Machine and tools in interaction for difficult materials

In the machining of hard-to-cut materials, both the machine and the tools must be capable of extraordinary performance. For this reason, the machine manufacturer Hardinge has long since formed technological partnerships with tool manufacturers. One of these partners is DTS GmbH, based in Kaiserslautern, Germany.

Hardinge GmbH in Krefeld is the Hardinge Group’s technology center in Germany. Specialized in the development of process-oriented solutions, the engineers and technicians keep their focus on customer’s requirements. Headed by branch manager Markus Herdegen, the team has long been dedicated to the challenges posed by hard turning and hard milling processes. Both machines and processes are continuously optimized here.

Cooperation partner DTS-Diamond Tooling Systems GmbH can draw on 25 years of experience in the development and manufacture of diamond and CBN tools. The tools are equipped with lasered cutting edges, especially developed for machining extremely hard materials. Today such tools are indispensable in machining production in the fields of turning, milling, grooving, drilling and reaming. DTS’s core competencies range from tool and process design to supporting the conversion from grinding technology to hard turning.

 

The successful cooperation is based on the high stability and performance of the Hardinge Super Precision hard turning machines and of course on the large selection of high-hard cutting tools from DTS GmbH. In consequence hard materials can now be turned very successfully that could previously only be machined by grinding. Turning has enormous advantages over grinding in many machining operations, be it in the production of ball bearings or in tool technology. For example, in machining defined contours at high speed, turning beats grinding with significantly shorter machining times, which makes turning very economical. In these cases, the comparatively expensive profile grinding wheels and pins can be dispensed with. The accuracy is also impressive: surface finishes of Ra 0.03 – 0.2 µm are achieved when turning hard metals and high-alloy hardened steels.

 The T42 is one of the smaller machines in the Super Precision range

The machine

The rigidity and stability of the SP Series CNC high-precision lathes make them ideal for hard turning and combined hard turning, milling and grinding operations to produce complex workpieces in a single setup. Measuring reports certify that the T-series has a continuous machine accuracy of 3 µm, a workpiece roundness of 0.25 µm (T42) and 0.70 µm (T65), repeatability (on all axes) of 0.76 µm and an achievable surface finish of better Ra 0.15 µm or Rz1.

 

The Hardinge Collet Ready spindle concept allows safe clamping of tool and workpiece directly in the spindle. The collet systems supported by the T-Series are not designed as adapter systems, as is usually the case. This reduces the cantilever length and keeps the machining of the workpiece as close to the spindle bearings as possible. The maximum rigidity of the spindle thus obtained is the pre-requisite for achieving highest precision.

 

The use of an independent Y-axis and driven tools improves the accuracy in milling operations and enables high-precision setting of the tool center for hard turning. Powerful main spindles with speeds of 6,000/5,000/4,000 rpm and speeds of 11/15/26 kW form the basis for high-precision turning.

 

The machining

The workpiece selected for machining consists of two different materials, steel 1.2343 (X 37 CrMoV 5-1) and carbide (G30 with 15% Co and a hardness of 1250 HV30). This carbide is mainly used in tool and mold making.

 

For the machining process the part is at first clamped in a 16C-E collet on the main spindle. The collet can be bored to a diameter corresponding the workpiece. The counter spindle is equipped with a square-profile collet from the Hardinge collet portfolio. Special contours can also be securely clamped with this type of collet.

 

Unmachined part/finished part – showing the hard processing of materials that are difficult to machine

With the DTS-CBN-H tools (milling cutters, chamfer milling cutters, diamond drills, etc.), hardened materials up to a hardness of 72HRC can be machined in smooth or interrupted cuts with best surface qualities. Even a V-plate can securely be used for interrupted cuts with high process-stability.

Turning the inner contour in carbide is up to 95% faster with the diamond inner turning tool than with grinding. An insert with wiper geometry brings higher feed rates for a significantly better surface finish, no matter if turning the face in hardened steel 52+2HRC, executing longitudinal turning and roughing, or finishing the face and outer diameter,

Pre-cutting of the V-groove in hardened steel 52+2HRC and finishing of the groove contour are performed with the 1 mm wide Micro-Line grooving system with CBN cutting edges for high-precision grooves and contours in hardened steels and hard metals, aluminum, GRP/CFRP, and various plastics. With the DTS CBN-Coat drills, holes can be drilled into the solid in hardened materials up to 68HRC without any problems. These can then be reamed with spiralized CBN reamers. The final engraving on the workpiece in hardened steel is carried out with a CBN ball cutter with ø 2.00 mm (with bearing), using driven tools and a programmable C-axis.

DTS Diamond Tooling Systems – Product Range

The economic use of ultra-hard high-performance cutting materials is only ensured if the machining process and the cutting material are perfectly matched. Since 2010, the two companies Hardinge and DTS have been working together again and again on challenging projects as well as on future-oriented technologies with the aim of facilitating machining processes. This includes the machining of tool steels and hard ceramics, but also of hard metals with cobalt or nickel binders.

 

For machining hard metals with a hardness of up to 1970 HV30, DTS GmbH has recently developed a new ultra-diamond. New 3D roughing and finishing chip grooves have been developed for controlled chip breaking in hard metal cutting, aluminum and lead-free brass.

 

The technology partners Hardinge and DTS will maintain the high demands on their products, which are being fast, precise and process-safe in the long term.

 

Contact addresses:

Hardinge GmbH                                                               DTS GmbH
Europark Fichtenhain A 13c                                           Industriegebiet Nord
D-47807 Krefeld                                                                Hans-Geiger-Strasse 11a
D-67661 Kaiserslautern

www.hartdrehen.com                                                        www.diamond-toolingsystems.com