The Grindometer

A valuable tool for comparing grinding wheels, evaluating grinding cycles, reducing cycle-times and troubleshooting grinding problems.

 

What it is: The Grindometer is a device that measures the grinding-wheel spindle power, in kilowatts or horsepower. This signal – when plotted vs. time – gives valuable information that can be used for comparing grinding wheels, reducing cycle times, eliminating grinding burn, and evaluating and troubleshooting grinding problems.

Who will benefit: The Grindometer is an excellent tool for people with have a good understanding of grinding and want to take their grinding operations to the next level. During his thousands of hours on the shop floor, Dr. Badger has used The Grindometer extensively. Examples of where The Grindometer has been used to evaluate wheels, reduce cycle times and troubleshoot grinding problems are given throughout The Book of Grinding.

Optimize Your Grinding Cycle

For a given set of grinding parameters, grinding workpiece temperature is proportional to grinding power. Therefore, an easy way to evaluate grinding wheels – and quickly determine which wheel is more likely to cause thermal damage and grinding burn – is to measure grinding power with the Grindometer.

How it

works

Facts

Wheel

Comparison

Cycle-time

reduction

Troubleshooting

Coolant

Evaluation

Thermal

damage

Example

companies

Technical

article

Cost &

Purchase

The Grindometer measures the current and the voltage in all three phases coming from the variable frequency drive into the grinding spindle motor and rectifies them to give the true grinding power, in kilowatts or horsepower. The signal is then sent to a data-logger, which can either log data offline, to be downloaded later, or sent directly to a laptop, to show a live plot of power vs. time.

 

This information is enormously useful in comparing grinding wheels, optimizing grinding cycles, evaluating coolants, troubleshooting grinding problems and reducing cycle times. It can also be used in grinding research for calculating specific energies and tangential forces.

 

 

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Caveat:

Measures actual power in kW or Horsepower (and not just current in amps) using three current clamps and three voltage clips.

 

Can be displayed live using a laptop or can be logged without a laptop and later downloaded.

 

13 hours uninterrupted without downloads, sampling at 10 samples/second. Good for overnight runs.

 

Most operators need about 8 hours on machine, hooking up and downloading to get a good handle on using both the hardware and software.

 

Either 110 AC or 220 AC; U.S.-style plug, U.K.-style plug or E.U.-style plug; specify upon ordering.

 

Included – explains hardware and software.

 

Includes four hours of off-site technical assistance from Dr. Badger via conference calls or Skype. Most companies choose to use this for grinding-cycle signal interpretation rather than instructions on how to use machine.

 

The Grindometer is an excellent tool for people who already have a good knowledge of grinding principles. It is not a “black box” – i.e., it will not tell the user what to do. Knowledge of grinding is necessary for drawing meaningful conclusions from the signal. The Grinding Doc will not sell a Grindometer to people with little to no grinding knowledge.

Most grinding wheel “tests” consistent of putting on the new wheel, grinding with the standard parameters of the current wheel, and seeing if anything drastic happens. Typically, wheel wear or grinding power are not measured, so no meaningful conclusions can be draw. This can be especially frustrating for wheel salespeople, as the wheel is typically run with the parameters that were optimized for the old wheel, giving the new wheel – even if it is indeed better – little chance of success.

 

The Grindometer gives a meaningful picture of how the wheel is behaving, particularly when evaluating grinding burn. The Grindometer signal is particularly useful when used in conjunction with the “No-Dress Test”, described in The Book of Grinding.

 

Right: Case-study of three different wheel specifications used in thread-grinding of taps, where thermal damage is of primary concern. Wheel 2 will give a significantly lower risk of thermal damage. However, this would not be known simply by listening to the grinding machine or by looking at the part after grinding.

When attempting to reduce cycle times, many grinders adopt the “grind faster” mentality – with disappointing results. A better approach is to map out the entire cycle, quantifying the time spent during grinding, dressing, cycling back, idle, part-change, etc., – and then make intelligent choices about which part of the cycle to address. When working with companies on reducing cycle times, Dr. Badger has had far more success with this approach than merely “grinding faster”.

 

The Grindometer is an excellent tool for visualizing a complete grinding cycle, both on a micro-level (a single cycle) and a macro-level (several hours over numerous parts). When the entire signal is seen in context, the decision about how to reduce cycle time is usually obvious.

 

Below: The Grindometer helps grinders visualize quickly where cycle-time is being wasted, both for a single workpiece (left: original cycle; center: new cycle) and for long runs over numerous workpieces (right).

