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Machining of composite Materials
J.Ramkumar
Micromanufacturing lab
Dept of Mechanical Engineering
IIT Kanpur
Mechanics of Reinforced Polymer Composites
Introduction • Composite materials have higher specific properties
• Good corrosive resistance
• Good fatigue resistance
• Selective properties
• Economic for small batch sizes
However because of
• Non homogeneous
• Anisotropic
• Reinforced properties
Difficult to machine – Abrasive chip leading to tool wear, workpiecedamage
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Classification: Particle-Reinforced (i)
• Examples:Adapted from Fig. 10.19,
Callister & Rethwisch 8e.
(Fig. 10.19 is copyright
United States Steel
Corporation, 1971.)
- Spheroidite
steel
matrix: ferrite (a)
(ductile)
particles: cementite(Fe
3C )
(brittle)60 mm
Adapted from Fig. 16.4,
Callister & Rethwisch 8e.
(Fig. 16.4 is courtesy
Carboloy Systems,
Department, General
Electric Company.)
- WC/Co
cemented
carbide
matrix: cobalt (ductile,
tough)
particles: WC (brittle, hard):
600mm
Adapted from Fig. 16.5,
Callister & Rethwisch 8e.
(Fig. 16.5 is courtesy
Goodyear Tire and Rubber
Company.)
- Automobile
tire rubber
matrix: rubber (compliant)
particles: carbon
black
(stiff) 0.75mm
Particle-reinforced Fiber-reinforced Structural
• Aligned Continuous fibers• Examples:
From W. Funk and E. Blank, “Creep deformation of
Ni3Al-Mo in-situ composites", Metall. Trans. A Vol.
19(4), pp. 987-998, 1988. Used with permission.
-- Metal: g'(Ni3Al)-a(Mo)by eutectic solidification.
Classification: Fiber-Reinforced (iii)
Particle-reinforced Fiber-reinforced Structural
matrix: a (Mo) (ductile)
fibers: g ’ (Ni3Al) (brittle)
2mm
-- Ceramic: Glass w/SiC fibersformed by glass slurry
Eglass = 76 GPa; ESiC = 400 GPa.
(a)
(b)
fracture surface
From F.L. Matthews and R.L. Rawlings,
Composite Materials; Engineering and
Science, Reprint ed., CRC Press, Boca
Raton, FL, 2000. (a) Fig. 4.22, p. 145 (photo
by J. Davies); (b) Fig. 11.20, p. 349
(micrograph by H.S. Kim, P.S. Rodgers, and
R.D. Rawlings). Used with permission of
CRC
Press, Boca Raton, FL.
• Laminates -
-- stacked and bonded fiber-reinforced sheets
- stacking sequence: e.g., 0º/90º
- benefit: balanced in-plane stiffnessAdapted from Fig.
16.16, Callister &
Rethwisch 8e.
Classification: Structural
Particle-reinforced Fiber-reinforced Structural
• Sandwich panels-- honeycomb core between two facing sheets
- benefits: low density, large bending stiffness
honeycomb
adhesive layerface sheet
Adapted from Fig. 16.18,
Callister & Rethwisch 8e.
(Fig. 16.18 is from Engineered Materials
Handbook, Vol. 1, Composites, ASM International, Materials Park, OH, 1987.)
Mechanics of Reinforced Polymer Composites
Choosing a process
• Reinforcement in composites – glass, graphite, boron, alumina and SiC – abrasive in nature and hard
• Majority of the machining happens to brittle fracture rather than plastic deformation ahead of tool.
• Depends on matrix property too
• Volume fraction plays an important role
• Part size and shape
• Number
Mechanics of Reinforced Polymer Composites
Role of matrix and reinforcement
• To protect the reinforcement materials
• To distribute the stress to the reinforcement materials
• To provide for the final shape of the composite part
Reinforcement
• To provide the composite high Mechanical properties
• To reinforce the matrix in preferential direction
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
a b
Evolution of matrix damage:(a) crushing and (b) cracking during chip formation.
Comparison between CFRP and GFRP.
Cutting tool spectrum
Mechanics of Reinforced Polymer Composites
Vibratory assisted turning
Mechanics of Reinforced Polymer Composites
Tool wear profile
Mechanics of Reinforced Polymer Composites
Effect of vibration
• For fibre orientation0o, in conventionalcutting lots of fibresare pulled out (1.a). Inultrasonic vibrationcutting, those fibresare absent (1.b).
• for fibre orientation90o, in conventionalcutting fibres are notcut at the edge of thesurface (2.a). Inultrasonic vibrationcutting, however,those fibres are notvisible (2.b
1.
2.
Schematic diagram of experimental setup
Mechanics of Reinforced Polymer Composites
Typical forces during drilling
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Thrust and torque over drilling cycle
Mechanics of Reinforced Polymer Composites
Delamination mechanism
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Hole quality assessment
Mechanics of Reinforced Polymer Composites
Delamination measurement techniques
Mechanics of Reinforced Polymer Composites
Varying drill geometry
Mechanics of Reinforced Polymer Composites
Varying drill geometry
Mechanics of Reinforced Polymer Composites
Vibration assisted drilling
Mechanics of Reinforced Polymer Composites
Advantage of vibration assisted drilling
Mechanics of Reinforced Polymer Composites
(III) Milling of FRP
Experimental setup for FRP milling
Contact and rubbing actions between the fibres and each cutting flutes as the tool rotates and cuts across the fibres(at centre position of the cutting flutes)
Milling is used, as a corrective end machining operation or to produce defined,high quality surfaces. The fibre type, reinforcement architecture and matrixvolume fraction are the most important factors governing tool selection andmachining parameter setting.
In the case of glass and carbon fibrereinforcement, it is the cutting toolmaterial, that dominates the toolselection
Quality achieved when milling thermoplastic matrix GFRP composite laminates
Surface roughness in milling of GFRP composites
Some experientialresults on surfacequality, when millingof FRP wereperformed as shown.
Laser drilling composites
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Processing materials by mixing fire and water
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites
Water jet cutting of composites
Mechanics of Reinforced Polymer Composites
Schematic diagram
Mechanics of Reinforced Polymer Composites
Water jet machining evaluation
Mechanics of Reinforced Polymer Composites
Typical AWJ cut kerf geometry: (a) end view of kerf, and (b) kerf wall roughness
a b
Machining of PMC by AWJM
AWJ set up
Traverse speed vs. kerf width and taper
Traverse speed vs. kerf wall surface roughness
Traverse speed are the superioroperating parameters for affectingthe surface roughness and kerftaper angle. With an increase intraverse speed bad surface finishand high kerf taper angle obtained
Water Jet Milling
Mechanics of Reinforced Polymer Composites
Conclusions
• An overview of various issues in machining of composites materials are discussed
• Latest research areas in machining of composites are covered
• Composites machining is always a challenging problem from engineers.
Mechanics of Reinforced Polymer Composites
Mechanics of Reinforced Polymer Composites