Marldon Airwipes for Extrusion Lines

Contents :

Application & principle

Competitive Advantage

Types Available

Stockists :

North America

Rest of the World

 

Marldon Airwipes - Application & Principle

In the extrusion of soft materials (usually insulated cables and tubes), air wipes are necessary for the proper operation of in-line printers and spark testers to remove water droplets or films which otherwise would cause print failure or false fault counts (risking shock hazards to cable users).

Air wipes protect process instrumentation, such as spark testers or diameter gauges, from damage by water carried into or sprayed onto the equipment.

Marldon air wipes achieve maximum wiping action with modest air consumption because the wipe orifice can be easily set to the optimum diameter required with enough clearance to allow for whip and vibration.

Air consumption varies directly with the orifice size; the smaller orifice used, the lower the air consumption.

These air wipes generate less noise and more than meet (the UK) Occupational Safety and Health Act limitations for 50% exposure time at a distance of one metre in all directions, and (the UK) Health & Safety at Work Act for 85Db maximum at a distance of two metres.

(All Marldon airwipes cater for generally round materials - we offer no equipment specifically to handle flat or profiled materials although they may prove satisfactory).

Competitive Advantage

Marldon airwipes all offer the facility to vary the cable path orifice diameter thus allowing one airwipe to cater for a range of cables with equal efficiency for each diameter cable. This contrasts with other manufacturer's products which usually offer fixed diameter orifices which means that a different unit will be needed to accomodate EACH cable diameter. With Marldon you only need one unit to cover the whole range of diameters.

And ...for high speed airwiping, the Marldon model 838 is the only airwipe to break the surface tension of the water during the drying process - increasing efficiency.

Types Available

Marldon manufacture 3 types of airwipe covering a wide range of cable / tube sizes and line speeds.

1. Adjustable Orifice Air Wipe - Picture & details

• Model 688 - from 2 to 12 mm. dia. at speeds up to 350 meters / min..
• Model 674 - from 3 to 22 mm. dia. at speeds up to 350 meters / min.
• Model 685 - from 12 - 65 mm. dia. at speeds up to 350 meters / min

2. Adjustable Post Airwipe - Picture & details

• Model 115 - from 50 to 115 mm. dia. at speeds up to 50 meters / min.
• Model 150 - from 50 to 150 mm. dia. at speeds up to 50 meters / min.

3. High Speed Airwipe - Picture & details

• Model 838 - from 0.5 to 8 mm. dia at speeds up to 1000 meters / min.

• An adjustable orifice diameter, calibrated for ease of set-up
  
• Total surround air jet
  
• Low noise levels at high wiping efficiency
  
• Automatic opening for knots
  
• Left or right hand operation
  

A single adjustable orifice air wipe will generally cover the complete range of diameters produced by one extruder. This makes it unnecessary to remove and replace complete wipe assemblies for different extruded products (as is the case with other manufacturers' air wipes).

The amount of water carried forward by the extrusion, and the ratio of air wipe orifice size to material diameter, are factors in establishing the speed limitation. Experience indicates a practical operating speed of up to 350 metre per minute under reasonable conditions.

The air wipe is installed after the water trough on the extrusion line, with the extruded material moving through at a right angle to the mounting face. The unit is usually mounted with the airwipe "wheels" one above the other, and with the hinged wheel uppermost (so that gravity will close the unit should it open due to the passage of lumps). However, if required, the unit can be mounted horizontally and a coil spring used to effect the closure after the passage of lumps.

As the cable moves through the airwipe, the air jet surrounds it and strikes at an angle blowing the water from its surface back upstream. When a knot or lump on the extrusion passes through, the upper airwipe half will ride over it and then return to its normal position, allowing safe passage.

The numbers on the face of the wiping heads indicate the largest extruded diameter which should pass through at that particular setting. Larger diameters will pass through, but with reduced clearances the movement or sagging of the cable would cause wear of the wiping heads.
To position the heads, unscrew the wing nuts and pull the heads away from the bracket. Turn the heads until the required cable diameter numbers coincide, then feel for the location and re-tighten the wing nuts.
As supplied, wheels are located on the left side of the frame mounting arms (as viewed from the exit end) for use in a left to right direction. Locating pins in the upper and lower wheel spindle assemblies, which mate with holes in the frame arms, permit the wheels to be replaced on the opposite side, while retaining the exact angle of the air jets to ensure optimum wiping action.
The direction at which the air strikes the cable is determined by the initial setting of the wiping head hub on the bracket and swing arm. Additional locating pin holes are provided in the bracket and swing arm to allow the repositioning of the spindles and air jets when cable travels in the opposite direction.
For vertically moving wire or cable, Marldon can supply a coil spring to keep the two wiping heads together.

Maintenance

Should dirty air clog the slits, these air wipes can be disassembled easily for cleaning. If the extrusion is permitted to drag on either wheel, it will eventually cause grooving of the surface.

This air wipe is designed for the removal of water and other low viscosity liquids from extrusions up to 8mm diameter at line speeds of up to 1000 meters/min. The 5-stage compound design of the Marldon high speed air wipe is adjustable to provide physical contact or minimal clearance from the extrusion which effectively removes a large proportion of liquid by breaking the surface tension, enabling the five pairs of air jets to wipe more efficiently using a lesser volume of air.

a) Automatic opening for ties, clamps or knots

b) Adjustable air discharge slits

c) Adjustable post position to accommodate alternative extrusion sizes

d) Extruded material support roller

a) Maximum wiping action with modest air consumption because the vertical posts from which the air is directed to the cable can be positioned to suit the cable diameter, and the slit length through which the air is discharged can also be adjusted.

Since air consumption varies directly with the slit length, the shorter the slit and the smaller the cable diameter, the lower will be the air consumption.

b) Low noise levels whilst operating at high wiping efficiency.

Tests show that when operating in the open, they more than meet Occupational Safety and Health Act limitations, and Health and Safety at Work Act, for 85Db max at a distance of 2 metres.

Advice

It should be remembered that air wipes should be installed in conjunction with air management systems to minimise air usage. Marldon offer an Airwipe Control Panel (see below) containing all the recommended components.

Marldon have combined the following three components in the Airwipe Control Panel which make dramatic savings on the demand placed on a compressed air supply.

• Moisture Filter (with automatic drain)

Dry compressed air makes a more efficient medium for the removal of water from cable at the airwipe head.

• Pressure Reducing Valve (with pressure indicated gauge).

Increased efficiency using dry air at the airwipe head makes it possible to reduce pressure and yet maintain the required water removal from the cable. Reduced pressure means reduced air consumption.

• Electric Shut-off Valve (24, 110 or 240 volt).

When linked into the line run switch the air supply to the wiper head will be shut off when the line is not running, saving expensive air.