The Grindometer power signal can reveal grinding problems that otherwise would be difficult to detect. Examples where the Grindometer was in troubleshooting:

  • An unknown surge in material removal rate (example: surge in multi-pass flute-grinding, when to slow down, how much to slow down).
  • A mini-crash of the wheel into the workpiece when offset distances are not set correctly, resulting in excessive wheel wear and loss of roundness.
  • Out-of-round or out-of-balance regulating wheel in centerless grinding (see example below).
  • Insufficient sparkout time (or too much sparkout time) in cylindrical-plunge grinding – Grindometer power signal tells user when steady-state has been reached.
  • Loading – Grindometer power signal increases with loading.
  • Poor self-sharpening – Grindometer power signal increases, particularly useful in ceramic-grit wheels.
  • Lack of dresser-wheel contact.
  • Incorrect programming – CNC grinding programs can be cryptic, the Grindometer can reveal anomalies.

 

Below: A centerless thru-feed operation that was producing chatter marks on the workpiece. A quick analysis of the power signal revealed surges – at 1.5 surges per second – which correspond to 90 RPM, the regulating-wheel speed. This quickly pointed the user toward an egg-shaped regulating wheel caused by an incorrect swivel angle and offset distance in dressing.

When changing to a new coolant, many companies take a “leap of faith” – trusting that the coolant-supplier’s new formulation will be better than the current formulation. Sometimes this works, sometimes it doesn’t (and occasionally it leads to disastrous results). A far better approach is to scientifically evaluate coolants – lubricating abilities (especially in materials with burn-sensitivity), ability to reduce loading (especially in carbide grinding), etc. – by measuring grinding power (and, therefore, heat generation). Since many coolants will be in a factory for 10+ years, choosing a good coolant over a mediocre coolant can result in savings millions of dollars in labor, scrap and wheel consumption. Taking a few days to evaluate coolants with The Grindometer is a worthwhile investment. Dr. Badger has assisted many companies with this simple yet important evaluation.

 

Below: Case-study of coolant evaluation in carbide-endmill grinding, performed with a large, international tool manufacturer and described in The Book of Grinding.

Thermal damage and “grinding burn” are caused by high workpiece temperatures. According to Jaeger’s Law of Grinding Temperatures, workpiece temperature is directly proportional to grinding power, which is what the Grindometer measures. Therefore, for a fixed set of grinding parameters, the Grindometer can be used to measure grinding power for different dressing conditions, grinding wheels and coolant configurations and directly assess the relative risk of burn. This approach is described in The Book of Grinding.

 

Below: Grinding power for two different sets of dressing conditions when grinding nickel-alloy turbine blades. For a fixed set of grinding parameters, workpiece temperature is proportional to grinding power. Therefore, Dressing Parameters 2 will give a lower risk of burn than Dressing Parameters 1.

Examples of companies who have a Grindometer®

U.S. carbide-tool manufacturer • turbine-blade manufacturer in Spain • crankshaft manufacturer in Brazil • grinding-wheel distributer in Germany • grinding-wheel manufacturer in Italy • HSS-tool manufacturer in Australia • U.S. carbide-tool manufacturer • grinding-wheel manufacturer in Mexico • HSS tool manufacturer in New Zealand •  U.S. tap manufacturer • grinding-wheel distributor in Mexico • U.S. carbide-shaft grinder • U.S. company grinding nickel-alloy turbine blades for the aerospace industry • carbide & PCD tool manufacturer in Sweden • grinding-wheel manufacturer in Israel • U.S. bearing manufacturer • tool manufacturer in Sweden • U.S. bearing manufacturer for the aerospace industry •  automobile-components manufacturer in Mexico • U.K. medical components manufacturer.

Technical article on power-monitoring

Article in Industrial Diamond Quarterly on power-monitoring in grinding. Download here.

Note: The Grinding Doc is currently developing Grindometer Deluxe, a wireless, stand-alone, plug-&-play unit that will be launched in 2020. Because of this, the standard Grindometer which has been available for ten years is no longer available for purchase. However, The Grinding Doc is offering the refurbished Grindometer, which is exactly the same as the standard Grindometer but produced from used components, at a much lower cost. It includes a one-year warranty.

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Alternate Payment:

$US 13500

 

$US 4650 / €4150

 

None. The refurbished Grindometer is identical to the original Grindometer, but is built from used components and then tested in-house before shipping.

 

One year.

 

Power meter, hall-effect current transducers and voltage clips, data-logger, software, instruction manual and all necessary cables, assembled in carry-on-sized plastic case. No additional components required. Can be used immediately upon delivery.  Comes with four hours off-site technical assistance from Dr. Badger for interpreting power signal to analyze grinding cycle.

 

Typically ships within one week of payment (postage included in price).

 

  1. Send email to admin@TheGrindingDoc.com.
    Specific voltage (110 VAC or 220 VC) and plug type (US, UK or EU).
  2. Pay.

 

Credit card

  $4650 in US dollars, click here

  €4150 in euros, click here

 

Payment can be made via check in US dollars, bank transfer in US dollars, or bank transfer in euros. Details and an official invoice can be found here.