Trad/non Trad 5 Flashcards
Why is machining commercially and technologically important?
- variety of work materials
- variety of part shapes and geometric features
- dimensional accuracy
- good surface finishes
Distinguish between generating and forming when machining work part geometries
Generating is the creation of work geometry due to the feed trajectory of the cutting tool. Examples include straight turning, taper turning, and profile milling. Forming involves the creation of work geometry due to the shape of the cutting tool; common examples include form turning and drilling.
How does a boring operation differ from a turning operation?
Boring produces an internal cylindrical shape from an existing hole, while turning produces an external cylindrical shape
What’s the difference between peripheral milling and face milling?
In peripheral milling, cutting is accomplished by the peripheral teeth of the milling cutter and the tool axis is parallel to the work surface; in face milling, cutting is accomplished by the flat face of the cutter whose axis is perpendicular to the work surface.
If you were to make a door knob shaped item from metal, describe the various machining steps you might take if you started a piece of long rod stock material
- cut off a shorter piece of stock material that can fit into the lathe
- load and centre the workpiece
- assuming your have a normal tool with no specific form, then perform a series of contour turning processes to get the shape you want
- once finished, use a parting tool and cut off the item from the stock material
Why would you make centring hole for a long cylindrical stock used for a lathe?
I’m order to position the tailstock to reduce the workpiece vibrations.
What are the advantages of boring a hole rather than drilling it out?
You can achieve different internal diameters
Name an application where you might use knurling
To apply a texture to a shaft to add grip to it
Why do we face off parts?
Often when we cut the raw stock material for turning, the surface finish is poor. Facing off allows us to have a smoother surface.
If you were using a lathe to create a thread what challenges might you come across if doing it manually?
In order to get a good thread you need the tool feed rate to be constant. This is difficult to do manually and often we use a level of automation with automatic feeds.
You are using bolts to attach a piece of metal to another and don’t want them to stick out from the surface. What machining operation would you perform to achieve this?
Counterboring
Describe the step you’d take to drill out an 8mm hole which you want to have high tolerance
- Start by drilling a small centre hole
- drill out a small hole e.g. 2mm
- gradually open out with increasing drill diameter sizes (e.g. 4mm then 6,7….)
- finish off with a reaming tool
Why are the non traditional material removal processes important?
1) the need to shape new metal alloys and non metals that are difficult to machine by conventional processes
2) the requirement of unusual and complex work part geometries
3) the need to avoid surface damage which is often associated with conventional machining
There are 4 categories of non traditional processes, based on principle energy form. Name the 4
1) mechanical, but not including conventional machining
2) electrical
3) thermal
4) chemical
How does ultrasonic machining process work?
Abrasives contained in a slurry are driven at high velocity against the work by a tool vibrating at low amplitude and high frequency. The tool oscillates in a direction perpendicular to the work surface and is fed slowly into the work, so that the shape of the tool is formed in the part. The abrasives, impinging against the work surface perform the chip removal.
