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How Shrink Fit Works

How Shrink Fit Technology Works

resources1The concept is simple. Each Shrinker tool holder is manufactured with an inside diameter slightly smaller than the shank diameter of the cutting tool. A heat induction unit is used to quickly heat the holder end of the Shrinker, expanding this inside diameter. At this point, the tool shank slips easily into the holder. As the holder cools, the resulting thermal contraction exerts a tremendous, uniform pressure around the entire surface of the tool shank leaving total concentric gripping strength.

Removing the tool is just as simple – you simply reverse the process! Tool changes can be accomplished in seconds, dramatically increasing machining productivity by reducing tool change downtime.


Superior Concentricity


The concentricity of shrink fit tooling is guaranteed .0002” or better with the cutting tool set in the shrunk condition.


Superior Balance


Shrink Fit Tools are manufactured for high speed operation. Balance pockets are machined in the drive keys on all V-Flange tooling, eliminating the inherent imbalance in V-Flange tooling. Shrink Fit tools are dynamically balanced on our Hoffman 2 plane balancing machine to G 2.5 at 20,000 RPM’s. Special tools can be manufactured to a G1.0 tolerance at 30,000 RPM. This results in balanced chip loads, better finishes, and increased speeds and feed rates. With no set screws the toolholder remains in balance leaving the cutting tool as the only variable.


Superior Rigidity


The average gripping force imposed on the shank of the cutting tool is 10,000 lbs. – more than 5 times that of collet, milling, or hydraulic chucks. It would take over 100 horsepower in order to turn the tool within the bore of the toolholder. An additional advantage is the shank of the tool is gripped 360 degrees the entire length of the bore; impossible with milling chucks and hydraulic chucks. These chucks leave an area of up to 1/4 inch from the end of the toolholder with no force applied to the tool shank. Using the Shrinker gives you the closest possible rigidity to an Integral Shank Tool with lower costs and more flexibility.


Superior Tool Life


The Shrinker Toolholding System extends tool life up to 100% or more. With the superior holding force, concentricity, and balance, the chip load is evenly distributed on the cutting edge. The rigidity established with the Shrinker enables cutting tool technology to be pushed to the maximum.

Superior High Speed Operation

In extreme high speed operations centrifugal force becomes an important factor in desired speeds and feed rates. With the holding force induced by the Shrinker system being superior, no other system can meet and maintain the clamping force. The Shrinker System is a must in extreme high speed applications and is superior at any speed. A very important feature of Balanced Shrinker Tooling is the extended spindle life with the superior balance and rigidity the Shrinker offers.


Superior Operating Parameters


Vector Smart Object1No holding system offers shorter extension length capability with concentricity of .0002” or less. Milling and hydraulic chucks offer excellent concentricity, but the mechanical clamping system requires additional extension and sacrifices rigidity. Conventional end mill holders can provide very short extension lengths, but sacrifice concentricity and provide 2 or 3 point clamping. The thin profile required for the Shrinker enable the operations to be performed with less interference. Tooling can be preset by simply controlling the depth the shank extends into the bore.


Simple Operation


The Shrinker System is truly the easiest system to use. The induction tool changer is by far the fastest and simplest method to change tooling, enabling the operator to remove the dull tool and insert the new tool. Seconds after the new tool is inserted, the bore shrinks back and can then be cooled; no wrenches to find, no vices, uniform chucking without torque wrenches, and faster than conventional clamping methods.




The Shrinker Toolholding System is by far the most economical system in the world today. The increased productivity and increased tool life can be measured. Additionally, reduced tool-change down time will contribute to the considerable reduction in costs.


Benefits for Shrink Fit Tooling


For critical high speed or high precision cutting applications, the Shrinker’s TIR and tremendous holding strength are benefit enough – most toolholders simply can’t achieve this degree of precision. Shrinker technology and design provides these benefits:


  • Best possible TIR (Total Indicator Reading)
  • Best possible balance
  • Best available gripping power
  • Increased tool and spindle life
  • Thin profile holders for machining hard-to-reach places
  • Design and build custom holders for any application
  • Short gauge lengths available for increased rigidity
  • Ability to preset for required tool length
  • Ideal for end milling, drilling, reaming, boring and all other critical rotary tool applications regardless of cutting tool material
  • Eliminates wrenches, collets, set screws and other accessories
  • Reduces costs associated with tool changes, holder maintenance and machine downtime



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