From traditional hobbing machines to modern indexable carbide inserts, much has changed in gear technology over the years. As innovative solutions to previous options emerge on the gear-milling scene, shops now have unique opportunities to achieve major productivity gains. Every gear manufacturer has the same goal in mind; to produce superior gear components in the most economical way.
Many times in gear production, only disparate solutions are discussed for shafts, splines, and gear wheels. But seeing it as a total component solution is a more flexible, integrated approach to increasing productivity. Like many metal cutting shops, components often go through numerous processes and operations to get to an end result. While almost every gear manufacturer also does some type of turning, until now, a turning tool did not exist that can accomplish everything required to prepare steel bar stock into quality gear components.
Unique Turning Tool for a Typical Gear Application
For some shops, prepping the steel blank to prepare for the gear milling process is still a cumbersome, multi-step and multi-tool process. Before the steel bar stock gets to the gear-milling phase, turning must take place to prepare the material. Gear and spline shaft producers have traditionally relied on a combination of tools to accomplish each task and achieve the desired finish. Starting out as a one-piece, blank or forged material, the inherent shape of the gear wheel and shaft complicates the turning process. Not one tool has been available that has the extended reach to successfully turn that section of the component.
To make this point, consider the process of turning steel bar stock on a lathe turret machine. One tool is used to face the front side of the gear wheel blank and often another is needed to face the backside. A third tool is needed to turn the outer diameter of the gear wheel, as well as the outer diameter of the shaft. But now, the CoroCut® QD from Sandvik Coromant, which is a system for parting, grooving and turning, has a unique application for gear manufacturers. It is one tool that can replace the several tools previously needed to machine gear blanks, singlehandedly facing both sides of the gear wheel, turning the outer diameter of the wheel and the shaft as needed. The CoroCut QD’s superior stability allows it to accommodate long reach situations. Figure 1
The Durability of CoroCut QD
To meet customer needs, CoroCut QD combines strong tools and inserts with rigid clamping and efficient coolant supply. It provides unbeatable process security in terms of good chip control and long reliable tool life and is the key to efficient production.
With such versatility and stability, the CoroCut QD system for parting, grooving and turning represents a major departure from previous generations of parting off tools. In addition to excellent chip control, it features new geometries and an over/under coolant system, both ideally suited to tackle the unique materials such as forged steel or made from powdered metals that are commonplace in gear manufacturing.
At the cutting edge, the cutting forces are high. To withstand this temperature, the tool material has high fatigue resistance and the tool tip seat features a backstop so the insert stays in its position preventing the seat from wearing down when the insert is indexed. Also the inserts themselves are developed with good coating adhesion and high edge-line security, for long tool life in every parting off operation.
In gear production, it’s common to encounter steel alloys with low sulfur content, which makes the material more difficult to machine. There is a greater tendency for workpiece material to create a built up edge (BUE) that can destroy insert edges and drastically reduce insert life. Using CoroCut QD’s over/under coolant through tools, the coolant gets closer to the cutting edge which helps control chips, ensures good surface quality and effectively controls temperature at the cutting zone. CoroCut QD features plug-and-play adaptors for many machines to create easy coolant connections. Sandvik Coromant recently added 100 new CoroCut QD holders in their latest release, all with coolant through technology, adding to the 87 introduced last year. Shanks are available in 1.25”, a standard length shank. Quick Start (QS) shanks, available in 20mm, 25mm and 0.750” and 1.00”, have a short shank length. QS Swiss shanks, in 10mm, 12mm, 16mm and 3/8”, ½”, 5/8” are more typical QS shanks for sliding head machines. Parting off blades sizes 21 and 25 with and without coolant through are available for .079” through .236”-wide inserts, and a new size 45 blade is available for .118, .157, .197, .236” wide inserts.
Over and under coolant helps control chips and keeps the insert edge cool which helps reduce flank wear for greater tool life predictability. Since the coolant is applied directly to the insert’s cutting edge it allows an operator to use tougher grades at higher than usual cutting speeds, making the process extremely secure even in difficult to machine materials. While all tools exhibit wear over their useful lives, gear manufacturers, especially high volume manufacturers, value predictability as much as any other factor. After a long run of parts, sudden insert failure translates to lost profits through scrapped components and unnecessary downtime. With CoroCut QD, operators can predict when new inserts are required and can incorporate insert changeovers into their production schedule giving them added control over their process. Figure 2
Grades, Geometries, and Materials
At the cutting edge, the cutting forces are high. To withstand these forces, the tool material has high fatigue resistance. This new material has fewer voids or inclusions, so shanks and blades are less prone to cracking. An added feature of the CoroCut QD is the smart, user-friendly clamping system for indexing inserts. Traditionally, inserts are pressed into the tool pocket which can cause wear. With CoroCut QD, the inserts are changed by lifting the top clamp which does not damage the insert and substantially extends the tool holder life. What makes it user friendly is that an operator can open the clamp with the wrench, and leave it in an open position to load an insert using both hands to speed up the indexing process.
CoroCut QD also uses a new generation of edge technology to produce a more consistent and tighter tolerance edge rounding. This high edge line contributes to a long, secure tool life. Using the latest advances in coating, Sanvik Coromant increased the level of coating adhesion strength and achieved more consistent coating thickness over different features of the insert. This new coating lasts longer, providing better wear resistance for increased tool life. These features allow operators to use a thinner insert, saving on material while maintaining the stability of the operation.
In perfomance tests against competitor products, CoroCut QD won the vast majority of tests with an average tool life increase of 85 percent. This translates into more components produced per insert edge. Check out these results and more on the Sandvik Coromant website at www.sandvik.coromant.com.
An Unlikely Solution with Excellent Results
To machine quality gear components in the most economical way, CoroCut QD brings security, predictability and optimized machine utilization to the gear manufacturer’s process. While it seems like an unlikely solution, this flexible parting, grooving and turning tool provides gear producers with one unique tool that allows them to perform most of their necessary turning operations. Accompanied by plug-and-play coolant, premium insert grades and insert geometry technology, CoroCut QD is getting the attention of gear manufacturers and turning them into believers.