Optimised solution to overcome instability, vibration and heavy interruptions in steel turning applications.

Cutting tool and tooling system specialist Sandvik Coromant has introduced its GC4335 insert grade for the turning of steels where unstable conditions or vibration issues prevail. GC4335 is designed to bring about secure and predictable machining, as well as shorter cycle times and better machine utilisation through reduced stoppages and longer insert life. Customers will benefit from an improved process with less risk of insert breakage, as well as reduced cost per component and faster return on investment.

GC4335, which features Inveio coating technology for maximum thermal protection, offers greater steel turning endurance through improved edge-line security in comparison with the p​revious-generation grade, along with greater resistance to flank wear, plastic deformation and crater wear.

“The new GC4335 is particularly suited for uneven forged surfaces, the turning of which can lead to frequent insert changes due to fatigue and failure,” explains Bimal Mazumdar, Product Manager-Turning. “Slowing down an operation to replace a broken insert means less production. When production is slower, fewer parts get completed per cycle and that affects overall profitability.”

Among those set to benefit from the introduction of GC4335 are general engineering shops, as well as automotive OEMs and tier suppliers and subcontractors in the oil and​​ gas sector. Typical components include tubes, valves, crankshafts, differential housings, flanges and rings to list a few.

Underlying reasons behind the performance of GC4335 include a new substrate that is well balanced between reliable toughness and resistance to plastic deformation. In addition, a new alumina coating delivers efficient heat transfer from the cutting zone to act as a heat barrier and the columnar MT-TiCN inner coating offers improved resistance against abrasive wear. A yellow TiN coating on the insert flank allows for easy wear detection.

To highlight the potential gains, an external face-turning application in dry cutting conditions saw GC4335 outperform a competitor insert on unalloyed steel (220 HB), delivering 3647 completed components in comparison with just 1980 (an 84% increase). The time in cut for this finishing operation was two seconds per component, while cutting speed was 145 m/min (475 ft/min), feed rate was 0.4 mm/rev (0.016 in/rev) and depth of cut was 0.35 mm (0.014 in). Equally significant gains are achievable against GC4235, the previous generation insert grade from Sandvik Coromant.

The GC4335 assortment is available in T-Max^® P and CoroTurn^® 107.

Tungaloy Corporation is adding a positive insert line to its existing FW & SW turning wiper insert range, allowing for feed rates and surface finish to dramatically improve in general turning operations.

Surface finish quality is directly influenced by feed rate and insert nose radius: the higher the feed rate, the rougher the surface generated by the edge of a given nose radius. In a conventional tactic, the feed rate is decreased to get a better surface quality. Tungaloy’s FW & SW wiper series have changed this through the effect of their uniquely developed cutting edges which allow the feed rate to be increased without deteriorating the surface finish quality. Wiper inserts allow running at up to double the recommended feed rate of a normal insert while still providing a surface quality a double that of a normal insert.

The new line of positive inserts incorporates SW chipbreakers, which will improve chip control in finishing and semi-finishing ID turning operations. This addition will complement the existing negative insert range in the FW & SW wiper series to cover wider range of applications to facilitate customers’ productivity increases.

The new positive inserts are available in T9100, a CVD grade for steel turning and NS9530, a cermet grade for thermal shock resistance, covering a great variety of workpiece materials.

If you don’t know much about insert failure and its negative impact on your manufacturing equipment, it’s similar to an athlete exhausting a good pair of running shoes. Much like a shoe under the weight of the runner wearing it, an insert endures tremendous stress over and over again; creating wear and tear. If not addressed, wear can cause pain for an athlete and inaccurate processes or poor productivity for a manufacturer.

Manufacturers, however, can analyze their used tooling to achieve maximum tool life and predict tool usage; thereby maintaining part accuracies and reducing equipment deterioration. By understanding the various mechanisms (listed below) that contribute to insert failure, you can take the appropriate course of action to ensure optimal cutting performance at all times.

Flank Wear

Normal flank wear, which occurs uniformly, is the most predictable of all failure mechanisms because it is largely due to normal abrasion. Similar to a jackknife blade that dulls over time, flank wear happens over time as the work material wears the cutting edge.

