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TRANSCRIPT
WATER JET CUTTING
Presented by:Umair Bukhari
Introduction To Water Jet: It is a tool using a jet of water at high velocity and pressure The process is same as water erosion found in nature but is
greatly accelerated and concentrated. True cold cutting process –no HAZ, no mechanical stresses
and environmental hazards. Not limited to machining –It has food industrial
applications. They are fast, flexible, reasonably precise.
Why Use Water Jet?
It can cut almost everything, with greater efficiency and productivity.
It is one of the fastest growing major machine tool processes in the world due to its versatility and ease of operation.
Water jets cut accurately, reduced scrap-saving money through greater material utilization.
As it is software oriented, we get correct shape, dimensions and size.
History:
Dr. Franz in 1950’s first studied water cutting for forestry and wood cutting.
1979 Dr. Mohamed Hashish added abrasive particles to increase cutting force and ability to cut hard materials including steel, glass and concrete.
First commercial use was in automotive industry to cut glass in 1983.
Soon after, adopted by aerospace industry for cutting high-strength materials like stainless steel and titanium as well as composites like carbon fiber.
How water jet works?
High pressure (60,000 psi), which when bombarded on the work piece erodes the material.
A high velocity water jet when directed at a target in such a way that, its velocity in virtually reduced to zero on striking the surface. Because of this water jet will make a hole in the material if the pressure is high enough.
Many variables such as nozzle orifice diameter, water pressure, cutting feed rate and the stand distance affect the performance.
Stainless steel plate (50 mm thick) machined with AWJ
Different engineering components machined with AWJ, shows the obtainable accuracy and precision
(Photograph Courtesy – Omax Corporation, USA)
Types of Water Jet:
The two types of water jets Pure water jet abrasive water jet.
A pure water jet is used to cut soft materials, and within just 2 minutes the very same water jet can be transformed into an abrasive water jet to cut hard materials by adding abrasives to it.
Pure water jet uses pure pressurized water whereas abrasives water jet uses abrasives like Aluminum oxide, silicon carbide and garnet.
Pure Water jet Cutting:
Schematic diagram of pure water jet cutting:
1. Water under pressure2. Water nozzle 3. Pure water jet4. Work piece 5. Cut width (kerf)
Pure Water jet Cutting:
Pure Water jet is the original water cutting method. In which pure water is compressed at very high pressure & released through a narrow opening.
It forms water jet, which comes out at the speed of up to 850 m/s
The largest uses for pure water jet cutting are disposable diapers, tissue paper, and automotive interiors .
Provides Very thin stream (0.004 to 0.010 inch in diameter is the common range) .
Very little material loss due to precise cutting.
Pure Water jet Cutting
Non-heat cutting ,Usually cuts very quickly. Able to cut soft, light materials(e.g., fiber glass
insulation up to 24" thick). Used to cut soft, thin, or porous material
Silicone VCT (tile) Foam Cork Teflon Composites Plastic
Abrasive Water jets:
Schematic diagram of abrasive water jet cutting:
1. Water under pressure2. Water nozzle 3. Water jet4. Abrasive feed (unpressurised)5. Mixing chamber (vacuum
chamber)6. Abrasive nozzle (focusing tube)7. Water jet with abrasive8. Cut width (kerf)
Abrasive Water jets:
In the abrasive water jet, the water jet stream accelerates abrasive particles and those particles,not the water, erode the material.
The abrasive Water jet is hundreds of times more powerful than a pure Water jet.
Extremely versatile process, No Heat Affected Zones, No mechanical stresses
Easy to program Thin stream (0.020 to 0.050 inch in diameter) 10 inch thick cutting, Little material loss due to cutting Quickly switch from pure water jet to abrasive water jet.
Applications :
The applications and materials, which are generally machined using WJ and AWJ, are given below:
Application
• Paint removal • Cleaning • Cutting soft materials • Cutting frozen meat • Textile, Leather industry • Surgery • Cutting • Drilling • Turning • Glass Fiber Metal
Materials
• Steels • Non-ferrous alloys • Ti alloys, Ni- alloys • Polymers • Honeycombs • Metal Matrix Composite • Ceramic Matrix Composite • Concrete • Stone – Granite • Wood • Reinforced plastics
Advantages of Water jet Cutting:
There are no heat affected zones (HAZ) The material does not get warped, discolored or
hardened Ability to manufacture burr-free parts
No jagged edges or burrs Near net shape cutting
Eliminates the need for secondary operations Can cut through thick materials
Up to 12” in thickness
Advantages (continued)…… Cheaper than other processes. Cut any material. (mild steel, copper, brass, aluminum;
brittle materials like glass, ceramic, quartz, stone) Make all sorts of shapes with only one tool. Unlike machining or grinding, water jet cutting does not
produce any dust or particles that are harmful if inhaled.
