Beginner’s Glossary of Feeds and Speeds Terminology

Hint: Keep this open in a browser tab while you’re learning G-Wizard

Term

Definition

When and Why Do I Need It?

Where Do I Find It?

Acceleration How fast your machine can change speed or direction of an axis in motion. This is only used by G-Wizard Editor to adjust its execution time estimate for G-Code.
Adj. Chipload Adjusted chipload is the chipload after it has been increased to offset effects like lead angle and radial chip thinning. It’s informational and only differs from chipload if your cut width is less than the radius of the cutter. Beginners should ignore it.
Adjust The Adjust button on the Machine Profile lets you apply power curves and machine weight compensation.

If you have power curve information for your spindle this will help ensure G-Wizard keeps feeds and speeds within the limits of the curve so stalling the spindle is less likely.

If you have a lightweight machine, using machine weight compensation will reduce spindle power to compensate for the fact that the machine is less rigid than full sized professional CNC machines.

These are advanced features to help you get the most out of your machine. A beginner might ignore them initially.

Axial Engage Short for “Axial Engagement”. It is basically what percentage of a diameter your Cut Width is. Informational only. Useful if you have some notion of what engagement you prefer to use for your work Beginners should ignore it.
BHN (Hardness) BHN is the Brinell hardness of a material. G-Wizard will adjust feeds and speeds based on the exact material and how hard it is. If you don’t know, just use the general family of the material. If you have more detail, click the “More” button and try to find your exact material. Or, choose the family and use “More” to enter your own Brinell Hardness value.
Chipload Chipload is how thick of a chip the cutter will cut. Beginners can ignore this. Others may use it to make sure they’re in a familiar range or to specify the chipload based on Manufacturer’s Recommendations for the specific brand of cutter you use. G-Wizard is fairly conservative, so again, Beginners can ignore it.
Chipload Adjustment A percentage adjustment to the chipload G-Wizard wants to use. This is a parameter on the Machine Profile. You can use it to permanently all cuts either more or less aggressive on chipload. Considered an advanced tuning parameter that Beginners should strictly leave alone until you really understand all that it entails.
ci Abbreviation for “cubic inches”. This is the Imperial unit for MRR (Material Removal Rate).
Climb Milling This refers to the relationship of cutter rotation to direction of feed. Refer to our free tutorial on Climb vs Conventional Milling for details. The Tips may tell you whether Climb or Conventional Milling is best for the scenario you’ve chosen for Feeds and Speeds.
Conventional Milling  This refers to the relationship of cutter rotation to direction of feed. Refer to our free tutorial on Climb vs Conventional Milling for details. The Tips may tell you whether Climb or Conventional Milling is best for the scenario you’ve chosen for Feeds and Speeds.
Coolant Refers to the various coolant options such as flood, mist, etc.. G-Wizard expects you to keep the chips clear and to provide lubrication for materials that will stick to the tool like aluminum. Beyond that, it makes no assumptions about coolant (dry, mist, flood, or whatever) except for the premium coolant options like TSC or PCN.
Coolant on/off time Time it takes for coolant to start or stop flowing once it is turned on. This is only used by G-Wizard Editor to help calculate run times of gcode programs.
Corner Adjust This is how much you should slow down in corners for optimum results if you’re not running an HSM tool path.

Most CNC’ers will ignore this. Consider using it for special situations where you want to get the fastest possible cycle times. Figure out the straight line fastest feedrate and then slow down by this much in corners.

You’ll find the Corner Adjust in the HSM area of Feeds and Speeds.

Curve Compensation Spindle Power compensation based on a power curve that relates spindle power to rpm. You specify this after clicking the “Adjust” button on the Machine Profile under Setup.
Cut KB Cut Knowledge Base The Cut KB lets you keep a record of prior cuts along with notes about how well they worked. Use it to record things like chatter and what happened when you sped up feeds and speeds so you can take advantage of the information down the road.
Deflection Refers to Tool Deflection. If we push a tool too hard, it will bend or deflect. Too much Tool Deflection leads to excessive wear and chatter which is even worse for Tool Life.

Tool Deflection is calculated and displayed for every cut in the Feeds and Speeds Calculator. You can calculate Cut Width, Cut Depth, and/or Feedrate to minimize Deflection with the Cut Optimizer.

If the Deflection is displayed in Red, it exceed recommended limits and should be dealt with.

Est. TEA Estimated Tool Engagement Angle Press the Est. TEA button to estimate tool engagement angle for a corner of a specific angle. There’s no need to do this if you have an HSM toolpath. G-Wizard will figure the TEA from the Cut Width (Stepover).
Feedrate How fast the tool will be fed into the cut.

G-Wizard tells you the Feedrate in the Results area. This is the “Feeds” part of “Feeds” and “Speeds.”

