Thread Milling Handbook
30Pages

About Thread Milling (general) > Thread Milling is a method for producing a thread by a milling operation.The most common way to produce a thread is still by tapping and turning but todaywe see more and more milling and this is because CNC milling machines with three simultaneous axes are very popular. These can now be found in every small workshop.To perform a Thread Milling operation, a helical interpolation movement is required.Helical interpolation is a CNC function producing tool movement along a helical path.This helical motion combines circular movement in one plane (x,y coordinate)...

? Enables machining of large work pieces which cannot be easily mounted on a lathe? Non-rotatable and non-symmetrical parts easily machined? Complete operation in one clamping? Threading of large diameters requires less power than threading by taps? No upper limits to bore diameter? Chips are short? Blind holes without a thread relief groove can be machined? Thread relief groove unnecessary? One holder used for both internal and external threads? One tool used for both right hand and left hand thread? Tooling inventory can be reduced to a minimum as small range of tooling covers a wide...

Tangential arc approach - The best method ! ! ! > How does the thread milling cutter enter and exit the workpiece? With this method, the tool enters and exits the workpiece smoothly. No marks are left onthe workpiece and there is no vibration, even with harder materials. Although it requires slightly more complex programming than the radial approach (see below), this is the method recommended for machining the highest quality threads. Internal Thread External Thread > 2 5 213645 1 1 34 16 2 1-2: rapid approach2-3: tool entry along tangential arc, with simultaneous feed along z-axis3-4:...

Vardex TM tools can produce external and internal,RH or LH threads depending only on the tool path which is programmed. The following drgs. will clarify it very easily.For conical applications such as NPT or BSPT, left hand tools can be used.In such a case the tool must be moved in the opposite direction. > External Internal > Right HandThread - Climb Milling Left HandThread - Climb Milling Right HandThread -Conventional Milling Left HandThread - Conventional Milling Right HandThread - Conventional Milling Left HandThread - Conventional MillingRight HandThread - Climb Milling Left...

Internal Coarse pitch threads are a combination of small thread dia. andrelatively large pitches. The thread milling operation is based on three-axes simultaneous movement so the profile shape on the workpiece is not a copy of the insert profile. In other words the profile is generated and not copied which is contrary to the thread turning operation. This fact causes a profile distortion, especially when machining coarse pitch internal threads. The profile distortion depends on four main parameters: ? Thread dia. ? Tool cut. dia. ? Thread pitch ? Profile angleFor internal threads, as a...

In general, Vargus recommends using the largest possible toolholder with the shortestoverhang and with max. possible cutting edges. The inserts selection will be determined according to the toolholder size and the thread type. For that, and in order to avoid profile distortion, we have three methods: Largest tool table method (p. 10-13) These new and friendly tables located at the begining of our catalogue are your guideand indicate the correct tool to use for every standard thread - coarse pitch and non-coarse pitch threads.The recommended toolholder is the largest (largest cutting dia.)...

Toolholder: TMC - toolholders for std. thread application - using TM2 inserts Toolholder: TMLC - long series for long threads - using TM2 inserts Toolholder: TMC 124/... - toolholders with reduced cut. dia. for coarse pitch applications - using coarse pitch 028/... TM inserts Toolholder: TMNC - toolholders for conical threads - using BSPT, NPT, NPTF inserts Note: L.H. toolholders are avaiable for the second cutting edge of the insert Toolholder: TM2C - TM2 twin flute toolholders with two cut. edges for fast operation - using inserts Toolholder: TMOC - TM2 twin flute offset toolholders to...

Insert: TM2 For standard threads Insert: TM (BSPT, NPT, NPTF) For tapered threads > 1 o 47 , Insert: Coarse Pitch 028/...TM2 For thread milling large pitch to bore diameter ratio Insert: TM2F For fine thread pitches Insert: TM2 IC 3/8B, IC 3/4ԔB For long threads extra vibration resistance Insert: TM IC 6.0 mm For small bore diameters min 9.5 mm Insert: IC 1/4 Laydown Thread Turning Single point thread milling with laydown thread turning inserts For very short thread or material with high hardness Insert: IC 5/8ԔV (T=6) Vertical Thread Turning Single point thread milling with vertical thread...

A thread on theexternal surface of a cylinder screw or cone The largest diameter of a screw thread. > Pitch Minor ؘ The distance betweencorresponding points onadjacent thread forms measuredparallel to the axis. This distancecan be defined in millimeters orby the tpi (threads per inch)which is the reciprocal of thepitch. On a straight thread, the diameter of animaginary cylinder, the surface of whichcuts the thread forms where the widthof the thread and groove are equal. > PitchCrest The smallest diameter of a screw thread. RootThreadAngleAngleMajor Helix > For a straight thread, where the...

Is it possible to produce more than two starts with Vargus thread milling tools? Yes it is possible! You just have to insert the pitch in the TM Gen as pitch multiplied bythe no. of starts. E.g.: Pitch 3.0 mm with two starts should be inserted as 6.0 mm pitch.Օ Why does the non-cutting edge of the insert sometimes break? This is a result of a vibration problems. Change the cutting conditions. Which tool is recommended for long threads TMO or TM2? TM2!TMO can machine long threads in one cycle but it is still one cut. edge tool. TM2 can machine shorter thread but as it has two cutting edges...

What is the purpose of the carbide core in the TM toolholders? The carbide core is used as an anti-vibration system.Օ Is it necessary to produce a relief groove when using TM tools? Not necessary, the tool can reach the bottom of a blind hole. I used std. inserts for coarse pitch thread and in spite of this I got the correct thread, or I used a larger tool than recommended in your tables and I got the correct thread? When you follow Vargus recommendations, we can guarantee the thread form exactlyacc. to standard as Vargus take into consideration the std. tolerances with relation to the tool...