PCBN solid inserts for finish hard turning 23:17

Base on requirements from customers, the evolution of PCBN has led to the development of different PCBN insert types. What is commonly referred to as the PCBN “format” is how the PCBN appears. As shown below, there are four main groups.

Tipped inserts

A small PCBN-tip is brazed onto a carbide insert. The tips can be on one side or on both sides of the insert.

Multi-bar inserts

PCBN bars are brazed onto a carbide insert. These inserts are double sided, and therefore only available as negative inserts.

Full faced inserts

These inserts have full PCBN-layer on one side of the inserts.

  

Solid inserts

The whole insert is made of PCBN. All corners on the insert can be used.

 

The most common application area for PCBN is hard turning of case hardened steel components, and traditionally tipped inserts are used. By converting to solid inserts, a much more cost efficient production can be achieved. On a solid insert the cost per edge is considerably lower than on a tipped insert.

Depending on if you are doing a copying operation, a straight internal, external or facing operaton, you might need a different shape of the insert. Rigidity and stability of the setup will also influence the choice of insert shape.

For these reasons, solid inserts are available in six different shapes from Seco Tools:

• TNGN11.. fixed pocket position, 6 edges/insert
• CNGN09.. fixed pocket position, 4/8 edges/insert
• DNGN11.. fixed pocket position, 4 edges/insert
• SNGN06/09.. fixed pocket position, 8 edges/insert
• RNGN09.. can be rotated freely in the pocket, depth of cut will determine number of edges/insert
• WNGA06.. fixed pocket position, 6 edges/insert

To improve productivity and efficiency in the operation even more, wiper geometries are available on several of these shapes.

A round insert has the largest “nose radius” of all inserts, and this will act as wiper, improving surface finish significantly. A round insert will also give maximum number of edges per insert. The table below shows the number of edges per side at different depth of cuts.

 

In an existing operation, it is not always easy to change tool holders, and presenting a solution with solid inserts is often met with skepticism, but after explaining the advantages with:

• number of edges per insert
• parts per insert

the initial reaction is often replaced by a keen interest. This has been the case at many customers over the years that these inserts have been available, and after implementation, it has helped them to improve efficiency, productivity and cost effectiveness. A few examples are shown below where tool life per insert has been increased significantly.

Hard turning of a gear bore was previously done with a CNGA120408 insert with 4 edges, with a total tool life of 800 components per insert. By changing to a solid round insert in CBN060K, tool life was increased to 3,200 components per insert (16 edges per insert). A rigid setup and a stable tool holder design eliminated the risk for vibrations.

Old solution:                                          New “Solid” solution:
CNGA120408                                         RNGN090300S-01525
Competitor PCBN                                   CBN060K
4 edges/insert                                          16 edges/insert
Tool life: 800 parts/insert                        Tool life: 3,200 parts/insert

 

Hard turning of another gear bore was previously done with a CCGW090308 insert with 2 edges, with a total tool life of 166 components per insert. By changing to a solid triangular insert in CBN060K, tool life was increased to 858 components per insert (6 edges per insert). A rigid setup and a stable tool holder design eliminated the risk for vibrations.

Old solution:                                           New “Solid” solution:
CCGW09T308                                         TNGN110308S-01525
Competitor PCBN                                    CBN060K
2 edges/insert                                            6 edges/insert
Tool life: 166 parts/insert                         Tool life: 858 parts/insert

 

Another advantage of solid inserts, the possibility to “plunge” a feature instead of using conventional axial turning will be discussed in a coming newsletter.

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: +86 186 167 90063 e-mail: henrik.sandqvist@secotools.com

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