Rapid flank wear, on the other hand, happens faster, especially when cutting abrasive materials, such as ductile irons, silicon-aluminum alloys, high temp alloys, heat-treated PH stainless steels, beryllium copper alloy and tungsten carbide alloys, as well as non-metallic materials, such as fiberglass, epoxy, reinforced plastics and ceramic.

You can reduce rapid flank wear by lowering your cutting speeds or, better yet, using a more wear resistant, harder or coated carbide grade.

Cratering

Cratering is a heat/chemical problem that often occurs when machining iron or titanium-based alloys because the tool dissolves into the workpiece chips.

You can avoid cratering by using a coated grade (preferably coatings with aluminum oxide), applying coolant, utilizing a freer cutting geometry to reduce heat, increasing lead angle, and reducing cutting speeds and feeds. The last corrective action can be counter-productive so it should only be used as a last resort.

Built-up Edge

Built-up edge occurs when fragments of the workpiece are pressure-welded to the cutting edge. This failure mechanism commonly occurs with gummy materials, low speeds, high-temperature alloys, stainless steels and nonferrous materials, and threading and drilling operations.

You can control built-up edge by increasing cutting speeds and feeds, using nitride (TiN) coated inserts, applying coolant, and selecting inserts with force-reducing geometries and/or smoother surfaces.

Chipping

Chipping originates from mechanical instability often created by non-rigid setups, bad bearings or worn spindles, hard spots in work materials, or powder metallurgical (PM) materials.

You can deter chipping by ensuring proper machine tool set up, minimizing deflection, using honed inserts, controlling built-up edge, and employing tougher insert grades and/or stronger cutting-edge geometries.

Thermal Mechanical Failure

A combination of rapid temperature fluctuations and mechanical shock can cause thermal mechanical failure. It is most often experienced in milling and interrupted-cut turning, facing operations on a large number of parts, and operations with intermittent coolant flow.

You can prevent thermal mechanical failure by applying coolant correctly or, better yet, removing it from the process completely, employing a more shock-resistant grade, and using a heat-reducing geometry.

Edge Deformation

Heat and pressure are two sources of edge deformation, which commonly occurs with high-heat operations, high speeds and feeds, or machining hard steels, work-hardened surfaces and high-temperature alloys.

You can control edge deformation by applying coolant, using a more wear-resistant grade with a lower binder content, reducing speeds and feeds, and employing a force-reducing geometry.

Notching

Notching happens when there is a difference in hardness or abrasiveness within a workpiece. It often occurs in materials with surface scale or oxidation as well as work-hardened, cast and irregular surfaces.

You can control notching by varying the depth of cut when using multiple passes, using a tool with a larger lead angle, increasing cutting speeds when machining high-temperature alloys, reducing feedrates, carefully increasing the hone in the depth-of-cut area, and preventing build-up, especially in stainless steel and high-temperature alloys.

Mechanical Fracturing

Mechanical fracturing occurs with any kind of excessive wear. Therefore, when the mechanical load is great enough, the insert breaks during the first moments of a cut.

You can avoid mechanical fracturing by correcting all other failure mechanisms besides normal flank wear, utilizing a more shock-resistant grade, selecting a stronger insert geometry, using a thicker insert, and reducing feedrates and/or depth of cut.

If your shop is experiencing insert wear, Seco can help. We have a wide variety of insert geometries, grades and coatings from which to choose, including our exclusive Duratomic coatings that improve toughness and wear resistance by altering the crystal structure at the atomic level. And if you?re not exactly sure how to maximize your operations, our team of metalworking experts can evaluate your processes and determine the best possible solutions for your needs.

About Author:

Don Graham is the manager of education and technical Services for Seco, responsible for all educational activities for the NAFTA market, new product testing and various other technical functions. Outside of work, he enjoys making maple syrup, restoring antique tractors and farming. Don can be reached at dgraham@secotools.com.

Seco’s new TK1501 and TK0501 insert grades incorporate the latest developments in next-generation Duratomic coating technology. The new dedicated cast iron turning grades reach a new level of toughness and wear resistance, as well as reduce tool waste and process more parts per edge.

With the latest Duratomic coating technology, these new grades have a wider application range and an overall increase in tool life and productivity. Seco’s exclusive Duratomic process manipulates aluminium and oxygen at the atomic level to create insert coatings with unmatched toughness and abrasion resistance. Their balance of toughness and hardness meets the highest performance demands consistently and reliably.

