Non Traditional Machining Flashcards
(30 cards)
Non traditional machining
Processes that removes excess material by various techniques involving mechanical, thermal, electrical, or chemical, energy. They do not use a sharp cutting tool in the conventional sense
Why is non traditional machining needed
The need for machine Newley developed metals and non metals that have special properties that make them difficult to be machined conventionally (like high hardness or toughness)
Need for unusual or complex geometries that cannot easily be accomplished by conventional machining
Need to avoid surface damage that often accompanies stresses from conventional machining
Ultrasonic machining
Abrasives in a slurry are driven at a high velocity against the work by a tool
Vibrating at low amplitude and high frequency perpendicular to work surface and is self into the part. Amplitude should be approx same as grit size and gap two times grit size.
What increases removal rate using an u.trasonic machine
Increased frequency and amplitude
How does the tool get Impacted during ultrasonic machining
Abrasive particles that erode work surface also erode the tool
Use of slurry in ultrasonic
Continuously circulated to bring fresh grains. Washes away work chips and grits
Water jet cutting
Fine, high pressure, high velocity stream of water is directed ro work surface to cause cutting of the work
In water cutting nets what’s the standoff and what’s its desired value
It is the distance between the nozzle and work surface, it should be small to minimize dispersion of fluid stream before it strikes the surface.
How does the size of the nozzle orifice impact t water jet cutting
It affects the precision of cut. Smaller is sued for diner cuts on thinner material.thicker is used for thicker stock
Advantages of water jet cutting
No crushing or burning of work surface from mechanical or thermal processes
Minimum material loss because of the narrow cut slit
No environmental pollution
Ease of automating the process
Limitations of water jet cutting
Not suitable doe brittle materials as they tend to crack
Abrasive water jet cutting
Abrasive particles added to jet stream to facilitate cutting.
Limitation of abrasive water jet cutting
Complicates process by adding to the number of parameters that must be controlled
Why is nozzle orifice greater in Abrasive water jet cutting
Larger to permit higher flow rates and more energy to be contained in stream before injection of abrasives
Why is standoff typically less in abrasive water jet cutting
Minimize effects of dispersion
Electric discharge machining
Shale produced by a formed electrode tool. Sparks occur across gap between too, and surface. Must take place in a dielectric fluid, which creates path for each discharge as the fluid becomes ionized in the gap. Discharges generated by pulsating direct current power supply connected to the work and the tool. Discharge occurs where they are closes.
How is tool wear usually measured
Ratio of work material removed to tool material removed
What causes tool wear in electric discharge machining
High spark temp
Problem of thermal energy processes
Finish is poor for some cases so subsequent processing required
Electric discharge wire cutting
Uses a small diameter wire as the electrode tool cut a narrow kerf in the work. Cutting action achieved by thermal energy from electric discharged between the electrode wire and work piece.
Why does electric discharge wire cutting maintain a constant kerf width
As wire cuts it is slowly and continuously advanced between a supply spool and take up stool to present a fresh electrode of constant diameter to the work.
How is dielectric applied for electric discharge wire cutting
By nozzle pointed at tool or work part is submerged in dielectric bath
Requirement form electric discharge wire cutting
Work material must be electrically conductive
