Catalogue - THINK MILLING, THINK KENNAMETAL - Kennametal - (Version JPG)

KENNAMETAL

Technical Information

Edge Condition Problems and Solutions (cont'd.)

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Introduction

Troubleshooting should be performed in a sequential method to identify and solve your milling problems. These problems can be recognized as premature insert edge failure, part appearance, machine noise or vibration, and the cutter's appearance. Successful troubleshooting requires that we correctly identify the problem, then take the necessary corrective action one step at a time. The five key areas of concern are:

1. cutting tool material (grade) 4. workpiece

2. cutter/adapter 5. set-up/fixturing

3. machine

This section will discuss possible causes and will recommend corrective actions for each of the five areas listed. Remember, if more than one step is taken concurrently, the real cause of the problem may never be discovered. Always perform one corrective measure at a time.

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Edge Condition Problems and Solutions

1. Chipping: Appears like normal flank wear to the untrained eye. Actually, normal flank wear lands have a fine, smooth wear pattern, while a land formed by chipping has a saw-toothed, uneven surface. If chipping is not detected soon enough, it may be perceived as depth-of-cut notching.

Chipping can also be caused by recutting of chips. A good example of this would be a slotting operation where chip clearance or chip gullet space does not allow the chips to evacuate cleanly. In this instance, packing of the chips also occurs.

In most cases, by changing to a stronger grade and/or to a different edge preparation such as a larger hone or T-land, or from a 90° (0°) cutter geometry to a lead angle cutter geometry, will resolve the problem.


problem	cause	solution
chipping	• chatter	• Check system rigidity for proper part clamping. • Correct worn gibs/bearings. • Check for improper cutter mounting.
	• edge prep	• Use largest hone or T-land possible.
*■ -™ — —■■ -	• grade	• Use a tougher grade.
	• built-up edge	• Increase speed.
	• feed	• Reduce feed per tooth.
	• recutting chips	• Choose cutter geometry with correct pitch for chip clearance. • Use air blast or coolant to remove chips.

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&d4v4MltLn0Hlnp Appears when chipping or localized wear at the depth-of-cut line on the rake face and flank of the insert occurs. Notching is primarily caused by the condition of the workpiece material. Material conditions prone to depth-of-cut notch include: an abrasive workpiece skin of scale, abrasive properties of high-temperature alloys like Inconel, a work-hardened outer layer resulting from a previous machining operation, or heat-treated material above 55 HRC.

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problem	cause	solution
depth-of-cut notching	• cutter geometry	• Change to a lead angle cutter.
	• grade	• Use a more wear-resistant grade of carbide.
	• feed	• Reduce feed per tooth.
	• speed	• Reduce speed.
	• edge-prep	• Use honed or T-land inserts.
	• programming	• Vary depth of cut on very abrasive materials.

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To place an order, contact Kennametal or your authorized Kennametal distributor, or visit www.kennametal.com.

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THINK MILLING, THINK KENNAMETAL - Kennametal - #501

Boring bar, Drill bit, Threading die, Lathe tool-holder, Turning insert