Non-Traditional Machining Processes Flashcards
Describe the Process
What two variants are there, & Explain the strength and weeknesses
High Pressure, High Velocity Water Directed at Work Surface for cutting (machining)
Pure Water Jet, Abrasive Water Jet
Pure water is only present in the stream - Water is the Primary Cutting Tool
Abrasive are particles that are added to the water stream - Abrasive is the primary cutting tool
Abrasive can cut Harder, Stronger and Thicker Materials
Abrasive is more costly
What are the 3 Electrochemical Machining Processes
Electrochemical Machining -Material Removal
Electrochemical Deburring - Removal of Imperfections called burrs
Electrochemical Grinding - Material Removal
Describe the Process
What materials can be used as electrodes
What Materials can be used
Electrochemical Machining
Material Removal by anodic dissolution
Part is positively charged
Large Potential sparks occur between Part and Cathode Tool
Material is depleted, then transported to a cathode tool
Flowing Electrolyte carries off depleted material
Copper , Brass or Stainless Steel
Any Electrically conducting Material
How do you calculate the volume of material removed by electrochemical machining
V=CIT
V = Volume of material
C= Specific Removal Rate of Work Material
I = Current
t= Time
Describe the Processes
Left: Adaptation of ECM to Remove Burrs in metal parts caused drilling
Right: Adaptation of ECM which uses a grinding wheel to sharpen tools
Material Removal by anodic dissolution
Part is positively charged
Large Potential sparks occur between Part and Cathode Tool
Material is depleted, then transported to a cathode tool
Flowing Electrolyte carries off depleted material
Explain an Advantage of ECG to a regular grinding wheel
Electrochemical material accounts for 95% of material removal.
ECG Grinding wheel under much less stress
Hence will last longer then a regular grinding wheel
Explain the Applications of EDM and ECM
Ability to remove material from delicate parts then conventional machining methods
Can remove material from any level of hardness or strength
Material Removal rate is dependant on melting point of work material
Describe the Process
Wire Electric Discharge Machining
Utilises a small diameter wire as Cathode Tool
Part is slowly fed past the wire along desired path
Material Removal by anodic dissolution
Part is positively charged
Large Potential sparks occur between Part and Wire
Material is depleted, then transported to a cathode tool
Flowing Electrolyte(dielectric fluid) carries off depleted material
Explain the Process
Electron Beam Machining
High-Velocity electron beam is focused through an electromagnetic lens
Diameter of Beam is Reduced
Elections impact work surface
Kinetic ENegry is converted to Thermal Energy
Concentrated thermal energy melts material in a localised area
What are the Benefits to Electron Beam Machining
What are some Aplications
Works on any Material
Beam diameter can be as small as 0.025mm
Drilling Very Small Dimater holes
Cutting very Narrow slots
Drilling holes with high Depth:Diamter Ratio
(Ratios greater then 100:1)
Explain the Process
Laser Beam Machining
Laser converts electrical energy into a light beam
Monochromatic and Highly Collimated (Parallel Rays) light is focused through Optical Lens
Laser Beam focused into Very Small Spot
concentrated thermal energy melts material in a localised area
How do you calculate the Power Density of a Laser Beam Machining Process on the Surface of a material.
Power Density = Power/ Area over which energy is entering
Power = Laser Power X (1- Laser Reflectivity)
What are the Benefits to Laser Beam Machining
What are some Aplications
Works on any Material
Beam diameter can be as small as 0.025mm
Drilling Very Small Dimater holes
Cutting very Narrow slots
Drilling holes with high Depth:Diamter Ratio
(Ratios greater then 100:1)
Explain the General Process for Chemical Machining
What is the typical penetration rate
Cleaning - To ensure uniform etching
Masking - a chemical that is resistant to the etchant (maskant) is applied selectively to portions that is not going to be etched
Etching - part is exposed to etchant (chemical) that removes material from unmasked regions
Demasking- Maskant is removed
The penetration rate is between 0.02-0.05 mm/min
What are the 3 Masking Methods
Explain how Each Work
Cut and Peel
- Maskant applied to whole part
-After maskant has hardened it is cut by hand and removed.
Screen Resist
- Maskant is painted through a stensil (Silk or Stainless Steel) onto surface areas that are not to be etched.
Photographic Resist
- Masking material contains Photosensitve materuaks
- Maskant is applied to part and exposed to light
through a negative image of areas to be etched
-Areas that have developed are then removed.
Explain what this diagram represents
Name a requirement for the chosen Etchant
Etchant Burrowing under applied Maskant
Etchant must not chemically attack the maskant
Describe the Process
Electroplating
Anode made of plating metal
Cathode is part to be plated
Direct current from PSU, is passed between the Electrodes through an electrolyte
Plating Metal is Applied to the Surface of the Part
