BIZOMAT MAKEOS · Manufacturing
Surface Grinding Planner (Speeds, Removal Rate, Power and Time)
What wheel speed, removal rate and spindle power does this surface grinding job need, and how long will it take?
Plan of a reciprocating surface grinding operation with the wheel covering the work width: wheel surface speed against the wheel’s maximum operating speed, speed ratio, contact length (as the grinding geometry tool), equivalent chip thickness, specific removal rate and removal rate, grinding power from your specific grinding energy against the spindle power, and passes and time for the stock with spark-out passes.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Wheel diameter | mm | Diameter of the grinding wheel. |
| Wheel speed | rpm | Spindle speed. |
| Wheel maximum operating speed (marked) | m/s | Maximum operating speed marked on the wheel; never exceed it. |
| Table speed | m/min | Table (work) speed. |
| Depth per pass | mm | Down-feed per pass. |
| Width ground | mm | Width of the ground surface (the wheel covers it in each pass). |
| Work length | mm | Length of the work. |
| Overtravel each end | mm | Overtravel beyond the work at each end. |
| Stock to remove | mm | Total depth to remove. |
| Spark-out passes | Passes with no down-feed at the end. | |
| Specific grinding energy | J/mm³ | Specific energy to grind the material with this wheel (your value from tests or the wheel maker; much higher for fine finishing cuts). |
| Spindle motor power | kW | Rated power of the spindle motor. |
| Spindle efficiency | % | Share of motor power available at the wheel. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Wheel diameter
- What it is
- The outside diameter of the grinding wheel as it is now. It sets the wheel surface speed and the contact length.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wheel speed rises in proportion to diameter.
- Get it right
- Use the current diameter; as the wheel wears and is dressed, its surface speed at the same rpm falls.
What this means: Wheel speed
- What it is
- The rotational speed of the grinding spindle and wheel.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2600 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wheel surface speed rises in proportion.
What this means: Wheel maximum operating speed (marked)
- What it is
- The highest surface speed the wheel is rated for, printed on the wheel or its label. The tool checks the calculated wheel speed against it.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 200 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 35 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- If the wheel is marked only in rpm, compare the spindle speed with that marked rpm directly.
What this means: Table speed
- What it is
- The speed at which the table carries the work past the wheel.
- Units and format
- Enter a number in m/min: metres per minute. The form accepts 0.000001 m/min to 100 m/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 m/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Removal rate and power rise in proportion, and grinding time falls in proportion.
- Get it right
- m/min, not m/s; the tool converts it.
What this means: Depth per pass
- What it is
- The down-feed of the wheel into the work for each pass: the depth of material removed per stroke.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.01 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Removal rate and power rise in proportion; fewer passes are needed.
- Get it right
- This is per pass, not the total stock to remove.
What this means: Width ground
- What it is
- The width of the surface being ground, covered by the wheel in each pass.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 40 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Removal rate and power rise in proportion.
What this means: Work length
- What it is
- The length of the workpiece in the direction the table travels.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Grinding time rises with the stroke length.
What this means: Overtravel each end
- What it is
- The extra table travel beyond the work at each end so the wheel clears the part fully before reversing. The tool adds it twice per stroke.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 500 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 25 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter the overtravel at one end only.
What this means: Stock to remove
- What it is
- The total depth of material to grind off the surface, from the rough size to the finished size.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 20 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Spark-out passes
- What it is
- The number of final passes made with no down-feed, letting the wheel finish out the deflection of the machine and work.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 50. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Specific grinding energy
- What it is
- The energy needed to remove one cubic millimetre of the material with this wheel and condition, from your tests or the wheel maker.
- Units and format
- Enter a number in J/mm³: J/mm³. The form accepts 0.000001 J/mm³ to 500 J/mm³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30 J/mm³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Grinding power rises in proportion.
- Get it right
- Fine finishing cuts need much more energy per mm³ than roughing; use a value for the actual depth of cut.
What this means: Spindle motor power
- What it is
- The rated power of the motor driving the grinding spindle, from the machine data plate.
- Units and format
- Enter a number in kW: kilowatts. The form accepts 0.000001 kW to 10000 kW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Spindle efficiency
- What it is
- The share of the spindle motor’s power that reaches the wheel after belt, bearing and motor losses.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 10% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 80% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Lower efficiency reduces the power available at the wheel.
- Get it right
- Type a percentage (80 for 80 %), not a fraction.
Method and formulas
- Wheel speed v_s = π d_s n_s ÷ 60 000; speed ratio = v_s ÷ v_w.
- Contact length l_g = √(a_e d_s) (as the grinding geometry tool); equivalent chip thickness h_eq = a_e v_w ÷ v_s.
- Removal rate Q = a_e b_w v_w; power = u Q.
- Passes = stock ÷ a_e (rounded up) + spark-out; time = passes × (L + 2 overtravel) ÷ v_w.
- Example: the wheel runs at 34.034 m/s; removing 100 mm³/s takes 3 kW and the job takes 0.51333 min.
Limitations
- One stroke per pass (wheel at least as wide as the work); cross-fed grinding needs more strokes.
- Specific energy varies strongly with wheel sharpness and depth of cut.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan a surface grinding operation
- Check the spindle power for a deeper cut
- Check a wheel speed against its marked maximum
Who it is for
- Grinding machinists
- Process planners
- Manufacturing engineers
What you get
- Wheel speed, speed ratio and contact length
- Removal rate and grinding power
- Passes and grinding time
Interpreting the result
- Halving the depth per pass halves the power but doubles the passes; a faster table can keep the time down.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1199–1268. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Grinding on a magnetic chuck
In Magnetic Workholding by the Numbers
What it covers: Surface grinding forces against magnetic holding, why a bowed part ground flat on the chuck springs back, thermal bow from grinding heat, chuck heating, and measuring at the right temperature.
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Open the Surface Grinding Planner (Speeds, Removal Rate, Power and Time) calculator