Corner Radius (Bull Nosed) Cutters Now With Huge Corner Rads from Cutwel
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Corner Radius (Bull Nosed) Cutters Now With Huge Corner Rads from Cutwel



With the advancement of more complex workpieces and 3D forms, the demand for corner radius slot drills and end mills with large radiuses has grown in recent years.  To meet this demand Cutwel has introduced a huge new range of corner radius tools to several YG-1 and Korloy milling ranges, including: 4G Mills (high speed machining), V7 Plus (HPC high metal removal machining) and Alu-Power (non-ferrous machining).  

The table below shows the maximum corner radius by tool diameter

Application/benefits of corner radius?


Using a corner radius slot drill or end mill may be a requirement of the workpiece specification, for example as a 3D form in mould or die manufacturing, or to add strength to a workpiece. It can also offer a large degree of protection to the cutting edge and prevent the tool from chipping, especially in aggressive machining such as HPC milling or high feed milling.

Corner radius slot drills and end mills are often called ‘bull nosed’ cutters, not to be confused with ball nosed cutters.


 Negative implications of using a large corner radius?


Applying a corner radius to a cutting edge to protect it from chipping is becoming more popular to increase tool life. However cutting efficiency can actually be reduced when larger corner radiuses are used because higher cutting loads are generated that in turn reduces the tool life. Inefficient cutting increases mechanical and thermal loads therefore Edge-chipping protection comes at the cost of increased temperatures and stresses on the machine and tooling.

So whilst a large corner radius can reduce the risk of the tool chipping, it can also make the cutting process less efficient and increase tool wear, a balanced view should be considered when selecting a large corner radius of whether or not it is 100% required.

Alternatives to Corner Radius for Edge Protection


There are alternative geometries to corner radiuses available for protecting the cutting edge on milling cutters, including chamfer edge preparation and reinforced cutting edges.

The chamfer edge preparation is a small 45 degree chamfer on the corner of the cutting edge.  Its main purpose is to protect the cutting edge on initial contact with the workpiece to prevent the tool from chipping.  It is particularly useful on materials like stainless steel or Inconel where a sharper, more positive cutting edge is preferred over a corner radius to prevent work hardening due to thermal resistance which can be caused by corner radiuses.  This feature is available on YG-1 product ranges including K2 carbide, V7 Plus, V7 Inox, Titanox Power and Jet Power rippers.

If a chamfer edge preparation or corner radius tool cannot be used because the corner of the work piece must feature a true 90 degree corner, tools are available with a 90 degree cutting edge featuring a reinforced cutting edge – also known as a gash land geometry.  This special geometry helps prevent the tool from chipping whilst maintaining the perfect 90 degree form.  This feature is available on YG-1 product ranges including 4G Mills, X-Power, Jet-Power, V7 Plus and Titanox Power

Need More Info?

Speak to one of our milling experts at Cutwel who can assess your application, work piece, tool holding, work holding and cycle time requirements and advise the best tool for you. Contact us on 01924 869 660 or alternatively speak to us on LiveChat