Exploring the future development of tools from machining challenges

Abstract: In recent years, the metal processing industry has developed rapidly, and its power comes from many aspects. For example, economic globalization, increased market competition, the use of difficult-to-machine materials, and awareness of environmental issues. As a result, the end user of the tool has made continuous improvements to the tool manufacturer. The general trend in the metalworking industry is to develop more advanced processing techniques.

In recent years, the metal processing industry has developed rapidly, and its power comes from many aspects. For example, economic globalization, increased market competition, the use of difficult-to-machine materials, and awareness of environmental issues. As a result, the end user of the tool has made continuous improvements to the tool manufacturer.
The general trend in the metalworking industry is to develop more advanced processing techniques. Although most of the epoch-making inventions in the history of tool development come from specialized scientific research institutions, it is the vast number of tool manufacturers that directly face specific processing challenges. Because tool manufacturers are at the forefront of developing new tool materials, tool structures and machining methods.
This paper will give specific cases for several aspects of machining challenges, and explain how tool manufacturers can advance the development of tools in practice.

New material processing challenges
Powder metal parts are an economical alternative. Parts made using powder metal technology have many unique advantages. Powder metal technology allows complex parts to be machined to approach final dimensions and contours, significantly increasing processing efficiency. Usually only one finishing is required. In addition, the powder metal technology deliberately leaves residual porosity within the part, which is very advantageous for self-lubricating, weight reduction and noise reduction. Some complex parts are difficult or impossible to manufacture using traditional casting processes and can be easily produced using powder metal technology. In summary, powder metal technology provides an economical method of producing parts. So what are the challenges of processing powder metal?
The processing difficulty of powder metal materials is often underestimated. Since powdered metal materials tend to contain hard particles in a soft, sometimes porous structure, the processor is often misled by the material hardness value. The particle hardness is as high as HRC70, while the macro hardness is as low as HRC10. Hard particles and porosity can cause microscopic fatigue of the cutting edge of the tool. The cutting edge of the tool is cut and cut as if it is between the particles and the particles and between the holes and the holes. Repeated small impacts cause small cracks in the cutting edge. These fatigue cracks are getting larger and larger, eventually leading to a micro-cracking of the cutting edge. This micro-crack is so subtle that it looks like normal wear and tear. A common deviation between particle hardness and macro hardness means that machining a powder metal part is like machining a grinding wheel.
The unique properties and processing characteristics of powder metal parts mean that high CBN content for increased wear resistance and fine grain size for improved cutting edge toughness are essential requirements for processing. The CBN200 insert is made up of CBN's high content of very fine-grained materials that meet these requirements. There is also a unique metal binder that makes the CBN200 an ideal processing solution. Its excellent wear resistance and toughness are ideal for minimizing processing costs.
By matching chamfering, width and cutting edge grinding, we have enhanced the cutting edge and thus improved tool life, improved surface finish and machining tolerances, enabling customers to achieve higher productivity and reliability. This cutting edge design is especially suitable for difficult to machine powder metal materials.
The valve seat on the cylinder head of the automobile engine is a typical powder metal part. The tool life of the valve seat hole is 5000 pieces processed by PCBN, and the life of the machine tool is 300 pieces. The life difference between the two is different. More than ten times. The replacement of carbide tools with superhard tool materials such as PCBN has become a trend in more and more applications.

Difficult to machine material breaking chip
Titanium alloys are well known as poor heat conductors, which means that the high temperature is maintained at the cutting point, resulting in alloying tendencies such as welding, bonding and diffusion, and the cutting edges are quickly damaged. The cutting characteristics of titanium alloys produce a thin, high-speed chip that is difficult to break into controllable debris. Typically, such chips will shift the conventional cooling transfer system, resulting in a lack of coolant at the cutting point and damage to the part. Conventional tools with large positive rake angles and sharp cutting edges minimize these effects, but the resulting long chips are difficult to control.
In response to the aviation industry's need to improve the cutting performance of titanium alloys, Seco developed the Jetstream tool. It is a revolutionary new solution to solve the long-standing problem of accurately transferring coolant to the cutting zone.
The Jetstream tool works by placing a concentrated coolant high pressure jet at a high speed straight to the optimum position near the cutting edge. This coolant jet lifts the chips off the rake face, improves chip control and tool life, and increases the cutting parameters used, and is not just for aerospace materials.
Jetstream tools have proven to be effective for almost all material groups and have a wide selection of coolant pressures.
Efficient heat dissipation from the cutting zone is one of the most important factors affecting tool performance. The benefits of using coolant for heat dissipation are clear and clear, until now the coolant is simply used to flush the area. For the coolant to be truly effective, it should be able to carry the heat away quickly from the cutting zone, and the directed coolant flow will deliver the coolant exactly where it is needed.
In order for the blade to work effectively, both the workpiece and the blade need to reach a certain temperature level. If the heat is too much, the tool life will be shortened; if the heat is insufficient, the chips will not form properly. When the chips are formed, the heat it contains needs to be taken away. The inability to remove heat quickly results in a ductile chip that is flexible and does not break, and its constant curling makes the operator inconvenient to operate.
Jetstream tools are very effective at removing heat from the cutting zone, allowing the chips to cool quickly and the chips harden to make them brittle. The chips thus obtained are easily broken and can be removed from the cutting zone.
With the Jetstream tool, Seco clearly understands the importance of directly transferring coolant to the tool/workpiece interface. It uses a minimum amount of coolant to provide effective cooling and also makes the chips brittle enough to break more easily, allowing for increased cutting speed and longer tool life (due to reduced work hardening and groove wear). Not to mention the elimination of downtime and parts damage associated with tangled long chips.
In the Seco test, the average tool produced Ti6Al4V parts with a cutting speed of 40m/min, a feed of 0.25mm/rev and a depth of 2mm. The machining cycle was 5min. With Jetstream, the cutting speed can be increased to 80m/min, and shortening the processing cycle to 3min, the productivity increased by 40%.

