Don't Chuck CNC Profits

Don't Chuck CNC Profits

Basic collet chucks are the most popular tool-holding system due to their flexibility and ability to secure a variety of shank sizes via a simple collet change. However, the flexibility also introduces multiple run-out tolerances, which can diminish the advantages.

The interchangeable collets are a primary problem with this system. Failure to follow proper tool colleting procedures will result in deformed collets, which reduces tool concentricity and holding power. These “flexible” collets should also be discarded after 400-600 hours of use, but this recommendation is often disregarded due to cost considerations. 

Several premium non-collet systems are available as an alternative to the collet-based systems. These systems exert direct pressure between the inside of the chuck and the tool shank — either through hydraulic or mechanical expansion and contraction. The primary obstacles of these premium systems are initial cost and limited ability to hold a variety of shank sizes within the same chuck.

Hydraulic chucks [hydro chucks] have long been considered the most precise chuck system available. While hydraulic forces may initially offer the best tool concentricity, this precision can diminish when the tool is subjected to typical cutting forces. The disadvantages of hydro chucks is their initial cost, which is typically two to three times that of standard collet chucks. The secondary problem involves the flexible internal pressure wall, which can deform if the tool shank is improperly inserted.

The most recent addition to the high-precision chuck solution involves shrink fitting tools into solid chucks. The induction heating system allows for rapid re-heating of the chuck receiver and easy removal of the dull tool. The controlled heat provided by induction heating allows a heat shrink chuck to be reused thousands of times without tolerance or metallurgical changes to the metal.

Source: Mark Alster is a regional sales manager for Leitz Tooling Systems. Visit or call (800) 253-6070.

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