You should put some images in here with certifications like the Better Business Bureau or any awards General Cutting Tools has. January 14, 2010
Greenfield Threading Tech Tip: Controlled Feed Rates When Thread Milling
Greenfield along with Cutting Tools Chicago aka General Cutting Tools defines controlled feed rates when thread milling. For thread milling applications, we recommend setting controlled feed rates within the program for the centerline of the spindle or tool. This method ensures absolute feed control of the tool through the entire thread milling operation.
As the tool moves around the centerline of the bore, the tool centerline must traverse at a slower IPM rate than the periphery of the tool at the cutting edge or major thread diameter. If the standard feed rate of RPM x feed per flute x number of flutes was applied to the spindle centerline, the tool would have an effective feed rate at the cutting edge that may exceed the capability of the thread mill, resulting in poor tool life and possible breakage. The programmed feed rate for the centerline is based upon the thread mill diameter selected. The larger the tool diameter, the greater the reduction required to ensure the proper operating parameters on the periphery.
Feed Compensation Formula for Internal Threading:
Centerline ‘PM2 = ‘PM1 x (Major Thread Diameter – Tool Cutting Diameter) Major Thread Diameter
Feed Compensation Formula for External Threading:
Centerline ‘PM2 = IPM1 x (Major Thread Diameter + Tool Cutting Diameter)
Major Thread Diameter
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January 13, 2010
Greenfield Basic Machining Tech Tip: Coolant Considerations
Although Greenfield Tap and Die manufactures cutting tools and not coolant, we at Cutting Tools Chicago aka General Cutting Tools understand how coolant can dramatically affect the performance of our tools and, ultimately, the cost of your operation.
Coolant performs two basic functions when used in drilling, milling, and threading applications:1) to reduce the heat generated during cutting, and 2) to lubricate and reduce friction between the chip and the tool.
Coolant, which is mostly water, helps to cool the chip when it is sheared away from the workpiece. It includes a small amount of oil which acts as a lubricant to improve the surface finish and evacuate cut chips from the flutes.
Because excessive heat and friction can dull a tool, coolant helps to extend tool life. Using the recommended water/oil ratio is important. Too often, users will alter this ratio significantly in an effort to reduce cost. This can cause tool life to decrease rapidly. For example, a drill which normally yields thousands of holes, may now only last for a few hundred holes.
When selecting a coolant, choose one that is suitable for both the material and the particular machining operation and follow the manufacturer’s mixing recommendations. For example, high-speed machining with carbide tools might require coolant, while tapping might require cutting oil.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 12, 2010
Greenfield Tech Tip: Selecting Coarse vs. Fine Threads
Cutting Tools Chicago aka General Cutting Tools along with Greenfield Tap and Die will explain how to choose between coarse and fine threads.
Coarse Threads:
Coarse threads are commonly used in applications requiring rapid assembly or disassembly and when corrosion or damage from handling or use is likely to occur. They allow for easier starting with less cross threading. In relatively low-strength materials such as cast iron, aluminum, magnesium, brass, bronze, and plastic, coarse threads provide more resistance to stripping than fine or extra fine threads. If subjected to heat, they are less likely to seize than fine threads.
Fine Threads:
Fine threads are commonly used for nuts and bolts in high-strength applications. While applications vary, in general, fine threads are approximately 10% stronger than coarse threads. They have less tendency to loosen under vibration because the smaller lead or thread helix angle provides better wedging action when the assembly is tightened. Fine threads are also used for fine adjustment and thin-walled applications due to the shallower thread height. The shallower thread height lowers the chip load per tooth and chip volume resulting in less tapping torque and breakage, particularly in difficult to machine materials. Less chip vc also means that more lubrication will reach the cutting teeth yielding longer tap life. Fine threads are generally easier to tap but require a larger tap drill than coarse threads, which improves the performance of the drill and tap.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 11, 2010
Greenfield Tech Tip: Tap Drill Charts – The Right Information?
