Mapal, a German cutting tool manufacturer, has found that the use of 3D printing (also known as additive manufacturing) technology to produce reduced-cut cutting tools is ideally suited to expand the dimensional specifications of its QTD internal cooling drill product line. Using Concept Laser's laser-melted 3D printing system, Marpa can produce QTD drills that are smaller in size than before, and can achieve some bit structure design that was 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 reduced-cut cutting tools is ideally suited to expand the dimensional specifications of its QTD internal cooling drill product line. Using Concept Laser's laser-melted 3D printing system, Marpa can produce QTD drills that are smaller in size than before, and can achieve some bit structure design that was difficult to achieve in the past.
The QTD series internal cooling drills are made of hardened steel with a V-block for the replacement of blades. This internal cooling drill has good chip formation and reliable chip evacuation and can be used to drill steel, stainless steel, cast iron and aluminum workpieces.
Previously, the minimum diameter of the QTD series drills was only 13 mm due to the size of the coolant inside the drill bit and the distribution of the coolant to the Y-shaped branches on both sides of the cutting insert. Further reduction of the drill diameter reduces tool stability while the coolant aperture remains constant, while reducing the diameter of the drill while reducing the cooling aperture limits the flow of coolant to the cutting edge, reducing its operation. efficacy.
Since May 2013, Marpa has been researching how to apply 3D printing technology (especially selective laser melting technology) to solve the production problems of small-sized internal cooling drills. The result of this research is the development of traditional New QTD drills with smaller diameters that cannot be produced by the process.
Marpa's R&D department uses two M1 LaserCusing additive manufacturing systems from Concept Laser of Germany to produce QTD drills with optimized coolant delivery channels. The system uses a laser to heat the metal powder in a specific area of the melting system and fuse the workpieces layer by layer. By laser-melting the workpiece, complex geometries (including internal geometries) that cannot be achieved with conventional machining can be constructed.
The new QTD drill bit of 3D printing adopts a spiral internal cooling structure, and the direction of the coolant passage is parallel with the spiral sipe of the drill bit, thereby increasing the stability of the drill core and improving the cooling performance. According to the company, this spiral-oriented cooling channel increases the coolant flow rate of the drill bit by 60%.
Thanks to the 3D printing process, Marpa can also change the cross-section design of the coolant channel, changing the circular channel that was drilled in the past to a triangular channel (see left in Figure 1). Compared to the circular channel, the coolant flow through the triangular channel can be increased by 30%. The combined optimization of the spiral and triangular cross-sections results in a 100% increase in coolant flow rate compared to the original drill structure.
Through the optimized design of the drill bit, Marpa has now been able to manufacture drill bit bodies with diameters <13 mm (up to 8 mm) using 3D printing. These small diameter QTD drills are produced in a hybrid process in which the shank is still machined in a conventional manner and the body is printed on a LaserCusing laser fused 3D printer with 1.2709 steel.
The body printing is done in two stages: first printing the core with the cooling system and then printing the outer body with a higher material density (to increase its hardness). In the print space of the LaserCusing system with a size of 250mm × 250mm × 250mm, 100-121 bit cutter bodies can be printed in batches at a time.
This hybrid production process allows Marpa to achieve the speed advantages and material performance of traditional tooling for tool holders, as well as the benefits of unattended production and optimized bit design through 3D printed bodies. For the company, 3D printing is not just an alternative process, it is used to fill production gaps and implement tool designs that are not possible in any other way.
Another example of a cutting tool made with 3D printing technology is the Revolution tool series of the German tool manufacturer Komet at the 2016 Chicago International Manufacturing Technology Exhibition (IMTS 2016). It is currently manufactured at Remetaw's selective laser-melted metal 3D printing equipment at its headquarters in Germany. Through one printing, a variety of different cutter bodies customized for production can be manufactured at the same time. After printing, the cutter body is cut from the bottom metal disc by EDM processing equipment, and the PCD cutting edge is brazed to the cutter body; The standardized shank of the milling cutter is mass-produced by traditional machining methods (can be produced at the customer's location at the Gomez plant); finally the laser body is used to weld the shank and the shank together.
The sipe density and helix angle of the milling cutter are important factors affecting the cutting performance. Increasing the number of sipe and increasing the helix angle can increase the feed rate and cutting efficiency of the milling cutter. The metal 3D printing process can produce a more scalar and denser body, and increase the sipe helix angle from the original 4°-5° to 20°, thus milling aluminum alloy and carbon fiber composites. Achieve higher material removal rates. At the same time, it can solve the problem that the processing of non-standard cutter body by traditional machining method is difficult and the processing cycle is long.
In addition, the 3D printing tool body can 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 transfer capacity of the coolant flowing to the tool tip, thereby improving cooling efficiency and tool life. . In addition to improving the performance of the milling cutter and the life of the tool, the application of 3D printing technology brings more freedom to its tool design, making the time-consuming and labor-intensive non-standard special tool customization business faster and more convenient.