Three cutting edges and a comprehensive program of tool bodies, slides, shims and cutting inserts allow CoroBore 820 to be configured to suit the widest possible range of applications. The same program can be utilized to bore productively with 3 cutting edges on the same plane, step bore and single edge bore.
CoroBore 820 consists of adapters with matching slides, shims and covers, making it possible to adapt the tool to various materials and conditions. | |
Adapter
The adapter has seats for three slides. When the slide screw is tightened the slide is pushed into the correct position due to the inclined surfaces of the adapter and slide. There are 9 adapter sizes – A to I – covering diameters from 35 to 306 mm, available with Coromant Capto and HSK couplings. Screws for slides are delivered together with the adapter. | |
Slide
Each slide has a setting screw pushing against stop pins. The setting screw only works when adjusting from smaller to larger diameters. You must slide the insert carrier slide back manually after backing off the adjusting screw. For the two smallest sizes A and B the setting screw is pushing against the setting pin.
It is preferable to set the slides to the desired dimension in a setting fixture. It is, however, possible to set the slides using a vernier caliper and measure over the setting pin and the inserts.
The shim-screws are fitted with cup springs making it easier to set the slides. Tightening of the screws slightly will keep the slides from tilting during setting.
In order to increase the diameter range, there are two sizes of slides for each adapter. Each slide has an engraved line to facilitate rough setting against scale on the adapter.
Slides are available for CoroTurn 107 CC and SC inserts with entering angles 90, 75, 84 and 95 degrees. CoroTurn RC slides are available from diameter 166 mm in styles CN and SN with entering angles 90, 84 and 95 degrees. |
Optional slide lengths |
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Wide bore range |
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| 90° | First choice for long tool assemblies and vibration prone operations |
| 75° | First choice for stack boring, interrupted cut, sand inclusions etc. |
| 84° | RC slides, for stack boring, interrupted cut, sand inclusions etc. |
| 95° | For wiper inserts |
Cover
A cover is a slide without insert seat. It is designed to protect the adapter body and maintain the balance of the tool when single edge boring is applied.
Shims
Shims are used to set slides to different heights to ensure that inserts start cutting in correct order. They are available in sets for each adapter size. Each set consists of two shims with different thickness.
Adaptability
There are three possibilities to set up CoroBore 820 for boring. |
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| 1. Productive boring | 2. Step boring | 3. Single edge boring |
| In productive boring all three slides are set to the same diameter and height. This is the basic setup for most boring applications. The feed rate is equal to feed per insert x three (fn = fz x 3). Only one insert is generating the surface. Rmax is therefore 9 times larger than when fn = fz. | In step boring the three slides are set to different diameters and heights - to ensure that inserts are starting cutting from smallest to largest diameter - shims are placed between slides and adapter. Step boring is used for large radial depth of cut and in long chipping material, where the chip width can be divided into three smaller easily handled chips. | In single edge boring only one slide is used. Covers protect the two support surfaces not used. Single edge boring is used for long chipping material - more space for chips, bottom holes and finishing. |
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Cutting data
Chip evacuation is critical when boring particularly in “Productive mode” (fn = fz x 3). Because a lot of chips are generated in a short time, particularly in small diameter holes, surface speed should be reduced to 50% of that recommended for turning. |
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Use feed per tooth (fz) according to recommendation for the geometry being used. |
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Feed per revolution
Productive boring fn = fz x 3
Step boring fn = fz
Single edge boring fn = fz |
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Max. radial depth of cut (ap) when in productive- and single edge mode should be max. half of the insert cutting edge length. |
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Max. radial depth of cut (ap) per insert when step boring should be max. half of the insert cutting edge length. Radial depth of cut (ap) for all three inserts will be 0.5 x 3 = 1.5 times insert cutting edge length. |
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| Quick start | Diameters < 166 mm | Diameters > 166 mm |
| Entering angle: | 90˚ | 84˚ |
| Inserts: | CoroTurn 107
CCMT XXXX | 08-PM 4225 |
| 08-KM 3215 |
| 08-MM 2025 |
| T-Max P
SNMG | 08-PM 4225 |
| 08-KM 3215 |
| 08-MM 2035 |
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| Feed fn: | 0.6 mm/rev | 0.8 mm/rev |
| Speed Vc: | 160 m/min | 160 m/min |
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