TK1501 and TK0501 integrate Seco’s EDGE INTELLIGENCE concept that combines extensive high-performance insert experience and knowledge in every cutting edge for every application requirement. Chrome Used-Edge Detection makes it easy to tell if an insert’s cutting edges have made contact with a workpiece. The inserts are optimised to provide the highest possible contrast to make it easy to instantly identify when an edge has been used, even in low-light environments. TK1501 and TK0501 grades’ Chrome Used-Edge Detection contributes to a potential 30 percent decrease in waste due to prematurely discarded inserts.

The inserts allow for increased productivity through higher speeds and feed rates. This results in a decreased chance of encountering production bottle necks on a shop’s turning machines.

The new grades are available in a comprehensive selection of geometries – from roughing to finishing – to provide a desirable surface finish in any application.

More and more travelers use modern train services because of their ease, cost effectiveness, comfort and safety.

It is therefore a matter of course for manufacturers of rail and train components to ensure that quality products and services continue to be delivered to the industry every day. Increasing reliability through new tools, materials and machining techniques, as well as supporting productive and cost effective maintenance of existing infrastructure, is crucial.

In 2013, the global market for railway technology was approximately 150 billion euros. This is expected to see an annual growth of 2.7 per cent over the next few years, reaching an average annual value of 176 billion euros before 2019.

The railway segment has been a focus for Dormer Pramet for many years, with the company offering customers a wide range of cutting tools to help with both production and maintenance. Tomáš Hantek is International Application Manager for Railway at Dormer Pramet.

“Railway wheels and rails are the most important components in any railway operation, as they represent the interface between vehicle and track. Therefore, both rail and wheel surfaces must always be of the highest quality.

“Any roughness or irregularity in surface quality can create undesirable forces, friction, vibrations and wear, developing unwanted effects on the vehicle and infrastructure. In the case of passenger vehicles, this can influence not only the comfort of the occupants, but also their safety.

“As an established partner to the rail industry in many locations around the world, Dormer Pramet supports the manufacture and re-profiling of wheels, as well as machining of axles, chassis, rail profiles and renovation, switches, base plates, mounted axles, junctions and other rolling stock components.

“With any contact between the vehicle wheels and rail surfaces, the materials must be strong enough to resist the normal (vertical) forces exerted by regular and heavy loads. The forces in the contact zone must be low enough to allow heavy loads to move at speed with little resistance and also large enough to generate acceleration, braking, and guidance of vehicles.

Rail treatment
“The most common mechanical noise from a train is generated between the wheel and rail contact. These ‘vibrations’ are transmitted through the ground and can even be felt in nearby buildings. Vibrations (in the range of 4 to 80Hz), or low frequency rumbling noises (between 30 and 250Hz), can also be transmitted into the vehicle itself affecting passenger comfort and vehicle life.

“To combat against this constant force between track and vehicle, there is a need to make sure the rail remains in a good condition. There are several reasons for rail treatment, but primarily it is an issue of operational safety. With the mechanical stresses in wheel and rail contact, cracks can appear on the surface of the rail. These have to be removed quickly before they spread and destroy the track area.

“A regular assessment of the rail profile is important for limiting damage to the track and rolling stock. Also, another objective is to enable modern high speed trains to use existing lines, while maintaining reliability and safety standards.

“Rail treatment can be performed in several ways. The most time-consuming involves the use of track relaying machines, which replace old rails with new. It is also possible to subject the existing rails to grinding operation, however, the disadvantage with this is that it offers a small depth of cut and can create sparks, presenting a potential fire hazard.

“However, an alternative option is dynamic rail milling. The re-profiling of a railway line without removing the tracks represents significant time and financial savings. It is therefore no surprise that dynamic milling of rails has become one of the most popular methods. But this ‘on the-move’ application requires specialised equipment to achieve optimum results.

“Dynamic milling can be performed by specially designed trains, operating at a constant speed of 700 meters per hour. Rails made of R350HT steel have good abrasion resistance, with a hardness of between 900 and 1,200 MPa. Sometimes the passage of trains results in the rail head being hardened up to 1,500 MPa.

