FAQs

What is the maximum thickness material a waterjet can cut?

A waterjet can cut through almost any thickness of material. For Flow machines, the maximum thickness is 300mm however this varies depending on your machine model. The key considerations with thick materials are: (a) the weight rating on the waterjet table, and (b) whether the workpiece can be supported in such a way that the waterjet does not also cut the workpiece support platform. 

 

Why should I buy a chiller? 

The purpose of the chiller is to maintain an acceptable oil temperature in the intensifier pump. If desired, it is possible to use mains water as the cooling medium, however, the effectiveness of this is dictated by: (a) the temperature of the incoming water - (in hot climates, the incoming water may be too hot to cool the oil effectively, which will lead to the pump over-heating, and (b) whether the amount of water consumed for cooling is acceptable (in a typical pump, the volume of water required for cooling alone is 11.5 litres per minute (690 litres per hour)).

 

Why does our waterjet cutting head keep blocking? 

One of the most common problems with a waterjet cutting machine is blockages in the cutting head. Clearing blocked focussing tubes can be a menace – consider the force applied to the debris when forced into the focussing tube at 55,000 psi! 

Generally there are four main causes of the problem (in this order): 

a) The Needle in the cutting head On / off valve is weeping.
This is the number one cause of cutting head blockages and this is caused by a leaking on / off valve needle. 
Typically the machine will make the first cut but after closing and moving to the second pierce, a blockage occurs immediately after the pierce and water flows up the abrasive feed tube. To function correctly the abrasive mixing chamber inside the cutting head must be completely dry. The cutting head on/off valve operates under very high pressure however over time the needle in this valve wears and when worn, the valve will drip high pressure water into the mixing chamber where normally dry abrasive then clogs the abrasive nozzles and the water from the cutting head flows back wards up the abrasive hose. The best way to determine if your cutting head is closing properly is to blow any water off the cutting head and then place a piece of cardboard underneath. Then with the cutting head closed, run the pump up to pressure and leave the machine with pressure holding static for 2 minutes. If the cutting head drips we recommend that you shut the machine off and install a replacement needle kit. Cutting head needle kits can last anywhere between 1 and 18 months and we recommend that you keep a spare kit and the right changeout tools on hand and always replace all parts of the kit.
 
b) Damp abrasive as a result of moisture in the compressed air supply.
Most waterjet systems use compressed air to push abrasive from the loading hopper to the cutting head and as moisture will cause the abrasive to clog, it’s extremely important that this air is completely dry. Its not uncommon for operators to start up a system which will run without any abrasive flow issues for the winter however as soon as the season changes and the humidity increases, so do problems with abrasive flow. The recommended solution to this problem is to install a refrigerated compressed air dryer on the outlet of the air compressor and an additional moisture separator on the outlet that feeds air to the waterjet machine. A good way to check for the presence of moisture in the abrasive is to remove the abrasive feed tube from the cutting head and open the abrasive valve from the machine controller and collect a handful abrasive and squeeze the abrasive in the palm of your hand. If the abrasive appears to mould and stick together it will be due to moisture and if dry, it will feel powdery and flow freely. If the abrasive is damp, the best course of action is to install an air dryer with a moisture separator then dump all abrasive from the feed hopper and supply hose and make a fresh start with new abrasive.
 
c) Contaminants in the abrasive.
Whilst not as common as the previous two problems, the condition of the abrasive is also a critical component of a waterjet. Oversize particles cause blockages in the abrasive nozzle and abrasive containing too much dust or fines simply won’t flow. Some things to keep in mind when selecting your abrasive is to purchase well graded abrasive from a leading manufacturer such as GMA Garnet. It's also important to make sure that the abrasive is stored in a dry place and make sure abrasive packaging is re-sealed as soon as loading has been completed. Always check that the abrasive is completely dry before loading and reject if the presence of moisture or contamination is suspected. Always open new abrasive by slitting paper bags with a sharp knife otherwise small pieces of paper or plastic will interrupt the abrasive flow and cause clogging at the cutting head. If there is a reoccurring problem due to contamination, it's best to dump the abrasive from the system and refill with clean abrasive.
 
d) The workpiece is touching the tip of the nozzle during startup.
When this happens, the cutting head opens and as the water can’t exit the abrasive nozzle, it travels up the abrasive hose instead. This is most likely to happen when cutting light sheetmetal and thin products. Often thin materials can float on the water and need to be weighed down or clamped to prevent floating and movement. 

Your focussing tube should now be clear and ready to cut!

What considerations are important when selecting abrasive? 

Selection of the right abrasive for your waterjet is a critical consideration. The key factors which will determine how consistently and efficiently the waterjet cuts include:
     (a) Consistent particle sizing – rogue grains cause blockages in the focussing tube
     (b) Proportion of dust and fines – dust causes problems with flow characteristics of the abrasive, and fines are particles which are too small to serve any useful cutting action.
     (c) The hardness of the grain - Soft grains fragment and break down on impact with the workpiece. Efficient waterjet cutting action requires tough, durable grains. Generally, older grains such as Western Australian’s GMA garnet, have been subjected to a longer weathering process which makes this material perfect for production cutting.

