What happens during tool shrinking?
Tool shrink-fitting does not mean that the size of the tool itself is reduced. Instead, the tool holder—into which, for example, a drilling or cutting tool is inserted—is heated briefly, precisely, and uniformly so that it expands.
This creates enough space in the tool holder to insert the tool. As it cools, the material of the holder contracts evenly on all sides. This ensures that the tool is clamped with high rigidity, maximum clamping force, and centered.
Why are special shrink-fit chucks needed?
Special tool holders, known as shrink chucks, are typically used for shrink fitting. They are specifically designed to retain their shape despite repeated heating and cooling. For example, they contain no moving parts, ensuring that their balance grade is maintained; it is also important that the concentricity of the shrink chuck is very high, because otherwise even a very precisely centered tool will be of no use.
Compared to conventional chucks, shrink chucks have the minor disadvantage that a separate chuck with the appropriate diameter is required for each shank diameter. However, this is offset by the significantly higher concentricity, which is of great importance for high-quality machined workpieces.
What is a shrink-fit machine, and how does it work?
A shrink-fit machine heats the shrink-fit chuck—the tool holder—uniformly and quickly using inductive current (i.e., via a magnetic field). With the appropriate tools and measuring devices, this not only ensures that the new tool is inserted with precise centering, but also allows for the necessary length accuracy to be achieved, measured, and corrected if necessary before the controlled cooling of the shrink sleeve. Appropriate sensors also prevent the shrink sleeve or the tool from overheating.
Automated shrink-fit technology ensures, for example, that the overhang length and all other parameters important for machining the workpieces are automatically measured and correctly adjusted—while still making the tool available again in the shortest possible time. This ensures short setup times and lower overall costs.
High-quality shrink-fit devices also feature their own cooling unit, in which the shrink-fit chuck is cooled evenly. Contact cooling is used, for example, while some devices also operate with water cooling. This reliable cooling system also eliminates the risk of burns, which could naturally occur if the heated tool holder were accidentally touched.
Set, shrink, and measure – the fully automatic all-in-one solution
With ZOLLER »redomatic«, shrinking your tools is a breeze and fully automated. Our all-in-one solution for setting up, shrinking, and measuring tools—with all processes handled automatically in a single workflow—features 4-axis CNC control, autofocus, a tool turret, an induction coil, a tailstock, and a cooling system.
Safe, economical, and precise
With the patented automatic length stop »asza«, it offers the ability to shrink-fit tools easily, quickly, and accurately to the target length with a precision of at least +/- 10 µm.
ZOLLER »redomatic« supplies only as much energy as absolutely necessary when heating the tool chucks, thereby also protecting your chucks; the shrink-fit guidance system we designed and the patented exhaust gas extraction system ensure greater safety for your employees.
Learn everything about our successful shrink-fitting solution here
What are the advantages of shrinking and unshrinking?
Shrinking and unshrinking tools offers a number of advantages:
- The tool can be centered before shrinking, which prevents misalignment and ensures high concentricity.
- The tool is held evenly in the shrink-fit chuck by high clamping forces.
- Specialized chucks provide high balance quality and do not deform even after numerous shrink-fitting operations.
- With a high-quality shrink-fitting device and a suitable shrink-fitting holder, the heating and cooling process takes less than a minute.
- For high spindle speeds and tools with long overhangs, no other clamping method allows for similarly precise tool utilization.
Everything in one place
With our ZOLLER »powerShrink« shrink station, you have everything you need for a quick shrink process in one place. Thanks to its modular design, you can easily adapt the workstation to your needs and requirements.
The station is universally compatible with all HSS and carbide tools ranging from 3 to 32 mm in diameter and is also suitable for extremely long tools.
