NUMROTOplus – Feed optimization based on the 3D removal rate QW’

Time is money – even when grinding tools
Every second counts, especially in series production of tools. Unnecessary grinding time has a direct impact on productivity and cost-effectiveness. NUMROTO already offers numerous options for optimizing machining time. Almost every distance and every feed rate can be programmed individually to make processes as efficient as possible. NUMROTO is now expanding these options with a new, intelligent function: 

Automatic feed optimization based on the removal volume
Machining feeds can now be automatically optimized based on the actual removal volume. The removal volume calculated in the 3D simulation serves as the basis for this process. This feed optimization offers particular advantages when the removal volume varies during machining, which is very often the case in practice, for example with:

• Flute cutting
• Tools with multiple spirals
• Conical tools
• Step drills

Even when grinding gash-outs, ball nose clearance operations and especially pockets for PCD inserts, the removal volume per unit of time is rarely constant. In such cases, the grinding time can be specifically reduced by means of an automatically variable feed rate.

Focus on quality and tool protection
However, effective optimization should not simply involve increasing the feed rate across the board. Excessive feed rates can impair grinding quality or lead to increased wheel wear. For this reason, NUMROTO provides various strategies that allow feed optimization to be individually adapted to each machining operation. The new function can be controlled using the following parameters, among others:

• Maximum desired QW’
• Maximum permissible removal rate in mm3/s
• Maximum feed factor during wheel engagement
• Maximum feed rate during grinding without removal (outside the blank)

In addition, NUMROTO offers a fine-tuning function in which the feed is reduced shortly before the first grinding contact and then gently increased as soon as the wheel is engaged. This may be particularly necessary when using grinding pins. For optimal functionality, it is essential to define the blank used as accurately as possible. NUMROTO provides various blank definitions for this purpose.

Practical examples

End Mill with Multiple Spirals (Pictures 2-5)
The following evaluation shows the wheel load (QW’) with constant feed (without feed optimization). During flute machining (yellow) and gash-out (cyan), the wheel’s maximum possible QW’ is reached only briefly, as the removal volume varies. In this example, the greatest optimization potential lies in the area of engagement (red arrow). After activating feed optimization, the maximum QW’ is achieved and maintained throughout the entire machining process. Feed optimization can generally be used for all machining operations in NUMROTO — for example, for reliefs on the OD or the tip. In this example, it was deliberately activated only for fluting and gashing, as this is where the time savings are most significant.

Stepped tool with pockets (Pictures 6-9)
Feed optimization was applied to all operations for this tool, but intentionally to a limited degree. The maximum feed factor was set to 1.5 to ensure optimal surface quality. Despite this conservative setting, the grinding time was significantly reduced. In this example as well, the feed had already been programmed so that the wheel load approached the maximum permissible QW’. Feed optimization therefore primarily takes effect in the engagement area, where the feed can be increased by up to a factor of 1.5. In practice, feed rates are often programmed more conservatively than technically necessary. In such cases, feed optimization is effective throughout the entire machining process, resulting in even greater time-saving potential.

Note
For technical reasons, feed optimization cannot be used for cyclical grinding operations or for regrinding.

Availability
The “Feed optimization via 3D removal rate” function is available as a new option in NUMROTOplus version 5.2.1 and higher.

If you are interested, please contact your machine manufacturer.