Tool wear in finish hard turning 03:01

Tool wear can be divided in 4 different groups, each containing a number of specific tool wear types.

• Abrasive wear – A change in tool geometry through continuous loss of tool material 
• Flank wear
• Crater wear
• Notch wear
• Deformation – A change in tool geometry without loss of tool material
• Plastic deformation
• Chemical Wear
• Diffusion
• Breakage – A sudden change in tool geometry with loss of tool material
• Edge breakage
• Chipping
• Flaking

In finish hard turning, the “desired” tool wear is abrasive wear; flank wear, crater wear and notch wear, all wear types that are continuous and predictable.

Deformation and chemical wear is not often seen in finish hard turning (unless the material hardness is below 50 HRC).

Breakages can happen, either as a result of too much abrasive wear, or due to a problem in the machine, like a component being clamped the wrong way.

Having only abrasive wear allows the user to run a test insert, establish a maximum tool life, and then set the tool life limit in the machine tool at a safe limit, let’s say 80% of maximum tool life. The user can then be sure that no sudden stops will occur due to breakages.

The desired tool wear should be a combination of flank wear and crater wear. Depending on material composition, notch wear can also be present.

A balanced tool wear like this tells the user that cutting data he is using is right. If the crater wear is too large, the cutting speed should be reduced, and if the flank wear is too large, the cutting speed should be increased.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Secomax™ CS100 – Selection of Edge Preparation 07:28

Earlier this year (2015) the SecomaxTM range of Sialon ceramic inserts was extended with the addition of a new edge preparation, called “T”. Previously only S-edge preparation was available as standard on ISO-inserts. On grooving inserts, the E-edge preparation is standard.

 So, when to select what?

First let’s explain the difference. The S-edge preparation means an insert edge that is both chamfered and honed. This makes the edge stronger, but it also increases the cutting forces, increasing the risk for vibrations.

The T-edge preparation means only chamfered cutting edge, there is no additional edge honing. This reduces the cutting forces, but it also makes the edge weaker.

The E-edge preparation is usually not found on ISO-inserts, it is mainly for grooving inserts, where often long overhangs are used, and the risk for vibrations must be minimized.

For ISO-inserts, the first choice is the T-edge preparation. It gives the user a good balance between edge strength and low risk for vibrations. If a stronger edge is needed, and the machining setup is rigid, the S-edge preparation can be used. Although the E-edge preparation is not standard on ISO-inserts, it can be had as a special, used if there is a high risk for vibrations, but usually with a reduction in tool life, since this is a very brittle edge-preparation.

Below are two examples of successful machining with the T- and the S-edge preparation.

Instable setup, T-edge preparation:
Facing of a larger component. Tool wear can also be seen.

Stable setup, S-edge preparation:
Facing of a smaller component.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Hard Turning Economics 23:43

When it comes to changing a process from grinding to hard turning, many things have to be considered. Besides the actual technical aspects, it is of outmost importance to understand how this change will influence the total manufacturing cost.

For a deeper understanding of the economic benefits of hard turning, it helps to consider a few factors that are sometimes overlooked and where the technical departments must work together with the purchasing department for example. These process factors are illustrated below.

CNC lathes are much more flexible in terms of machining capabilities. Tool changes can be made in less than two minutes, without the production time losses necessary for a wheel change. Worn PCBN tools may be quickly indexed to a new edge or removed and replaced with new inserts, and do not require truing or dressing to maintain the cutting profile. This flexibility allows for fast, cost-effective production, even in small batches of parts.

The floor space is also an important factor. CNC lathes have less of a foot print than grinders in general and do not require coolant systems. Also, as an example, a grinder is a much larger investment than a CNC lathe, which is typically one-half to one-third of a grinder’s cost. So the machine investment itself is also much lower for a lathe compared to a grinding machine.

Further, the structure of most PCBN grades permits for productive machining in difficult conditions, including interrupted cuts, and typically does not require the use of coolant. This helps to keep costs down while eliminating the environmental concern associated with coolant use. Just the cost of coolant and taking care of grinding residues is many times higher than taking care of the dry turning chips and swarfs.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Stefan G Larsson Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340572 Mobile +46761367807 email:stefan.g.larsson@secotools.com

Boost your productivity with Secomax™ round inserts in grade CBN060K 00:25

In some applications it is necessary to perform both semi-finishing and finishing to achieve correct surface finish and tolerance. The semi-finishing is just a way to remove material and prepare the component for the finishing cut.

Secomax™ grade CBN060K has a patented superalloy binder, superior cBN particle distribution and an optimized multi-layer PVD coating. If semi-finishing can be performed with a round insert the Secomax™ grade CBN060K is a really productivity booster. A round insert has the largest “nose radius” of all inserts, and this will act as wiper, improving surface finish significantly and it fits perfect together with the unique properties of CBN060K.

