Front case incombustion chamber, it’s a thin walled ring piece with poor rigidity and largematerial removal rate is prone to deformation. There arepositioning side assembled as locating and connecting role, also precision locatinghole and screw connecting hole alongside. External surface have various kind ofbosses, holes and grooves with different function. With high dimensionprecision, strict technical requirements, the case internal structure iscomplex with narrowed ring groove area, small space for tools operation; thinwalled components ring part and uneven thickness. All of above factors lead topoor stability and rigidity of the case parts operation, also worse radialdeformation resistance.
Components materials ishigh-temperature alloy Inconel 718, with the features of high hardness, highstrength, high-temperature resistance and difficult-to-cut. Under high cuttingtemperature, tools generate rapidly diffusive wear and severe work-hardening. Thus,cutting operation becomes more difficult with large cutting force in operationand usually up to two to three times more than that of steel. Low heatconductivity coefficient and poor thermal conductivity make heat intensivelyaccumulated around the tool nose and generates high heat in operation.
Machining process is as follow：
External rough turning of small face——Internal roughturning of large face—— Large face basis Turning ——Rough and finish turning ofsmall face——Internal finish turning of large face ——External ring groovesmilling——External boss profile milling——Face milling of external boss——Externalboss profile clearance milling——Inner-wall ring grooves milling——Milling ofRing grooves on inner-wall for large face(1)——Milling of Ring grooves oninner-wall for large face(2)—— Clearance milling of inner-wall ring groovesprofile for large face——Finish milling of inner-wall T grooves for largeface——Basis finish turning——Large face finish
blank finished product（ red part）
Blank is forging pieces, after roughing it becomespreliminarily model, blank get rid of 50% material removal turn into finishedproducts. Complex structure with thin walled components feature, deformation inoperation will bring difficulty in machining. In tool selection, inserts withsharp edges geometry should be the first choice due to its capability of lowercutting resistance and deformation.
External rough turning of small face:
Machining features: Roughing operationwith high allowance removal rate and has high machining efficiency requirementas well.
Machines: CNC verticallathe
Tool selection principles: with relatively simple contour structure
inroughing, machining efficiency should be the emphasis in
operation. Ceramictools are the first choice,
obtained successful experiences inaerospace industry,
RCGN\RNGN round inserts series can dramatically increase
efficiencywith combination of CA1000.
Insert with positive angle inexternal turning：CRSCR3232P09（RCGN090700）
Insert with negative angle in faceturning：CRDNN3232P12（ RNGN120400）
Cutting data：V=200m/min，fr=0.25mm/r
Internal rough turning of largeface
Machining features: Roughing operation with highallowance removal rate and has high machining efficiency requirement as well.
Machines: CNC vertical lathe
Tool selection principles: With the same tool in thisprocess and the former one, it is able to complete external turning andinternal cavity with the help of positive ceramic.
Tool：CRSCR3232P09
Insert：CA1000/ RCGN090700T01015-V
Cutting data：V=200m/min，fr=0.2mm/r
Large face basis turning
Machining features: base-levelturning
Machines: CNC vertical lathe
Toolselection principles: For High-temperature finishing, thin walled componentsneed for sharp geometry to lower cutting force, high indexing accuracy andrepeatability, safe and fasten clamping system of tool holder. CT is suitable for high-temperature thin walled alloy finishing, 55 ° Dshape insert can secure high insert nose strength, also possess sharpnessgeometry and precision ground of locating surface to improve indexing repeatability.M type clamping system ensures safety and fastens champing. Choosing as its excellent wear-resistance can improve tool life.
Tool：MDJNR3232P15
Insert：DNEG150608
tool：MDJNL3232P15
insert：DNEG150608
Cutting data：V=40m/min，fr=0.15mm/r
Rough and finish turning of smallface
Machining features: Big face finish turning is applied tolocate machining of internal and external cavity of small face. It has complexstructure and involving special grooves requiring non-standard tools design,thin wall generate large cutting resistance.
Machines: CNC vertical lathe
Toolselection principles: Grooving use square head in roughing operation, roundhead for finishing, tools for internal special groove are tailor-made, toolsfor external grooving is standard, sharp geometry is applied in finish turning.Insert ZIMF suitable for high-temperature alloy rough grooving, ZIGQ is appliedin finish profiling, tool holders for internal special groove are tailor-made,tool holders for external grooving is standard. NF-geometry is recommended asits sharp geometry, with M type clamping method. Choosing as itsexcellent wear-resistance can improve tool life.
grooves in internal surface：QEKS3232R12-6N（ZIMF608N-NM/ZIGQ6N-NM）
grooves in external surface：QEGS3232R12-4N（ZIMF406N-NM/ZIGQ4N-NM）
special grooves in internal cavity face: special tool 1（ZIMF304N-NM/ZIGQ3N-NM）
special grooves in internalcavity face: special tool 2（ZIMF304N-NM/ZIGQ3N-NM）
special grooves in internalcavity face: special tool 3（ZIMF608N-NM/ZIGQ6N-NM）
Cutting data： Cutting data: Square head for roughing：V=40m/min，fr=0.25mm/r
Roundhead for profiling：V=50m/min，fr=0.15mm/r
Inner cavity：MDJNL3232P15（DNEG150608）
Basis：MDJNR3232P15（DNEG150608）
Cutting data:：V=50m/min，fr=0.15mm/r
Internalfinish turning of large face
Machining features: internal and external cavity, basisturning, the thickness of thinnest part reached 3.5mm only, severe deformationin machining
Machines: CNC vertical lathe
Tool selection principles: Inserts for finishing ofhigh-temperature alloy, high indexing accuracy and repeatability, thin-walledcomponents need sharp geometry to lower cutting force, ensures safety andfasten of toolchamping.correspondent product series: NF standard turning geometry suitable forhigh-temperature alloy thin-walled pieces machining, due to angle restriction,35°V shape insert demonstrates strong universality, and precision ground oflocating surface to improve indexing accuracy and repeatability. M typeclamping system ensures safety and fastens champing. Choosing grade YBG105 as itsexcellent wear-resistance can improve tool life.
Tool：MVJNR3232P16（VNEG160408）
Tool：MVJNL3232P16（VNEG160408）
Cutting data：V=50m/min，fr=0.15mm/r
