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• Darren Madlansacay

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CNC PURE WATER JET CUTTING MACHINES Darren Cedrick S. Madlansacay 2011-45294 ME 136 WIJ

CNC Water Jet Cutting Machines comprises of technology that considers a hydraulic pump procuring regular tap water or a mixture of water and abrasive substance, and pressurizing it up from 30,000 to 100,000 psi. The water passes through a tiny opening containing a gemstone ( material that withstands the cutting pressure at the tip), constraining and concentrating the volume through the nozzle The diameter of the jewel orifice ranges from 0.010 to 0.015 in. This concentrates the energy into the opening, creating velocity of up to 960 km/hr. It is characterized into two major types: Abrasive and Pure Waterjet Cutting. DIFFERENCE OF ABRASIVE AND PURE WATERJET CUTTING:

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Figure 1.Pure Water Jet Cutting: The jewelled nozzle channels thewater to produce a high pressure exit velocity of the jet

Figure 2. Abrasive Jet Cutting. An additional set up to the pure water jet cutter supplying abrasive to the high pressured water

Water jet cutting is divided into two subcategories. Abrasivejet is where an abrasive (esp. garnet, pyrite & olivine) is coalesced with a waterjet to accelerate the cutting process and quickly erode most materials. Pure waterjet does not involve an abrasive, utilizing only the jet of water to graze. The latter starts out the same as a pure waterjet but as the thin stream leaves the nozzle, a vacuum sucks the abrasive which then mixes it with the water. CNC PWJ MULTI-AXIS DIMENSION CUTTING: CNC Pure WaterJet Cutting can occur in 1 –D continous waterjet slitting and cutting, 2D cutting table where the cutting head moves along the X and Y axes according the command given by the computer. The z axis adjusts the height in generally non-flat surfaces. We also have the 3-D subgroup where in addition to the three major axes ( X, Y,Z), a rotation axis is added. This gives way to cutting out complex geometries. What really stands out with this cutting process One very special feature of the PWJM is its use in the modern 5 axis ( multiaxis machining). This is where computer aided manufacturing and computer aided design supports cutting in translation in X,Y,Z. Basically, manufacturers primarily focusing on flat 2-D surface can now produce 3-D models like pipes and cylinders ( for abrasivejet cutting), thanks to the inherent properties and the low structural deformation in cutting by the waterjet method.

Figure 3. CNC Waterjet machine capable of 5 axis dimension cutting

ADVANTAGES OF CNC PURE WATER JET CUTTING :

Figure 4. Pure Water Jet Cutting Machine at work

Pure water jet cutting is said to be one of the versatile cutting processes as it caters to a number of parameters as it: (1) Removes taper and induces only minimum stress in the sections you are removing. With this, brittle materials like ceramic and glass become conducive for the pure waterjet cutting. (2) Is a cost and time efficient cutting process that (3) Eradicates the problem of thermal distortion or hardening. Energy by the form of heat is carried along by the water as it flows down to the catch tank. It produces no burned edges, burrs and little need for secondary finishing. (4) Saves the manufacturer a lot of material since nesting ( laying out cutting patterns) is applicable. This significantly reduces the amount of scrap material produced during cutting. (5) Precision is a key feature of a purewaterjet cutter, adhering to diameters of less than 300 microns at a deviation of plus minus 1 micron while cutting at a rate of 4 cm per minute. Its most reliable use is due to the extremely fast set-up and programming of the design to be cut. A machining head is controlled by a computer, following the specifications indicated in your drawing (thru CAD programming).

(6) Fixturing is relatively easy, just loading the drawing by means of a software, setting the depth and thickness of cut. Very little material is also removed due to cutting. (7) No structural changes in the material including change in hardness (strain hardening) (8) Completely environmentally friendly, as no pollutants are produced in the process (9) Easy programming with the likes of CAD and CAM software LIMITATIONS: CNC Pure Waterjet Cutting is limited to soft and non metallic materials materials like cloth, paper, foam, rubber and other brittle materials. This is due to the very low cutting forces brought about by the thin stream. This is not suitable for high production requirements due to the very costly maintenance costs of the equipment. APPLICATIONS: PWJ is able to produce many products in the mainstream market. Components for car interiors like carpets, mats, compartments and leather seat cushions are cut using this process. The textile industry also is major user of this type of cutting process especially parting VCL ( Vinyl Composition Tiles). Some of the material cutting appications of PWJ include:

Figure 5. Diapers for infants , among the earliest products of the waterjet technology

Figure 6. Foam structures derived from base material through waterjet

SOURCES: .N.p.Web.23 May 2015.

.N.p.Web.23 May 2015. .N.p.Web.23 May 2015. .N.p.Web.23 May 2015.< http://www.flowwaterjet.com/en/waterjet-technology/purewaterjet.aspx> .N.p.Web.23 May 2015.< http://www.kmtwaterjet.com/kmt-waterjet-systemsolutions.aspx> .N.p.Web.23 May 2015. .N.p.Web.23 May 2015.

PICTURES OBTAINED FROM: https://blog.compete.com/2010/10/27/diaper-wars/ http://www.coreindustry.net/waterjet.php http://www.thefoamfactory.com/blog/index.php/waterjet-cutting-offers-fast-andaffordable-foam-fabrication