Movement of Workers in the working area

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Movement of Workers in the working area

• Chapter 9

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• There are many types of activity where workers
  move at irregular intervals between a number of
  points in the working area, with or without
  material.
• This situation occurs very often in industry and
  business.
• In manufacturing operations, it occurs when
• bulk material is being supplied to or removed
  from continuous process, and is stored around the
  process
• an operator is looking after two or more
  machines
• manual workers are delivering materials to or
  removing work from a series of machines or
  workplaces.
• Outside manufacturing operations, examples are
• in stores and shops where a variety of materials
  are being removed from or put away into racks or
  bins
• in restaurant and canteen kitchens during the
  preparation of meals
• in laboratories where routine tests are carried
  out at frequent intervals.

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• The string diagram
• The string diagram is a scale plan or model on
  which a thread is used to trace and measure the
  path of workers, material or equipment during a
  specified sequence of events
• The string diagram is a special form of flow
  diagram, in which a string or thread is used to
  measure distance. It is necessary that the string
  diagram be drawn correctly to scale.
• The string diagram is started in exactly the same
  way as all other method studies by recording all
  the relevant facts from direct observation.
• A string diagram can be used to plot the
  movements of materials, and, especially when a
  work study person wants to find out easily just
  how far the materials travel.

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• Example of a string diagram Storing tiles after
  inspection
• RECORD
• In this operational example, tiles are unloaded
  from kiln trucks on to the bench, where they are
  inspected. After inspection they are placed on
  platforms according to size and type.
• The loaded platforms are taken on hand-lift
  trucks to the bins where the tiles are stored
  until they are required for glazing. Using a
  string diagram to find out whether the
  arrangement was in fact the one involving the
  least transport.

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• EXAMINE critically
• A study of the diagram shows at once that the
  most frequent movement is the 10 x 10 and 15 x 15
  rows of bins. Tiles are constantly being
  withdrawn for glazing.
• DEVELOP the new layout
• The first step in developing the new layout is to
  locate the bins containing the most handled tiles
  as near as possible to the inspection bench and
  those containing special feature tiles as far
  away as possible. The distances covered were
  reduced from 520 to 340 meters, a saving of 35
  per cent.

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• Worker - type flow process chart
• Flow process chart Worker type
• Flow process chart Material type
• Flow process chart Equipment type
• A worker-type flow process chart is a flow
  process chart which records what the worker does.
• Service and maintenance work, laboratory
  procedure and much of the work of supervisors and
  executives can be recorded on this type of
  charts.
• The charting procedure used in compiling a
  worker-type flow process chart is almost exactly
  the same as that used on material-type flow
  process charts.
• The definition of the worker-type chart is that
  it records what the worker does. The definitions
  of the other two flow process charts, however,
  state that they record (material type) how
  material is handled or treated, and (equipment
  type) how the equipment is used.

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• Example of a worker-type flow process chart
• Serving dinners in a hospital ward
• RECORD
• Figure 37 shows the layout of a hospital ward
  containing 17 beds. When dinners were served by
  the original method, the nurse in charge of the
  ward fetched a large tray bearing the first
  course, together with the plates for the
  patients, from the kitchen.
• The food was usually contained in three dishes,
  two of which held vegetables and the third the
  main dish. The nurse placed the tray on the table
  marked Serving table in the diagram.
• She set the large dishes out on the table, served
  one plate with meat and vegetables and carried it
  to bed 1. She returned to the serving table and
  repeated the operation for the remaining 16 beds.
  
• She then repeated the complete operation,
  replacing the plates emptied by the patients with
  plates containing their portions of the second
  course and returning the used plates to the
  serving table, where she stacked them.
• Finally she made a tour of the ward, collecting
  up the empty plates from the second course, and
  carried everything on the tray back to the
  kitchen.
• The operation has been recorded in part on the
  flow process chart in figure 38 but only enough
  has been shown to demonstrate to you the method
  of recording, which it will be seen is very
  similar to that used for material-type flow
  process charts, bearing in mind that it is a
  person and not a product that is being followed.

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• EXAMINE critically
• A critical examination of the flow process chart
  in combination with the diagram suggests that
  there is considerable room for improvement.
• The first Why? which may come to mind is Why
  does the nurse serve and carry only one plate at
  a time? How many could she carry?
• The answer is almost certainly At least two.
  If she carried two plates at a time, the distance
  she would have to walk would be almost halved.
• One of the first questions asked would almost
  certainly be Why is the serving table there, in
  the middle of the ward? followed, after one or
  two other questions Why should it stand
  motionless? Why can it not move round? Why not a
  trolley? This leads straight to the solution
  which was adopted.
• DEVELOP the new method
• It will be seen from the broken line in the
  diagram (representing the revised path of
  movement of the nurse when provided with a
  trolley) and from the flow process chart that the
  final solution involves the nurse serving and
  carrying two plates at a time (which also saves a
  small amount of serving time).
• The result, as will be seen from the process
  chart, is a reduction of over 54 per cent in the
  total distance walked in serving and clearing
  away the dinners.

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