It may be difficult to give clear answers to all the questions surrounding threads, but the effort to understand technological progress is well worthwhile when measuring results. What is the best function of solid carbide and indexable thread tools? What is the best solution for difficult-to-process materials? New paint? geometry? Leading suppliers have loaded their product portfolio with advanced tools to accomplish this task. The following are some of the tool solutions and the basic principles behind their development.

Jeff Dei, president of Carmex Precision Tools LLC in Richfield, Wisconsin, said that technological advancements and market forces have promoted new developments in indexable and solid carbide threading tools. "Nanotechnology coatings provide more precise threads and longer tool life. In addition, the emergence of complex molds has led to the development of newer shapes, providing better cutting geometries," he said.

In spiral indexable tools. Carmex's vertical thread milling cutters are available in single-edge and multi-edge configurations. Multi-edge inserts have 4 to 8 cutting edges and can be used for internal and external threads. According to the company, the spiral shape provides smooth cutting with low cutting forces.

"The changes in the market have also affected the development of tools," Dei said. "For example, the trend towards smaller and more complex parts has led to an increase in demand for tools designed specifically for Swiss-style applications. Several of our production lines, including Swiss Line, Tiny Tools and Mini Tools, provide Carmex's for these applications. Spiral advantage'."

Carmex has developed a variety of material-specific tools in indexable and solid carbide versions. "Applications involving difficult-to-machine materials and high-temperature alloys have greatly promoted the development of material-specific tools," Dei said. "Thanks to the development of new materials and nanotechnology, we are now able to match the correct coating or coating to the substrate to provide the best results for specific applications. For example, it is designed for processing long threads ranging from small to large diameters. The designed Slim MT production line uses a cemented carbide/coating combination to extend tool life and increase productivity in processing difficult-to-machine materials."

In many cases, according to Dei, comparing the market share of cemented carbide tools with indexable tools is actually a question of "apples and oranges". "For example, cemented carbide is a necessity for small-diameter internal applications, including many uses in Swiss-style machining," he said. "The necessity of clamping and the advantages of multiple cutting edges limit indexable tools to larger applications."

He added that improvements in the machines that produce parts have promoted advances in threading and milling. "For example, many machines today are lighter and faster than earlier devices that relied on mass and weight to reduce vibration," Dei said. "In addition, we have seen more multifunctional machine tools with both milling and turning functions. As a tool manufacturer, we have the responsibility to see the'big picture' and respond accordingly."

Mark Ford, YG-1's global product management director for thread processing, said that YG-1 Tool Co., located in Vernon Hills, Illinois, offers a series of taps, covering everything from tool rooms to high-volume repetitive production. "We divide our products into several different categories of metric and unified faucets, including Combo Tap multi-purpose faucets with and without internal cooling," Ford said. "Tools are designed around specific material groups, including stainless steel, aluminum, superalloys, and cast iron. Other tools are more targeted to specific applications, such as pipe taps, rolling taps and threaded inserts."

YG-1's popular 60° helical groove TiAlN coating uniform and metric thread milling cutter is another option for threading, which can be provided with or without cooling. The combination of multi-function tool drill, thread milling cutter and chamfering in one setting is especially suitable for niche applications. "These tools require the right applications and the right environment to be effective," Ford said. "In the thread milling production line, YG-1 provides pipe threads, NPT, NPTF, NSP and NPSF, but does not provide gas pipe threads in the United States."

For high-speed tapping, YG-1's Synchro Tap is designed for very free cutting. "Synchro Tap has very little contact with the workpiece, so it can run at higher spindle speeds. The tool has features and geometries that create free cutting. In tapping, your feed or feed rate is fixed, and Based on the pitch or lead of the tapping. The only option to increase productivity is to make the spindle run faster," Ford explained. "Synchronized taps are designed to run in a synchronized tapping cycle and be firmly fixed, or better yet, use a synchronized tool holder. This allows users to obtain spindle speeds that are two to three times higher than traditional taps."

