Ironer maintenance is the key

Rental laundries rely on the output of the ironer or calender. It is the cash generator for the flatwork business and the degree of regular maintenance will determine not only productivity but also quality of finish.

Claims that a superb and all-embracing maintenance regime can effectively double ironer productivity compared with a system that simply responds to breakdowns are frequently met with disbelief. Yet all it takes is for the production manager to work in closer co-operation with the laundry engineer.
Now more and more laundries are coming to recognise the opportunities that exist in most plants.
For example, when a decision is needed on which ironer to buy to support expansion, very few launderers will bother to look up the evaporation performance claimed for their existing ironers and compare this with what is actually being achieved.
If they did, then ironer sales might show a sudden dip, because many plants are accepting output that is only 60-70% of what is achievable. On a plant with three ironers, this means that there is often the opportunity to obtain the output of a fourth ironer for little more than a day or two's ironer maintenance!

Basic principles
The ironer is a large heat exchanger that delivers its drying and pressing heat very efficiently, because it uses direct heat transfer - the sheet is in direct contact with the heated metal bed.
This gives it a thermal efficiency approaching 95%, which compares starkly with the 50% efficiency of the tumble dryer.
This may be why those plants which minimise conditioning and make the ironer do the drying can produce better overall energy consumption data than those who slavishly pre-dry pillowcases for three or four minutes to "enable the ironer to run faster".
The large heat exchanger, which the ironer beds represent, can only be used effectively if they are covered with drying linen, which means consistent edge-to-edge feeding. Ironer rolls that run at high linear speeds are frequently only operating at 50% capacity, if there are gaps between the pieces where nothing is being dried. The worst-case scenario is reached when the high linear speed means that pillowcases do not dry in one pass and have to put through twice. Some laundries use just two operators to man four lanes, run the machine slowly with no pre-conditioning and achieve the same output per hour as others double feeding or using excessive pre-drying. They also end up with all of the towels dry as well, using the extra tumbler minutes created.
In order for a steam-heated ironer to dry efficiently and effectively, the beds must be supplied with steam at the right pressure. For polycotton and cotton-rich, this means a bed temperature of 165-167C, which translates into a steam pressure of 7-8bar, allowing for the normal temperature drop across the bed wall. For 100% cotton, temperatures up to 194C will give more rapid drying and a superb finish.
Getting this heat into the drying sheet or pillowcase requires good heat transfer surfaces, which calls for dry saturated steam with no water droplets in it. Spray from the surface of a hard working boiler will form an insulating layer on the inside of ironer beds and reduce productivity by around 5%. The extra liquid condensate will also stretch steam trap capacity to the limit and at peak times will result in flooded beds.

Role of the vacuum fans
An ironer can never work efficiently if the water vapour is not removed from the drying work as quickly as it is formed. This is the role of the vacuum fans, which suck through the hollow centres of the rolls (by means of the perforations provided for this purpose in the curved surface) to remove the water vapour and take it out through the roof to atmosphere.
Keeping the vacuum pipework and seals leak-free and clear of wax will often improve ironer performance out of all recognition.
The strength of the vacuum can be determined by the laundry engineer using a simple vacuum gauge placed firmly on the outer layer of roll clothing.
A reading in the range 40-80 Pascal is needed, with the strongest vacuum going to the front roll (which does disproportionally more work).
Checking that the air holes in the metal roll are clear (when re-clothing, for example) will also pay dividends.

Roll clothing
Some ironers are made with just a single layer of clothing, formed from a rectangular piece wrapped around the roll and secured with a line of stitching.
On others there are up to three turns of clothing, trimmed to give an exact number of layers all the way round. This preserves a perfectly circular cross section and therefore provides an even ironing pressure.
Relatively recent developments have reduced this to two layers of thicker clothing, with greater strength and therefore less tendency to stretch in use.
Two layers also offers the opportunity of building in greater porosity and hence better vapour removal through the vacuum fans.
This can make the performance of an old ironer, which was originally fitted with three turns, now perform better with two turns than when it was brand new.
Getting the roll diameter of the re-clothed ironer so that each roll is a perfect fit to its bed is a vital part of the re-clothing exercise and one that is frequently neglected and not checked.
The ironer should have been supplied when new with girthing tapes for this purpose. If these are no longer available then new ones should be obtained as a matter of urgency. They are vital.

A mattress of springs
The clothing rides on a "mattress" of springs, which might be either coil or leaf types.
If the clothing has been allowed to become damp (through poor vacuum and low air flow) then some springs will have rusted and must be replaced.
The ironer will only work properly if the springs are all working correctly, with the same resilience.
Any work to replace rusty ones should be swiftly followed by improvements to the vacuum or replacement of clothing blinded with wax or starch, so that the shiny new ones do not go rusty in turn.

Roll-to-bed pressure
The air rams used to hold the beds up to the rolls (or on some designs the rolls down to the beds) are critical to the heat transfer performance.
A firm and consistent pressure is needed to maintain the heat transfer coefficient and hence effective drying and sheen.
However, it is important not to exceed then maximum pressure stated in the manufacturer's manual (because of the risk of flattening the roll cladding).
If the ironer appears to need excessive roll-to-bed pressure then there is something else wrong (such as the roll-to-bed fit, for example).

Roll-to-roll stretch
The surface speed of each roll is designed to be slightly greater than that of the previous roll, so as to stretch the textiles over the "gap" pieces of the beds between the rolls.
This stretching is achieved partly by the roll-to-roll speed differential and partly by the drag between the moving textiles and the static beds.
The roll-to-roll stretch is usually set up to be 0.2% between the rolls, so that the drag against the bed can be minimised by waxing at the appropriate intervals.

Moisture retention
It is fifteen times more expensive in energy terms to tumble dry one litre of moisture than it is to squeeze it out in the membrane press or during final extract in a washer-extractor. It is still five times more expensive to calender it out.
It is therefore understandable that those laundries with by far the best ironer productivity have spent much time and effort on minimising moisture retention at the membrane press, with some outstanding results. This kind of effort really does pay dividends.
For 100% cotton, the best presses (achieving 40-45bar for 60 seconds) can get final moisture retention down to around 45% and even lower with warm rinsing. This gets the ironer off to a flying start, even with no conditioning.
Achieving the sort of rewards described here will provide higher output and lower energy consumption. Many fabrics will give a much better finish if ironed without conditioning, especially pure linen and linen-cotton mixes.
With teamwork between production and engineering, these benefits are there for all to realise and if past performance is anything to go by, then the benefits will be substantial.