Search strategies & product mix templates
Call off-sequences have major impacts on the laundry’s bottomline. Use search strategies or product mix templates to control the call off.
Batch sequences surely have hard bottom line effects. And yes, the product mix method is a static solution to dynamic problems. It doesn’t reflect all the variations taking place in the laundries – in volumes, qualities, availabilities, demands, consumptions, and so on – but it’s better than no formal or systematic targeted planning at all.
A norm or template for choosing batches in the check-in to send into the production is that ratio between different categories which (measured in processing time) best utilizes the laundry capacities evenly along process routes. The basis of the templates are categories grouped according to their process routes, e.g. one group of categories which have to pass a large item ironer, and one for categories passing the towel folders.
Normally there are between 5 and 10 such category groups in the laundry. Then a norm could look like this:
For each batch of drywork headed for the manual folding tables also select (at the same time):
• 2 batches for the tunnel finisher,
• 2 batches for the small item ironer line,
• 3 batches for the large item ironer line, and
• 5 batches for the towel folders,
– arranged in a compatible sequence, which among other things prevents dryer jams and bath exchanges.
Working out a product mix norm
Product mix norms are based on known, good results and attempt at recreating these good results, without, however, regard for the changes in the laundry set-up that occur continuously. Working out a norm follows two simple steps:
Step 1. Synchronize distribution and production:
Make a coherent master plan for an entire, typical week’s production, as if there where no day intervals. Then split the plan up, corresponding to days and shifts. You cannot do this in real life, because linen and textiles collected on a Friday may be produced on a Wednesday in the master plan. This is important information though, because it tells us how to release production potential by improving planning pre-conditions, which is important input to the distribution planning. Synchronize distribution and planning this way, and adjust customer stocks accordingly. Finish master planning based on synchronized, realistic day collections and deliveries.
Step 2. Plan each production shift:
Having done that, take each day’s plan and make shift plans as if all buffers where empty at shift start, empty again at shift end, and aim at keeping all buffers empty during production – except upstream from bottle-necks – but do not empty the laundry of the work in progress at shift ends. We don’t want to start each shift with an empty laundry, only to avoid redundant batches in the buffers. In this way make plans for each shift and each day in the week, by means of good operation strategies. Use Gantt-charts, like the one below, where each coloured beam represents a batch, and the colour represents the category.
Soon a pattern appears. The pattern is a template for the ideal batch category sequence, a product mix, which makes batches fit best to the laundry’s process route capacities – the ideal product mix for each given shift’s production. Maybe you want to make alternative product mix norms depending on the optimization criterion, available capacities, categories in the check-in, different days, different times of day, and the like.
You then end up with perhaps a plan A, B, and C, for each of the situations you expect to face in the production.
The necessary information
But to use operation strategies in practice, whether it is for dynamic planning or as the basis for product mix norms, you need access to mission critical information, like process speeds per batch category, and the total variable cost per kilogram of a given category along a process route. You need to know your production and its key figures, which very few actually do.
Something else is, that during the formulation of operation strategies and product mix norms you also experience some of the constraints, which machines and processes place on good planning, like precedence constraints from conveyor systems, long, closed process lines with no chance of intervention, and dependent consumptions in continuous batch washers, etc.
And then formulating a good operation strategy becomes as important an exercise to purchasers and machine designers, as it is to planners and managers because it uncovers critical considerations to take when designing a laundry set-up and layout.
And like the operation strategies, the product mix norms are also aimed at keeping all three key performance indicator (EAE, RAE and BAE, see my previous blog entry) values high – at the same time.
A heap of considerations
While the batch flow in this way is being worked out, the workstations have to be manned. When doing so a series of parameters have to be taken into consideration, among others:
- batch priorities (from possible rush-orders)
- completion of customer-unique goods
- employee skills and skill levels
- mandatory / optional number of operators on each workstation
- upstream and downstream buffer contents
- full / partial / no overlap
- job rotation systems
- etc.
In practice the organization of the work varies from laundry to laundry, both with regards to the conditions taken into consideration, and with regards to line of command and field of responsibility.
