• Thread tap is used for producing internal threads.
• Thread tapping
• Thread turning
• Thread milling
• Faster processing
• Good process reliability
• Better Quality
• Low production costs per thread
• Suitable for Mass production
• Body • Shank • Tang • Land • Flutes • Heel • Cutting Face • Chamfer • Chamfer Angle • Crest • Flank • Hand • Chordal Hook • Tangential Hook • Hook Angle • Lead • Major Diameter • Minor Diameter • Pitch Diameter • Spiral Point • Square • Angle of Thread • Half Angle Thread
• On the entire body of tap the grooves cut on the space between two lands, are called flutes.
• These are made in length from top to bottom
• The particles of metal cut while cutting threads are coming out of these flutes and these are also used for supplying lubricant inside.
• The face of the cutting tool against which the material is moved is called the cutting face.
• The tapering of the threads at the front end of each land of tap by cutting away and relieving the crest of the first few teeth to distribute the cutting action over several teeth.
The angle formed between the chamfer and the axis of tap by cutting away the relieving the crest of the first few teeth to distribute the cutting action over several teeth
• The part of a helical thread surface which connects the crest and the root and which is theoretically a straight line in an axial plane section.
• A concave face having an angle of inclination specified between a chord passing through the root and crest of a thread form at the cutting face, and a radical line through the crest at the cutting edge.
• The angle of inclination of a concave face usually specifies either as Chordal Hook or is Tangential Hook
• The distance a screw thread advances axially in one complete turn.
• On a single start tap the lead and pitch are identical.
• In a multiple start tap the lead is the multiple of the pitch
• The diameter of the minor cylinder or cone, at a given position on the axis that bounds the roots an external thread of the crests of an internal thread
• The diameter of an imaginary cylinder or cone, at a given point on the axis, of such a diameter and location of its axis that its surface would pass through the thread in such a manner as to make the thread ridge and the thread groove equal and, therefore, is located equidistant between the sharp major and minor cylinders or cones of a given thread form.
• On a theoretically perfect thread, these widths are equal to one half of the basic pitch (measured parallel to the axis.)
• The angular fluting in the cutting face of the land at the chamfered end.
• It is formed at an angle with respect to the tap axis of opposite hand to that of rotation.
• Its length is usually greater than the chamfer length and its angle with respect to the tap axis is usually great enough to direct the chips ahead of the tap.
• The angle included between flanks of the thread measured in an axial plane.
• The distance a screw thread advances axially in one turn. On a single-thread screw the lead and pitch are identical. On a double thread the lead is 2X pitch, on a triple lead is 3X pitch, etc.
• Hand tap • Machine Tap • Form Taps • Nip Taps • Machine Screw Tap • Gas Tap • Master Tap • Extension Tap • Bend Shank Tap • Stay Bolt Tap • Interrupted Thread Tap • Plug Tap
• Straight Flute Tap
• Spiral Point Tap
• Spiral Flute Tap
• Flutes are straight along the axis of the body.
• It has a slanted angular gash in each flute on the front end of the taps flute at the cutting chamfer to manage the chips.
• Chips move away from bottom of the hole
• Suitable for tapping threads in through holes.
• Flutes are wrapping around the Tap’s axis in a spiral or helical configuration.
• Chips are moves out of the hole toward the tap shank and opposite of the tapping direction.
• Suitable for tapping threads in blind holes.
• Hand Taps are used for cutting internal threads by manually with Tap wrench.
• Hand Taps consist of a set of three Taps
• In Taper Tap 8 to 10 threads are rubbed and chamfered on the lower side.
• The lower end of this tap is equal to the tap size (pilot) drill.
• Taper Tap is easily set in the drill holes and performs the job of starting a thread.
• It is also known as a second tap.
• Chamfered to 3 ~ 5 threads is made on the lower side.
• It is used to provide proper depth and shape to threads that have been made by the taper tap.
• If threads are to be cut through the drill holes then only these two taps are used.
• It is also known as Finishing Tap.
• It is the third tap of the hand tap set.
• It is used after using the Taper and Plug Tap.
• Besides, it is also used for cleaning and finishing the threads which are cut through the entire drill.
• Chamfered at its end for on one or one and a half threads.
• It is used for cutting gas-type threads, for fitting at places where any liquid or gas passes through the pipes and no leak is allowed.
• In this type of tap 1 ½ threads towards the lower portion are chamfered and there is some taper in the body length.
• It is ¾ taper per foot to avoid gas/liquid does not leak.
• Machine taps are used for cutting internal threads with a tap drill machine.
• Machine Taps are used by holding them in a special holder.
