CoroDrill 870

Designed for the intermediate hole-tolerance area of H9–H10, the CoroDrill^® 870 exchangeable-tip drill saves time and reduces your cost per hole.

CoroDrill^® 870 can be tailored to optimize applications through diameter range, steps and length possibilities. Holes can be made more efficiently and closer to the specifications required, leaving holes better suited to subsequent operations.

Benefits

The interface between tip and drill is simple, accurate, and stable. Optimized drill flutes facilitate chip evacuation and with tip changing possible while the tool is still in the tool holder, you do not lose valuable cutting time. The new cutting edge geometries and grades provide a safe cutting process with optimized chip control, high penetration rates and a long dependable tool life.

Reliability and security
Easy handling and secure tip changing
Long tool life and high penetration rates
Excellent hole quality
Optimized chip evacuation
Lower cost per hole

Features

Secure, high-precision interface between drill body and tip for extra stability
Tip changing possible while tool is in the machine to reduce downtime
Drill flutes with optimized shape, size and helix angle provide safe chip evacuation and overall tool stability
Rigid drill body for high penetration rates and excellent hole quality
Internal coolant for all drills
Torque values and key codes marked on drill body
-PM 4234 for steel and -KM 3234 for cast iron

Geometries with high process security, good chip control, high penetration rates and premium hole quality
-KM geometry with chamfered corners for optimized hole quality at exit and increased tool life in cast iron
Grades with predictable wear as well as long and reliable tool life at high productivity rates

-GP 4234 pilot geometry for steel and cast iron

To make a pilot hole prior to drilling with 6×D drills and longer
Enables a smooth and secure entry into the pilot hole for the long drill and generates excellent performance and hole quality

Tailor Made 45° chamfer drill for producing chamfered holes in one operation is available

Application

Hole tolerance: H9–H10
Hole diameter range: 10–25.90 mm (0.394–1.020 inch)
Hole depths: up to 8 × drill diameter
Typical hole types: pre-holes for taps and bolt holes

ISO application area

Recommendations

For quick and easy tool mounting, gently press the tip down and towards the support surfaces while tightening the screw to the recommended torque shown on the drill body. Preferably use a torque screw driver to ensure that the tip is securely seated.
Internal cutting fluid is recommended in order to secure safe chip evacuation.

For optimum stability and minimum run-out, clamp CoroDrill 870 with a CoroChuckTM 930 hydraulic chuck with sealed cylindrical collet.

Note: Never use a CoroChuckTM 930 in combination with an ISO 9766 shank without cylindrical collet!

Cutting data recommendations for CoroDrill 870

Recommended drilling strategy for lengths ≥6×DC

	~0.5xDC			v_c= 100% m/min (ft/min) f_n= 100% mm/rev (inch/rev)
1. Use a CoroDrill 870 ≤ 3xDC with -GP geometry to drill a pilot hole with depth ~0.5xDC			2. With the ≥ 6×DC drill; enter the pilot hole with recommended cutting speed and feed and continue drilling