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