“To re-profile the rails, two milling units are used. The first roughens the surface, the second one finishes it, and the two units act on both rails simultaneously.

“The final rail profile and high quality surface finish are ensured by the grinding units, while metal chips produced during milling are transferred to a nearby container, making sure no debris or swarf is left on the track.

“Another option is the use of a truck which can switch between road and rail by changing its wheel type. This uses only one milling unit on each side, so the cutters perform only a finishing operation.

Safety
“It is standard practice that during the re-profiling of rails, insert indexing due to wear is done on board the train performing the milling. To reduce down time, operators often change the whole milling cutter, and to do this, they must leave the train.

“However, renovation of railway infrastructure is usually done at night when there is less traffic. To improve safety it is advisable to avoid changing the cutter during a shift, especially at night. The normal distance covered when milling during a standard shift is between 3,000 and 3,500m. Dormer Pramet’s rail milling inserts and cutters have a durability of more than 3,700m, meaning staff can stay on the train for the whole shift.

“Our range for the rail industry includes disk mills, cartridges and indexable inserts for dynamic rail milling. Pramet’s rail milling cutters, for example, have a diameter of 600mm, a cutting speed of between 220 and 280m/min, and each cutting tooth can deal with between 3.5 – 5mm of rail length, cutting to a depth of between 0.5 and 1.5mm.

“A variety of universal and removable cassettes are also available, with each consisting of a casing which is identical for left and right hand rails, supporting both roughing and finishing applications.

“These cassettes are also used for different rail profiles – the AHC (Anti-Head-Check, for rails used by trains operating at speeds up to 160 km/h) and the UIC 60E2 profile for high speed lines. When the profile needs to be changed it is only necessary to replace two out of the eleven inserts in each cassette.

“This delivery of cutting tools specifically for dynamic rail milling applications and our aim to continuously develop new products for the industry, has allowed us to develop strong partnerships with some of the world’s leading railway companies.

“Dormer Pramet was recently appointed by Deutsche Bahn (DB) in Germany to supply the dynamic milling cutter equipped with removable cassettes and inserts. DB serves more than seven million passengers and a million tons of freight every day in Germany. The company also has significant presence around the world, operating in 130 countries, generating revenues of around 38 billion euros.

Railway wheels
“As well as re-profiling of rails, Dormer Pramet has experience in the machining of railway wheels, and is constantly looking to meet customers’ requirements for reliability and productivity.

“Similar to rails, railway wheels have to be treated regularly. It helps to improve running behavior, noise level and safety. Machining of railway wheels also requires specific technology based on the principle of copy forming with a round cutting edge. One of the main challenges is to determine the optimum chip thickness and heat distribution.

“By cooperating with manufacturers around the world with a combined annual production of more than 8 million wheels, Dormer Pramet is close at hand to provide technical support and expertise in this area.

Future development
“A continuous dialogue over many years between ourselves, manufacturers and suppliers ensures Dormer Pramet is ideally placed to meet growing industry demands for quality and reliability.

“While we already have a large number of products in this segment, more are added to our assortment every year. However, before being released to the market, all our new tools must meet a strict list of key requirements. This includes the ability to offer reliability in the cutting process, longevity and productivity for the customer, optimum chip fractionation, dimensional accuracy and stability and high surface quality.

“Only when these features are guaranteed, will we offer them to manufacturers, ensuring continuous development for the railway sector as a whole for years to come.”

KOMET has developed a 6xD indexable insert high-performance drill bit that retains its stability even when working without a centring point or guide rails.

5xD is as good as it gets when it comes to the length/diameter ratio of drilling tools. Or at least, that’s what was previously thought, since larger ratios have a considerable adverse effect on stiffness; until now, stable machining operations and adequate feed rates have been mutually exclusive. But the KOMET GROUP has been hard at work, pooling its many years of experience and sophisticated development methods to come up with a new, 6xD drill bit with performance data that will not fail to impress.

The impetus for the project was provided by a customer who enquired about the possibility of a productive 6xD 33-mm drill bit for making large screw holes for bearing rings of the kind used in wind turbines, for example. Tools of this size normally have guide elements, such as a centring point or guide rails, which makes the manufacturing process significantly more complex and drives costs skywards. In the words of Dr. Michel Maes, Head of Development at the KOMET GROUP, “Although you can find cheap 6xD drilling tools on the market that do not feature guide geometries, these are generally only able to work at relatively low feed rates and are therefore not particularly productive.”