YG-1's cemented carbide taps are designed for casting materials, aluminum and cast iron. Compared with the 150 sfm of traditional faucets, they can achieve up to 200 sfm of surface footage. "Cemented carbide absorbs a lot of heat and has excellent wear characteristics, but it tends to be brittle," Ford said. "Cemented carbide taps require some different ways of thinking when processing, which is very suitable for high-volume applications, such as transmission lines for automotive parts."

To unravel the mystery of choosing the right faucet for an application, Ford developed a training program that he called the 10 Questions of Success (see sidebar). "Answer these 10 questions and you will be closer to success the first time," he said. "Shops usually don't know if they have the right tool, because this is a very small tool. Unlike a drill or an end mill, you cannot adjust the chip load or programming," he said. "With just one click, you must design it into the tool to overcome the inability to make adjustments in real time. When you run the tap, the control is such that it only allows running at a certain percentage of the spindle speed. This is your turn A tool that reaches the bottom of a hole, stops and returns in the reverse direction. Every other round tool moves forward."

Tool breakage and scrap are a continuing threat to the successful threading of high-value workpieces such as molds and high-temperature alloys used in aerospace applications. According to Justin Ripple, product manager of Allied Machine & Engineering in Dover, Ohio, thread milling can produce high-quality threads with lower tool pressure and lower heat for threading difficult-to-machine materials. It also provides deeper threads for these materials.

Allied Machine provides tools for complete hole processing, including roughing, reaming, threading and finishing holes, and provides services for various customers such as molds and aerospace. "Thread milling allows our customers to use one thread milling cutter to machine multiple diameters without having to reserve a tap for each hole diameter," Ripple said. "In addition, there is no removal of damaged taps in die and die applications, and the cost of scrapping high-value workpieces in these applications is high. Even the eye bolts that hold the die require threads. For those heat-resistant aerospace workpieces, thread milling It generates less heat than other thread machining, which directly increases tool life."

The newest member of Allied Machine's thread milling products is the solid carbide AccuThread T3, which is designed for work-hardened or difficult-to-machine materials, such as stainless steel, tool steel, and high-temperature alloys.

The high-quality AccuThread T3 solid carbide thread milling cutter is optimized for difficult-to-machine materials. Ripple said: "Since its launch, AccuThread T3 has achieved great success, so we are expanding the production line to 1"-8 UN and 24-3 ISO. Including left-handed cutting, allowing the tool to climb milling when moving from top to bottom to form a right-handed thread. Three cutting teeth cut the smallest thread at a time, reduce side deviation, and cut precise thread shape materials with a hardness of more than 55 HRC in a deeper place, and can even reach 60 HRC materials and customers. "

For thread milling, the machine tool must have a three-axis linkage interpolation function. For this operation, Allied provides Insta-Code programming that can be downloaded from its website. Inputting processing conditions and required threads will generate a program. "Insta-Code is very popular, we and our customers are using it, and they can add it as an engineering resource." Allied Machine’s website also provides a link to its pocket guide for thread milling cutters, which contains Comprehensive information about different threads and cutting conditions.

In addition to solid carbide tools, Allied Machine also provides two types of AccuThread replaceable insert thread milling cutters, bolt connections and pins to flexibly meet the various threading applications found in the processing shop.

Sandvik Coromant (Sandvik Coromant) provides a comprehensive method of internal and external thread turning, and provides products and guidelines to optimize material applications and industry performance. According to product expert turning team leader Kevin Burton and aerospace industry expert Scott Lewis, the most important threading application considerations are chip control, blade wear, thread quality and tool life. He said that threading performance depends on selecting the correct insert type, geometry, feed, and programming for various thread forms, such as general and general motion, aerospace, pipe threading, and highly specialized applications in the oil and gas industry. There are threads.

In order to maximize processing efficiency, Sandvik Coromant introduced CoroThread 266 high-precision coolant solution with iLock high-precision tool holder. "CoroThread 266 is suitable for all insert geometries, materials and thread profiles, as well as low to high coolant pressures," Lewis said. "The combination of a supercoolant for chip formation and a supercoolant to extend the life of the insert can produce higher product quality, processing efficiency and process safety in all external thread turning applications." CoroThread 288 exceeds 1,000 The pressure of psi accurately provides coolant pressure to the cutting zone. "The iLock high-precision tool holder handles the extreme forces exerted on the blade and provides excellent stability for final accuracy, surface finish and product consistency," Lewis said.

