Tools, tips & productivity. Praxis-Report No. 19. Hard turning with SPK-WURBON and SPK Mixed Ceramic

Transcription

1 Tools, tips & productivity Praxis-Report No. 19 Hard turning with SPK-WURBON and SPK Mixed Ceramic

2 Tools, tips & productivity Tools - Inserts + tooling systems Tips - Recommendations for application + machining technology & Productivity - Engineering + process optimization to improve your machining productivity in cast iron and hardened steel

3 Hard turning with SPK-WURBON and SPK Mixed Ceramic - an economical grade combination WURBON (CBN) or ceramics for hard turning processes? It is not a question of which grade to choose. The best results depend on the right combination of both grades. Consider that both materials can be used for machining steels up to a hardness of 65 HRC. The standard grinding process has reached its maximum potential. Modern processes like hard turning can replace grinding-operations in many areas such as the machining of chuck-parts. In many cases, large batch producers, striving to reduce production costs and increase productivity, now use hard turn instead of grinding. When considerering the high requirements of hard turning the grade must have special characteristics such as high wear resistance, excellent hardness and warm hardness, all of which must be combined with high compression strength, chemical stability and sufficient fracture strength. Essentially, these factors determine the quality of the workpieces produced. The grades SPK-WURBON and SPK Mixed Ceramics fulfill these requirements. The best economical use often requires a combination of both grades. The SPK Mixed Ceramic SH 2 is SPK-Wurbon SPK Mixed Ceramic SH 2 characterized by a fine grained, homogeneous structure, in which particles of titanium-carbide-nitride have been dispersed on the basis of AL 2 O 3. These increase the hardness, wear resistance and edge strength and thus also increase the performance when hard turning. When hard turning under continuous cutting conditions and lower grinding allowance the application of SPK Mixed Ceramic is favoured generally over that of SPK-WURBON. The benefit of this is a lower cost per cutting edge. A guide to the selection of the right grade is shown in the following table. 3 Applications of SPK Mixed Ceramic and SPK-WURBON when hard turning. Continuous cut Continuous cut Intermittent cuts Coolant Grade stable conditions unstable conditions light medium heavy recommendation SH 2 dry / wet WBN 650 dry / wet WBN 600 dry / wet WBN 550 wet / dry WBN 500 dry / wet Main application Additional application

4 Production of SPK-WURBON grades 4 The SPK-WURBON grades are classified within the group of polycrystalline cubic boron nitrides. These grades are characteristic with respect to high hardness, warm hardness, pressure strength and all posses better fracture toughness. Raw materials are CBN grades, which are produced through a highpressure, high-temperature procedure. (T = C; p = 5 7 GPa). These grades come together with one binder material, either as a large Hexagonal Boron Nitride (chemical compound from boron and nitrogen) CBN-synthesis (T = C; p = 5 7 GPa) CBN circular blank or a laminated circular blank with a CBN-layer of mm on a sintered carbide base layer. From these circular blanks segments are cut out and soldered on a carbide base layer. The segment is then ground to produce a suitable cutting geometry. Large CBN inserts are cut out by means of laser, from a CBN circular blank and then ground with the appropriate cutting geometry. Cubical Boron Nitride Binder material (ceramic or metallic) Sinter process Circular blank Wire-cut EDM / Laser-cutting Segment Soldering of the segments CBN-Inserts

