Fresh Market Ltd: The Iceberg lettuce harvest CASE Introduction Fresh Market Ltd. is an important division of a privatel
Posted: Wed May 04, 2022 7:37 am
Fresh Market Ltd: The Iceberg lettuce harvest CASE Introduction
Fresh Market Ltd. is an important division of a privately-owned
farming company specializing in vegetable growing and distribution.
Its most important customer group is the major Canadian
supermarkets which require fresh produce to be delivered to them
364 days a year. The company has all the staff, expertise and
specialized facilities needed to supply these supermarkets
throughout the year. One of the most important products of this
company is Iceberg lettuce, which is grown in Prince George during
the summer and in Vancouver during the winter. Iceberg lettuces are
dense and round, but are easily bruised so have to be harvested
with great care, after which they are stored and transported in
chilled conditions to avoid deterioration. From the time of
cutting, they must be packed quickly to minimize water loss and
taken rapidly to a cool store. Market demand varies greatly,
dependent on the season and on weather conditions, with demand
rising rapidly in periods of hot, dry weather and in the preceding
day. Supermarkets rely on weather forecasts to predict demand for
salads and fresh sandwiches The Harvesting Rigs The company has
developed specialized machinery to assist in the harvest of
millions of Iceberg lettuces every year. Each of the company’s six
Iceberg lettuce picking machines (known as ‘rigs’) is a large
mobile factory which is mechanically powered to move very slowly
across the enormous lettuce fields, at a speed and direction
controlled by the supervisor using a simple joystick control. The
rig runs on caterpillar tracks which allow it to cross the soft,
deep peaty soils on which lettuces thrive. However, in very wet
conditions, this very heavy piece of equipment can get stuck and
may need assistance from an additional crawler tractor. At the very
back of the rig is attached an open-fronted road trailer, into
which the trays of packed lettuces are carried and stacked. This
trailer can be released when full, and attached to a four-wheel
drive tractor for subsequent transportation to the company’s local
cold store. 2 Another trailer is then connected in its place to
allow picking to continue uninterrupted. Each crew (picking team)
comprises 17 people and a supervisor; there are nine cutters, five
packers and three people preparing cardboard trays, labeling the
individual supermarket lettuces and carrying completed trays and
crates to the trailers. The supervisor, who is fully responsible
for product quality and output of the rig, also provides assistance
at any point on the rig to relieve any short-term bottleneck and to
cover any short period when an operative needs to leave the rig.
The crew members are paid piecework, and usually work eight-hour
days (plus breaks), although overtime may be necessary on very busy
days in mid season. Crew members of the most successful teams can
earn more than double the BC hourly minimum wage, but this requires
sustained effort and concentration, and cooperative crew behaviour.
The Picking Process The nine cutters work on the ground in a wide
line just in front of the rig, which slowly moves towards them.
They stand astride the rows of lettuce, working slowly backwards.
The average cutting speed per person, in good conditions, is eight
seconds per iceberg lettuce. Within this cycle time the picker
selects and cuts each lettuce using a sharp, slightly hooked knife,
trims away the outer leaves (which are often muddy and/or damaged),
and then drops the prepared lettuce into a polythene bag pulled
from a bundle attached to the cutter’s waist belt. The cutter can
choose to leave uncut any lettuces exhibiting defects, for example,
under-size, poor shape or damaged, and these are later ploughed
back into the soil. They are also very skilled at judging lettuce
weights, and will avoid under- or over-sized specimens. The
best-quality wrapped lettuces are then thrown carefully forward to
a packer. Others are thrown further forward straight into plastic
crates of 20 for subsequent industrial processing, depending on
quality. These are known as ‘process grade’ and are used to make
prepared salads and bulk chopped lettuce for the sandwich industry.
In persistently wet weather, the average picking rate can slow by
up to 25 per cent, as a result of a combination of mud slowing the
picking and packing process, rigs getting stuck and a general
deterioration in morale of the crew. The five packers sit on seats
attached to the front of the rig, in front of the pickers and just
off the ground. They seal the bags with tape, and place the lettuce
in a single layer in cardboard trays, selecting (grading) them –
the best quality for the supermarkets in trays of 10, the remainder
for wholesale markets in trays of 12. On average, this task takes
five seconds per lettuce. The full trays are then quickly pushed
forward to the final group of employees who work further back on
the rig, higher up and level with the trailer floor. These three
workers have several tasks. Firstly, they have to erect the
cardboard trays from flat ‘cut and creased’ blanks which the
company buys in from an outside supplier of cardboard packaging.
