A HUGE LEAP FORWARD IN DRILLING STEEL
A new innovative cutting tool concept elevates hole-making performance in steel.
A secure, efficient hole-making process is vital in today’s machining. Productivity is an important factor in competitive manufacturing when it comes to making holes in large numbers. The modern high performance drill has to provide a combination of fast penetration rates, predictable tool life and give consistent results. Dedication comes above all-round capability to minimize the overall cost of making a hole.
WHAT DOES IT TAKE FOR A DRILL TO BE REALLY EFFICIENT TODAY?
Dedication to workpiece material, higher cutting speed, and penetration rates are essential. Vital properties include consistently making holes within a close tolerance band, common to a large number of hole types, and maintaining machining security throughout a long tool life. Also key: the ability to work easily from the start, with potential for optimization.
A drill with these abilities will provide new opportunities to raise productivity levels, particularly on modern machines with high specifications. However, the drill should also provide the versatility to give any machine (with spindle speed capacity) the scope to make use of higher cutting speed potential.
An all-purpose drill is not competitive enough to fully optimize the production of numerous holes of the same diameter. Today’s manufacturing demands require a modern drilling concept, specially developed to address this specific application: from the cutting edge to the flute design. While a twist drill may seem like a straightforward solution, it will not come close to the performance of today’s newly developed, solid cemented-carbide drills.
WHAT IS THE APPLICATION RANGE IN QUESTION?
The area of hole-making in steel, suitable for improvement with a solid cemented carbide standard drill, is the diameter range of 0.118 in to 0.787 in, drill depths of 3-8 times the diameter. Many of the holes within this range have hole tolerances of IT 8-9, surface finishes of Ra 0.8-1.8 microns (depending upon material and application), straightness limits of 0.003-0.005 in per drilled 3.937 in, and demands for minimized entry- and exit-burring.
In addition to straightforward holes in a flat, horizontal entry/exit surface, the drill has to have no restrictions in tackling most hole configurations such as inclined entry/exit surfaces, convex or concave surfaces, holes needing chamfers, and cross-path holes. The material dedication within the ISO-P area needs the versatility to efficiently machine all types of steels, from low carbon, unalloyed, high carbon, and high alloyed steels, to steel castings with hardness ranging from125 HB to 350 HB.
The greater penetration rates and longer lengths drilled provide real benefits in volume component production, across multiple industries. A new benchmark is being set with productivity increases of 100+ percent. Machine shops can use the new solid carbide drill’s higher penetration rates and increased durability to remove bottlenecks in production, caused by out-of-date drilling capability.
Even if a bottleneck is not apparent, the new performance drill will help reduce overall component machining time, simplify setup issues, eliminate multiple tool changing stops and lead to low supervision or previously impossible unmanned machining. Tool economy can be improved through reconditioning facilities. In varied production settings, the drill’s efficiency, higher speed, and lower cutting forces, allows for maximum machine utilization.
The tool’s forgiving character helps alleviate inefficient or unsatisfactory applications within its main application area, even if slightly misapplied. The drill has, however, been developed for higher cutting speeds – to be the fastest, most secure drill for steel. It is not designed for low cutting speeds, where underperforming can lead to other problems.
WHAT LIES BEHIND THE UNIQUE, NEW DRILL CONCEPT?
The CoroDrill 860 is the result of advanced and extensive research and development. The unique concept’s success is due to new progress in tool development, tool manufacturing processes, interaction between development disciplines, and real manufacturing applications.
At the start of the development project, drilling in low carbon and low alloy steels was used to establish the basis for this completely new drill geometry, dedicated to the ISO-P application area. After initial development work, field trials and interaction with various manufacturing companies led to a chain of optimizations of the various geometrical parameters and flutes on the drill. As the work proceeded, alloyed steel, carbon steel, steel castings and high alloy steels with increasing hardness, and other material structure demands, were introduced into the development processes.
During and after this interchange between development work and hole-making trials at numerous machine shops, sound cutting data values were established for realistic recommendations for higher performance levels with the tool. In establishing the drill parameters and cutting data levels, a basis was also formed for designing the size of the program of drill diameters, lengths and hole capability – as well as indications of predictable results.
HOW IS THE NEW DRILL DIFFERENT TO EXISTING CONCEPTS?
The drill point geometry is unique with a new, innovative design, providing a cutting action which is markedly more effective and smoother. The lower cutting forces contribute to longer tool life. This, through generating more of controlled wear development, as opposed to more destructive, rapid wear. Ideal chip formation has also been a main target, where advanced simulation of chip formation was just one of the means used to establish the geometry of the point. The completely new cutting edge is the result of input from development and extensive trials, in which both macro- and micro-geometry developments have contributed to the new drill point.
A new edge corner design has been evolved to ensure high security, resulting in the elimination of edge-chipping tendencies. The micro-geometry has undergone considerable development where, for example, the form and size of the edge rounding, and even the process on the cutting edges, is a completely new development. The more controlled edge rounding contributes to minimizing cutting forces and lowering the generation of heat on the edge, and thereby the extent of tool wear.
In addition to the improved cutting action, the edge rounding coating has been optimized to improve material adherence. The substrate of the carbide drill has also been developed to provide proper toughness for the various drill diameters to reliably provide higher cutting speeds in steel.
In addition to unique drill point geometry, the drill flutes have been completely redesigned. The patented flute progression play a vital role in chip evacuation. Efficient and trouble-free chip evacuation of both short- and long-chipping materials is achieved to meet the required security at the higher machining rates that are encountered throughout the steel area.
The coating and post processes for the drill manufacturing has been developed with a new technology, contributing to its higher performance and results. The optimum shape, surface texture and gloss throughout the flutes, in combination with the increasing widening in size for the longer drills, provide much improved chip transition out of the machining zone and the drill itself.
New innovations of this scale in drill technology do not occur often. This new concept is a result of a new approach, extensive research and development, and collaboration in manufacturing, resulting in a huge move forward in hole-making technology. It is proving to represent a new generation of solid carbide drills. It is a drill for applications in steel where high standards of competitiveness are set in production, and where the priority machining parameter is lower cost per hole.
About the Author: Christer Richt is the technical editor of Metalworking World, the customer magazine published by Sandvik Coromant and provided by Sandvik Coromant USA, 1702 Nevins Road, PO Box 428, Fair Lawn, NJ 07410-0428, firstname.lastname@example.org, www.sandvik.coromant.com.