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Toolmaker Produces Drills with Additive Manufacturing

 

MAPAL Inc. (Aalen, Germany; Port Huron, MI) is a manufacturer of precision tools for applications in metalworking, including precision drilling, reaming, milling, and turning for the automotive, mechanical, tool, and plant engineering industries. At EMO 2015, MAPAL exhibited its QTD cutting insert drill that was produced by additive manufacturing for 8–12-mm diameters. Previously QTD insert drills smaller than 13-mm diameter were not available because they were difficult to produce with the required smaller coolant channels through the tool. Central coolant supply weakened the core of the drill and as the cooling channels get smaller, the flow of coolant to the insert is reduced.

The QTD series insert drills are additively manufactured from metal powder using the LaserCusing system from Concept Laser Inc. (Grapevine, TX; Lichtenfels, Germany). The hybrid manufactured tools include a tool shank that is machined conventionally and the drill that is laser melted with additive methods. The approach makes the manufacturing process significantly more economical. According to Dr. Dirk SellMAPAL is using Concept Laser’s LaserCusing to additively manufacture small diameter QTD insert drills with new cooling duct profiles.mer, head of research and development at MAPAL, “Hybrid strategies are the ideal methods of choice. Simple component parts are machined and more complex areas are then built up additively.” Using laser melting the smaller diameter QTD insert drills are able to be additively manufactured with 100% increased coolant flow rate, increased core stability due to coolant channels running parallel to the flute. Sizes come in 1.5×D, 3×D, 8×D, and 12×D lengths with inserts type 1-4 for steel, stainless steel, cast iron, and aluminum.

“We manufacture the QTD insert drill on the hull/core principle. First the core of an insert drill is built with the cooling system, which is added to the conventional shaft. In a second additive run, the outer hull is built up with higher densities, which is close to the ideal for a good drill bit—hard outside and soft inside,” said Sellmer.

The greatest advantage of transitioning from a conventional manufacturing strategy to additive manufacturing is that it facilitated design of entirely new geometry, increasing the performance of the tools. “The additively manufactured insert drill has a cooling concept with spiral ducts, which improves the cooling performance. Compared with the previous central coolant supply with the Y diversion, a spiral coolant routing increases the coolant flow by 100%,” said Sellmer.

“It also increases the core stability with coolant ducts which run parallel to the flute. The cooling is also improved by the new coolant duct profiles which deviate from the usual circular form with a slightly triangular shape that optimizes the geometrical moment of inertia and the flow rate. Tests found that choosing a cross section of this type increases the flow quantity by 30%. Coolant profiles like this can’t be produced conventionally, and the coolant flows at a pressure of 1.6–3 bar.

The new coolant concept produces better cooled drills that are available for longer drilling tasks and an expanded range of smaller drill diameters. Stainless steel is used. According to Dr. Sellmer, the powder requirement is calculated from the effective construction weight plus 10% and the scrap material is easy to recycle. Internal tension in parts which must be removed from rotating tools that are conventionally manufactured is removed from the part internally during the additive build process.

At MAPAL, two Concept Laser M1 cusing systems with a central material supply container are used. The medium performance range system has a build envelope of 250 × 250 × 250 mm. The QTD insert drills are created as 10 × 10 or 11 × 11 unit solutions in this build envelope, producing 100 to 121 drills in one setup. The build rates of the 400-W lasers are between 6 and 18 cm3/h. In order to avoid contamination, the M1 cusing operates under a nitrogen protection gas atmosphere. During processing, the laser heats the powder material to 60–70° C for fusing. The thermal expansion in the build process has to be taken into consideration in the design. However, after initial successes with series production, the demand for internal capacities is also growing and has been extended with 24 hours, 7 days a week untended production.

According to Matthias Schneider, an employee in the RQTD insert drills feature new slightly triangular cooling duct profiles that increase flow rate by 30% in tools that can’t be produced conventionally.&D department, reasons for choosing Concept Laser’s LaserCusing process include ease of handling, accessibility, and user friendliness. The process is cited for its variable parameters that facilitate testing of new product designs. “Topology options for LaserCusing stand out due to the stochastic control of the slice segments which are processed successively. This exposure strategy induces the lowest tension in the component,” said Schneider.

Changes in design are also apparent in MAPAL’s new weight-optimized, additively-produced external reamers. The lighter the external reamers are, the better they work, something that is particularly true for machining small-diameter shafts. Conventionally manufactured 8.5-mm steel external reamers weigh 400 grams. This weight and the resulting mass inertia severely restrict the maximum step speeds. Additive manufacturing allows lightweight external reamers to be built with integrated balancing potential.

According to Dr. Sellmer: “The mass distribution of the honeycomb structure of the external reamers functions like balancing wheels. We call the internal cavities balancing profiles. The balancing profiles enable us to achieve virtually perfect concentricity of the rotating tools. A rib structure, specially designed for the applications, which has been registered for a patent, reduces the new 8.5-mm external reamer’s weight to 172 grams, resulting in a better performance for this rotating component, faster machining, and increased precision. The Concept Laser’s LaserCusing process is being used to additively manufacture direct components, tool inserts, prototypes, and low-volume products for the jewelry, medical, dental, automotive, and aerospace industries. The system processes powder materials made from stainless steel, hot work tool steels, cobalt-chromium alloy, nickel-based alloy and reactive powder materials such as aluminum and titanium, as well as precious metals like gold and silver alloys.

For more information from Concept Laser Inc., go to www.conceptlaserinc.com, or phone 817-328-6500: for information from MAPAL Inc., go to www.mapal.com, or phone 810-364-8020.

 


This article was first published in the April 2016 edition of Manufacturing Engineering magazine. Read "Toolmaker Produces Drills with Additive Manufacturing" as a PDF. 


Published Date : 4/1/2016

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