Greenfield along with Cutting Tools Chicago aka General Cutting Tools answers the question of whether tap drill charts have the right information. While many factors contribute to tap failure, drill hole size is one that is often overlooked. When a problem arises, you may check the drill size being used against a tap/drill chart. If it appears correct, you might look for some other cause for the failure. But, are the tap/drill charts giving us the right information?
First, it is important to note that these tap/drill charts were developed in the 1950s and 60s. Drill diameters for the various thread sizes were selected based upon the “probable” hole size a standard bright jobber drill with a conventional point would produce. For example, a #7 (.201 “) diameter drill used for a 1/4-20 thread would generally produce a hole that was approximately .004″ larger than the drill’s diameter, or about .205″. Comparing that to the .196-.207 hole size required for that tap, the #7 drill produces a hole near the maximum limit, which is ideal. This results in an approximate 70% thread height. Removing most of the excess material with the drill significantly reduces the load on the tap without reducing the strength of the thread.
Today, things have changed significantly. There are many advanced drill designs, materials, points, coolant holes, and coatings. The accuracy of all drills has also improved dramatically due to enhanced drill manufacturing equipment and processes. Today’s advanced drills, powered by more accurate, highspeed, computer-controlled machine tools, are producing holes much closer to, or even the same as, the actual size of the drill.
Using modern drills, CNCs, and holders with conventional drill charts could result in tap breakage where none existed before. The #7 drill may no longer be the correct drill size for a 1/4-20 thread. It may be producing a hole much too small for successful tapping. While it is recommended that the tap/drill chart be used as a reference, or starting point, for selecting a drill diameter for the best hole size, the finished hole size is the most important factor. In the case of the 1/4-20 thread, any drill that produces a hole close to .207″ could be used. Even a #5 (.2055″) or a special diameter may be acceptable based upon the drill design and conditions.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 10, 2010
Greenfield Tech Tip: Shrinking Threaded Holes
Shrinking threaded holes is Greenfield Tap tech tip from Cutting Tools Chicago aka General Cutting Tool. At times, threaded holes will “close in” or shrink due to either heat or build-up. In both cases, the threaded hole becomes tighter in the process. To correct this condition, use a slightly larger tap to compensate for shrinkage. This practice is common for parts to be plated.
If build-up occurs, try this simple solution: Multiply the amount of build-up by four, and then increase the tap’s H limit size accordingly. For example, if the build-up equals .00025″ build-up, then .00025 x 4 = .0010. .001 ” is equivalent to two H limits; therefore, if you were using H6, you should use H8.
If the shrinkage occurs due to heat, the solution is to use a larger tap. While there is no formula that will give you an exact number for choosing a larger tap, our recommendation is to use your GO gage as a guide. If the GO fits snugly, but still enters all the way, one or two H limits should be sufficient. If the gage locks up tight from the start, then three, four, or more H limits are probably necessary. (Each H limit is .0005″ larger than the previous one.)
One important note regarding heat shrinkage: When parts shrink, they shrink in ALL directions. A threaded hole affected by heat shrinkage will get smaller in diameter and also shrink along the axis of the thread, producing less than the desired pitch thread. (Think of this as if you were compressing a coiled spring, making the distance between each coil smaller.) The effect would be similar to attempting to screw a 1.5mm pitch thread gage into a 1.25mm threaded hole. While this kind of error isn’t overly significant, it does happen. Refrain from choosing a tap with a long lead, anticipating that it will shrink to normal after heating. Generally, the configuration of the part determines the amount of shrinkage. We recommend starting with a tap that is a few H limits larger to see how it gages.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 9, 2010
Greenfield Tech Tip: Tapping Titanium
Greenfield Tap tech tip of tapping titanium from Cutting Tools Chicago aka General Cutting Tools. Titanium and titanium alloys are most often found in aerospace applications due to their light weight and high strength. However, other industries are discovering the benefits of titanium as well.
One of the characteristics that makes titanium difficult to tap is its tremendous elastic memory. During tapping, the material closes tightly around the cutting tool, generating friction and heat, and resulting in increased wear of the cutting edges. This material also easily work hardens.