Note that there are two Feedrates displayed. The one immediately to the right of the Feedrate label is the normal feedrate. Optional a “Plunge” feedrate may be displayed. See Plunge for more.

Feedrate Factor When using an HSM toolpath, the feedrate may be sped up by the Feedrate Factor. The Feedrate Factor is displayed in the HSM area. Clicking the “Use HSM” checkbox will cause G-Wizard to increase the Feedrate by the Feedrate Factor.
Flood “Flood” refers to Flood Coolant Flood Coolant is a coolant option found on the Machine Profiile. With Flood Coolant, liquid coolant is sprayed directly onto the part.
Flutes The number of cutting edges or inserts on the cutter. Flutes are specified in the Feeds and Speeds Calculator.
Hourly Rate The Hourly Rate the machine should be charged at. Hourly Rates are only used by G-Wizard Estimator. It includes an Hourly Rate Calculator to make it easy to estimate what hourly rate you should be charging.
HP Horsepower, the spindle power. Found on the Feeds and Speeds calculator and Machine Profiles.
HSM Feeds and Speeds HSM is the abbreviation for High Speed Machining. These are special toolpaths that keep a constant tool engagement angle. Feeds and Speeds includes an HSM option to calculate feeds and speeds when using HSM toolpaths.
Interpolate Interpolation is the process of making a hole by moving an endmill in a helical pattern. Pressing the Interpolate button brings up the Interpolation Mini-Calc which can be used to figure feeds and speeds for accurate hole interpolation. This is an advanced function beginners need not worry about.
IPR IPR is the abbreviation for “inches per revolution.” This is basically the chipload times the number of flutes. Looked at another way, if you had a cutter removing the same material that only had one flute, it would slice off one chip that was IPR inches thick each revolution of the spindle. This is an informational figure displayed in Feeds and Speeds. Beginners should just ignore it.
IPT IPT is the abbreviation for “inches per tooth”, which is basically the same as chipload. See chipload above.
Machine Profiile    
Machine Weight The weight of the machine. This appears on the Machine Profile and is used for the weight adjusted power curve that compensates for the low rigidity of smaller machines.
Max Feed The Maximum Feedrate the CNC machine is capable of while cutting. Appears on the Machine Profile and also on the Feeds and Speeds applet. G-Wizard will limit feeds to this value.
Max Rapids The Maximum Feedrate the CNC machine is capable of while moving the cutter. Normally the same as Max Feed, but some machines can move faster than they can cut accurately. Appears on the Machine Profile
Min Word Time Minimum time to process any g-code word. Faster controllers have shorter times. This is used by G-Wizard Editor to estimate gcode execution time.
Mini-Calc G-WIzard Calculator includes a collection of special calcuators for special CNC situations called “Mini-Calcs”. Mini-Calcs are accessed as a row of buttons in the Mini-Calc area of the Feeds and Speeds applet.
Mist A type of coolant comprised of droplets of mist suspended in a stream of compressed air and sprayed onto the part and cutter. This is a coolant option on the machine profile. G-Wizard doesn’t award an advantage for flood or mist. It assumes you’ll do whatever it takes to clear chips and to lubricate when cutting materials that stick to cutters like aluminum.
MRR MRR is the abbreviation for “Material Removal Rate.” MRR is a measure of how quickly material is being removed. Faster MRR’s mean shorter cycle times. CADCAM Wizards try to optimize the cutting recipe for best MRR’s.
PCN PCN is the abbreviation for “Programmable Coolant Nozzle”, a type of premium coolant system. PCN options appear on the Machine Profile and Feeds and Speeds applet. If you select PCN in Feeds and Speeds you will get higher feedrates as a bonus. You must tell G-Wizard your machine has a Programmable Coolant Nozzle in the Machine Profile before you can select the option in Feeds and Speeds.
Plunge Plunge is the Plunge Feedrate. This is the rate you can feed an endmill if you plunge it straight down.

Endmills can’t cut as quickly when plunged as when they cut with their sides. Be sure to use the Plunge Feedrate whenever plunging.

Plunge is also the name of the Mini-Calc used to calculate feedrates for Plunge Milling toolpaths.

