Chatter 1

[vibegeek]

What technologies are currently being used to monitor for and control chatter in grinding applications?

 

[humboldt]

For a correct answer you should explain if you have to work with grinding wheels or with belts and on which machine.

 

[ornerynorsk]

The human ear is probably the most sophisticated mechanism to monitor for chatter. Experience is the remedy.

 

[RamingtonStall]

Concerning the monitoring of Chatter, I agree with Humboldt and ornerynorsk.

Concerning the correction, IF you are talking about Grinding, then:
1) Machine and Set-up Rigidity. Grinding wheel speed, feed rates, etc.
2) Grinding wheel condition as far as Wheel Trueing, Wheel Dressing, and perhaps Conditioning or "Wear-In".
3) Grinding wheel Grade to take into account workpiece geometry, material, operation, desired stock removal, desired grinding rate, surface finish and tolerances, etc.
4) Coolant type and application method,

More specific Questions would be required for more specific answers.

 

[Abrasive]

Chatter isn't a simple problem since it can come from many origins and there are many different solutions. The problem is essentially created by resonance within the machine tool that amplify vibrations that can originate in a wide variety of sources ranging from wheel slippage to noise from nearby machine tools. From a theoretical and technical perspective, a good summary of the state-of-the-art understanding of chatter was presented by I. Ianaski at a recent CIRP meeting. A copy of his paper, Grinding Chatter - origin and suppression, was provided to SME Members last year in an electronic format. One solution described in the paper has been to vary the speed of the grinding wheel to prevent the onset of steady state vibrations that are a source of resonance. Other solutions include introducing vibrations into the machine tool in a phase relationship that essentially cancels the culprit vibration regardless of their source. Of coarse from a practical prespective one can conduct a trial and error process to isolate the source of vibration and then make appropriate corrections. But that take time and effort. What to do next will depend upon how serious the problem is and how badly you need to resolve it.

 

[vibegeek]

I'm mostly interested in grinding wheel applications in a production environment where some on-line type of monitoring is needed to alert operators to difficulties. Has anyone seen such a thing that actually works?

 

[RamingtonStall]

There are Grinding Cycle Monitors available which can be either portable units to connect to permanent pick-ups on the machines. Alternately, you could connect such Grinding Cycle monitors to the machines on a Spot Check or Specific Problem Solving basis.

These Grinding Cycle Monitors are used in the Bearing Industry as well as many Cutting Tool Industry applications. Normally, however, where these GCM units are being used, the problems are more advanced than a simple Chatter Detector.

Also, Grinding wheel consultants can frequently modify the system for Wheel type and Grade, Wheel Speed, Coolant type and application method, Trueing/Dressing methods, infeed and thrufeed rates, etc., etc.

Would Need Specifics to advise further. RamS@Free-Market.net

 

[metrat]

Various types of vibration monitors are typically used to aid in identifying the cause of chatter, as RamingtonStall indicated. We typically look at various frequencies and base line critial machines to identiy potential problems early. They can also be used to fine tune a process to avoid problems.
Different grinding processes (centerless grinding vs. internal grinding) may requires somewhat different approaches.