5 Classification of the SPK-WURBON grades The classification of the cubic boron nitride depends on the CBN content. The CBN content, binder and grain size determine the SPK-WURBON grade. Turning of hardened steel materials, up to 65 HRC, is possible with a CBN content from 45 to 65%. (WBN 500, WBN 550, WBN 600, WBN 650). These low CBN content SPK-WURBON grades are offered as corner tipped inserts. Generally grades with a CBN content from 70 to 95% offer higher toughness and higher wear resistance against abrasive wear. (WBN 100, WBN 700, WBN 750). In the area of high performance cutting, they are preferred for turning and milling of chilled cast iron, sintered steels, superalloys, grey cast iron and nodular cast iron. These high CBN content SPK-WURBON grades are offered primarily as large inserts from solid material (WBN 100). In addition corner tipped grades (WBN 700, WBN 750) are available. 5 Low CBN content 45-65% (ISO classification: BL) Key applications: Hard turning of hardened steel with a hardness of HRC SPK grades: WBN 500, WBN 550 WBN 600, WBN 650 High CBN content 70-95% (ISO classification: BH) Key application: Turning and milling (WBN 100) of chilled cast iron, sintered steel, superalloys, grey cast iron and nodular cast iron. SPK grades: WBN 700, WBN 750, WBN 100

6 Applications of the SPK-WURBON grades Low CBN content 45-65% 6 WBN 500: This is the recomended grade for the application of heavy interrupted cutting of hardened steel. An additional application is that of the machining of sintered steel and carbides. WBN 550: This is a particularly suitable grade for wet machining, hard turning with light interrupted cutting, and continuous cutting under unfavorable conditions as well as low and medium cutting speeds from m/min. WBN 600: This is the first choice for the general application of hard machining. Areas of application include hard turning with continuous cutting to medium intermittent cutting, as well as dry and wet machining. The ideal cutting speed is within in the range of m/min. WBN 650: This is a high performance grade with a good wear resistance together with low toughness. Because of the fine grain structure, this grade is particularly suitable for applications requiring good surface quality and dimensional accuracy. The area of application is hard turning with a high cutting speed ( m/min) alongside continuous cutting and stable conditions. W B N Wear resistance WBN W B N W B N Toughness Applications of the SPK grades in hardened steel (55-65 HRC)

7 Applications of the SPK-WURBON grades High CBN content 70-95% 7 WBN 700: This is a corner-tipped variant for the machining of GCI and NCI materials, as well as sintered steel materials and chilled cast iron. WBN 750: This is the recomended grade for the corner-tipped variants used in the application of finishing on grey cat iron material, as well as for the machining of sintered steel materials. WBN 100: This solid CBN grade is the first choice for roughing and finishing of grey cast iron and the machining of chilled cast iron, nickel-based hard material and hard material coatings. W B N Wear resistance W B N W B N Toughness Applications of the SPK grades in cast iron (GCI, NCI), sintered steel, superalloys and chilled cast iron

8 Execution variants of the SPK-WURBON inserts 8 Variants Schematic Description Grade illustration A B CBN one-side tipped, 1 corner CBN one-side tipped, 2 corners WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 U CBN tipped, full thickness, 4 corners V CBN tipped, full thickness, 6 corners WBN 600 WBN 650 WBN 700 W CBN tipped, full thickness, 8 corners F CBN one-sided full face laminated WBN 600 WBN 700 S CBN solid WBN 100 Length of the CBN element Code letter S L Dimension l 1 (mm) > 0.8 > 3.0 l 1 Example: CNMA T-BL chamfered length of the CBN element > 3.0 mm CBN one-side tipped, 2 corners With SPK-WURBON inserts the length of the CBN element has a minimum length of 2.2 mm, even with the code letter S.

