Picking and clipping to improve ironer rates

Running the ironer line can be a high-cost, labour-intensive operation. Some laundries will have up to six people feeding sheets and other flatwork and, in the UK, total labour costs could be as much as £38 per hour.

If those six workers are only achieving 450 sheets/hour this works out at 8.4p per sheet. Increasing that rate to 900 per hour by making the operators’ task easier with a machine to untangle the sheets before they arrive at the ironer line effectively halves the labour cost so each sheet now only costs 4.2p.

Some countries have even higher labour costs and these markets have driven the move to automate the feeding process with the use of remote reeding stations where a buffer of clipped sheets can be built up and transferred to the ironer line automatically. This produces a feed rate that more closely matches the speeds obtainable from the modern ironer.

Sheet pickers

Untangling sheets manually can be a frustrating business. The work is repetitive and can be hard and tiring, even when operators have been trained in the best techniques and stand on anti-fatigue mats to reduce the strain. If operators have to twist round to reach the sheets due to poor training or a cramped layout, then they can risk back injuries.

The sheet picker is designed to extract each sheet from the barrow-load of tangled sheets from the wash-line and drop it into an adjacent empty barrow that is then taken to the feeder operators who can now remove and clip sheets easily and safely.

A good automatic sheet picker will grasp the highest textile protruding from the load in the barrow, lift it up to ensure there is only one item and then drop it into the adjacent barrow. If the picker removes two sheets at once, it will recognise this and drop them back into the barrow and then repeat the picking operation.

When choosing a picker it is very important to match its speed to the ironer’s maximum rate as this is the speed at which the ironer should be run in the future.

The ironer need only be fed correctly edge-to-edge to gain the maximum output continuously and this maximum speed will decide the number of manned feeding stations needed.

The advantage of using a picker is that it will eliminate any gap between sheets as they leave the feeder. If the picker’s capacity is lower than that of the ironer most of its benefit is lost as the ironer’s full capacity will never be realised.

The laundry engineer will need to tune the picker so that the mechanical hand that grips the sheets operates correctly.

The hand must grasp the sheet firmly enough to ensure that it does not slip out under its own weight but not so tightly that it leaves a mark or makes a hole.

It is equally important to allow the linen to be released if it is so tangled that there is a risk of tearing. The point at which the linen is allowed to slip out of the mechanical hand’s grip is also very important.

Pickers need headroom so it is important to check the clearance needed in the picker’s spec and that the laundry building is high enough to accommodate this. Many laundry buildings do not have sufficient room and it may not be possible to resolve the problem once the machine has been bought.

Pickers also need floor-space on the main workflow line, so the siting and orientation are vital.

It is also very important that laundry management discusses the decision to install a picker with the ironer team and persuade them

of the advantages before placing the order.

Once the ironer is delivering the increased output continuously, it may then be possible to raise this further by increasing the steam pressure from 8 to 10bar, improving the roll-to-bed fit, raising the vacuum and improving clothing porosity.

Single-clip feeders

An ironer can only achieve its optimum rate if this is being matched by the feeder operators and there are no interruptions in feeding. If an operator pauses, even if just for a few seconds, or has to leave the line for a meal break or to get another barrow of work, the daily production rate will fall and may not be recovered.

The single-clip feeder is designed to solve this problem. It is sited at a remote station and takes a single clipped corner and builds up a buffer stock of clipped sheets on an overhead monorail that runs from the feeder to the ironer.

Each sheet is then pulled down from the buffer stock in sequence and laid down automatically onto the ironer feed-bands.

The mechanical feeder takes the clipped corner to one side of the ironer, finds the other corner automatically and then lays the sheet down exactly square to the direction of travel through the ironer. The leading edge is then tensioned to keep it taut and ensure that the sheet is flat and square.

For this to work successfully and reliably, the initial single-clip must be correctly positioned on the sheet, with the hem on the correct side of the clip and with the right distances between the hem and the selvedge, just as on a conventional feeder.

The clip lifting mechanism will not supply all the force needed to lift the sheet out of the barrow and into the space beneath the monorail. The operator may need to “help” the sheet out of its tangle. Therefore to obtain the maximum rate from each operator, the single-clip feeder needs to be used in conjunction with a sheet picker.

The single-clip feeder enables the faster operators to clip more sheets than the slower ones. It also allows four feeders to clip enough pieces to build up a larger buffer stock to let operators take meal breaks two at a time without slowing the flow of linen to the ironer.

In this way maximum output is maintained at all times.

It is important to remember that there is a limit to the size of the buffer stock. This will partly be governed by the monorail’s storage capacity but also by the time that the linen can be left before it starts to dry out.

If the linen does start to dry, any residual alkali will tend to migrate to the areas that are still slightly damp and this will lead to localised galling or yellowing.

This is a bigger problem in hard water areas than in those where the water is naturally soft because water softener does not remove the ions that cause galling.

Sheets that have started to dry when they reach the ironer line can become creased during ironing and emerge with a rough-dried effect that will spoil the result.

Special provisions may be needed for quality control when using a single-clip feeder. This is because the operator does not see the opened sheet and so cannot check for residual stains or holes.

This can be remedied to some extent by automatic inspection or by the folder operator – if there is one and if the sheet can be seen from this work-station.

If such inspection is not possible, stains and holes will build up in the circulating stock. The solution is to inspect the circulating stock at regular intervals, possibly every three months. During these inspections, stained sheets should be gathered up and sent for re-wash and those with holes collected and ragged.

The inspection should be done from a position over the ironer and loads should be inspected for a week to ensure that the checks cover the whole circulating stock.

Successful operation of the single sheet-clipper and remote feeding with automatic lay-down requires meticulous laundry engineering. Every sheet must be laid down correctly because if there are no operators at the front of the ironer line a misfeed can result in damage to the ironer.