27.8 Water-jet Machining

Question 1

What is it? (WJM)

Answer 1

Cutting all types of nonmetallic materials

Suitable for contour cutting of flexible materials

No thermal damage

Noisy

Question 2

How does WJM work?

Answer 2

The principal of WJM is based on the force that results from the momentum change of a stream of water. This is the energy source

This force is sufficiently high enough to cut metallic and non metallic materials.

Use of a narrow nozzle- enough strength for the water jet to act like a saw.

See diagram and learn parts

Question 3

Specs?

Answer 3

• a pressure level of about 400MPa is generally used for efficient operation, although pressure as high as 1400MPa
• jet nozzle range between 0.05 and 1mm
• depending on material and on water jet pressure, thickness can range up to 25mm. Can be higher
• water speed around 900miles/hr

Question 4

Applications?

Answer 4

A variety of materials including plastics, fabrics, rubber, wood products, paper, leather, insulating materials, brick and composite materials

Because its efficient and clean operation, compared to other processes eg Wire EDM, it is used in the food processing industry for cutting and slicing food

Question 5

Why is it used widely in the food processing industry?

Answer 5

• clean and efficient, sanitary
• pure water
• consistent cut widths
• eliminates cross contamination
• reduces cell damage= improved shelf life
• fast processing speed
• high output
• ultra narrow cut
• reduces product waste
• minimal human contact

Question 6

Comparison to Wire EDM?

Answer 6

• cleaner operation- environmentally safe
• more efficient
• material does not have to be conductive
• no heat
• cut can start at any location, no need for start hole
• flexible materials
• little wetting of workpiece

BUT

• rougher surface than EDM
• not as accurate