Lean Thinking

Lean Thinking

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  • Ralf Lippold
    Ralf Lippold    Premium Member   Group moderator
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    Queues - a sign of not being LEAN?
    Hello all together,

    as the summer is approaching with large steps lots of us will go on holiday either via plane or train.

    Don't you experience queues while buying the ticket, checking the luggage in, queues in front of the airplane doors, etc. etc.?

    As often in real life the time of the customer isn't part of the cost chain -at least not seen from the provider side;-(

    So what could be done to overcome that un-perfection of the process resulting in unhappy customers? Waiting in line is by the way the equivalent of WIP (work in progress) in a productioin line in a company. There the WIP is measured and being noticed as it is part of the company part of the complete value chain.

    There could be solutions such as:

    1. Booking ticket via internet where the customer can decide when it is the right time for him to do that, without waiting in line

    2. Check-in, due to the 9/11 events there is a more complex security handling at the airports (not implemented sometime in the original layout of the airport, and acting now as the bottleneck. So early evening could be way to overcome the waiting problem or installing more machines for x-raying.

    What do you think of the described problem and possible solutions?

    Have a nice weekend

    Ralf
    This post was modified on 26 May 2007 at 04:40 pm.
    • 26 May 2007, 11:59 am
  • Ralf Lippold
    Ralf Lippold    Premium Member   Group moderator
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    Re: Queues - a sign of not being LEAN?
    What is bothering you in your personal life while in interaction with other "players"?

    Wouldn't this be a real case for lean change to start?

    What do you think?

    Cheers

    Ralf


    PS.: My last non-lean experience has been with a frequent flyer program where I didn't get the bonus miles on my account in order to plan future trips in summer. There had been -to call center officer's information- no error log files and after some further tries from my side almost all data went through smoothly. Not sure how many of you had ever problems with their bonus miles
    • 01 Jun 2008, 11:54 am
  • Rudi Burkhard
    Rudi Burkhard
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    Re^2: Queues - a sign of not being LEAN?
    Hi Ralf,

    Are queues not a fact of life! Having a queue does not mean NOT Lean.

    If there is plenty of capacity at all workstations, then every job will zip through production very very quickly. There is nothing to hold up any job. BUT - the process would not be lean at all. (Southwest airlines apparently used to solve the problem of queues by putting many more people on check-in desks at peak times. When comparing with other airlines they put significantly more on - avoided queues and made happy customers . And they gained market share- at least partly due to that. Other airlines took a cost approach and kept a much flatter level of capacity throughout the day - too many sometimes, not enough service at other times.)

    Anyway - the story shows the dilemma and why it is there. Employees work 8 hours in sequence - but capacity is need at specific times. So either I build enough capacity for good service or I minimize my cost by employing some sort of average number of people.

    In a factory it is the same. Demand is uncertain - it varies. Capacity is what it is. Machines are also variable - sometimes they produce well at or near capacity, sometimes there are problems. With 6-sigma you can reduce variability - but never eliminate it.

    Your process will always have some part of it that is the 'weakest' link - the unit that has the least capability. Run your process and queues (the biggest ones) will accumulate in front of this weakest link. So, this queue is unavoidable.

    This weakest link will also determine the capacity of your system - because it is the weakest (has the least amount of capability). This means that in order to get the most from it you MUST have a queue there sitting in front of it. If the queue were not there your machine would stop from lack of work. This is a WASTE of capacity.

    Often the factory or process has plenty of capacity - it is the market that is limiting demand. Then the thinking is a little different:

    In an Make to Order situation you want enough capacity so that every order goes through the process quickly. You also want to minimize WIP to short lead-times as much as possible. The queue in front of the weakest link will still exist, but be very short. Also, you need to be careful what due dates you promise. What you do NOT want is to make the client wait beyond the quoted lead-time. That queue is a big No No!

    In a Make to Stock situation you deliberately put inventory (a sort of queue) into the warehouse in anticipation of customer orders. There is only one reason to hold stock for clients and that is whenever your supply chain takes longer than the customer is willing to wait. So you have the queue and not the customer. Why do you do this? To not WASTE your client's good will - eg to keep him loyal. So that queue also does not mean you are not Lean.

    Of course there are ways to minimize lead-times and stock levels without jeopardizing customer service. However, wasting customer's goodwill is a very big and costly waste.

    Rudi
    • 01 Jun 2008, 5:10 pm