Midwest Cutting Tools

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Mar 27, 2017

The many shapes of carbide burrs and how to use them.

Burrs come in a broad range of shapes. And, for good reason. These various shapes allow you to achieve just the right profile, edge or cut for your project. Here’s much more detail on burr shapes and the types of applications they are designed for.

Carbide Ball Burrs

Ball or spherical shaped carbide burr are ideal for creating concave cuts in your material or to shape and hollow out an area. Small diameter ball burrs are often used for intricate carving projects.

Carbide Tree Burrs

Tree-shaped burrs are excellent for rounding off edges and making concave cuts. Use the pointed end for cutting in hard to reach areas and acute angled contours.

Carbide Inverted Cone Burrs

Inverted cone shaped carbide burrs are ideal for making v-cuts and rear side chamfering in a broad range of materials.

Carbide Pointed Cone & Carbide Round Nose or Ball Nose Burrs

These pointed burrs work extremely well for rounded edges and surface finishing in difficult to reach areas or tight and narrow angles and contours.

Cylinder Burrs

End cut cylinders with a cutting edge on the end are excellent for contour finishing. Cylinder burrs without end cut (flat on the end and no cutting edge) are ideal for contour finishing and right angled corners.

Flame Burrs

Flame burrs (wheel-shaped burrs with a smooth top and fluted sides) are great for channel work and shaping.

Countersink Burrs

These carbide cone burrs are ideal for beveling, counterboring, chamfering and for getting into acute angled areas.

Contact Midwest Cutting Tools

Have questions about which burr is right for your job? Contact Midwest Cutting Tools today. We manufacture and resharpen virtually every burr type and size.

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Mar 08, 2017

What it takes to effectively machine aluminum.

If you’re having trouble cutting aluminum with general purpose mills, there’s a reason.  Aluminum is a soft metal that requires end mills with specific geometries and characteristics. Here’s the details.

Because of the soft nature of aluminum, a sharp edge and high rake angle are required to separate chips from the workpiece. Positive rake angles up to 25 degrees radial and 20 degrees axial are commonly used.

When cutting aluminum, a high helix angle, around 45 degrees is also optimal. The helix helps move chips out of the cutting zone and provides an excellent surface finish. The high angle also softens the impact at the entrance of the cut, resulting in a smoother cut.

A two or three-flute mill with open flute design is needed for easy chip movement away from the cutting zone. Surface finish on the flute is also important. Long-chipping, low silicon aluminum alloys will typically stick to end mills. As a heated chip flows over the flute, it will try to adhere to the tool surface. One solution to this is an extremely slick commercial tool coating that reduces the friction coefficient on the flute surface.  A good example of this is a ZRN coating that has a friction coefficient of less than 0.1.

When chip management becomes an issue, consider using a coolant-through end mill. Coolant ducts exit in the flute area and help move chips out of the cutting zone.

All of these end mill and coating features help reduce the probability of built up edge, a problem that occurs when a general-purpose end mill is used in aluminum machining. Built up edge is the accumulation of material on the cutting edge. Once this happens, the cutting action becomes more of a tearing action. Surface finish is reduced immediately and spindle load increases dramatically. If your application requires cutting a full width slot, tool breakage is likely before you can adjust the feed hold control.

Midwest Cutting Tools manufactures a broad range of outstanding aluminum end mills, both standards and specials and offers ZRN coatings.  To learn what end mill is right for your aluminum machining job, contact us today.

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Feb 27, 2017

Helix angles – How do they affect end mill cutting action?

1/2 inch mill with 45° helix angle –

Selecting the optimal helix angle can be the difference between a perfect work piece and a do-over.

Here are details on why the helix angle is important and how it affects the cutting action. Most standard end mills are manufactured with helix angles as low as 15° and as high as 60°. General-purpose end mills are typically around 30°. Any increase in the helix angle increases the effective shearing action. This reduces cutting forces and the amount of heat generated during the milling process. Chip ejection is also improved.
Lower helix angle end mills are used on more difficult to machine materials where maximum edge strength and rigidity are important.

With straight flutes, the load build-up is almost instantaneous. This situation makes the end mill prone to vibration or chatter.

With helix angles, chip load is applied to the entire flute length in a progressive siding action. This makes the cutting forces much more constant with less chance for chatter. End mills with a higher helix also tend to produce much better work piece finishes. The 50° and higher helix angles significantly reduce side loading on the mill making it possible to mill thin wall sections with much less deflection.
At Midwest Cutting Tools, we can manufacture mills with helix angles from 15° to 60°. If you have questions about the right helix angle for your applications, contact us today.

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