Economy first
And you may use work organisation for several purposes, more or less intentionally. However most laundries agree that it is all about keeping expenditure at a low, controlled level – when it comes to the crunch, economy comes first. And with the kind of competition most laundries are subjected to today, every day matters.
In a practical, limited economy, costs and working capital carries great weight, which we have to respect when organizing the work in the laundry. But hold on a second. How can work organization have any influence on costs at all?
Isn’t organization just something white-collars invented to have something to talk about?
In smaller laundries with simple, clear productions, where few people handle most operations, in close contact with each other, and the manager is taking part in the production, organisation matter little. But laundries are bigger now, cycles are shorter, decisions reach out farther in time, the work is specialised, involve more people, margins are smaller, and consequences more important than ever.
There need not be several hundred people employed before lack of authority, responsibility, communication, coordination and management costs. The batch flow is a goods train roaring down the rails. Should be. And should stop at nothing.
And it is the duty of the work organisers to see to it that the right operators are at the right spot, at the right time, doing what is necessary to keep the train going. Failing to do so may cost the entire laundry’s total variable costs to turn, start and speed up this train again.
And organisation of the work is not determined by education, professional background, unionization, collective agreements or the like. Not when it comes to controlling costs and working capital. In this context the membership of a union is actually irrelevant.
Economy is material flow
With batch sequences, process route choices and operator allocations we control the material flow. From the material flow originates inventories, work in progress and the total variable costs, and with that the major part of the laundry’s cost complex and working capital tie-up.
In this context the most important role of the work organisation is to place responsibility, authority and information.
When the planners choose batches for production and arrange their sequences into the laundry, we have to make sure they know:
- what articles are required in the dispatch department
- planned dispatch sequences
- the current load on all workstations
- current buffer contents
- work in progress
- key cost
- process speed, and
- capacity load figures,
and are able, and have the means, to calculate consequences ahead of decisions accordingly.
When asking the planners to select batches for production we also need to give them the authority to allocate operators in the laundry, in the check-in, in the wash room, in finishing sections as well as in the dispatch department. And hold them responsible.
If we do not place the authority with the real planner, we should not allow ourselves to hold the planner responsible. And sometimes the batch flow is determined not by cost, market or flow considerations, but by the shouting of the women in the laundry. They get more linen and the planners are left alone. Sometimes washer operators are inclined to choose batch sequences and process routes that keep a low water consumption, because that is what the managers normally hold them responsible for.
But sequences determine so much more, also productivity. So what is most important – water or productivity?
Both, if the planners have the ability to balance both considerations at the same time. If not, then productivity.
Management should for that reason first of all give the planners access to information on work and capacity load, before talking about water consumption. And hold them responsible for it.
Material flow determines allocation
The material flow governs allocation needs, so responsibility for material flow and allocation should be placed with the same person – be it the planner, the washer operator, the bag jockey, the foreman or the head lady.
And if we want to use the work organisation to limit and control expenditure we must require from the material flow, that it is a flow of demanded articles, in the right quantities and qualities, at the right time, at a minimum of costs.
The first four of these requirements are met by giving the person responsible access to the necessary information to determine what articles are demanded, how many, in what quality and when they are due. But the last one – at a minimum of costs – has to do with execution, which has to do with skills and skill levels, which have to do with allocations. We know it.
Productivity increases by up to 10% when we allocate according to skill levels.
The organisation of the work has substantial consequences. And in more than one respect. Work organisation is also the sequencing of batches on each workstation. If you produce apportioned (to order) you sometimes experience that even though everybody in the production are working hard and productivity is high, you can’t seem to get the trucks going.
Nothing seems to be completed before everything has been pushed through the production. Other days things go smoothly, the trucks leave in time, in a steady flow, even though the production is calm and quit. In manufacturing industries this effect is caused by “bills of materials”.
In our industry the effect is the same, but caused by and called something else. In the following blog entry I’ll show you the cause, I’ll end work organisation, and I’ll go through methods for calculating the manning of the laundry production.
Hans arbejde er baseret på års erfaring med virksomhedsdrift og ‑planlægning på mange niveauer, både i produktions-, service- og udviklingsvirksomheder (bl.a. 8 års erfaring som vaskeridirektør).