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Mastercam - Chip Thinning RCTF and Iscar HEM

5/15/19 6:00 AM / by camInstructor Mike

This is video explains Chip Thinning (RCTF) and Iscars HEM found in Mastercams Dynamic toolpaths.

If you are using one of Mastercams Dynamic motion toolpaths, the option to enable RCTF, Radial Chip Thinning Factoring, becomes avaialble. Also in these toolpaths, if you select an Iscar Endmill to this toolpath, Iscars HEM, High Efficiency Machining, also becomes available.

The use of these two settings in conjunction with the Dynamic toolpath motion, you will increase the metal removal rate of the toolpath which also reduces the overall cycle time. 


RCTF - When selected, Mastercam applies radial chip thinning calculations to the toolpath. This option is also automatically applied when the ISCAR HEM checkbox is selected. The following toolpaths are supported: All 2D High Speed toolpaths, Face, Pocket, Slot Mill, Horizontal Area, Dynamic OptiRough, Area Roughing, and Circle Mill.

ISCAR HEM - Select to activate the ISCAR HEM (High Efficiency Machining) options. By selecting this option, the RCTF (radial chip thinning factor) option is automatically applied. This field display only when an ISCAR CHATTERFREE tool is selected for a Dynamic milling or Dynamic OptiRough toolpath.

HEM Factor - Adjusts the ISCAR tool's feed rate and spindle speed values to achieve maximum speed and efficiency. Enter a value in the field or use the slider positioned directly above the field to adjust it. You can enter a value from 1 up to 5, depending on the selected machine and tool configuration. Mastercam displays the corresponding feed rate and spindle speed values below the field. When you enter the maximum HEM Factor allowed by the machine and tool configuration, Mastercam displays a message marked with an asterisk and marks the threshold value in the same manner. 


Both RCTF and HEM are effected by the stepover percentage used in the toolpath. When using HEM, you will be limited to only a few selections for the stepover percentage whereas with RCTF, you can define any value you want.

When trying to push cutters to their limits, some often get caught up in high feedrates and spindle speeds. These make for great stories but don't show overall efficiency. For this you must calculate the MRR, Metal Removal Rate, of the toolpath. It's a fairly simple calculation...

Width of cut x Depth of cut x Feed in Inches Per Minute = Metal removal rate in cubic inches per minute

The higher then number for MRR, the better.


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Topics: Mastercam 2019, Mastercam, Mill

camInstructor Mike

Written by camInstructor Mike

camInstructor Mike is Mike Wearne, an avid machinist, cnc programmer and overall connoisseur of all things machining. Mike is one of camInstructor's resident cad/cam/cnc experts and works part time at his local college teaching aspiring machinists how to program CNC Machines of all types.

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