The new KOMET KUB Pentron® 6xD indexable insert drill bit has been designed to be a low-cost, high-performance alternative without guide elements, which does not compromise on productivity or process reliability – just like the successful KOMET KUB Pentron® 5xD, which the Besigheim-based drilling specialists used as the gold standard for stiffness in this latest endeavour. Development Engineer Julius Osterried explains, “Our finite element analyses concluded that the stiffness of a 6xD tool was up to 45 per cent less than that of a 5xD tool.” To counteract this, the developers had to make changes to the basic body, since both the substrate from the KOMET® KUB Pentron® and the successful Pentron W80 indexable inserts were to be retained for the new tool design.

Julius Osterried describes the next stage in the development process: “To establish the kinds of loads that would be encountered, machining tests were conducted in which forces were measured, and the results from these were compared with results achieved using simulation tools – both numerical and hybrid.” “We collaborated with other organisations such as universities, who were able to bring the latest scientific expertise to the table.” In a screening, the KOMET® developers then established which geometric characteristics have a significant influence on stiffness. Armed with these findings and their experience, they used the design of experiments (DoE) and finite element (FEM) methods to optimise the geometry of the basic body in order to achieve a stiffness that is sufficient to withstand the specific loads to which it is subjected on the lateral force plane. The development team turned promising design variants into prototypes and validated them by means of drilling tests.

The results of this testing were used to create the final design of the new, 6xD drill bit, which was then taken to the customer for field testing. The drill bit needed to prove itself for roughing operations in 42CrMo4 quenched and tempered steel. At feed rates of up to 0.12 mm/rev and cutting speeds of up to 176 m/min, the new, 6xD drill bit has done just that, achieving positive results in terms of the hole diameters it can drill, which are within the tolerance limits set out in the specifications. In addition to this, the anti-penetration cutting forces of the drill bit, chip evacuation and quality of the drilled hole fulfil the customer’s requirements.

Head of Development Dr. Michel Maes concludes, “With this kind of cutting data and the results it has achieved in testing, the new KOMET®KUB Pentron® 6xD indexable insert drill bit without additional centring point is set to be a highly productive tool for 42CrMo4V machining. It allows us to achieve tool life travel of up to 9.9 m. Not only are these figures considerably higher than comparable drill bits without guide elements, but they also demonstrate that the new tool can hold its own against its guided counterparts. Ultimately, our customers are very pleased with the outcome.”

The new KOMET KUB Pentron® 6xD indexable insert drill bit is now already in use in the field, and developers have wasted no time getting to work on additional 6xD drill bits with other diameters.

Image Credit: KOMET Group

Smart thinking has led to simple solutions for some old problems associated with indexable insert drilling. Difficulties such as chip clogging on deep holes, dissimilar rates of wear on inner and outer inserts due to differing peripheral speeds, plus flexing and wear of the drill body itself have all been resolved with a new and innovative design.

New US chipbreaker for stainless steels

The existing tried and trusted UM chip breaker and range of grades for steels, stainless and cast iron has been complemented with a new chipbreaker that has been specially designed for stainless steel applications. This new US breaker displays a varied cutting edge that features both sharp and strong geometry along its length. This combination provides the well known characteristics needed for successful cutting of stainless steels – namely those of sharpness and strength.

Different grades for inner and outer inserts

The outer insert in this type of drill naturally runs at a higher speed than the inner, thereby leading to higher levels of wear. Consequently the inner insert needs to have a higher level of stability and resistance to fracturing at lower speeds. This anomaly has been negated by using a CVD coated outer insert that has higher abrasion resistance, in tandem with a PVD coated inner insert that can cope better with fracturing forces and resistance to welding. This combination means improved reliability and fewer changes of insert for increased levels of productivity.

Interchangeable inserts with 4 cutting edges

The SOMX type inserts are interchangeable from inner to outer position, have 4 cutting edges and a unique wavy chipbreaker design for improved chip control. The peripheral edge also has a wiper type geometry for excellent hole wall accuracy and surface finishes. The inserts are also positioned in such a way that when cutting, they are both equally in contact with the workpiece, thereby reducing drill body flex to provide a more consistent performance.

