You should put some images in here with certifications like the Better Business Bureau or any awards General Cutting Tools has. January 24, 2010
Greenfield Taping Speeds Tech Tip
Taping speeds are significant to your tap life. Cutting Tools Chicago aka General Cutting Tools along with Greenfield explains what you need to know. The factors considered when trying to determine the best tapping speeds are:
- Material to be tapped
- Length of chamfer on tap
- Percentage of full thread to be cut
- Length of hole (depth of thread)
- Pitch of thread
- Cutting fluids
- Machine equipment
- Horizontal or vertical tapping
The best and most efficient operating speeds for taps cannot be calculated with the same certainty as for many other metalcutting tools.
With other tools, the feed per revolution can be set at any desired point and can be varied as conditions demand. Taps, on the other hand, must always be advanced at a rate equal to one pitch for every revolution. The style of tap may vary the conditions. For example, with a bottoming tap, the first thread on each land cuts the full height of thread, while, with a taper or starting tap, a number of threads do their share of the cutting before the full height of thread is reached.
The depth of thread also varies, depending on the pitch. The coarser the thread, the greater the advance of the tap per revolution and the greater the amount of material removed.
The method of feeding the tap, and the type of equipment for driving, also influence the permissible speeds. If taps
are mechanically fed at the proper rate of advance, they can be operated at higher speeds than if they are required to feed themselves and pull some part of the machine along with them.
Speeds may be modified to take into account any or all of the factors listed to the left.
Speeds must be lowered as length of thread increases because, in deep thread holes, the accumulated chips increase friction and interfere with lubrication.
Bottoming taps must be run slower than plug taps.
Tapping of full height of thread calls for slower speed than if the commercial 75% height only is required.
Coarse-thread taps in the larger diameters should be run more slowly than fine-thread taps of the same diameters.
The quantity and quality of cutting fluid may affect the permissible speeds as much as 100%.
Taper threaded taps, such as pipe taps, should be operated at from 1/2 to 3/4 the speed of a straight thread tap of comparable major diameter.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
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January 23, 2010
Importance of Proper Lubricants in Tapping
Greenfield along with Cutting Tools Chicago aka General Cutting Tools reminds you that applying the proper lubricants in tapping operations can result in longer tap life, increased production, better workpiece size control, smoother and more accurate threads, less resharpening, and more efficient chip removal.
Generally, for best tap performance, straight cutting oil should be used. For non-ferrous and non-metallic materials, a coolant or a cutting fluid (light oil or soluble oil) is recommended.
Often, machining centers are equipped with a coolant or a cutting fluid that contains enough water and oil to provide adequate cooling and lubrication for a variety of tools and workpieces. However, most soluble blends are not suitable for tapping applications. Tapping, especially with thread-forming taps, requires more lubrication than cooling. A coolant or cutting fluid might lack the lubrication necessary to obtain acceptable tool life and part finish. Consult your coolant specialist for recommendations.
After you select the proper lubricant, it is also important to choose the right method of application and pressure. For tapping, use more than one nozzle around the tap. The nozzles should be located as close to the surface of the part as possible, be positioned at an angle close to the axis of the tool, and point directly into the hole to flush the chips from the flutes. For horizontal tapping, where the tap is stationary and the workpieces is rotating, consider using two streams of lubricant, one on each side of the tap.
Whether you are tapping vertically, horizontally, or on an angle, make sure the lubricant reaches the cutting lands of the tap at all times, especially at the point or chamfered portion. Brushing or squirting oil or fluid onto the tap does not provide sufficient lubrication. In fact, heavy viscosity oil may cause the chips to “stick” or “cling” to the tap, increasing the chance of breakage. In addition, when the lubricant is automatically applied only on the forward motion of the tap, you should time the application of the lubricant so that it will reach the hole before the tap starts to cut. This applies particularly to machines on which the cutting fluid is automatically shut off during the tap’s reversal.
For maximum effectiveness, it is often best to force the lubricant into the hole under pressure. The amount of pressure applied varies depending on the tapping method, hole depth, and tapping speed.
Try to keep tapping lubricants as clean as possible using a filtering system or other equipment. Dust and other foreign particles can contaminate the oil and decrease its effectiveness. Be sure to thoroughly clean machines and oil tanks when adding new lubricant and at regular intervals to ensure optimum tapping results.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
We ship to Illinois, Iowa, Indiana, Wisconsin, Michigan, Minnesota and the reset of the US.
January 22, 2010
The Proper Use and Care of Gages Illinois
Cutting Tools Chicago aka General Cutting Tools in conjunction with Greenfield Tap and Die explains the proper use and care for your gages. Limit-type thread plug and ring gages are important tools in any Quality Control program. These gages are used to determine whether a product’s threads fall within maximum and minimum functional size limits.
Product size limits are expressed in terms of pitch diameter, which is theoretical. Limit-type gages check the “functional” size of the threads, or the capability of product threads to assemble with mating parts, and the degree of tightness or looseness of the fit. Functional size takes into account not only the pitch diameter, but also the effects of deviations in other factors such as lead, angle, roundness, and helical path.
Decisions regarding whether to accept or reject a product are made based on its functional size. Obtaining an accurate functional size evaluation depends upon three key factors: 1) the accuracy of the gages used, 2) proper care of the gages, and 3) correct use of the gages.
Gage Accuracy
The initial accuracy of the gage is the responsibility of the gage manufacturer, who should manufacture the gage within specified allowable tolerances. Maintaining gage accuracy then becomes the responsibility of the user and involves properly caring for and correctly using the gages.