Feeds above 0.6 mm/rev can be used for the semi-finishing operation with good result and long tool life.

A round insert offers also the highest number of cutting edges.

For example:
RNMN090300S-01525 CBN060K (Insert diameter 9 mm) Cutting depth 0.3 mm, 80% utilization = 28 cutting edges/insert

Boost your productivity with Secomax™ round inserts in grade CBN060K.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Per Ola Jönander Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340818 Mobile +46703163555 email:perola.jonander@secotools.com

Secomax™ CBN170, MDT and JETSTREAM 03:42

The Secomax™ grade CBN170 is the world’s first PCBN grade with a whisker reinforced binder. This unique composition makes the inserts withstand the high forces, the high temperatures and the abrasiveness associated with machining of hardened nickel-based superalloys.

The patented Secoloc™ serrations between the holder and insert on Seco Tools MDT-inserts (Multi-Directional Turning), makes it the most rigid groove-turning system on the market.

Jetstream Tooling® delivers coolant to the optimum position close to the cutting edge. The penetration of the high-energy jet into the tool–chip interface reduces the temperature gradient and eliminates the seizure effect, offering adequate lubrication at the tool–chip interface with a reduction in friction in addition to alteration of the chip flow conditions resulting in lowering of component forces and consequently tool wear rate.

An example where these three Seco Tools unique characteristics; CBN170, Secoloc and Jetstream together is the solution for optimized grooving of hardened nickel-based superalloys is shown below:

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Per Ola Jönander Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340818 Mobile +46703163555 email:perola.jonander@secotools.com

Rough hard turning of rolls application example 04:10

In hard turning applications, the definitions for a rough cut and a finish cut are based on depth of cut:

• Rough cut depth of cut ap > 0.5 mm
• Finish cut depth of cut ap < 0.5 mm 

For rough hard turning, usually a high cBN-content grade (80-90% cBN) is used, and for finishing, a low cBN-content grade (40-65% cBN) is used.

Most components in the automotive industry, like gears and shafts, are case hardened and only require a finish cut before assembly. In the bearing industry as well as in the manufacturing of rolls, rough hard turning is a more common operation.

The main requirements on a CBN-grade for rough hard turning are:

• high abrasion resistance
• high hot hardness

But they also need to be tough enough to withstand e.g. variations in depth of cut.

A customer was using ceramics for hard turning of a roll. He was taking 10 cuts, each 0.15 mm depth of cut, to remove the total stock of 1.5 mm. To finish the component, he needed 40 edges.

Ceramics are not suited for these kinds of operations due to their lack of toughness. By using rough hard turning with a CBN-insert, tool life was increased significantly and thereby reducing machine downtime due to insert change. With this method, he only needed 2 edges to finish the component.

By using rough hard turning, productivity can be increased significantly compared to e.g. grinding or the use of multiple finishing cuts

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

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Hard turning optimization application example 00:24

In finish hard turning it is vital to reach the required surface roughness tolerances, since it is the final operation before assembly. The most common way to increase productivity in hard turning is to use a wiper insert. A wiper insert will allow you to increase the feed rate, while maintaining low surface roughness values, and reaching long tool lives.

When machining a curved surface, like in a profiling operation, the approach angle changes depending on where you cut, and a wiper insert will not work. So what can be done?

In the following example, we analysed the influence from edge preparation and coating when machining the raceway of a bearing ring:

• Changing edge preparation
• Small edge hone & large edge hone
• Using a coating
• CBN010 & CBN010C

We decided to keep all cutting data parameters the same, to be able to see the influence from the test parameters. As can be seen below, using a large edge hone combined with a coating gave the best tool life.






This is a real application example, and the results should not be taken as general recommendations.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Hard Turning wiper application example 23:10

In finish hard turning it is vital to reach the required surface roughness tolerances, since it is the final operation before assembly. The most common way to increase productivity in hard turning is to use a wiper insert. A wiper insert will allow you to increase the feed rate, while maintaining low surface roughness values, and reaching long tool lives.

 For a wiper to work properly, there are two criteria:

• The surface has to be straight
• A specific approach angle is needed 

For a CNGA-insert, the approach angle k should be 95o. On a straight surface (a) the wiper works. If the workpiece is tapered (b), the wiper will not work, since the approach angle is less than 95o. When machining a curved surface (c), the approach angle changes depending on where you cut, and the wiper will not work.

As long as the machined surface is straight, a wiper can be added to the insert to fit the actual approach angle. In the following case, machining of an inner diameter on a large gear, the approach angle was 15 degrees.

When machining straight surfaces, a wiper insert should always be the first choice, and after our visit, we proposed to use a wiper insert. In this case, the customer requested that the first test was to be done at the existing cutting data, and tool life was significantly improved.