This tray preparation entails a folding and tucking action, and 3
one skilled worker can make and stack the trays in an average of
about seven seconds each. Typically, half of this person’s time is
spent on this activity, and the remaining time on labelling. The
next task is to label all the supermarket lettuces. Self-adhesive
labels are provided on a long roll, and are simply peeled off and
stuck on each lettuce bag. These labels customize the lettuce for
individual supermarkets and also provide the bar code and
sellby/use-by dates. Although they have to be positioned carefully
with minimal creasing, a skilled worker can apply a label about
every two seconds. On completion, each tray is then pushed forward,
ready for conveyance to the trailer by another worker. Each filled
tray or crate has to be carried from the deck of the rig into the
transport trailer, where it is stacked. Although the walking time
for this action depends on the extent to which the trailer has been
filled, an average time is approximately 15 seconds, which includes
the time needed to return for the next tray or crate. This is the
heaviest task, so the three workers rotate the jobs on the upper
level of the rig. The supervisor is based here too – weighing
equipment and quality records are kept at the back of the rig – so
is able to assist with these jobs when needed. Trailers are changed
approximately every two hours, but this does not stop the operation
of the picking, packing or labelling part of the rig. Two workers
are needed to uncouple the trailer and reconnect the empty
replacement. This takes approximately 10 minutes. On average,
during a normal working period, each worker uses about five per
cent of the time for personal needs and for occasional activities;
such as collecting packaging material. Breakdown time averages
approximately two per cent of the available time, and this is
usually used for cleaning and preparation. Although the supervisor
is able to assist others when the need arises, he or she spends
about two hours a day on quality assurance. Statistical process
control (SPC) is used to ensure that lettuce weight is within the
requirements of each customer, and samples are inspected to ensure
that their appearance remains within tolerance. Records of quality
and output are maintained per rig. Output statistics During a busy
period of sustained good weather in August, the average daily
(eight hours) output from each rig was as follows:
Supermarket 1800 trays
Wholesale 230 trays
Process 200 crates
Case Questions
1) What are the inputs and outputs of the transformation process
described in this case? 2) What are the main operations objectives
for the macro-operation? 3) How would you describe the type of
process and the layout systems used in this unusual operation? 4)
Calculate the capacities for each part (microoperation) of the
Iceberg rig, and from this estimate the total capacity. To what
extent does the overall capacity depend on the product mix? What
problems are encountered when attempting these capacity
calculations?
Fresh Market Ltd. is an important division of a privately-owned
farming company specializing in vegetable growing and distribution.
Its most important customer group is the major Canadian
supermarkets which require fresh produce to be delivered to them
364 days a year. The company has all the staff, expertise and
specialized facilities needed to supply these supermarkets
throughout the year. One of the most important products of this
company is Iceberg lettuce, which is grown in Prince George during
the summer and in Vancouver during the winter. Iceberg lettuces are
dense and round, but are easily bruised so have to be harvested
with great care, after which they are stored and transported in
chilled conditions to avoid deterioration. From the time of
cutting, they must be packed quickly to minimize water loss and
taken rapidly to a cool store. Market demand varies greatly,
dependent on the season and on weather conditions, with demand
rising rapidly in periods of hot, dry weather and in the preceding
day. Supermarkets rely on weather forecasts to predict demand for
salads and fresh sandwiches The Harvesting Rigs The company has
developed specialized machinery to assist in the harvest of
millions of Iceberg lettuces every year. Each of the company’s six
Iceberg lettuce picking machines (known as ‘rigs’) is a large
mobile factory which is mechanically powered to move very slowly
across the enormous lettuce fields, at a speed and direction
controlled by the supervisor using a simple joystick control. The
rig runs on caterpillar tracks which allow it to cross the soft,
deep peaty soils on which lettuces thrive. However, in very wet
conditions, this very heavy piece of equipment can get stuck and
may need assistance from an additional crawler tractor. At the very
back of the rig is attached an open-fronted road trailer, into
which the trays of packed lettuces are carried and stacked. This
trailer can be released when full, and attached to a four-wheel
drive tractor for subsequent transportation to the company’s local
cold store. 2 Another trailer is then connected in its place to
allow picking to continue uninterrupted. Each crew (picking team)
comprises 17 people and a supervisor; there are nine cutters, five
packers and three people preparing cardboard trays, labeling the
individual supermarket lettuces and carrying completed trays and
crates to the trailers. The supervisor, who is fully responsible
for product quality and output of the rig, also provides assistance
at any point on the rig to relieve any short-term bottleneck and to
cover any short period when an operative needs to leave the rig.
