Summary
9.1
Updated April-09
Lecture Notes
Chapter 9 Analyzing and Improving
Efficiency
ENTERPRISE EXCELLENCE
9.2
Updated April-09
Learning Objectives
• 6S Process
• The Seven Forms of Waste
• Takt Time
• Cycle Time
• Routing Analysis
• Work Content Analysis,
• Process Availability Analysis
• Just-in-Time
• Kanban
• Work Cell Design
9.3
Updated April-09
Analyzing and Improving Efficiency
• Effectiveness is the foundation of success
• Efficiency is a minimum condition for survival after
effectiveness has been achieved.
• Effectiveness is doing the right things.
• Efficiency is doing things right
• Once effectiveness has been achieved, efficiency
improvements must begin immediately and
continue for the life cycle of the enterprise
9.4
Updated April-09
Analyzing and Improving Efficiency
• In a typical business, it is not unusual to find isolated
parts of the system running at peek efficiency (95 to
100%). However, efficiency for the entire system is
usually less than 40 percent.
• This often happens because the more efficient
operations create problems (such as bottlenecks or
increased inventory) for the system as a whole
• When making a system more efficient, the whole
system must be considered to avoid sub-optimization.
This "system" focus must go beyond your business
processes to customers and suppliers
9.5
Updated April-09
Analyzing and Improving Efficiency
9.6
Updated April-09
Analyzing and Improving Efficiency
Tools we use to analyze and improve efficiency
9.7
Updated April-09
6S Process
1. Sift: Remove unneeded and unused items from
the workplace.
2. Sort: Arrange work site tools, equipment, and
materials in the most convenient location for
process use. Identify, label, and color code.
3. Shine: Clean the work area, tools, and
equipment. Tag equipment abnormalities.
4. Standardize: Document work site layout,
location of tools, equipment, and materials.
Establish a plan and team assignments to
maintain operational readiness.
5. Sustain: Follow the plan. Improve the plan and
work site.
6. Safe: All appropriate safety controls in place.
Safety equipment properly identifies All safety
equipment unobstructed and accessible
• The 6S process, or simply 6S, is a structured program to systematically
achieve total organization, cleanliness, and standardization in the
workplace:
1. A safe and uncluttered work site, free of hazards
and workarounds.
2. Tools, equipment, and materials are located within
safe and easy reach. Waste of motion is at a
minimum.
3. The work site, required tools, equipment, and
materials are clean, defect-free, and ready for use.
4. Plan with documented, graphic work site layout
showing proper location and amounts of required
tools, equipment, and materials, including visual
controls and coding, with required team member
actions and assignments.
5. A continuously ready operational work site,
excellent housekeeping.
6. Eliminate all hazards and provide a safe work
environment.
Category Required Actions Desired Outcomes
9.8
Updated April-09
6S PROCESS: EXAMPLE - BEFORE
9.9
Updated April-09
6S PROCESS: EXAMPLE - AFTER
9.10
Updated April-09
The Seven Forms of Waste
• The Seven Forms of Waste:
1. Overproduction - Overproduction occurs when operators make parts even though
they are not immediately needed. It is a key waste in manufacturing environments
for parts to stack up
2. Waiting - Any time in which goods are not being moved or worked is waste.
3. Transport - Excessive movement and handling of goods increase the likelihood of
damage, increase communication requirements, and add time to corrective actions.
4. Inappropriate processing - Inappropriate processing occurs when excessively
complex operations or equipment have been installed where simpler solutions were
more appropriate
5. Unnecessary inventory - Carrying costs—especially those that hide other supply
chain problems—are incurred by unnecessary inventory
6. Unnecessary motion - Each time an employee must unnecessarily bend, stretch,
or reach to complete a process step, it creates waste
7. Defects - Defects are direct costs, and they are the most prominent example of
waste
9.11
Updated April-09
Takt Time
• Takt time is calculated by dividing the available working time (AWT)—which is the
effective work time available by customer demand (a projected amount).
• To calculate the takt time for a process where the customer demand is projected to be
35 pieces per day, proceed as follows:
Takt time = available working time / customer demand
= 420min per day / 35pieces per day
= 12 min / piece
• The required takt time to meet the projected customer demand of 35 pieces per day is
12 minutes per piece.