By adding a wiper, the tool life was increased significantly, and using higher feed rate also improved productivity.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

PCBN Positive Helix Wiper Inserts 00:29

To use wiper inserts is the most common way to increase productivity in metal cutting, and is today an established method. The feed rate can be increased and the surface roughness can be decreased significantly, allowing for much longer tool life (calculated in components).

The main drawback with wiper inserts is the higher cutting pressure. The wiper radius is acting as a large nose radius, and the radial cutting force component is significantly much higher than with a standard insert, and this increases the risk for vibrations. In stable setups, this is not a problem, but it can be a problem in many operations:

• when machining “smaller” inner diameters on gears
• when machining long and slender parts like shafts
• when machining components clamped in only one end 

Where it has often been impossible to use wiper inserts.

 A solution for these difficult operations was developed by Seco, called the HelixTM wiper, where the insert chamfer angle varies around the insert nose radius. This significantly decreases the radial cutting force component (as shown in the figure below with up to a 30% decrease), allowing the wiper technology to be used, with all the productivity and component quality benefits for the customer.

The Helix wiper has been very successful, allowing customers to take advantage of the wiper technology. Standard inserts are today available in the following geometries:

Below are two examples of gear machining with Positive HelixTM wiper inserts. Left is an example of a small ID turning operation, the diameter is 32 -0.012/-0.028 mm and the surface roughness requirement is Ra=0.5 mm. Right is an OD turning operation, where tool wear caused vibrations after only 38 minutes TIC. The Helix wiper allowed for almost double tool life.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Secomax™ X-edge preparation 05:17

Rough machining of white cast iron requires chamfered and honed cutting edges. The material is hard, abrasive and contains impurities such as sand from the casting process. Chamfering of the insert strengthens the PCBN cutting edge and thereby ensuring consistent and maximum tool life.

Secomax™ X-edge preparation is a double chamfer solution that’s give the cutting edge unbeatable edge strength.

The x-edge preparation and CBN500 is an unbeatable combination when rough machining of white cast iron.

RNMN120400X-05015 CBN500

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Per Ola Jönander Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340818 Mobile +46703163555 email:perola.jonander@secotools.com

Surface Finish when Milling Grey Cast Iron with PCBN 06:06

Seco Tools’ range of PCBN products include a range of milling cutters and inserts, primarily for milling of grey cast iron components, but that also can be used for milling of hardened steel and iron components.

A common question is what surface finish can I get when milling with PCBN-inserts? Well, it will depend on the setting of the milling cutter. When milling with PCBN, it is important that all inserts take the same load; any insert sticking out will result in reduced tool life and poorer surface finish. The inserts should be within 0.002 to 0.004 mm of each other. If a wiper insert is added, this should be positioned between 0.025 to 0.1 mm above the other inserts depending on workpiece material and operation. It is always recommended that the cutter should be set-up outside the machine in a pre-setter.

Since this a parameter that is difficult to control, it was decided to do the tests with only 1 insert. Grey cast iron was selected as workpiece material, and the parameters were:

• Feed rate 0.05 – 0.3 mm/tooth
• Insert nose radius 0.8, 1.2 and 1.6 mm 

Wiper inserts were also evaluated in the test. The depth of cut was set to 0.5 mm, and the cutting speed to 1,500 m/min.

The average profile deviation, R_a, was measured after each test, and the results plotted as a function of feed rate for each of the nose radii and the wiper insert.

As can be seen, the R_a-value increases with increased feed rate and decreases with increased nose radius in much the same way as in turning. By far the best surface finish is achieved with the wiper-insert.

At low feed rates, it is possible to reach R_a -value of 0.5 mm, but to maintain that surface finish when increasing the feed rate, it is necessary to use a wiper insert. Even at the highest feed rate, 0.3 mm/tooth, the R_a-value is less than 0.6 mm.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Removal of a case hardened layer 01:24

In most cases, case hardened steel components for the automotive industry (gears, shafts, sleeves etc.) are soft machined, case hardened and then a final cut is used to reach the required surface and dimensional tolerances.

In some cases though, there is a need to remove the case hardened layer. It can be that the component needs to be welded together with another component, and this cannot be done if the surface is hardened to 62 HRC.

This is a very challenging operation, where tool life is usually very low. PCBN is the best insert material for machining hardened surfaces, and when removing only 0.1-0.2 mm, tool life is very long. But if you need to remove 1 mm, how do you do that? 1 mm down into the component, the hardness is only 40-45 HRC and tool life will decrease significantly due to chemical wear.

