Grizzly G0705 Calculating Spindle Speed for Milling, To calculate the needed spindle speed in RPM

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Calculating Spindle

Speed for Milling

Before calculating the spindle speed for a milling operation, you must first understand the concept of "Cutting Speed" and how it differs from "Spindle Speed."

Cutting speed is defined as the rate at which a cutting tool's edge passes across the surface of a workpiece. It is generally measured in "surface feet per minute" (sfm), which represents the theoretical distance the cutting edge would travel across the material in a straight line in one minute.

Every workpiece material type has an ideal cut- ting speed to maximize cutting tool life, based on the hardness and microstructure of the mate- rial. The cutting speeds listed in Figure 29 are intended to serve as a basic guideline only. For a high degree of accuracy, we recommend referring to MACHINERY'S HANDBOOK or spindle speed calculators on the web for more detailed informa- tion.

Cutting Speeds for High Speed Steel (HSS)

Cutting Tools

Workpiece Material

Cutting Speed (sfm)

 

 

Aluminum & alloys

300

 

 

Brass & Bronze

150

 

 

Copper

100

 

 

Cast Iron, soft

80

 

 

Cast Iron, hard

50

 

 

Mild Steel

90

 

 

Cast Steel

80

 

 

Alloy Steel, hard

40

 

 

Tool Steel

50

 

 

Stainless Steel

60

 

 

Titanium

50

 

 

Plastics

300-800

 

 

Wood

300-500

Note: For carbide cutting tools, double the cut- ting speed. These values are a guideline only. Refer to the MACHINERY'S HANDBOOK for more detailed information.

Figure 29. Cutting speed table for HSS cutting

tools.

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It is important to note that the cutting speeds shown in Figure 29 do not represent the recom- mended spindle speed in RPM. The relation- ship between cutting speed and spindle RPM is dependent on the diameter of the installed cutting tool. When a tool's cutting edge rotates, as is the case with a milling machine, the cutting speed of that tool is directly proportional to its diameter. Tools with larger diameters produce greater cut- ting speeds because each cutting edge travels farther per revolution of the spindle. Therefore, a larger diameter cutting tool will require a slower spindle speed to achieve the same cutting speed as a smaller cutting tool.

To calculate the needed spindle speed in RPM:

1.Use the table in Figure 29 to find the cutting speed required for the workpiece material.

2.Measure the diameter of your cutting tool in inches.

3.Use the following formula to determine the needed spindle speed in RPM for your opera- tion:

4.Refer to Speed Changes on the next page to set your spindle speed to the position closest to the RPM value given by the formula.

5.During operation, adjust the feed rate by increasing or decreasing how fast you turn the handwheels to fine-tune the performance of the cutting operation. To maximize tool life, use the highest feed rate possible without bogging down the machine or causing the tool to chatter.

Failure to follow cutting speed guidelines when setting spindle speed may threaten operator and bystander safety with ejected parts or broken tools, and will put undue strain on moving parts, shorten tool life, and create poor workpiece results.

Model G0705 (Mfg. since 09/09)

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Contents Model G0705 Page Table of Contents Contact Info IntroductionManual Accuracy Machine DescriptionIdentification Machine Data Sheet Other Features Wearing Proper APPAREL. Do not wear SafetySafety Instructions for Machinery Hearing PROTECTION. Always wear hearSafety Instructions for Machinery Additional Safety for Mill/Drills Full-Load Current Rating Power SupplyAvailability Circuit InformationVoltage Conversion Grounding RequirementsExtension Cords Minimum Gauge Size 12 AWGTo rewire the Model G0705 for 110V opera- tion 110V ConversionJumper positions on terminal block Cord rewired for Model G0705 Mfg. since 09/09 Unpacking SetupNeeded for Setup Description QtyCrate Contents Figures 11 Qty InventoryNot Shown Cleanup Before cleaning, gather the followingSite Considerations Using the Included Leveling Bolt Mounting OptionsUsing Machine Mounts Mounting to Shop FloorAssembly Mounting to a WorkbenchTo assemble your machine Moving & Placing Machine LevelingTo move your machine into position Test Run Break-In To break in the spindleOperations Operation OverviewBasic Controls Spindle controls Model G0705 Mfg. since 09/09Head crank Calculating Spindle Speed for Milling Cutting Speeds for High Speed Steel HSS Cutting ToolsTo calculate the needed spindle speed in RPM To change spindle speeds Speed ChangesTools Needed Qty PositionUsing the Drill Bit Speed Chart Calculating Spindle Speed for DrillingLubrication Suggestions To operate the micro-adjustment handwheel Spindle HeightTo install tooling Loading ToolingTo remove tooling To install the drill chuck onto the arbor Drill Chuck Arbor Collet AdaptersTo use the drift key Depth Stop To calibrate the depth stopLongitudinal Feed Table TravelGraduated Dials Cross FeedG9299-10 Yuasa-Type Rotary Table AccessoriesH2689-R-8 Quick Change Collet Set G1076-52-PC. Clamping KitG9765-9-PC. Ball End Mill Set H8370-Power Feed for MillsG2861-Face Mill G4051-Carbide Insert for Face Mill G5641-1-2-3 Blocks G9815-Parallel Set H5556-Edge Finder SetMaintenance Cleaning ProtectingSchedule Points requiring periodic lubrication are LubricationTable Leadscrews Items Needed QtyBelts Belt tension Model G0705 Mfg. since 09/09Service TroubleshootingSymptom Possible Cause Possible Solution To adjust the table gibs To adjust the spring tensionGibs Return Spring Adjusting spring tension Tighten the black thumb knob Leadscrew BacklashWiring Wiring Safety InstructionsG0705 Wiring Diagram Electrical component locations Headstock Headstock Parts List DescriptionPCAP05 Base Base Parts List Electrical Components Breakdown and List 309Labels Breakdown and List Warranty Card CommentsGrizzly INDUSTRIAL, INC BOX BELLINGHAM, WAWarranty and Returns Warranty and ReturnsOrder Hours a DAY
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