 

What happens to the garnet after it has been used to cut material, and how do I remove it from the waterjet bath?

Spent garnet is accumulated in the waterjet bath below the cutting table. The garnet will accumulate over time, and will eventually need to be removed by shovelling out manually, by a vacuum truck or with an automatic sludge removal system.

 

How do we dispose of our waste abrasive? 

Garnet abrasive is a totally inert mineral sand which is a gemstone in its larger forms. When used as an abrasive in a waterjet, the waste will consist of the abrasive, town water and a very small proportion of the material which has been cut. As most common metals don’t contain any toxic substances the metal fines eroded from the kerf (width of cut) don’t constitute a hazard for waste disposal. 

Garnet waste containing blanks vs clean garnet waste

The presence of metal blanks and offcuts in waste abrasive generally causes concern with waste authorities so it is recommended that the abrasive to be disposed of is separated from waste metal and offcuts. This is best achieved by using a garnet sludge removal machine in conjunction with a set of blanks / offcut collection screens which prevent offcuts mixing with garnet waste.

For operations that waterjet cut materials containing lead or beryllium

If abrasive has been used for cutting products containing lead or beryllium, the waste abrasive will contain traces of these materials and will likely constitute a hazardous waste. Abrasive used for cutting these materials would need to be laboratory tested to determine the correct method for disposal. In this instance, the waste authority will require samples of the abrasive waste material to be tested in a TCLP (Toxic Characteristic Leaching Procedure) test to determine whether the heavy metals would leach out in a landfill situation.

 

Is garnet recyclable? 

Garnet waste is recyclable, however, the cost of drying and re-screening to a standard acceptable for waterjet is significant. Due to the fact that a large proportion of the garnet is broken down to fines during the waterjet cutting process, this is generally deemed uneconomical. 

 

Is a waterjet cutter the best machine for my business? 

Like many tools and processes which have a “sweet spot,” waterjet cutting also has a unique set of advantages which combine to deliver benefits which often can’t be achieved by other way.

There are many businesses who wouldn’t think of using anything other than a waterjet and each of these waterjet owners have very definite reasons for this.

Here are some of the reasons why: 

Stainless Steel and Aluminium fabricators: For stainless steel and aluminium, it’s about the ability to cut these products in any thickness, with no dross or heat stain and with an edge quality which is second to none. If you have production people who spend long periods of time grinding or linishing parts to achieve a satisfactory finish, then waterjet is great news for your business. With only the finest burr on the bottom edge of the plate, waterjet parts are quickly prepared for fabrication which greatly reduces time spent on secondary processing (cleaning up parts after cutting). Waterjet also has the added advantage of having the ability to cut a number of layers of material stacked together which saves loading time when cutting thin materials.

Rubber lining and gasket manufacturing: If you are in the rubber or gasket business, it's hard to go past what can be achieved with a waterjet machine. Cut any type of rubber in any thickness at high speeds in a single pass. A key advantage of cutting rubber with waterjet is that there is no odour, no burning and the ability to cut program the machine to cut fine detail which would normally only be possible to cut with a die.

Stonemasons & Kitchen benchtop manufacturers: The introduction of ultra-hard, new generation materials such as porcelain have brought many challenges to the stone fabrication business. Fabricators who once used mitre saws to cut all manner of stone products found cutting porcelain very slow and unpredictable with ongoing issues caused by the blade tracking off course and slabs cracking due to stresses within the slab. A good quality, 5-axis bevel cutting waterjet can cut mitres, undermount sink and tap holes in porcelain cleanly and accurately, and without dust.

We are looking at purchasing a new machine for benchtop manufacturing, should we purchase a combination saw & waterjet machine or a standalone waterjet?

Recognising the flexibility of waterjet, many 5-axis saw manufactures are now offering hybrid saws with an added waterjet. Whilst this sounds appealing, it is wise to remember that a saw and a waterjet are two entirely different technologies. For sawing, the slab of stone must be supported by a sacrificial layer of board so that the saw blade doesn’t come into contact with the steel support slats. This doesn’t work so well with the waterjet because the waterjet cuts straight through the stone and the sacrificial board which keeps the stone up off the steel slats. 

General engineering and prototyping:  If you are in the prototyping and product development business then waterjet is great news for your business. The advantage of the waterjet process is the ability to switch between cutting one material and the next simply by changing the feed rate of the motion system. No tool changes are required regardless of material type or thickness. Another benefit is that waterjet exerts very little force on the product being cut so many jobs can be cut without the need for elaborate clamping. Very light materials such as plastics, aluminium and sheet metal should be secured as these lighter products can float on the wash caused by the waterjet.

Wear and armour plate manufacturers. Wear and armour plates are plates are generally tempered in a heat soak process. For this reason it’s particularly important to prevent these plates being reheated by cutting with processes such as oxy or plasma cutting or the properties the plates are designed for will be compromised. With the ability to cut through hardened plates without heat generation, waterjet is the ideal tool for armour and wear plate cutting operations.

 

 

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