Advantages (continued)……. Leaves a smooth finish, thus reducing
secondary operations. Clean cutting process without gasses or oils. Water jet cutting can be easily used to produce
prototype parts very efficiently. An operator can program the dimensions of the part into the control station, and the water jet will cut the part out exactly as programmed.
Get nice edge quality from different materials.
Disadvantages:
A limited number of materials can be cut economically. While it is possible to cut tool steels, and other hard materials, the cutting rate has to be greatly reduced.
Another disadvantage is that very thick parts can not be cut with water jet cutting and still hold dimensional accuracy. If the part is too thick, the jet may dissipate some, and cause it to cut on a diagonal.
Taper is also a problem with water jet cutting in very thick materials. Taper is when the jet exits the part at a different angle than it enters the part, and can cause dimensional inaccuracy.
Water jet lag
Process comparison:
Water jets vs. Lasers cutting
Abrasive water jets can machine many materials that lasers cannot. (Reflective materials in particular, such as Aluminum and Copper.
Uniformity of material is not very important to a water jet.
Water jets do not heat your part. Thus there is no thermal distortion or hardening of the material.
Water jets are safer. Maintenance on the abrasive jet nozzle is
simpler than that of a laser.
After laser cutting
After water jet cutting
Process comparison:
Plasma cutting Vs. Water jet cutting
If the parts require no mechanical post-processing, for example, if they only need to be welded or they are simple parts, plasma cutting is more cost effective.
If the parts are required post processing, or if aluminum or other materials are used that are not well suited to plasma cutting, then water jet cutting is usually the most cost effective option.
Process comparison:
Flame cutting Vs. Water jet cutting
If the cutting edge quality of flame cutting fulfills the requirements, then flame cutting is more cost-effective than water jet cutting.
Water jet cutting provides benefits with respect to the surface, because depending on the process there are no weld spatters and no burr formation.
The part can also be processed further without thermal heat treatment and straightening.
Process comparison:
Water jets vs. Electrical discharge machining
Water jets are much faster than EDM Water jets machine has a wider variety of materials (virtually any material). Uniformity of material is not very important to a water jet.
Water jets do not heat the surface of what they machine. water jets require less setup and can cut even non
conducting materials. water jets can be considered to be like super-fast EDM
machines with less precision.
Comparison of component surface and structure analysis:
20 mm mild steel, cut with the abrasive water jet (left) And
the laser jet (right)
Water jet cutting is a cold process, so there is no structural influence.
The heat transfer during laser, plasma and flame cutting changes the structure
Environmental issues and future :
Nowadays, every manufacturing process is being re-evaluated in terms of its impact on the environment. For example, use of conventional coolants in machining and grinding is being looked upon critically from the point of view of its impact on environment. The environmental issues relevant to AWJM are, water recycling spent water disposal chip recovery abrasive recovery and reuse
Environmental issues and concerns have lead the researchers to use such mediums and abrasives that do not require disposal, recycling or lead to pollution. Work is going on in the area of high-pressure cryogenic jet machining .
Cryogenic Abrasive Jet Machining
In Cryogenic Abrasive Jet Machining, liquid nitrogen replaces the water phase and dry ice crystals (solid CO2 crystals) replace the abrasive phase leading to no need of disposal or waste generation.
The removed work material in the form of microchips can be collected much easily reducing the chances of environmental degradation.
Conclusion:
Relatively new technology has caught on quickly and is replacing century-old methods for machining.
Used not only in typical machining applications, but food and soft-goods industries
As material and pump technology advances faster cutting rates, longer component life and tighter tolerances will be achievable
Gave us the way for new machining processes that embrace simplicity and have a small environmental impact
Photo Gallery
Photo Gallery
Abrasive Waterjet
Photo Gallery
Red Tinted Glass
9.25” Aluminum
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