Processing efficiency challenge
The times are changing, and increasing efficiency competition requires more efficient processing methods. High feed milling is the key to keeping the company ahead.
High feed milling is actually a roughing method developed for high metal removal rates to increase productivity and save machining time. Combine a shallow depth of cut (no more than 2 mm) with a large cutting arc radius or a small lead angle to direct the cutting force toward the axial machine tool spindle.
This milling method achieves a processing speed that is three times faster than conventional methods. It does not use a larger depth of cut during cutting (which will shorten the tool life), but instead proceeds from the opposite direction. It protects the tool by pairing shallow depths of cut with high feed per tooth. And a higher metal removal rate than ordinary processing is obtained.
This approach has many advantages. For example, the cutting force points in the axial direction to the machine tool spindle; reduces vibration and thus extends tool life; high feed milling (HFM) method utilizes smaller lead angles; minimizes radial cutting forces and maximizes axial cutting forces Reduce the risk of vibration and obtain stable processing; this method can even improve cutting parameters when in large overhang processing.
With a small depth of cut and a faster feed per tooth, more than 1000 cm3 of workpiece material can be removed per minute. In fact, sometimes the feed rate can be increased to 10 times the normal value. And even if it is a roughing method, it can still get close to the shape of the finished product. This allows the user to skip semi-finishing and perform the final finishing directly. The possibility of producing more parts for each machine.
The HFM method is very effective for cavity milling, especially for mold machining. In addition to pocket milling, it can also be used in machining methods such as face milling, helical interpolation milling and plunge milling. The HFM method has been adopted in more machining fields, and tool manufacturers are also exploring ways to improve processing economics.
In addition to the most common triangular inserts, square inserts with 4 cutting edges have also been used for high feed milling cutters.

Processing economic challenge
Square shoulder milling has a large share of milling. Regardless of the difficulties encountered in processing, users want a solution for an economical tool that increases productivity while reducing the cost per piece. Multiple cutting edge tools already exist, but users are also looking for tools that offer the lowest cost per edge.
The economics of square shoulder milling are also reflected in the following aspects. The user wants to achieve a true 90° straight wall for the first time, without having to use another milling process that is costly and time consuming. Some multi-blade tools are very noisy and have a strong vibration, so the surface roughness is not ideal. Milling tools with low noise and low vibration are required, and smaller tolerance inserts (peripheral grinding) and insert seats are required. Customers need high precision tools to achieve the best quality surface finish. Reducing the inventory of different tools helps increase profits. Customers need square shoulder milling cutters for a variety of different machining applications, including face milling. In fact, customers want a reliable, cost-effective, and preferred solution for general processing.
Seco Tools' Square-6 product is a unique square shoulder cutter with a triangular blade. Turbo Cyclone milling cutters with 2 cutting edges per insert are the most common square shoulder milling cutters for fast cutting and high machining efficiency. The fly in the ointment is that the blade has a small number of effective cutting edges and lacks an advantage when it comes to economics. The Square-6 has six cutting edges, so the cost per cutting edge is low and very economical. The axial rake angle of the insert seat is negative, but the positive-angle cutting edge on the insert ensures a positive pre-cutting angle, thus ensuring high performance. With three different blade geometries and three different pitches, Square-6 offers the same high performance in a wide range of materials, processes and conditions.
The 90° lead angle ensures a true 90° square shoulder in a single pass, saving production time. The coated body has a longer tool life. The pre-hardened body and the peripherally ground inserts offer better precision and reliability, as well as improved precision and tolerances of the parts being machined.
The triangular square shoulder milling insert has six cutting edges, which increases the difficulty of manufacturing the body. Common Turbo cyclone milling blades and square inserts are single-sided inserts with 2 and 4 cutting edges, respectively. The Square-6 blade is double-sided, placing higher demands on the design and manufacture of the blade holder on the arbor. But with the advancement of manufacturing technology, its processing has not become a problem. Therefore, with the continuous advancement of manufacturing technology, economical products like Square-6 will continue to emerge.