To successfully tap titanium, consider the following:
- Choose a tap specifically designed with additional clearance to overcome the extreme elastic memory of the material. Tap clearances would include extra back taper of the threads from the front to the back of the thread section, full radial clearance in the threads across the tap lands, and additional relief in the tap chamfer area. All of these features are used to reduce friction and heat.
- In some cases, larger H limits might be required to overcome the shrinkage.
- Choose a tap made from premium grade materials to prevent heat and wear resistance. Greenfield Tap and Die offers these in our standard product lines.
- TiN+CrC/C surface treatment was developed to improve tapping performance in titanium alloys.
- Lubrication and proper pre-tapped hole size are vital to success. Use a compatible tapping fluid that provides plenty of lubrication to reduce friction.
- Select a drill that will produce the largest hole size allowed by the thread class callout (2B or 3B).
- Due to the additional clearances required, positive feeding of the tap is highly recommended.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 8, 2010
Greenfield Tapping Tech Tip: Tap Design and Applications
Greenfield Tap and Die along with Cutting Tools Chicago aka General Cutting Tools tapping tech tip of tap design and applications. Today, it seems as though there are as many tool designs as there are part materials to be tapped. However, a closer look at the geometry of the various specialty taps developed for these materials reveals a few basic design philosophies:
- The most common and easiest to machine materials are soft, ductile materials that produce long, continuous (stringy) chips. They range from non-ferrous such as aluminum and copper, to mild to medium alloy steels, and also include some free machining stainless steels. These materials are easy to cut, produce minimal heat, and are not very abrasive. Taps for these materials are designed with medium to high hook cutting geometry and minimal or no thread relief. They are made from general purpose high speed steel such as M1 or M7, with an oxide, nitride surface treatment or Titanium Nitride (TiN). Most GP taps or those for stainless, fall into this category.
- The second group of materials includes heat-treated ferrous materials, generally above 275 Bhn. These materials are generally abrasive and do not produce chips easily, and heat generated during cutting becomes a consideration. Taps for these materials are designed with low or negative hook cutting geometry, relief to generate a chip, and require heat-resistant cobalt or tungsten based HSS such as M42, Rex 45, or T15. Thin film coatings TiN, TiCN, TiN+CrC/C and TiAIN are often preferred for lubricity, heat resistance, and abrasion resistance. Heavy duty and HP taps for hard alloys are designed with these features.
- Tough alloys such as nickel and titanium make up the third group. While generally not hard, these materials exhibit a toughness that makes it very difficult to produce a chip. They also have more elastic memory (closing in) which causes friction and heat, are quite abrasive, and easily work harden. The chips produced are generally long. The taps designed for this group are similar to those for hard materials, but the hook and relief are often higher to reduce friction and heat. When tapping materials such as titanium, higher H limits are recommended to overcome shrinkage.
- The last category includes materials that produce very broken chips or powder, such as cast iron or brass. Because these materials are cast, they are abrasive but soft. The taps for this group normally feature a low or neutral hook, and no relief, other than the back taper, is required. General purpose HSS is often sufficient, and either a nitride surface treatment or one of the thin film coatings such as TiN or TiCN helps with abrasion resistance.
To place an order, contact General Cutting Tools, your authorized Greenfield Tap and Die distributor.
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January 7, 2010
Greenfield Tapping Tech Tip: Tap Hook and Relief
Greenfield along with Cutting Tools Chicago aka General Cutting Tools is illustrating some tech tips for use in your shop. Four basic design features are incorporated into the design of all cutting tools, including taps. They are cutting face (hook), relief, base material, and surface treatment or coating. This tip discusses hook and relief. The cutting face, or hook, is that portion of the tap flute between the major and minor diameter of the thread that cuts or shears the workpiece material. The entry angle of the cutting face into the workpiece material is measured in degrees, from positive to negative, from a perpendicular reference line through the axis of the tool. Positive hooks are used for soft materials such as aluminum, mild steel and stainless that produce continuous (stringy) chips. Due to the positive angle, the cutting faces are fragile and may chip easily. Negative hooks are used for materials that produce broken or powder chips, or those that have been hardened. This type of cutting face is much stronger and is less prone to chipping.
