Extensive analysis of cutting edge

Solid carbide cutting tap

Edge rounding is measured on the first tooth of a solid carbide (SC) thread tap. The surface structure inside the groove is scanned, then the roughness parameters are determined according to DIN EN ISO 4287/88 and DIN EN ISO 13565, and the height parameters according to DIN ISO 25178.

Measuring device and measuring method

The measurements are made by the TOOLinspect measurement system, of which different sizes are available. The measurement system combines two measuring methods in a single system: The edge rounding is captured in “focus variation” mode because of the high flank angles. Roughness measurements are made by the patented confocal method. Data are analyzed by the MountainsMap software. In addition, data can be fused into a point cloud. In this way, the benefits of confocal measurement can be combined with those of focus variation measurement.

Measuring the cutting edge (1st tooth)

Left image:
Extract of the screw tap

Right image:
2D image of the real surface with extract (white stripes) used for the determination of the profile series

Profile series (grey) determined of 500 single profiles and average profile (green) for the determination of the edge parameters.

Determination of cutting edge parameters

cutting edge parameters determined at the average profile

R = 8,01 µm  Radius of cutting edge

β = 95,0° Wedge angle

K-factor = 0,6 
The cutting edge is titled towards the rake face.

Δr = 5,01 µm  Elevation difference (distance from edge crest to line intersection)

sγ= 13,3 µm   Distance from relief point of rake face to line intersection

sα = 22,2 µm  Distance from relief point of flank to line intersection

Analysis according to DIN EN ISO 4287 and DIN EN ISO 13565

Because the surface develops a preferred direction during grinding, measurements are made at 90° to the machining direction. Amplitude parameters obtained from a profile section according to ISO 4287/88 and DIN EN ISO 13565 only allow for limited surface analysis, since they are only scanned along one line. Structural components lying outside this line are therefore disregarded. This can lead to incorrect analyses. Accordingly, a series of profiles are taken over the entire scanned surface segment using the analytical software MountainsMap®. (Image above: intensity view of the surface structure in the groove. The nominal form of was removed and a S-Filter of 2.5 µm was used.)

Primary profile series, produced by a series of 1000 horizontal profile sections. (green: Cross-sectional profile; grey: Envelope profile of all measured profiles)

Minimum, maximum and mean values and standard deviation are calculated from this profile series. From this, it can be determined how greatly the determined values vary over the entire surface.