• It is necessary to have reverse speed in the drill machine so that tap can be extracted from the job easily after completing the thread.
• Taps with which threads are cut in the holes of less than ¼ diameters are called Machine Screw Taps.
• Two or four threads are chamfered on the lower side.
• It is also known as Flute less Tap, Roll Taps, and cold forming taps.
• They form threads by displacing material without producing chips.
• Better thread gauging and avoids oversize threading
• This type of taps is used to cut threads like the thread rolling process in soft metals like aluminum, brass, copper, lead, stainless steel, carbon steel, cast steel, leaded steel and zinc as well as other mild steels and medium alloys.
• It does not cut any material.
• One distinguishing feature of this tap is that there are no flutes in this tap but threads are cut on its entire body.
• A tap having an odd number of lands with alternative teeth in the thread helix removed. In some cases alternative teeth are removed only for a portion of the thread length.
• Before driving the tap for cutting internal threads of a job, a hole of appropriate size is to be done with drill bit.
• The size of the drill should be equal to the core diameter of the tap.
• If the size of the drill is greater the threads, it would not form proper threads.
• If the size of the drill is less. There would be difficulty in cutting threads and there would be a danger of the tap being broken.
Recommended hole size for various Thread Tap Sizes are as follows.
|Tap size||Pitch||Drill size (mm)|
|M1.6 x 0.35||0.35||1,25mm|
|M2 x 0.4||0.4||1,6mm|
|M2.5 x 0.45||0.45||2,05mm|
|M3 x 0.5||0.5||2,5mm|
|M3.5 x 0.6||0.6||2,9mm|
|M4 x 0.7||0.7||3,3mm|
|M5 x 0.8||0.8||4,2mm|
|M6 x 1||1||5mm|
|M8 x 1.25||1.25||6,8mm|
|M8 x 1||1||7mm|
|M10 x 1.5||1.5||8,5mm|
|M10 x 1.25||1.25||8,8mm|
|M12 x 1.75||1.75||10,2mm|
|M12 x 1.25||1.25||10,8mm|
|M14 x 2||2||12mm|
|M14 x 1.5||1.5||12,5mm|
|M16 x 2||2||14mm|
|M16 x 1.5||1.5||14,5mm|
|M18 x 2.5||2.5||15,5mm|
|M18 x 1.5||1.5||16,5mm|
|M20 x 2.5||2.5||17,5mm|
|M20 x 1.5||1.5||18,5mm|
|M22 x 2.5||2.5||19,5mm|
|M22 x 1.5||1.5||20,5mm|
|M24 x 3||3||21mm|
|M24 x 2||2||22mm|
|M27 x 3||3||24mm|
|M27 x 2||2||25mm|
• Tap Handle is also known as Tap wrench.
• Tap handle is used to hold and rotate the Hand Tap to cut threads in a work piece.
• Tap handles are of three types:
a) Solid Tap Handle
b) Adjustable Tap Handle
c) “T” Type Handle
• Solid tap handle is made solid on both sides handles are fixed for convenience.
• In the middle rectangular part, two separate rectangular grooves are cut across the tap.
• Taps of two sizes can be hold and used in these.
• It is in fact a kind of chuck in which three jaws is fitted.
• Different types of small taps are held in this chuck.
• A hole is bored on the upper side of its shank and a rod is put across, with its help the tap tied to the rod can be easily rotated.
• Standard Tolerance is ISO Class 2; 6H; 2B; Zone 3.
• Other Tolerance like ISO Class I, ISO Class 3, 4H, 5H, 7H, 4G, 6G, 1B, 3B, Zone I, Zone2, Zone4
• Special tolerances will be maintained as per request of customer
• Tap drill hole of appropriate size is essential before tapping.
• Tap should be properly cleaned before using the tap.
• Use tap handle according to the tap.
• Keep equal pressure of the hand on both ends of the tap handle.
• Tap should be moved forward and backward and we should prevent any jolts.
• Tap should be cleaned properly after use and kept safely.
• If the size of the drill is less there would be difficulty in cutting threads and there would be a danger of the tap being broken.
• If the size of the drill is greater the threads would not be of the proper depth. Thus, it is essential that the drill should be of proper size.
• The size of a drill is called a tap size drill.
• Incorrect /wrong selection of pilot drill
• Incorrect / Wrong sequential use of Taps
• Inappropriate tap for work material
• Unequal application of force
• Insufficient work holding
• Incorrect /wrong selection of pilot drill
• Incorrect / Wrong spindle speed and feed setting in the Tapping Machine
• Insufficient work holding