Hydraulic Hose Cutting Machines – Latest Approach
New blades – new apporach
Hydraulic hose is one of the most indestructible components you’ll ever encounter. It should be durable enough to contain high fluid pressures, pressure cycling, repeated bending back and forth, high temperatures, a variety of other detrimental conditions, and remain in service for years. But the same material characteristics that make hydraulic hose stand up to such tough conditions also make them difficult to cut. Therefore, most hose cutoff machines have used an abrasive wheel. The wheel runs at high speed to grind or melt away rubber and other soft materials in the hose and high-strength steel reinforcement wires.
If you buy pre-assembled or pre-cut hose assemblies, you’re probably not aware of the dirty job conventional hose cutting can be. It generates smoke and leaves debris inside the hose. This debris usually consists of burnt rubber, metal particles, and even abrasive particles from the cutting wheel. Unless all of this contamination is removed, it will get into a hydraulic system and can clog filters and cause machine malfunctions and component failures. Technicians sometimes blow compressed air through a finished hose assembly in an attempt to remove these hose cutting by-products. This practice is better than nothing, but it can’t remove all of the contamination, and in many cases it may just redistribute it through the ID of the hose. It’s no wonder, then, that equipment has become popular specifically to clean hydraulic hose and tubing assemblies before they are installed onto a system.
Ensuring that hose assemblies are completely clean prior to installation should always be done. And one of the best ways to clean a hose is to prevent the introduction of all this contamination in the first place. Many hydraulic technicians are accomplishing this by using a high-strength steel blade and a new concept in hose cutting procedure.
To understand this new method, let’s first examine the conventional method, which uses an abrasive wheel. Abrasive wheels cut a path equal to the thickness of the wheel and deposits most of that debris inside the hose being cut or up the exhaust chute, although a portion may be sucked away by an exhaust system. This method creates melted rubber, molten metal, and abrasive grit in the air which necessitates the exhaust system.
The abrasive wheel cuts using friction from grains of abrasive stone that come in contact with the hose materials and grind them away. As the abrasive grains become loaded up with melted rubber and steel, they break off and allow new sharp abrasive grains to be exposed and continue to melt more hose rubber and steel braiding. If the abrasive grains in the wheels are too fine, they load up after a few cuts, and the wheel starts cutting out of square. When the wheel becomes gummed up with melted rubber, it must either be replaced or cleaned. Both of these add substantial cost to the hose cutting process.
Conventional hose cutting techniques use an abrasive wheel that generates heat, smoke, and debris that can contaminate hydraulic systems. Abrasive cutting offers two main advantages — fast cutting and relatively low initial investment in equipment.
However, this low initial cost is offset by the cost of evacuation systems, which must be used because of the smoke and potentially toxic fumes generated. This cost is often overlooked and can run into thousands of dollars. The high heat generation also presents a potential fire hazard if not designed and maintained correctly. The smoke is toxic to breathe and hazardous to your health because it contains petrochemical particulates in the air that OSHA can measure.
A dramatic departure from conventional hose cutting methods differs in two ways. It uses a circular knife, rather than a grinding wheel, to cut hose, and it bends the hose during the cut. The circular knife slices a hose rather than cutting a path through it, so it does not deposit debris into the hose other than dust and some smoke. Bending the hose during the cut applies tension, so the hose pulls away from the blade as it is cut. This eases cutting and keeps the hose ends from rubbing against the spinning blade.
However, blade designs and hose cutting machines from different manufacturers are not necessarily interchangeable. A circular knife that works well on one design of machine may not work at all on another. If the circular knife is used correctly on a compatible hose saw, only dust will be created and there will be almost no smoke or smell.
When properly performed, the operation will work as follows: The hose is pre-bent before the knife starts to cut. As the knife slices into the bent hose, tension from the bending pulls the cut surfaces away from the blade and cutting area. As the blade advances further across the hose, increased bending continues to open the cut even further.
Because the hose opens up faster than the knife penetrates, the hose does not pinch the blade. There is no contact between the sides of the blade with the hose, so no smoke is generated because there is no friction. If the hose is not continually bent, it will pinch onto the spinning blade, and the resulting friction will create heat and smoke, blade failures, and possibly stall the machine. Therefore, continual bending of the hose is paramount to the success of using circular knives to cut hose. But, again, many saw designs do not take this into account. The blades are no better than the machinery on which they are mounted, so selecting the right machine can mean the difference between a clean cut and one that is no better than with an abrasive wheel.
New hose cutting technique uses a blade that slices through hose like a knife instead cutting through it life a saw or grinding wheel. Bending the hose during the cut aids the process, which avoids the disadvantages of conventional cutting.
Differences between blades
Circular knife blades are made of high-speed tool steels and come in a variety of types including smooth edge, serrated edge, and scalloped edge. Each knife edge was developed for a specific application, with new blades under constant development as new types of hoses enter the market.
∎ A smooth edge knife is ideal for all types of hose cutting because it creates the least amount of dust. However, when cutting any hose that has a significant amount of steel wiring in it, such as 4- and 6-wire hose, the knife edge would become dull quickly. A dull blade requires greater application force to cut, so the cutting speed must be slower. The ideal applications for a smooth edge knife are for cutting industrial rubber hose with no steel in it. Other popular applications include large diameter cloth hoses with helical wire and exterior steel braided hose where the braiding is taped, annealed, or welded in the machine before the cut is made.
∎ A scalloped edge knife was developed for more aggressive cutting using a wavy edge that makes an interrupted cutting contact into the hose. This interrupted cut severs the steel braiding inside a hose and cuts with less pressure on manual machines than a smooth edge blade does. For this reason, the scalloped edge blade has been the most popular blade used by equipment manufacturers or anyone cutting their own hose. The most popular applications include cutting all types of hydraulic, pneumatic, polyurethane, PVC, and thermoplastic hose.
UNIFLEX® Cutting Machines blades lasts 7 times longer, cuts twice as fast, generates less smoke, less debris in the hose and less heat. Reduces the risk of separation of the rubber from the wire.