9 Chamfer geometry As well as making the correct choice with respect to the substrate material, it is also important to specify the most suitable chamfer geometry for the machining application. The chamfer geometry affects not only the tool life of the insert but also the surface quality and dimensional accuracy of the work piece. Chamfer T E chamfered rounded Application First choice for continuous and intermittent cut when hard turning. Particularly suitable for the machining of cast iron or large projecting length. Used mainly with the grade WBN F sharp edged Particularly suitable for the machining of cast iron. Used in combination with the grade WBN 100. Optimizing the chamfer geometry is possible in special cases and can lead to a further increase in productivity. S chamfered + rounded This is especially suited for hard turning and is used in combination with SH 2. The cutting edge length has additional stability together with high strength. Better surfaces and faster feed rate by ZZ geometry (Wiper) A small cause a large effect. This is perhaps the best way to describe the huge increase in performance in finish turning, achievable with ZZ geometry. Note: ZZ geometry is also known in the industry as Wiper geometry. The application of such ZZ inserts makes it possible to double the feed rate and thus increase the productivity. Standard geometry ZZ geometry Example for the identification of ZZ inserts: Equal feed rate = doubled surface quality or Increasing of the production quality CNMA T-BL95Z025 identification to ISO blank angle = 95 width of the ZZ chamfer = 0,25 mm Double feed rate = equal surface quality Increasing of the productivity The standard program of the ZZ inserts covers most applications used in hard turning. For a further increase in productivity, as well as optimization of the respective process, we offer a customized solution.

10 Hard turning with SPK-WURBON and SPK Mixed Ceramic Application examples from practice 10 Material: 16 MnCr 5 Hardness: HRC Machine: Weisser Coolant: no Criterion: R z max 2,5 µm Insert: Grade: SH 2 SH 2 Shift bushing Cutting data RH LH v c (m/min): f (mm/rev): 0,08 0,08 a p (mm): 0,40 0,40 Tool life: 250 pieces 250 pieces Remark: The workpiece is a cold-rolled blank (high material compression). Material: 20 MnCr 4 E Hardness: HRC Machine: EMAG VSC400 Coolant: no Criterion: R z 10 µm / 110 H6 Insert: CNMA T-BL95Z025 Grade: WBN 550 WBN 550 Crown wheel Cutting data v c (m/min): f (mm/rev): 0,14 0,12 a p (mm): 0,15 0,15 Tool life: pieces 1500 pieces 15 Remarks: At v c = 170 m/min and f = 0,14 mm/rev tool life fluctuations were depending upon the material load. Reducing to v c = 150 m/min and f = 0,12 mm/rev constant, 1500 pieces could be machined.

11 Hard turning with SPK-WURBON and SPK Mixed Ceramic Application examples from practice 11 Chain wheel Material: Sintered steel Sint D 30 Hardness: HRC Machine: Mazak Coolant: no Criterion: 15 µm flatness / R z 6,3 µm Boring: R z 6,3 µm / 40 H7 Insert: CCMW 09T308 T-AL TCGT SD Grade: WBN 750 SC 15 (Cermet) Cutting data 1 2 Boring v c (m/min): f (mm/rev): 0,13 0,10 0,10 a p (mm): 0,30 0,10 0,30 Tool life: 550 pieces 550 pieces 550 pieces Remark: The flat surface is machined with two cuts, to achieve a flatness of 15 µm. 0, H7 84 Way disk Material: 15 CrMo 5 Hardness: 62 HRC Machine: Coolant: no Criterion: Pre-machining of the contact surface Insert: CNGX S05020 Grade: SH 2 Cutting data v c (m/min): 130 f (mm/rev): 0,30 a p (mm): 0,2 0,3 Tool life: 100 pieces Remark: To minimise grinding time the surface will be turned to leave a minimal stock. Using CBN an extended tool life of around 30% can be realized although at the same cutting data SH2 is a more economic alternative due to its substantially lower cost

