Technical Information

Technical Information
Technical Information
Spindle Connections
The Importance of a Strong Connection
Many component materials are switching to lighter, high-strength materials,
like titanium, to increase fuel efficiency. To save time and money, machinists are
challenged to maximize metal removal rates at low cutting speeds and
considerably higher cutting forces. Machine tool builders must also provide
greater stiffness and damping in their spindles to minimize undesirable vibrations
that deteriorate tool life and part quality.
Though these advances contribute to greater productivity, the weakest point is
often the spindle connection itself, which needs high torque and must overcome
high-bending applications.
Current Spindle Connections
To fulfill the increasing demand for high productivity, an important element to
consider is the tool/spindle connection. This interface must be able to withstand
high loads and maintain rigidity throughout the machining process. In most cases,
the connection determines how much material can be removed on a given
operation until high tool deflection or chatter result.
High-performance machining is accomplished using high feeds and depths of cut.
Because of advances in cutting tools, there is a need for spindle connections that
utilize available power.
Several different types of spindle connections were developed and/or optimized
over the last few decades. Due to its strong cost/benefit position, the 7/24 ISO
taper became one of the most popular systems on the market. It has been
successfully used in many applications, but its accuracy and high-speed
limitations prevent it from becoming a more advanced and productive system.
Choosing What’s Right
With more materials that are tougher to machine and require considerably higher
cutting forces from the machine tool, choosing the spindle interface wisely to
maximize cutting edge performance is key to success.
• One surface contact.
• Relatively low stiffness.
• Possible runout due
to taper fitment.
• Low axial accuracy.
• Two surface contact.
• Higher static and
dynamic stiffness.
• Higher axial and
radial accuracy.
• Rigid system.
• Two surface contact.
• Higher axial and
radial accuracy.
• Less mass — faster quick
change and higher speeds.
• Higher stiffness than
7/24 tapers.
Our response to this traditionally weak point has been the proven KM system,
and now we are introducing the next generation KM4X . The combination of the
KM4X’s high clamping force and interference level lead to a robust connection
and extremely high stiffness and bending load capacity for unmatched
performance in titanium machining.
The advent of face contact represented a major step over the standard 7/24
taper. Combining face contact with a 7/24 solid taper provides higher accuracy.
However, this also presents some disadvantages. Loss of stiffness at higher
speeds or high side loads are some of the major flaws apparent in this system.
Most of these tools are solid, and the spindles have relatively low clamping force.
This results in limited connection stiffness, as radial interference needs to be
minimal. The required tolerances to achieve consistent face contact are thus
very tight, leading to high manufacturing costs.
The KM spindle connections greatly outperform the conventional 7/24 steep
taper and its face taper contact derivatives HSK and PSC systems. KM4X
is the best large, heavy-duty spindle connection for rigidity because it has
superb balance between bending and torsion capabilities from the machine tool.
7/24 ISO Taper 7/24 Taper Face Contact HSK KMTS (ISO) KM4X
• Three surface contact.
• Superior static and
dynamic stiffness.
• Static and rotating
applications.
• Higher speed.
• Higher stiffness than HSK
and 7/24 tapers.
• Three surface contact.
• Superior static and
dynamic stiffness.
• Static and rotating
applications.
• Highest maximum speed.
• ISO (HSK) Gripper.
M8 www.kennametal.com