Техническая информация Sumitomo - страница 16

Basics of Drilling

• Run-out Accuracy
• Peripheral Run-out Accuracy when Tool Rotates

(Units: mm)

For the run-out accuracy of web-thinned drills, not

MDS140MK

only the difference in lip height (B) but also the run-

0.25 S50C v ＝50m/min out after thinning (A) is important. c f＝0.3mm/rev 0.20 0.15 0.10 0.05 Center run-out 0

(B): The difference of the lip height run-out 0.005 0.02 0.1 0.05 0.02 0.1

(B) (mm)

• When the tool rotates Peripheral

Hole Expansion Cutting Force* Run-out

The peripheral run-out accuracy (mm) 0 0.05(mm) 0 10 (kg)

of the drill mounted on the spindle 0.005 should b e controlled within 0.03mm. If the run-out exceeds

0.09

the limit, the drilled hole will also

become large causing an increase

* Horizontal cutting force.

in the horizontal cutting force, Drill: MDS120MK Work material: S50C (230HB)

which may result in drill breakage. Cutting Conditions： c=50m/min, =0.3mm/rev, =38mm

Run-out: within 0.03mm

Water soluble coolant

• Run-out: within 0.03mm

When the work material rotates 0.03mm

Not only the peripheral run-out at the drill edge (A)

but also the concentricity at (B) should be controlled

within 0.03mm.

• Influence of Work Material Surface

Work material with slanted or uneven surface (Entrance) (Exit)

If the surface of the hole entrance or exit is slanted or uneven, decrease the feed rate to 1/3 to 1/2 of the recommended cutting condition.

• How to Use a Long Drill

N

• Problem

When using a long drill (XHGS type), DAK type drill,

SMDH-D type drill, or SMDH-12.5D type drill at high

rotation speeds, the run-out of the drill tip may cause

a deviation of the entry point as shown on the right, bending the drill hole and resulting in drill breakage.

• Remedies

Method 1

Step 1 Step 2 Step 3

1xDC pilot hole 2 to 3mm (same dia.) n=100 to 300min –1 Short drill Method 2 * Low rotational speed minimises centrifugal forces and prevents drill bending.

Step 1 2 to 3mm Step 2

(n=100 to 300min–1) f =0.15 to 0.2mm/rev

Hole bend

Position shift

Drilling under recommended condition

Drilling under recommended condition