Mapal, a German cutting tool manufacturer, found that the use of 3D printing (also known as additive manufacturing) technology to produce material-reducing cutting tools is very suitable for expanding the size and specifications of its QTD internal cooling drill bit product line.Using Concept Laser's laser melting 3D printing system, Mapal can produce QTD drill bits with smaller dimensions than before, and can realize some drill bit structure designs that were difficult to achieve in the past. German cutting tool manufacturer Mapal found that the use of 3D printing (also known as additive manufacturing) technology to produce material-reducing cutting tools is very suitable for expanding the size and specifications of its QTD internal cooling drill bit product line.Using Concept Laser's laser melting 3D printing system, Mapa can produce QTD drill bits with smaller dimensions than before, and can realize some drill bit structure designs that were difficult to achieve in the past.

The inner cooling drill bit of the QTD series is made of hardened steel, and there is a V-shaped block on the tool body for installing replaceable blades.This internally cooled drill bit has good chip-forming performance and reliable chip removal performance, and can be used for drilling steel, stainless steel, cast iron and aluminum workpieces.

Previously, since the coolant inside the drill bit was limited by the size of the conveying channel and the distribution of the coolant to the Y-shaped bifurcation on both sides of the cutting blade, the minimum diameter of the QTD series drill bit could only reach 13mm.While the coolant pore size remains the same, further reducing the diameter of the drill bit will reduce the stability of the tool, while reducing the diameter of the drill bit, reducing the cooling pore size will limit the flow of coolant delivered to the cutting edge and reduce its working efficiency.

Since May 2013, Mapa has been studying how to apply 3D printing technology (especially selective laser melting technology) to solve the production problems of small-size internally cooled drill bits, and the result of this research is the development of a new type of QTD drill bit with a smaller diameter that cannot be produced by traditional technology.

Mapa's R&D department uses two M1 LaserCUSING additive manufacturing systems from German Concept Laser to produce QTD drill bits with optimized coolant delivery channels.The system uses laser heating to melt the metal powder in a specific area of the system, and the workpieces are welded together layer by layer.By printing the workpiece by laser melting, complex geometric shapes (including internal geometric shapes) that cannot be achieved by traditional machining can be constructed.

The new type of 3D-printed QTD drill bit adopts a spiral internal cooling structure, and the direction of the coolant channel is parallel to the spiral tool groove of the drill bit, thereby increasing the stability of the drill core and improving the cooling efficiency.According to the company, this spiral cooling channel can increase the coolant flow of the drill bit by 60%.

Due to the 3D printing process, Mapa can also change the cross-sectional design of the coolant channel, changing the circular channel formed by drilling in the past to a triangular channel (see Figure 1 on the left).Compared with the circular channel, the flow rate of coolant through the triangular channel can be increased by 30%.Compared with the original drill bit structure, the optimized design of the combination of spiral direction and triangular cross-section can increase the coolant flow rate by 100%.

Through the optimized design of the drill bit, Mapa Company can now use 3D printing to manufacture a drill bit body with a diameter of <13mm (as small as 8mm).These small-diameter QTD drill bits are produced by a hybrid process. Among them, the shank is still processed in a conventional manner, while the tool body is printed and manufactured with 1.2709 steel on a LaserCUSING laser melting 3D printer.

The printing of the tool body is carried out in two stages: first, the drill core with a cooling system is printed, and then the outer tool body with a higher material density (to increase its hardness) is printed.In the printing space of the LaserCUSING system with a size of 250mm×250mm×250mm, 100-121 drill bit bodies can be printed out in batches at a time.

This hybrid production process enables Mapa to not only obtain the speed advantage and material efficiency of manufacturing tool holders by traditional processing methods, but also obtain the benefits of unattended production and optimized drill bit design through 3D printing tool bodies.For the company, the use of 3D printing is not just an alternative process, but is used to fill production gaps and realize tool designs that cannot be achieved in any other way.

Another example of using 3D printing technology to manufacture cutting tools is the Revolution series milling cutter launched by the German tool manufacturer Komet at the 2016 Chicago International Manufacturing Technology Exhibition (IMTS 2016). The non-standard cutter body of the milling cutter is currently manufactured at the German headquarters of Komet with Renishaw's selective laser molten metal 3D printing equipment.Through one-time printing, a variety of different tool bodies customized for customers can be manufactured at the same time. After the printing is completed, the tool body is cut from the metal disc at the bottom with EDM processing equipment, and the PCD cutting edge is brazed to the tool body; the standardized tool holder of the milling cutter is manufactured in large quantities through traditional machining methods (it can be produced at the Gaomaite factory where the customer is located); finally, the tool body and the tool holder are welded together by laser brazing process.

The groove density and spiral angle of the milling cutter are important factors affecting its cutting performance. Increasing the number of grooves and increasing the spiral angle can improve the feed speed and cutting efficiency of the milling cutter.The metal 3D printing process can produce a tool body with a larger number of tool slots and a denser arrangement, and the spiral angle of the tool slot is increased from the original 4°-5° to 20°, thereby achieving a higher material removal rate when milling aluminum alloy and carbon fiber composite materials.At the same time, it can also solve the problem of high processing difficulty and long processing cycle of non-standard tool bodies manufactured by traditional machining methods.

In addition, the 3D printing tool body can also increase the number of cooling holes in the milling cutter, and adopt a coolant channel geometry with a complex spiral structure to improve the heat conduction capacity of the coolant during the flow to the tip, thereby improving the cooling efficiency and tool life.In addition to improving the performance and tool life of milling cutters, the application of 3D printing technology also brings greater freedom to their tool design, making the original time-consuming and laborious non-standard special tool customization business faster and more convenient.