Radial Engage Radial Engagement is the amount of cutter actually in the cut lengthwise along the axis of the cutter. It is expressed as a percentage of diameter. Displayed on Feeds and Speeds for informational purposes. Beginners may ignore it.
Ramp Ramp is a Mini-Calc used to slow down Feeds and Speeds when ramping down into a cut. Pressing the Ramp button brings up the Ramp Mini-Calc which can be used to figure feeds and speeds for a ramping entry to a pocket. This is an advanced function beginners need not worry about.
RPM Spindle RPMs Spindle RPM’s are the “Speeds” part of Feeds and Speeds. G-Wizard recommends the best RPM for the cut based on parameters you enter.
RPM Factor When using an HSM toolpath, the spindle rpms may be sped up by the RPM Factor. The RPM Factor is displayed in the HSM area. Clicking the “Use HSM” checkbox will cause G-Wizard to increase the spindle rpms by the RPM Factor.
Sfc. Speed Surface Speed is a measure of how fast the cutting edge is moving across the material as it cuts a chip. The limiting factor is generally heat if the surface speed is too high. Surface Speed is shown for the cut. Beginners can ignore this. Others may use it to make sure they’re in a familiar range or to specify the surface speed based on Manufacturer’s Recommendations for the specific brand of cutter you use. G-Wizard is fairly conservative, so again, Beginners can ignore it.
SFM SFM is an abbreviation for “Surface Feet Per Minute”, a measure of Surface Speed. See “Sfc. Speed” for more.
Sim Time Adj Sim Time Adjust is a percentage adjustment that can be applied to calculated time it will require for a gcode program to execute. Appears on the Machine Profile. It’s only used by G-Wizard Editor.
Slot Slot refers to cutting a full width slot. Pressing the “Slot” button sets the cutter diameter to full width. Note that if you are using a tool that is tapered or ballnosed, you will be limited to the effective diameter based on the cut depth.
Spindle Type Spindle Type refers to the spindle taper type. Beginners, if you don’t recognize your spindle taper type just put in “Other.” It’s a conservative choice.
Stepover Stepover is a synonym for Cut Width.  
Stickout
This unsupported length of the tool. Measure from tool tip to where the tool goes into the tool holder. On tools smaller than 1/8″, measure from tip to where the larger diameter shank reaches full diameter. Stickout is very important for tool deflection calculations.
Surface Finish Surface finish refers to the smoothness of the finish based on ridges left by successive tool passes. There is a Surface Finish Mini-Calc that is available for Ballnosed Endmills and for Lathe Turning.  
Surface Speed Surface Speed is a measure of how fast the cutting edge is moving across the material as it cuts a chip. The limiting factor is generally heat if the surface speed is too high. Surface Speed is shown for the cut. Beginners can ignore this. Others may use it to make sure they’re in a familiar range or to specify the surface speed based on Manufacturer’s Recommendations for the specific brand of cutter you use. G-Wizard is fairly conservative, so again, Beginners can ignore it.
TEA TEA is an abbreviation for Tool Engagement Angle TEA is part of the HSM Toolpath feeds and speeds calculator. When using an HSM Toolpath, it is calculated automatically based on the Cut Width. Beginners should avoid HSM Toolpaths until they get some experience under their belts.
Tool Change Time The chip to chip time in seconds for a tool change. Used by G-Wizard Editor and Estimator to calculate cycle times.
Tool Changer Slots Number of slots in your machines tool changer. Enter “1” if your machine has no tool changer.  
Tool Engagement Angle See TEA.  
Tool Life Refers to the effect on Tool Life of reducing the rpms or surface speed. G-Wizard Calculator has a built-in Tool Life calculator based on the Taylor equations that will tell you how much a reduction in RPM can save you in terms of increased tool life. This feature is found on the Machine Profile.
Torque The Torque on the cutter based on current feeds and speeds. Found in the column headed by MRR on the Feeds and Speeds calculator. Probably not of interest to many and not for Beginners.
Tortoise – Hare The Tortoise-Hare slider can be used to dial a cut in from conservative finishing cut (Tortoise) to aggressive roughing cut (Hare). It adjusted chipload and rpms according to its position. The far left (full Tortoise) position is special as it is the slowest you can go without rubbing. The Tortoise Hare slider may be found on the Feeds and Speeds Calculator as well as CADCAM Wizards.
Travels Travels refers to the distance the various axes on a CNC machine can move. Travels are used by G-Wizard Editor.
TSC TSC is the abbreviation for “Through Spindle Coolant”, a type of premium coolant system. TSC options appear on the Machine Profile and Feeds and Speeds applet. If you select TSC in Feeds and Speeds you will get higher feedrates as a bonus. You must tell G-Wizard your machine has Through Spindle Coolant in the Machine Profile before you can select the option in Feeds and Speeds.
Vacuum Vacuum is a special Mini-Calc that will limit cutting forces to the amount of force a vacuum table or fixtue can apply to the part so that you don’t pop your parts of the vacuum table. The Vacuum Mini-Calc is accessed by pressing the “Vacuum” button in the Mini-Calc area.
Weight Adjusted Weight Adjusted is a special Spindle Power setting that derates Spindle Power based on the work envelope (travels) and weight of the machine. It seeks to compensate for machines that lack the rigidity of Professional quality VMC’s. It is accessed by pressing the “Adjust” button on the Machine Profile.