• Takt time is the key to synchronizing all process operations. When all processes run at
takt time, unevenness and overburden are eliminated. When takt time and cycle time
are in balance, waste is eliminated.
• However, takt time and cycle time are not the same thing. Cycle time is the time it takes
to complete one task and may be less than, more than, or equal to takt time.
9.12
Updated April-09
Cycle Time
• Cycle time (‘‘order-to-deliver cycle’’) is the total time from the beginning to the end
of the process, as defined by you and your customer.
• Cycle time includes:
• Process time (during which a unit is acted upon to bring it closer to an output),
• and delay time (during which a unit of work is waiting for the next action.
9.13
Updated April-09
ROUTING ANALYSIS
• Routing analysis provides an assessment of work-flow
patterns and cycle time in each process work center and
work activity you have mapped.
9.14
Updated April-09
Work Content Analysis
• We now move to evaluating process cycle and total time. This is
accomplished by assessing setup time, machine time, and labor time for each
process element.
1. Setup time: For a product set up is accomplished daily. Other products
may require setup more or less frequently. This setup time is not the same
as the line turnover time for changes of casts and dies.
2. Labor time: The direct labor times used in each process step for each
product produced.
3. Machine time: In some cases machine time is the same as labor time and
in other cases it is significantly different.
Setup time, direct labor, and machine time are measured during receipt and
inspection, cleaning, assembly, brazing, test, rework, final inspection, and
packaging.
9.15
Updated April-09
Process Availability Analysis
• Process availability, sometimes called operational availability (Ao), is the time a system or process
is up and running. It is the probability that a process is available to perform when called upon.
• Availability is calculated as the ratio of operating time over operating time plus downtime
Ao = MTBM / MTBM + MDT
where,
MDT: Mean down time
MTBM: Mean time between maintenance
Low pressure test: Using MTBM as 48 hours and MDT as 3 hours,
Ao = 48 / 48 + 3 = 0.94
High pressure test: Using MTBM as 30 hours and MDT as 8 hours,
Ao = 30 / 30 + 8 = 0.79
• The probability that both test systems are available is simply the probability (Pa)(Pb) = availability. In
this case, the availability of test equipment in work center is:
System availability = (Pa) (Pb) = (0.94) (0.79) = 0.74
9.16
Updated April-09
Just In Time (JIT)
• This strategy refers to a body of practices that calls for goods to be produced
as closely as possible to when they are sold. The availability of raw materials
(within hours of consumption or provision of a service) is assumed by this
strategy. Just-in-time (JIT) is one of the pillars of the Toyota Production
System (which is virtually synonymous with Lean).
• In pure manufacturing terms, JIT is a material requirement planning approach
in which:
• Hardly any inventory of parts or raw materials is kept at the factory
• Little to no incoming inspection of parts or raw material occurs.
• Kanban (which is discussed later) is the tool used to help implement just-in-
time. The focus of all the JIT/kanban efforts is reduced inventory and reduced
WIP
9.17
Updated April-09
Kanban
• Two types of production systems exist: the push system and the pull system.
• In a push system, production schedules are developed for each work area based
on sales forecasts. Components are produced in the work areas and then
pushed downstream. This means that the more efficient operations may bury
downstream operations with product. And when this happens, material flow is
interrupted, workstations become disconnected, and production lead times
increase.
• In contrast, a pull system controls the flow of work through the factory by
releasing materials into production only when they are needed. Production is
always triggered by demand from the next work center. The system that signals
this demand is known as kanban.
• In Japanese, the word kan means ‘‘card,’’ and the word ban means ‘‘signal.’’
Kanban means ‘‘signal cards.’’
9.18
Updated April-09
Work Cell Design
• When designing a cell, a set of specific design objectives
(criteria) need to be established. The following is a list of general
criteria for good cell design:
1. Ensure material flows in one direction.
2. Reduce material and operator movement.
3. Eliminate storage between operations.
4. Eliminate double and triple handling.
5. Locate parts as close as possible to point of use.
6. Use task variation to reduce repetitive motion.
7. Locate tools and parts within easy reach of operators.
8. Reduce walking distances.
9.19
Updated April-09
Wrap-up
• 6S Process
• The Seven Forms of Waste
• Takt Time
• Cycle Time
• Routing Analysis
• Work Content Analysis,
• Process Availability Analysis
• Just-in-Time
• Kanban
• Work Cell Design