Sandvik Coromant has a wide range of thread grades and geometries, covering most materials and applications. Burton described the types of threaded inserts and their geometry: "There are three different types of threaded inserts: full-tooth profile for high productivity; V-shaped profile 60° and 55° for the most common applications; and multi-point Inserts can achieve efficient and economical thread processing in mass production." Sandvik Coromant offers three geometric shapes of inserts: universal type for various materials; F-sharp geometry for viscous or viscous materials Shape; C chipbreaker geometry of low carbon, alloy and some stainless steel materials.

Burton said that the type of feed and blade inclination cannot be ignored. "Three different types of feed will have a significant impact on the threading process, affecting chip control, blade wear, thread quality and tool life. The choice of feed method is affected by the machine tool, blade geometry, workpiece material and thread pitch."

Burton describes three types of feeds—modified side, radial, and incremental—and their programming requirements:

Corrected flank infeed: Most newer CNC machine tools can be programmed to modify the flank infeed. It is used with C geometry because the chip breaker does not work during radial infeed. The axial cutting force reduces the risk of vibration and controls the chip direction. This is the first choice for most threaded operations; chips are similar to traditional turning and are easier to shape and guide.

Radial feed: used for all manual machine tools and most canned CNC programs. It is the first choice for hardening materials and is suitable for fine pitch.

Incremental feed: usually used for very large contours and pitches or long working thread cycles, where the tool life needs to match the thread length. Difficult chip control. Special programming is required.

Burton stated that GC1125 is the preferred material for ISO P, M, K and N materials in CoroThread 266. . Optimized for steel thread and medium and high speed. Advantages and features include high abrasion resistance and the possibility of fewer passes. "

For thread turning, Iscar USA in Arlington, Texas has introduced two new carbide grades, IC 806 and IC 1007, which are very suitable for aerospace materials. According to Randy Hudgins, national product manager for turning and threading, IC 806 has achieved great success in turning and has become a good choice for threading, while IC 1007 (a hard substrate with TiAIN PVD ​​) It is equally effective for processing hard materials and aerospace materials.

Iscar provides a full range of thread milling and thread turning products, and has introduced a new insert product for thread turning with a multi-angle design. Hudgins said: "The insert has 5 or 10 corners, while for standard tile threading there are two or three corners." "For example, the Pentacut format has five corners, and the DecaIQ blade doubles to 10 corners. .DecaIQ thread is more suitable for UN thread, from 32 pitch to 16 pitch standard thread. Penta 27 is a wider insert that can create wide thread geometry, such as Acme, stub Acme or many for oil and gas High-quality connecting thread. ”

A major improvement in Iscar's thread turning capabilities is the JHP high-pressure coolant delivery system with retractable nozzles for easy blade replacement. "With JHP, we are able to send the coolant directly into the cutting zone. For many threads (such as 60° V threads), the insert reaches a very small point, which is fragile and easily heated. Place the coolant directly Entering the cutting zone can significantly increase tool life and chip control," Hudgins said. "When cutting stainless steel and high-temperature materials, using high-pressure coolant to feed the coolant directly into the cutting area will make the chips more brittle. Even if you don’t plan to divide the thread chips into 6 and 9 like turning, you can crimp them and make It will not wrap around parts or tools."

In addition to grinding inserts and pressed or molded inserts, Iscar also offers combined inserts: Type B inserts are particularly suitable for aerospace materials. Type B blade is a grinding blade with a pressed chip former on the top of the blade, which can provide sharp edges for cutting high temperature or viscous materials.

According to Hudgins, troubleshooting threading issues usually becomes one of several issues. "One of the biggest problems in threading can usually be solved by changing the feed method-the angle of entry into the thread," he said. "One of the simplest but least recommended methods is straight zero-degree feed. You can join both sides of the insert at the same time. A lot of heat is generated, and the use of an improved side feed can reduce the heat and pressure during cutting, and Protect the trailing edge. Another problem is that the machine may not always be on the center line. This situation is caused by the machine crash and can be easily corrected. Modern CNC machine tools and Swiss machine tools have the ability to offset the Y axis, thus The problem of machine eccentricity is alleviated."