12 Recommendation for SPK-WURBON grades and Mixed Ceramic SH 2 12 SPK-WURBON grades v c (m/min) a p (mm) f (mm/rev) Grey cast iron Roughing ,0-5,0 0,35-0,60 Semi-roughing ,5-2,5 0,20-0,35 Finishing ,5-1,5 0,15-0,30 Super finishing ,2-1,0 0,10-0,20 Ductile cast iron Finishing ,0-2,5 0,15-0,30 Super finishing ,5-1,5 0,10-0,20 Hardened steel (55 65 HRC) continuous cut ,1-0,5 0,05-0,20 lightly intermittent cut ,1-0,5 0,05-0,20 medium intermittent cut ,1-0,5 0,05-0,20 heavily intermittent cut ,1-0,5 0,05-0,20 Chilled castings Semi-roughing ,0-2,5 0,20-0,65 Finish turning ,1-1,0 0,10-0,30 Ni-Hard Semi-roughing ,0-2,5 0,20-0,30 Finish turning ,1-1,0 0,10-0,20 Sintered metals Semi-roughing ,0-2,5 0,20-0,30 Finishing ,5-1,5 0,10-0,25 Super finishing ,1-1,0 0,10-0,20 Hard coatings Semi-roughing ,0-2,5 0,20-0,30 Finish turning ,1-1,0 0,10-0,20 WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 Mixed Ceramic SH 2 v c (m/min) a p (mm) f (mm/rev) Grey cast iron Finishing ,3-1,0 0,20-0,60 Super finishing ,2-0,5 0,08-0,25 Ductile cast iron Finishing ,3-1,0 0,20-0,40 Super finishing ,2-0,5 0,08-0,20 Hardened steel (48 56 HRC) Roughing ,5-2,0 0,08-0,20 Finishing ,1-0,5 0,12-0,30 Hardened steel (57 64 HRC) Roughing ,5-2,0 0,08-0,20 Finishing ,1-0,5 0,12-0,30 = Recommendation = Alternative

13 Types of wear when hard turning SPK insert types 13 Types of wear... Flank wear Crater wear and their solutions reduce the cutting speed increase the feed rate choose a wear resistant grade choose a sharper micro geometry use a positive insert reduce the cutting speed change feed rate (usually a reduction) choose a sharper micro geometry (flatter chamfer) choose a more wear resistant grade Flaking on the insert surface raise the feed rate reduce the cutting speed check the center hight stable cutting edge application (rounded) Breakout of the cutting edge reduce the cutting speed reduce the cutting depth stable cutting edge application bigger corner radius choose a tougher grade improve stability SPK insert types CCGW CCMW DCMW SCGW SCMW 80 CNGA CNMA 55 DNGA DNMA 90 SNGA SNMA CNGN CNMN DNGN SNGN SNMN TCGW TCMW TPMW TPUN VCGN 80 WNMA 60 TNGA TNMA 35 VBMW VCMW TNGN TNMN VNGA VNMA RNMN

14 Inserts SPK-WURBON und SPK Mixed Ceramic Delivery programm 14 ISO SPK ref.no.* Grade WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 SH 2 CCGW T CCGW 09 T3 04 T T3 08 T CCMW T- AL T- AL E- AL E- AL CCMW 09 T3 04 T- AL T3 08 T- AL T3 12 T- AS T3 04 E- AL T3 08 E- AL T3 12 E- AS CCMW 09 T3 04 T- BL T3 08 T- BL T3 04 T- BL 95Z T3 08 T- BL 95Z T3 08 E- BL T3 04 E- BL 95Z T3 08 E- BL 95Z CNGA T T CNGN T T T T CNMA T- AL T- AL T- AS CNMA T- BL T- BL T- BS T- BL 95Z T- BL 95Z E- BL 95Z E- BL 95Z

15 Inserts SPK-WURBON und SPK Mixed Ceramic Delivery programm 15 ISO SPK ref.no.* Grade WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 SH 2 CNMA T- US T- US CNMN T - S T - S T - S CNMN T - S T - S T - S CNMN T - S T - S T - S CNMN T - S T - S T - S DCMW E- AL DCMW T- BL T- BL DCMW 11 T3 04 T- AL T3 08 T- AL T3 12 T- AS DCMW 11 T3 04 TL- AL 93Z T3 04 TR- AL 93Z DCMW 11 T3 04 T- BL T3 08 T- BL T3 04 E- BL T3 08 E- BL DNGA T T DNGN T T T T DNMA T- AL T- AL

