BIZOMAT MAKEOS · Manufacturing
Stock Removal Plan (Bar Volume, Chips, Machining Time, Power)
How much of this bar blank turns into chips, how long does it take to remove at my cutting conditions, and does the machine have the power?
Plan for machining a part from round bar: stock volume and mass from the bar diameter and cut length (as the solid volume tool), the material removed for the finished part volume and the material yield, the metal removal rate, cutting and motor power from the specific cutting force (as the turning power tool), the cutting time to remove the stock, and the stock cost, checked against the machine power and your least yield.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Bar diameter | mm | Diameter of the bar stock. |
| Cut length of the blank | mm | Length of bar cut for one part, including facing and parting allowances. |
| Finished part volume | cm³ | Volume of the finished part (from CAD). |
| Density | kg/m³ | Density of the material. |
| Bar price | $/kg | Price of the bar. |
| Cutting | ||
| Cutting speed | m/min | Cutting speed for roughing. |
| Feed | mm/rev | Feed per revolution. |
| Depth of cut | mm | Depth of cut. |
| Specific cutting force kc | N/mm² | Specific cutting force of the material. |
| Machine efficiency | % | Efficiency of the spindle drive. |
| Available spindle power | kW | Spindle power. |
| Least material yield | % | Least share of the bought material that ends up in the part. |
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: Bar diameter
- What it is
- The diameter of the round bar stock the part is machined from.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Stock volume, mass and cost rise with the square of the bar diameter.
- Get it right
- Use the actual bar size you buy, which is often a little larger than the largest finished diameter.
What this means: Cut length of the blank
- What it is
- The length of bar cut off for one part, including the facing allowance, the parting width and any length held in the chuck.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Stock volume, mass and cost rise in direct proportion to the cut length.
- Get it right
- Include the parting and facing allowances, not just the finished part length.
What this means: Finished part volume
- What it is
- The volume of material left in the finished part, normally read from the CAD model.
- Units and format
- Enter a number in cm³: cubic centimetres. The form accepts 0 cm³ to 100000000 cm³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 150 cm³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger finished volume means less material removed, a shorter cutting time and a higher yield.
- Get it right
- Enter cubic centimetres, not mm³: 1 cm³ = 1000 mm³.
What this means: Density
- What it is
- The density of the bar material, used to turn the stock and chip volumes into masses.
- Units and format
- Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.000001 kg/m³ to 20000 kg/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 7850 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Stock mass, chip mass and stock cost rise in direct proportion to density.
What this means: Bar price
- What it is
- The price per kilogram of the bar, from your supplier quotation or stock price list.
- Units and format
- Enter a number in $/kg: money per kilogram. The form accepts $0/kg to $10000/kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with $3/kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The stock cost rises in direct proportion to the price.
- Get it right
- If you buy by the metre, divide the price per metre by the mass per metre.
Cutting
What this means: Cutting speed
- What it is
- The roughing cutting speed at the tool edge, from the insert maker’s data for this material.
- Units and format
- Enter a number in m/min: metres per minute. The form accepts 0.000001 m/min to 5000 m/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 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 direct proportion to cutting speed, and the cutting time falls.
- Get it right
- Enter metres per minute, not spindle speed in rpm.
What this means: Feed
- What it is
- The feed of the tool for each revolution of the part when roughing.
- Units and format
- Enter a number in mm/rev: millimetres per revolution. The form accepts 0.000001 mm/rev to 10 mm/rev. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 mm/rev 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 direct proportion to feed, and the cutting time falls.
- Get it right
- Feed per revolution, not per minute.
What this means: Depth of cut
- What it is
- The radial depth of each roughing cut, measured from the surface before the cut to the surface after it.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 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 direct proportion to depth of cut, and the cutting time falls.
- Get it right
- Depth of cut is on the radius; the diameter shrinks by twice this per pass.
What this means: Specific cutting force kc
- What it is
- The specific cutting force of the material: the cutting force per square millimetre of chip section, from the tool maker’s data.
- Units and format
- Enter a number in N/mm²: newtons per square millimetre (equal to MPa). The form accepts 0.000001 N/mm² to 10000 N/mm². Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2000 N/mm² as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Cutting and motor power rise in direct proportion to the specific cutting force.
- Get it right
- Take it from the tool maker for your material group and feed; it changes with chip thickness.
What this means: Machine efficiency
- What it is
- The efficiency of the spindle drive from motor to cutting edge, used to turn cutting power into motor power.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% 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
- A lower efficiency raises the motor power needed.
- Get it right
- Type the percentage itself (85 for 85 %), from the machine maker if known.
What this means: Available spindle power
- What it is
- The spindle motor power the machine can supply, from the machine specification.
- 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 15 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the continuous rating at the spindle speed you will run, not the short-time peak.
What this means: Least material yield
- What it is
- The smallest share of the bought bar material that must end up in the finished part for the route to be acceptable.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 40% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Type the percentage itself (50 for 50 %).
Method and formulas
- Stock volume = π D² ÷ 4 × L (as the solid volume tool); removed = stock − finished.
- Removal rate Q = v_c × a_p × f; cutting power = k_c a_p f v_c ÷ 60 000; motor power = cutting ÷ efficiency (as the turning power tool).
- Cutting time = volume removed ÷ Q; yield = finished ÷ stock.
- Example: 282.74 cm³ of bar, 132.74 cm³ to chips (53.052% yield); 44.248 s at 180 cm³/min and 7.5 kW.
Limitations
- Roughing time only; finishing, tool changes and handling are extra.
- Constant removal rate; small diameters may be speed-limited.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Decide whether a part is better near-net-shape
- Estimate roughing time from bar
- Check a machine’s power for heavy roughing
Who it is for
- Process planners
- Estimators
- Machinists
What you get
- Stock volume, mass and cost
- Volume removed, chip mass and yield
- Removal rate, power and cutting time
Interpreting the result
- Low yield on costly material points to forgings, castings or near-net bar sizes.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 82–88, 1084–1101. Topic reference; no source tables or recommended settings are reproduced.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Stock Removal Plan (Bar Volume, Chips, Machining Time, Power) calculator