 Well, there are a few alternatives:

• Multiple cuts with PCBN 
• This will work, but the deeper you go, the more affected the insert will be by chemical wear. Time in cut will also be longer due to multiple cuts.
• One PCBN cut and one or more cuts with carbide 
• You could remove the hard surface with PCBN, and then change to carbide for the subsequent cuts. The problem with this is that the ends of the component will still be 62 HRC, even when you have removed the hard skin, and this will influence tool life. Also here, time in cut will be longer due to multiple cuts, and one tool change from PCBN to carbide.
• One “roughing” cut with PCBN 
• Tool life will be affected by the lower hardness, but time in cut per component is low. 

The data below shows one successful example of removing the case hardened layer on a gearbox component using one “roughing” cut.

Each application when you remove the case hardened layer is unique, and very often involves extensive testing to find out which method is best. In this case, using Seco Tools’ solid CBN300 insert, and taking a roughing cut proved to be the optimal.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

Secomax™ CS100 – T preperation range extension and Ceramic tool holder additions 06:56

The existing CS100 “S” preperation insert range (chamfer and edge hone) is now complemented by a number of “T” preperation insert styles.

“S”preperation geometries are commonly used in rough turning or milling operations where stability is good. “T” preperation (chamfered, no honing) inserts that are now added are recommended for pre machined surfaces and/or when poor stability is an issue.

Application example, see below.

 A range of tool holders, shank and Capto style are now introduced as non-stocked standard items.

Those holders are “N” classified with a two weeks delivery time. The range of tool holders support the most commonly used insert types including our standard ISO and grooving style inserts in grades CS100 and CW100.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Product Manager: Anders Wickman Product Manager SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340254 Mobile +46703431200 e-mail:anders.wickman@secotools.com

Secomax™ PCBN & Steadyline® - Unbeatable combination 01:36

Boring operations of big components, in for example white chromium iron, are very challenging when it comes to minimize vibrations. This is an important issue both due to the fact that vibrations reduces tool life, but also since it may be specific surface demands that makes it impossible to accept any vibrations.

But now it can be possible to optimize the operations further thanks to our Steadyline® systems with a pre-tuned damping system. It can allow up to four times bigger depths of cuts and impressive surface improvements.

For PCBN inserts, there is the option to go for the GL-heads for TN11- and RN09-style inserts. The GL-system is a short and compact system with optimal damping effect and the same repeatability accuracy as Seco-Capto. This unique and patented system allows coolant flow through the head if necessary. The Steadyline® turning range is available in three diameters, ø32, ø40, ø50, and three lengths, 6xD, 8xD, 10xD. They are also available in two shank designs – Seco-Capto or Cylindrical.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Stefan G Larsson Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340572 Mobile +46761367807 e-mail:stefan.g.larsson@secotools.com

Turbo 10 PCD – A well-known friend in a new suit 12:00

The Turbo family is well-known for both Seco’s customers and competitors. Beside the carbide inserts, we also have the option of using PCD in the sizes Turbo12 and also Turbo09. But the latter is being replaced by the new size, Turbo10. This is not only a change of size, but also a big product improvement. The pockets in the milling bodies have been improved in respect to the supporting surfaces, which makes the inserts more stable in the pockets and a stronger locking screw is used. An insert which is more stable in the pocket also result in a more stable cutting process with less risk of vibrations, which will improve surface quality and tool life.

The insert design is also better than the old Turbo09. The rake angles are more easy-cutting, which reduces the cutting forces and risk for vibrations. Furthermore, it also improves tool life. The Turbo10 PCD insert is also designed to be working together with carbide inserts in the same milling body, where the PCD insert works as a wiper insert.

Material: AL7075

Cutter: R220.69-0040-10-6A
Insert: XOEX10T304F PCD20
Vc: 1500 m/min
Fz: 0.15 mm/tooth
Vf: 10800 mm/min
Ap: 3.5 mm

Author: Stefan G Larsson Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340572 Mobile +46761367807 email:stefan.g.larsson@secotools.com

Secomax™ CBN010, the universal uncoated cost saver 23:37

Secomax™ CBN010 is a low cBN content grade with an average grain size of 1.5 µm and titanium carbide (TIC) binder. Newly developed manufacturing methods employed for CBN010 provides an extremely uniform microstructure, with fine cBN grains evenly distributed throughout the ceramic binder, providing improved material properties and optimum wear resistance in application.

Increased chip resistance allows for the production of high quality cutting edges, which are essential for high precision machining with excellent surface finish as required in industry today.

Secomax™ CBN010 is recommended in many different materials and applications. It is mainly intended for finishing operations and is available in four different insert formats: Solid, full face, tipped and multi-tipped formats, all including a number of wiper options. CBN010 is also available in a number of MDT inserts. Almost everything is possible: grooving, copying, turning, plunging, face and internal machining.

Secomax™ CBN010 is the true universal uncoated cost saver.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Per Ola Jönander Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340818 Mobile +46703163555 email:perola.jonander@secotools.com