Tool body

The tool body is designed with through coolant holes and an optimum sweep of the flutes that provides extra metal thickness behind the direction of the principal cutting force. This controls tool body deflection and helps to achieve reliable deep hole drilling up to 6 x D. Additionally the body surface is heat treated to prevent wear from chip evacuation. The sizes available are Ø17mm-Ø33mm and in L/D=2, 3, 4, 5 and up to L/D=6.

ISCAR is introducing the PENTA IQ D40 with a PB chipformer for parting and grooving bearing steel, soft steel and other ductile materials.

Currently, PENTA D40 inserts are available only with the “C” type chipformer that features a negative land suitable for parting at high feeds and for hard materials.

In order to cover the application range of low to medium feed ranges, and for machining soft and ductile materials, ISCAR is introducing new PENTA D40 inserts equipped with the PB chipformer.

The PB chipformer, which was successfully introduced on the PENTA 34 inserts, features a similar chipformer design like the “C” type, only it has a 0° frontal edge rake inclination and no land (the cutting edge is reinforced by a larger honing than the standard). This chipformer configuration exerts low cutting forces suitable for machining materials like bearing steel and soft materials.
The PB chipformer can successfully cover the application range of the “J” type chipformer.

Seco Tools recently introduced two new PCD-tipped milling insert grades for use with its popular Turbo 10 cutters. PCD05 and PCD20 are well-proven PCD grades that produce unmatched surface quality in finish machining applications, primarily in aluminium, but also in titanium alloys. These workpiece materials are typically found in aerospace and automotive applications. The new grades are also highly effective in cutting polymers and fibre-reinforced composites.

PCD05 and PCD20 milling insert grades work alone or alongside carbide inserts in the same Turbo 10 cutter body. When used with carbide inserts, the PCD insert grades serve as wiper inserts in fixed pockets. Conversely, running the PCD05 and PCD20 in one Turbo 10 cutter body optimises their potential and ensures maximum cutting parameters.

Featuring solid carbide insert bodies, the PCD05 and PCD20 come in the company’s X010 insert size with a corner radius of 0.4 mm (.016″) and wiper length of 1.08 mm (0.43″).

The Turbo 10 cutter bodies that hold the PCD05 and PCD20 include precision milled pocket seats that improve run-out, stability and tool life by providing optimal contact between the tool body and insert. Integrated through-coolant channels support high productivity and promote excellent chip evacuation. Because of their high levels of flexibility, Turbo 10 cutters work in slotting, shouldering, ramping, facing, pocketing, plunging and turn milling applications.

Following the success of serrated cutting edge insert geometries for high-efficiency rough milling, ISCAR is applying this approach to HELITANG T490 indexable cutters by introducing a new milling insert: T490 LNMT 1306PNTR-FW.

The new insert was designed for the standard pocket of T490-13 tools.

The serrated wavy cutting edges of the insert provide the following advantages:

• Split (crush) chips into small segments
• Reduce cutting force and thus power consumption
• Increase cutter stability
• Improve chip evacuation
• Substantially improve performance of extended flute cutters

Due to the above-mentioned features, cutters carrying the new insert provide extra efficiency in rough milling, especially in the following cases:

• Operational stiffness is low (high overhang, poor workholding, thin-walled workpiece, etc.)
• Machine power is limited
• Chip evacuation is difficult in narrow slots or deep cavities

T490 LNMT 1306PNTR-FW Insert for T490-13 Milling Cutters
The double-sided tangentially clamped insert with 4 cutting edges is intended for mounting on
extended flute cutters and also on face and endmills.

In order to provide an overlapping effect and achieve optimal chip crushing, it is recommended to mount the inserts in alternating edge configuration on adjacent flute cutters

Main application: machining deep square shoulders and edging using extended flute
milling cutters.

The new insert is produced from ISCAR SUMO TEC carbide grade IC830. The combination of
the grade with the serrated geometry of the insert cutting edge ensures effective milling on steel, martensitic and ferritic stainless steel (ISO P class materials) as a main field of application and also austenitic, duplex and PH stainless steel (ISO M class materials) and high temperature alloys (ISO S class materials).