Super Premium Cutting Tools
Welcome to the world of Magnum Super Premium twist drills. The following pages describe the features and benefits of the Magnum line and why they are the finest tools available for most drilling and cutting applications These heavy duty drills are recommended for recommended for use in work hardening grades of stainless steel and other tough metal drilling applications.
WHY CHOOSE MAGNUM?
Substantially longer cutting life - The nitro-carburized flute has an increased Rockwell hardness.
Cuts harder materials - The flatter point takes a smaller chip. More torque is directed to a smaller area. This allows drilling into materials with hardness of over 30 on the Rockwell "C" scale.
Stops drill walking - The split point design gives accurate starting without the use of a center punch.
Holds tighter hole size - The split point design is self centering. This limits the normal oversize drilling characteristics.
Outstanding quality appearance - The rich amber gold color sets it apart from commodity cutting tools.
Runs cooler, uses less torque - 135 degrees point takes a smaller chip resulting in less heat. Friction is reduced by amber gold surface treatment.
Stops chuck slippage - Flats on drill shanks allow easy positive chuck grip.
The Magnum drills will substantially outperform cobalt drills in work hardening stainless steel applications. This performance advantage is the result of construction differences between the two types of drills. Cobalt drills, manufactured to Type J NAS 907 specs, have a very thick web. This web is necessary to limit breakage of the brittle cobalt steel. Magnum drills are made of special hi-moly tool steel, which is much tougher than cobalt steel. The web on a Magnum drill can be thinned considerably due to the toughness of the steel.
A Magnum drill with its thin web will penetrate the work hardening stainless fast enough to continually cut beneath the chip which is hardening from deformation. This means the drill is cutting softer steel. The cobalt drill, with its thick web, cannot be fed at a fast enough rate to cut beneath the area which ishardening. As a result the cobalt drill is continually drilling into hardened steel.
Work hardening grades of stainless are the 300 series with the exception of 303, which is free machining. Free machining grades include the 400 series in addition to type 303. A quick way to identify work hardening vs free machining stainless is to observe the chip formation. Work hardening chips break up during the drilling process, while free machining chips are long and stringy.
Cobalt drills are recommended for free machining stainless (400 series & 303), titanium alloys and other high tensile strength materials. These applications require the high red hardness of cobalt steel to counter the substantial heat generated in the drilling process.
We begin the manufacturing process of Magnum Super Premium drills with a special high molybdenum tool steel and harden the steel to a range of 64.5 to 66 Rockwell C. This range is tighter than the standard industry specifications of 63.5 to 66 Rockwell C. This tighter specification yields a more consistent drill with a higher average hardness and therefore more resistance to wear.
In the process of transforming this hardened hi-moly blank into a finished Magnum Super Premium drill there is a series of grinding operations. The first major step is the grinding of the flutes. We hold to 1 /2 of industry standard tolerances when grinding flutes. For example: If standard tolerances are + .002, we hold + .001 . Tighter tolerances for flutes mean more accuracy and consistency in subsequent grinding operations, such as clearance grinding, pointing and split pointing. These three operations all use locating pins to sense the side of the flute. This determines where the machines begin their grinding process and thus increased accuracy in flute width translates directly into more accurate and consistent clearance, points and splits. The major beneficiary of these tighter tolerances is the user, who will see more consistency from drill to drill.
The flute has a very thin case of nitro-carburized surface to provide extra wear resistance along the cutting edge of the point. A full nitro-carburized treatment would result in added brittleness, which is not desirable in maintenance applications and other hand held drill uses.
The split point is the final grinding process and it is very important in that it provides the drill with self-centering /non-walking characteristics. The split also reduces the thrust required to penetrate a work piece. The illustration shows the two starting points which give the split point drill its self-centering/non-walking characteristics.
The last manufacturing step is a low temperature stress relieving process which imparts a straw gold color to the drills and improves lubricity.
The Magnum 1 /2" shank S & D drill, shown here, has a unique radial split, which follows the shape of the flute. This split allows us to increase the angle of the split and provide greater chip clearance without grinding away large portions of the heel of the point as we would with a conventional split. Large diameter drills are used with increased feed rates which require more torsional stiffness and greater chip clearance. The standard or conventional split with an angle greater than 500 would weaken the point due to the large amount of steel removed from the heel of the point.The radial split allows the performance advantage of greater chip clearance, without a decrease in torsional stiffness.
Our mechanics length drills as well as our S & D drills have 3 flats on the shank. These flats allow for a strong positive chuck grip of the shank and virtually eliminate the potential for the drill to slip in the chuck, even if all 3 jaws have not been tightened securely. Flats are a very strong feature for maintenance and associated hand drilling applications.
The Magnum series is an effective replacement for cobalt drills in work hardening stainless applications. The key to Magnums performance success against cobalt is the difference in the point and web construction. In illustration "A" the cobalt drill on the left has a very thick web at the point. Now compare it with the Magnum web on the right. The Magnum web is about 1 /2 the cobalt web thickness. The thicker the web of the drill the greater the thrust required to cut a given type of metal. The cobalt drill with its thick web requires substantially more feed force to cut than does the Magnum drill.
In work hardening steels such as 304, 306 and 316 stainless, the cobalt drill cannot penetrate fast enough to cut the chip before the chip hardens. The result is that the cobalt drill continually drills into semi-hardened material. The Magnum drill with its thin web can be fed faster and cuts beneath the chip before it hardens.The Magnum drill will be cutting softer material and have a longer life than the cobalt drill. It is recommended that the feed rate be increased 30 percent when switching from cobalt to Magnum drills in work hardening applications. This switch also requires that RPMs be reduced 30 percent for Magnum drills.
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