16 Inserts SPK-WURBON und SPK Mixed Ceramic Delivery programm 16 ISO SPK ref.no.* Grade WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 SH 2 DNMA T- US T- US T- US RNMN T - S F - S RNMN T - S RNMN T - S F - S RNMN T - S SCGW 09 T3 04 T T3 08 T SCMW 09 T3 04 T- AL T3 08 T- AL T3 04 E- AL T3 08 E- AL SNGA T T SNGN T T T SNMA T- AL T- AL T- AL SNMA T- WL T- WL T- WS SNMN T - S T - S T - S SNMN T - S T - S T - S

17 Inserts SPK-WURBON und SPK Mixed Ceramic Delivery programm 17 ISO SPK ref.no.* Grade WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 SH 2 SNMN T - S T - S T - S SNMN T - S T - S T - S TCGW T T TCMW T- AL T- AL E- AL E- AL TCMW 16 T3 04 T- AL T3 08 T- AL T3 04 E- AL T3 08 E- AL TNGN T T T T TNMA T- AL T- AL T- AS TNMA T T TNMN T - S T - S T - S TNMN T - S T - S T - S TPMN T- AL T- AL E- AL E- AL

18 Inserts SPK-WURBON und SPK Mixed Ceramic Delivery programm 18 ISO SPK ref.no.* Grade WBN 500 WBN 550 WBN 600 WBN 650 WBN 700 WBN 750 WBN 100 SH 2 TPMW T- AL T- AL TPUN T T T VBMW T- BL T- BL E- BL VCGN S S S S VCMW T- BL VCMW T- BL T- BL VNMA T- US T- US T- US VNMA T T T T WNMA T- AL T- AL T- AS WNMA T- VS T- VS T- VS * Complete the SPK ref.no. with the code number of the chamfer and grade: CNMA T - BL WBN

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20 High Performance cutting ceramics and more. As the leader of modern cutting technology we have helped our customers for more than three decades in the planning, execution and optimization of new tooling systems. All of these services are incorporated within the SPK Cutting Tool Division of CeramTec AG, the specialist in high performance ceramics within Dynamit Nobel group. However, ceramic cutting tools are certainly not everything that CeramTec produces. Seven other divisions help to industry to solve, special wear, corrosion and isolation problems, with a multiplicity of products made of high performance ceramic. Medical Products Division Mechanical Systems Division Chemical Applications Division Electrical Applications Division Electronic Applications Division Piezo Applications Division Mechanical Applications Division and Textile Applications Sales branches of SPK cutting tools: France CeramTec AG Innovative Ceramic Engineering Bureau de Représentation en France 51, rue Pierre F Clichy Tel /99 Fax cutting_tools@ceramtec.de U.K. CeramTec UK Ltd. SPK Cutting Tool Division Unit 16, Mercia Business Village Torwood Close Westwood Business Park GB-Coventry, CV4 8HX Tel Fax spk@ceramtec.co.uk Italy CeramTec Commerciale Italiana Via Campagnola, 40 I Bergamo Tel Fax ceramtec@ceramtec.191.it Sweden CeramTec Scandinavia Innovative Ceramic Engineering Klippan 1J S Göteborg Tel Fax sales@ceramtec.pps.se Spain CeramTec Ibérica Innovative Ceramic Engineering, S.L. Santa Marta, E Vilassar de Mar (Barcelona) Tel Fax ceramtec@terra.es USA CeramTec North America Corp SPK Cutting Tools PO Box 89, One Technology Place Laurens, SC Tel Fax Toll Free information@ceramtec.com The adresses of our foreign reprensentatives will be given to you on request. Presented by: CeramTec AG Innovative Ceramic Engineering Geschäftsbereich SPK-Werkzeuge Gottlieb-Haefele-Str. 7 D Ebersbach/Fils Sales: Tel. +49 (0) Fax +49 (0) Engineering: Tel. +49 (0) Fax +49 (0) cutting_tools@ceramtec.de WZ /GB LO Printed in Germany