What is a hydraulic chuck?

A hydraulic chuck is a type of spindle tooling, which are typically used on CNC milling machines to hold cutting tools. Hydraulic chucks are designed to be used in applications where high accuracy and rigidity is needed.

Hydraulic chucks are filled with hydraulic fluid which is pressurised when the grub screw (on the side of the holder) is engaged. This process closes the bore of the tool holder, clamping the tool in place with forces up to 890kN (commonly found in high torque hydraulic chucks).

What are the main features of Hydraulic Chucks?

The hydraulic fluid used to clamp the cutting tool also acts as a vibration dampener, which reduces vibration and chatter during machining processes. This improves tool life and surface finish, as well as ensuring superior accuracy versus standard tool holding like ER collet chucks and end mill holders.

Chucks come in a range of different geometries depending on the application performed, including:

• Short and rigid chucks are ideal for heavy duty applications. Partnered with hydraulic reduction sleeves, there is the ability to clamp from 1mm up to 32mm in diameter.
• Slim chucks are used in nominal diameter clamping where clearance may be tight.
• Ultra-short chucks are made for use with extra-long length drills.
• Long, slim and tapered chucks can be used in 5-axis applications, for instance in the mould and die industry.
• Long and narrow chucks feature a slim nose profile for long reach applications.
• Slim nose profile chucks are for long reach applications.

Hydraulic chucks provide up to 40% more tool life than shrink fit holders, with its high clamping forces being reliable at up to 170°C without any reductions in spindle speeds. Runout accuracy is just 3 micron, compared to the 10 micron runout in ER collet chucks or 5 micron in slim chucks. This accuracy comes from just one turn of the grub screw, meaning super-fast set up times when tooling up.

Get up to 900Nm clamping forces with YG-1's Power E-Hydro Chuck - find out more in the video below:

When would you use a Hydraulic Chuck?

Hydraulic chucks are becoming more popular due to their higher levels of versatility over shrink fit chucks. You would opt for a hydraulic chuck when you want unbeatable performance for tooling. The combination of high clamping forces and low run-out work hand in hand, giving your tooling the best chance of success.

Not only this, but due to the increased confidence given by a hydraulic chuck, you will be able to push your tooling faster and harder. Higher productivity is achieved, as well as making you more competitive through improved tool life, greater metal removal rates and slashed cycle times. Tools can also be changed in the machine spindle, a feature not present in shrink fit chucks. Over time, the initial cost of a hydraulic chuck will be more than covered by these benefits.

Next generation tooling is manufactured with advanced geometries that push machines much further than before. A standard side lock arbor or collet chuck would not compliment these new tooling innovations appropriately. Instead, you’d be underperforming in your cutting data whilst achieving a poor surface finish (due to vibrations/run-out) which may even cause your cutting tool to chip or break.

When machining materials like Titanium, Inconel and Stainless Steel, tool pull-out is common in collet systems, especially when using advanced machining techniques like high feed or trochoidal milling. Having exceptionally high clamping forces from a hydraulic chuck eliminates tool pull-out, hence preventing scrapped jobs and damaged tools in these difficult machining conditions.

Summary

Hydraulic chucks are the best option for HPC and HSC machining using high performance tooling (e.g. YG-1’s V7 Plus or Titanox milling cutters). High torque clamping means a very little chance of pull-out when machining at high speeds and feeds. High radial rigidity provides a superior runout accuracy and better tool life compared with other tool holding options.

For more information or for any advice on tool holding solutions please get in touch with Cutwel today on 01924 869610, email sales@cutwel.net or visit our website at www.cutwel.co.uk.