Boring is defined as a method to enlarge or improve the quality of an existing hole. Sandvik Coromant offers several flexible boring tool systems available in a wide diameter range for rough- and fine boring. Sandvik Coromant offers a complete programme of boring tools, from diameter 19 to 1275 mm (0.748 to 50.20 inch). Successful chip control Chip formation and chip evacuation are critical issues in boring operations, especially in blind holes. Make sure chip breaking and evacuation is satisfactory. Chip jamming affects hole quality and reliability/tool life. Insert geometry and cutting data is crucial. Use cutting fluid to improve chip evacuation, tool life and hole geometry.
Inappropriate cutting data can lead to too short/thick chips and excessive cutting forces, resulting in deflection and vibration. Long chips can accumulate in the hole and cause surface finish deterioration and chip jamming, leading to insert breakdown.
Ideal chips should be in the form of defined commas or spirals that are easily evacuated from the hole. Factors that have an influence on chip breaking are:
Coromant Capto coupling is the only modular tooling system designed for all metal cutting operations, including all hole making methods. The same cutting tools and adaptors can be used in different applications and machines. This makes it possible to standardize on one tooling system for the entire workshop. Remember the following:
Chip evacuation, cooling and lubrication between the tool and the workpiece material are primary functions of cutting fluid. This affects the hole quality and tool life. Most of Sandvik Coromant’s boring tools are designed for internal cutting fluid supply. Use internal cutting fluid to get the fluid as close as possible to the cutting edge.
Use a mixture of 5–8% soluble oil.
Higher pressure and volume improves chip evacuation.
Mist cutting fluid or minimal lubrication can be used, especially in aluminum. Dry boring can be performed in short-chipping materials, preferably in horizontal or through hole applications. Boring Tool life will be reduced. Compressed air will improve chip evacuation greatly.
Note: Dry machining is never recommended in stainless steel (ISO M) and HRSA (ISO S) materials. External cutting fluid supply is acceptable in short chipping materials but must continuously be directed to the cutting zone. If not possible, try dry boring.
Roughing
Roughing is primarily focused on metal removal and is performed to open up an existing hole made by methods such as pre-machining, casting, forging. Rough boring prepares the hole for finishing.
Face grooving
To produce an axial groove in a component, it is important to choose correct tool holder for the insert. The tool holder must be adapted to the bending radius of the groove and should therefore be curved. Chip control is essential in face grooving, the chip should be long enough not to get stuck in the groove, but short enough not to get stuck around tool or component.
Finishing
Fine boring operations are performed to complete an existing hole and to achieve a close hole tolerance, correct positioning with high quality surface finish. Machining is carried out with small cutting depths, generally below 0.5 mm (0.020 inch).
Single-edge boring is used for finishing operations with small cutting depths when close tolerance (IT6 to IT8) or high quality surface finish is required. The diameter of a fine boring tool can be adjusted within microns with a high precision mechanism. Single-edge boring can be applied with a rough boring tool for finishing of holes with tolerances of IT9 or larger.
Inappropriate cutting data can lead to too short/thick chips and excessive cutting forces, resulting in deflection and vibration. Long chips can accumulate in the hole and cause surface finish deterioration and chip jamming, leading to insert breakdown.
Ideal chips should be in the form of defined commas or spirals that are easily evacuated from the hole. Factors that have an influence on chip breaking are:
- The insert micro- and macro geometry
- Cutting depth, feed and cutting speed
- Material
- Nose radius
- Entering angle
- Stable tool set-up
Coromant Capto coupling is the only modular tooling system designed for all metal cutting operations, including all hole making methods. The same cutting tools and adaptors can be used in different applications and machines. This makes it possible to standardize on one tooling system for the entire workshop. Remember the following:
- Choose shortest possible adaptor
- Choose strongest possible adaptor
- If reduction is needed, use tapered version if possible
- For long overhangs (>4 x DCON), use dampened adaptors
- For long overhangs, ensure rigid clamping with flange contact to spindle if possible.
- The Coromant EH system delivers great tooling flexibility – choose from an extensive variety of heads, adaptors and shanks.
- Reduced tool inventory with standardized tools minimizing machine downtime
- For boring operations requiring long reach, as in large machining centres in the diameter range of 1–36 mm (0.039–1.42 inch). Deep pockets is a typical application where the Coromant EH system offers the required reach without limiting process security
- For maximum stability, choose largest possible coupling size and shortest possible overhang
- Increase the dynamic stiffness by adding a dampening mechanism
- For long overhangs (>4 x coupling diameter), use dedicated tools (Silent tools)
- If reductions are needed, use tapered version if possible
- Coromant Capto Tailor Made red/ext. adaptors are available for optimized design hence highest stability
- For long overhangs, a machine tool with a flange contact machine interface coupling provides best performance, e. g. Coromant Capto coupling, HSK, Big-Plus.
Chip evacuation, cooling and lubrication between the tool and the workpiece material are primary functions of cutting fluid. This affects the hole quality and tool life. Most of Sandvik Coromant’s boring tools are designed for internal cutting fluid supply. Use internal cutting fluid to get the fluid as close as possible to the cutting edge.
Use a mixture of 5–8% soluble oil.
Higher pressure and volume improves chip evacuation.
Mist cutting fluid or minimal lubrication can be used, especially in aluminum. Dry boring can be performed in short-chipping materials, preferably in horizontal or through hole applications. Boring Tool life will be reduced. Compressed air will improve chip evacuation greatly.
Note: Dry machining is never recommended in stainless steel (ISO M) and HRSA (ISO S) materials. External cutting fluid supply is acceptable in short chipping materials but must continuously be directed to the cutting zone. If not possible, try dry boring.
Roughing
Roughing is primarily focused on metal removal and is performed to open up an existing hole made by methods such as pre-machining, casting, forging. Rough boring prepares the hole for finishing.
Face grooving
To produce an axial groove in a component, it is important to choose correct tool holder for the insert. The tool holder must be adapted to the bending radius of the groove and should therefore be curved. Chip control is essential in face grooving, the chip should be long enough not to get stuck in the groove, but short enough not to get stuck around tool or component.
Finishing
Fine boring operations are performed to complete an existing hole and to achieve a close hole tolerance, correct positioning with high quality surface finish. Machining is carried out with small cutting depths, generally below 0.5 mm (0.020 inch).
Single-edge boring is used for finishing operations with small cutting depths when close tolerance (IT6 to IT8) or high quality surface finish is required. The diameter of a fine boring tool can be adjusted within microns with a high precision mechanism. Single-edge boring can be applied with a rough boring tool for finishing of holes with tolerances of IT9 or larger.