Thread issues may not be discussed too much, but they do exist. "Interestingly, when talking to operators, programmers, and engineers, if you ask them what went wrong, almost no one would say threads," said Luke Pollock, product manager at Walter USA LLC, Waukesha, Wisconsin. Bird's nest or other chip problems occur when tapping. If possible, we usually try to push end users to thread forming or thread milling. Depending on the material or application, the tap has a very special design, so tool selection may become very difficult. "

Walter has a full range of tapping, thread forming and thread milling products, and has launched a series of taps TC117 and TC217, which are positioned in the Advance series for general applications.

According to Pollock, the Walter product line includes three tool categories. Supreme stands for the highest level of technology and performance; execution tools provide an economical solution with a focus on price; Advance stands for an effective balance between price and performance. The versatility of the Advance product line makes tool selection easy, which means it is suitable for most materials, including ISO P, M, K and S. Walter's customers are looking," Pollock said.

According to Pollock, Walter's multi-row thread milling cutters are often seen as a problem solver with tapered threads or fewer teeth to reduce chatter. "But the design of Walter's multi-row thread milling cutter allows lower cutting forces to allow faster feed of the tool, matching or shortening cycle time compared to cutting taps," he said. "We have two different styles: a solid carbide version for threads smaller than 7/8" (TC620) and an indexable version (T271x) for threads larger than 7/8". These tools enable users to obtain All the advantages of thread milling-such as reduced cost per thread and longer tool life-without sacrificing cycle time."

In order to produce high-quality aluminum alloy internal threads while saving critical processing time, Emuge-Franken NA of West Boylston, Massachusetts, and Audi AG of Ingolstadt, Germany have studied a new type called Taptor Thread cutter technology, which combines twist drills with a tap.

“In traditional thread production, machining is carried out in two steps: the first step is pre-drilling, and the second step is to use taps, cold-formed taps or thread milling cutters to machine the threads,” said Product Director Mark Hatch, adding that The required tool changes will result in longer machining times.

"Taptor has a unique drilling part with several threaded teeth which are arranged axially at a short distance from the drill tip to produce threads in blind and through holes, thus eliminating the entire machining process-pre-processing Drilling cycle," Hatch said. "The Taptor tool developed by Emuge-Franken processes both the core hole and the thread in one operation. This process (Audi has applied for a patent) is basically divided into two steps. In the first step, the movement of the tool corresponds to synchronous tapping. Therefore, , The drilling feed per revolution matches the thread pitch. In the second step, the tool cuts freely at the drilling depth. And the thread teeth form a circumferential undercut. Then Taptor retracts through the generated thread."

According to Hatch, in combination with Emuge Speedsynchro Taptor chuck holders with integrated drive gears, higher cutting speeds can be achieved. For example, when machining a cylinder head side with 26 threads of M6 2×D in a 0.47 inch (12 mm) deep cast aluminum, Emuge-Franken reports that using Taptor tools can save 41% of the time, that is, two threads per thread. Combination of seconds and Speedsynchro Taptor chuck.

Every thread produced meets the specifications of DIN ISO 965 (metric ISO thread). Create an undercut at the bottom of the thread, the length of which corresponds to the lead-in chamfer of a traditional thread tool. Screws can be screwed into this undercut. The Taptor process can be used on any machine that supports synchronous tapping and has a spindle with torque support and a tool magazine that can accommodate Speedsynchro Taptor tool holders.

According to YG-1’s Mark Ford, answering these 10 questions, you will be closer to the first successful threading:

What is the size, spacing and grade of the fit?

What is the gauge limit marked on the thread gauge?

What is the hit material?

What is the diameter of the hole?

What is the depth of the hole and how many full threads are needed?

Is the application through hole or blind hole?

Is the application vertical or horizontal?

What is the cooling capacity of the machine and clamping system?

Can threads be roll-formed?

What are the painting requirements?