Properly Caring for Gages
Gages should be handled with care to avoid damage and premature wear. Mishandling gages can result in unnecessary costs, both for replacement gages and, more importantly, for improperly rejected products. Gages should also be calibrated regularly to ensure they are within acceptable tolerances.
Use the following tips to properly maintain your gages:
- Keep gages clean and lightly oiled, if possible, both during use and when in storage. Light oil will prevent rusting, greatly increase wear life, and help to prevent “loading” or “smearing” of product material onto the gage threads. (In some applications, using oil on a workpiece might not be acceptable, so be sure to check the material specifications before using an oiled gage.) Using Seal Peal plastic dip on gage threads in storage is also acceptable.
- Protect gages from nicks, jams, and other damage by providing a protective box in the work area.
Using Gages Correctly
Correctly using gages will not only extend their life but also yield accurate results when evaluating threads. Refer to the following usage tips:
- Clean parts before gaging. Remove any dirt or chips so the gage can check product size unaffected by foreign material.
- Align and start threads carefully. Cross-threading can damage the end threads of both the product and the gage.
- Gages are not sizing tools! They must travel over the full length of the product threads or, in the case of blind holes or imperfect run-out threads, they should travel as much of the length required to enable assembly.
- GO gages must enter or be entered by product threads without undue force or pressure.
- NO GO gages have limitations on entry. It is usually preferable that they do not enter; however, some entry is generally allowable and the limitations vary for different gage standards. For inch threads, NO GO entry is limited to not more than 3 turns; for metric threads, NO GO entry is limited to not more than 2 turns.
- Don’t force the gage. Use reasonable light pressure only.
- Use thread ring gages equally from both faces. We often find that ring gages submitted for re-inspection or reconditioning are tapered from wear only on the stamped side. The ring gage is designed to be used from either face, and alternating use from each end will prolong wear life.
By properly using and caring for your gages, you can achieve a number of sound, economical benefits:
Prolonged wear life
Extended periods between calibrations
More reliable results in evaluating product threads
Acceptance of the maximum size range of the product tolerance. Thus, preventing defective threads from reaching the market
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
We ship to Illinois, Iowa, Indiana, Wisconsin, Michigan, Minnesota and the reset of the US.
January 21, 2010
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January 17, 2010
Greenfield Threading Tech Tip: Why Are “H” Limits for Roll Form Taps Higher Than for Cut Thread Taps?
Cutting Tools Chicago aka General Cutting Tools along with Greenfield Tap & Die helps explain and take the mistery out of the “H” limits on taps. Roll form tapping is an effective way to produce internal threads in production applications. There are many benefits to this process, including the absence of chips. Before proceeding with roll form tapping, consider the material to be tapped, the hole size before tapping, the machine capabilities, and the class of fit requirement after tapping.
In the case of fit, the requirement for the finished thread is the same regardless of whether it is a cut or rolled form thread. Use 5/16-18 2B internal thread as an example. 2B is the designation for internal thread minimum and maximum values after tapping. It is normally checked with GO and NOT GO thread gages. For cutting this thread, the recommended tap “H” limit value is H-5; but, when roll forming the same thread, the recommended value is H-7. There are published charts in our catalogs detailing other sizes and for recommendations.
The reason for the larger “H” value is the slight shrinkage that occurs in the hole after the tap is removed. All metals have a memory and will try to spring back to their original shape. When displacing metal using a roll form tap, this condition will occur. The higher “H” limit compensates by forming a slightly larger thread which shrinks slightly after the tap is removed. Other factors may interfere, but, generally, the recommended “H” limit values published for cut or roll form threads will deliver acceptable gaging results.
Contact General Cutting Tools, your authorized Greenfield Tap and Die distributor for more information.
We ship to Illinois, Iowa, Indiana, Wisconsin, Michigan, Minnesota and the reset of the US.
January 16, 2010
Greenfield Threading Tech Tip: Pipe Taps… How Deep to Thread?
Greenfield Taps with Cutting Tools Chicago aka General Cutting Tools answers the question: Do you know how deep to run a pipe tap into a drilled hole before it stops? In other words, do you know when the pipe thread is either too small to accept the L-1 thread plug gage, or too large to be flush with the surface of the hole being tapped within ± 1 turn on the gage?
Pipe threads are sized differently than standard straight threads. They are based on the basic size at the top of the threaded hole produced by the pipe tap. The basic size, commonly called the 12-thread count, occurs approximately 12 threads from the front of the taper pipe tap. This means you can run any standard projection pipe tap into a drilled hole approximately 12 threads from the front of the tap, which should be the approximate basic size for that pipe.
General purpose pipe taps are appropriate for threading a wide variety of materials, both ferrous and non-ferrous.
Ground thread pipe taps are standard in American Standard Pipe Form (NPT) and American Standard Dryseal Pipe Form (NPFT). NPT threads require the use of a sealer, like Teflon® tape or pipe compound. Dryseal taps are used to tap fittings which will give a pressure-tight joint without the use of a sealer.
The nominal size of a pipe tap is that of the pipe fitting to be tapped, not the actual size of the tap. The thread tapers 3/4″ per foot.
All pipe taps are furnished with 2 1/2 to 3 1/2 thread chamfer.
Short projection pipe taps are made with a projection shorter than standard for taper pipe tapping where the depth of tapping is limited.
Special short projection taper pipe taps can be furnished with American National Standard Taper Pipe thread (ANPT), or Dryseal American National Standard Taper Pipe thread (NPTF, PTF-SAE Short, or PTF-SPL Extra Short).
For information on short projection pipe taps and hole preparation for NPT, NPTF, and ANPT internal pipe threads, consult Greenfield’s Technical Bulletins.
Special short projection pipe taps and left hand pipe taps are available through Lightning’ Service.