The crew members are paid piecework, and usually work eight-hour
days (plus breaks), although overtime may be necessary on very busy
days in mid season. Crew members of the most successful teams can
earn more than double the BC hourly minimum wage, but this requires
sustained effort and concentration, and cooperative crew behaviour.
The Picking Process The nine cutters work on the ground in a wide
line just in front of the rig, which slowly moves towards them.
They stand astride the rows of lettuce, working slowly backwards.
The average cutting speed per person, in good conditions, is eight
seconds per iceberg lettuce. Within this cycle time the picker
selects and cuts each lettuce using a sharp, slightly hooked knife,
trims away the outer leaves (which are often muddy and/or damaged),
and then drops the prepared lettuce into a polythene bag pulled
from a bundle attached to the cutter’s waist belt. The cutter can
choose to leave uncut any lettuces exhibiting defects, for example,
under-size, poor shape or damaged, and these are later ploughed
back into the soil. They are also very skilled at judging lettuce
weights, and will avoid under- or over-sized specimens. The
best-quality wrapped lettuces are then thrown carefully forward to
a packer. Others are thrown further forward straight into plastic
crates of 20 for subsequent industrial processing, depending on
quality. These are known as ‘process grade’ and are used to make
prepared salads and bulk chopped lettuce for the sandwich industry.
In persistently wet weather, the average picking rate can slow by
up to 25 per cent, as a result of a combination of mud slowing the
picking and packing process, rigs getting stuck and a general
deterioration in morale of the crew. The five packers sit on seats
attached to the front of the rig, in front of the pickers and just
off the ground. They seal the bags with tape, and place the lettuce
in a single layer in cardboard trays, selecting (grading) them –
the best quality for the supermarkets in trays of 10, the remainder
for wholesale markets in trays of 12. On average, this task takes
five seconds per lettuce. The full trays are then quickly pushed
forward to the final group of employees who work further back on
the rig, higher up and level with the trailer floor. These three
workers have several tasks. Firstly, they have to erect the
cardboard trays from flat ‘cut and creased’ blanks which the
company buys in from an outside supplier of cardboard packaging.
This tray preparation entails a folding and tucking action, and 3
one skilled worker can make and stack the trays in an average of
about seven seconds each. Typically, half of this person’s time is
spent on this activity, and the remaining time on labelling. The
next task is to label all the supermarket lettuces. Self-adhesive
labels are provided on a long roll, and are simply peeled off and
stuck on each lettuce bag. These labels customize the lettuce for
individual supermarkets and also provide the bar code and
sellby/use-by dates. Although they have to be positioned carefully
with minimal creasing, a skilled worker can apply a label about
every two seconds. On completion, each tray is then pushed forward,
ready for conveyance to the trailer by another worker. Each filled
tray or crate has to be carried from the deck of the rig into the
transport trailer, where it is stacked. Although the walking time
for this action depends on the extent to which the trailer has been
filled, an average time is approximately 15 seconds, which includes
the time needed to return for the next tray or crate. This is the
heaviest task, so the three workers rotate the jobs on the upper
level of the rig. The supervisor is based here too – weighing
equipment and quality records are kept at the back of the rig – so
is able to assist with these jobs when needed. Trailers are changed
approximately every two hours, but this does not stop the operation
of the picking, packing or labelling part of the rig. Two workers
are needed to uncouple the trailer and reconnect the empty
replacement. This takes approximately 10 minutes. On average,
during a normal working period, each worker uses about five per
cent of the time for personal needs and for occasional activities;
such as collecting packaging material. Breakdown time averages
approximately two per cent of the available time, and this is
usually used for cleaning and preparation. Although the supervisor
is able to assist others when the need arises, he or she spends
about two hours a day on quality assurance. Statistical process
control (SPC) is used to ensure that lettuce weight is within the
requirements of each customer, and samples are inspected to ensure
that their appearance remains within tolerance. Records of quality
and output are maintained per rig. Output statistics During a busy
period of sustained good weather in August, the average daily
(eight hours) output from each rig was as follows:
Supermarket 1800 trays
Wholesale 230 trays
Process 200 crates
Case Questions
1) What are the inputs and outputs of the transformation process
described in this case? 2) What are the main operations objectives
for the macro-operation? 3) How would you describe the type of
process and the layout systems used in this unusual operation? 4)
Calculate the capacities for each part (microoperation) of the
Iceberg rig, and from this estimate the total capacity. To what
extent does the overall capacity depend on the product mix? What
problems are encountered when attempting these capacity
calculations?