequence and frequency of tool change
The three most important factors in the development of the tool change
strategy are to:
Line availability (or the loss of availability due to tool change)
Personnel (staff availability and staff costs) and
Tool (loss) costs.
The increasing availability through clustering of tool changes is thus
possible that occur during a tool change time of two components (Figs.
1 to 4 - see gallery). First, a machine-induced block of time and the
other a tool-dependent component.
The machine-induced block of time is obtained at each start and stop
the machine, regardless of how many tools are actually changed on the
machine. It typically arises in that example will open doors before
the tool change, the work area is free of chips or removed that after
the exchange work materials from the work area or happenings in the
control must be acknowledged.