The relief of a tap may be found on the chamfer’s major diameter (required for tapping), or in the threads, in the form of radial clearance or back taper. Radial or thread relief is the thinning of the tooth from the cutting face to the heel to relieve cutting pressures and friction across the land of the tap. Thread relief is applied for materials that are tough, hard, or have high elastic memory (shrinks or squeezes the tap creating friction). Back taper is the reduction of the major, pitch, and minor diameters from the first thread at the front of the tap to the last thread near the shank. While thread relief is applied for specific applications, back taper is applied to all taps.
To place an order, contact General Cutting Tools, your authorized Greenfield Tap and Die distributor.
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January 6, 2010
Greenfield EX-HPC Extreme High-Performance Solid Carbide Taps for Through Hole Tapping
Extreme high performance tapping by Greenfield from Cutting Tools Chicago aka General Cutting Tools can be in your shop.
Features/Benefits:
- runs 5 times faster, lasts 4 times longer than conventional taps
- enhanced tap precision and design for superior accuracy of product thread
- fully cylindrical shanks for use with hydraulic or shrink-fit holders for optimal performance
- may also be used with Tremendous Grip High Precision (TGHP) collet holders
- common fractional or metric tap shank sizes that match solid carbide tap drill shanks (DIN 6535)
- tap runout less than 10 microns (0.0004″) for superior thread quality and excellent tap performance
- newly designed cutting edges modified by a patented process to resist chipping
- patented PVD nanolayer TiAIN/TiN coated carbide grade for highest edge strength and wear resistance (other patents pending)
- available with straight flutes or left hand spiral flutes (right hand thread)
- left hand spiral flute taps designed for maximum chip control and free cutting in through holes
- engineered custom solutions available upon request
- through coolant hole, semi-bottoming chamfer, straight flute design for blind holes available on request
- after use, can be factory reconditioned to original patented specifications and tolerances
Application Information:
- may be used at 4-5 times the tapping speed of HSS taps and still obtain 4 times life
- designed for use on CNC machines with synchronous or rigid tapping control and precision tool holders
- low-carbon steel
- free-machining steel
- medium and high plain carbon, alloy, and tool steels
- ferritic, martensitic, and PH stainless steels (not recommended for austenitic 303, 304, 316 SS)
- ductile (nodular) and malleable cast irons
- gray cast iron
- use straight fluted taps for sizes M16 and larger and for ductile and cast iron and for materials producing broken chips
- use on high-speed drilling/tapping machines and machining and turning centers that are equipped with rigid hydraulic, shrink-fit, or TGHP precision collet tool holders
To place an order, contact General Cutting Tools, your authorized Greenfield Tap and Die distributor.
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January 5, 2010
Tap Into the Future of High Performance Tapping
High performance tapping by Greenfield Taps from Cutting Tools Chicago aka General Cutting Tools can bring your shop to the next level in threading with higher quality threads, faster cutting speeds, lower cycle time, higher productivity, saving you money and increasing profits.
Greenfield has unmatched high-performance tapping with our family of Exotic Material (EM) taps, specially designed to thread stainless steels, pre-hardened mold steels, nickel alloys, titanium, titanium alloys, and aluminums.
The enhanced tool geometry creates less tapping torque, provides better chip removal, and increases coolant flow to the cutting teeth for more efficient threading and longer tap life.
Greenfield’s new patented Solid Carbide Tap, designed for through hole tapping in mild steels, steel alloys, ferritic and martensitic stainless steels, and irons, can increase production rates up to 4X with 4X longer tap life.
They have a broad selection of state-of-the-art thin film coated taps standard from stock to match your toughest tapping application.
Greenfield’s in-house too/ coating capabilities lead the industry! Choose from Titanium Nitride (TiN), Titanium Carbonitride (TiCN), Titanium Nitride and Chromium Carbide Carbon (TiN + CrC/C), Titanium Aluminum Nitride (TiAIN), and Chromium Nitride (CrN). These are available in full package quantities only.