74 Quality Assurance
Key Items of Concern in the CI Process
One-Piece Flow
One-piece ow is a production technique in which the work moves from one
operation to the next one piece at a time, continually. Ideally, there is no batch
or build-up of parts at any given point in the process. The idea is to make one
then move one. Why is this important? Because it will help to achieve
• Shorter lead time
• Better communication
• Improved quality
• Visual management
• Less space
• Reduced costs
The process of implementing the one-piece ow is based on a ve-step approach.
Step 1
Identify product families and collect data. Typical items should be
• Process work sequence
• Required daily customer demand
• Operating time
Process Improvement Team:
Opportunity:
Item 1 Plan Actual
Item 2
Action:
Leader:
Priority:
Results:
Win or Opportunity
FIGURE 8.2
Typical form to generate or summarize events of the PDCA model.
75Commitment to Continual Improvement
• Manual times (load, unload, etc.)
• Machine cycle times
• Walk distance and times
• Tooling locations
• Tool change times
Step 2
Calculate Takt time. The reader should be familiar with two types of Takt
time. The rst one is spelled Tact and the second is Takt. Both are calculated
the same way. However, the difference is that Tact time is based on either the-
oretical or surrogate data, and is used for preliminary analysis or planning.
As the real data are generated, the theoretical or the surrogate data should
be replaced with the actual data. Takt time is the time needed to produce one
unit of a product to meet the customer demand. It is calculated as
Takt Time =
Operating Time
Customer Demand
where
Operating time = (Shift Time per Day)−(Planned Downtime per Day)
Customer demand = Average Daily Volume (as determined from the mas-
ter delivery schedule)
Takt time is very important and is used to verify both volume and capac-
ity. As a result, this facilitates how the operator will work on the line and
at what rate. It is customary that the Takt time and the operator’s work and
rate do appear on the Production Board and they should be the same as the
calculated numbers. The reason for this display is to
• Highlight overproduction and waiting wastes
• Identify process difculties quickly
• Reduce nish goods and work-in-process inventory
• Highlight imbalances
An example of Takt time is as follows:
Shift time per day = 2 × 8h (3600s/h) = 57,600s
Planned downtime per day = 2 × 30min (60s/min) = 3600s
Operating time = 5 7, 6 0 0 −3,600 = 54,000s
Customer demand = 800 + 700 + 600 + 200 = 2300 pieces
Takt time = 54,000s/2,300 pieces = 23.5s
76 Quality Assurance
Always round down Takt time. In this case, it is 23 s. This means that
the customer requires one part every 23s. This is a very important number
because it is used to set the production rate equal to the customer demand
rate. It also helps in
• Synchronizing operations of all departments to customer demand
• Preventing overproduction
• Determining optimal stafng
• Driving capacity analysis and equipment utilization
• Creating the appropriate ow
Takt time is not affected by
• Associate speed, skill, or attendance
• Machine breakdowns
• Part/material shortages
• Quality problems
On the other hand, Takt time is affected by
• Number of shifts
• Shift lengths
• Relief/no relief, breaks, and so on
• What parts are assigned to which line
• Order volume
Because of these items, the Takt time must be periodically double-checked
as demand changes or other factors may inuence it.
Step 3
Determine the work elements (tasks) and time each element. If an element
can be done repeatedly, it can be standardized. We should strive to stan-
dardize the best. Standardized work is generally accepted as using the most
effective combination of employees, materials, and machines to perform an
operation using the best method to meet the customer demand with as little
waste as possible. Standardization is important because it
• Minimizes process variation introduced by the operator and elimi-
nates unnecessary motion
• Helps to balance work load and labor to best meet customer demand
• Provides the baseline required for continual improvement
77Commitment to Continual Improvement
The standardized work elements are generally considered as
• Calculating Takt time. It serves as a baseline for customer demand.
• Standardized work sequence. An effective set sequence of work per-
formed repeatedly by team members who are processing or assem-
bling a product. (Special note: Standardized work sequence must be
xed and observed.)
• Standard work-in-process. This means using a minimum amount
of work-in-process inventory so employees can complete their stan-
dardized work smoothly, repeatedly, in the same sequence, with
the same movement, and so on To accomplish this, the following
sequence of events must take place:
• Develop data collection sheets. This must be done with actual
data from the shop oor.
• Develop a work combination table. A table with cross-
reference of the operator, tasks, time, and any other pertinent
information.
• Develop a work chart. A summary chart of all pertinent infor-
mation. For maximum effectiveness, it should be displayed in
the work cell.
• Develop a work balance sheet. The information in this chart will
guide the cell into continual improvement.
Step 4
Create an operator balance chart. Make sure the appropriate cycle time
is appropriately associated with the right work element and operator.
This may be accomplished by understanding the process. There are two
approaches for this: (1) traditional process ow diagram and (2) value
stream map.
Traditional Process Flow Diagram
The purpose of the process ow chart is to identify, understand, and dene
the activities or steps in a process. Once the process is documented, it is
important to determine the health of the process. A good process is effective,
efcient, adaptable (exible, robust), and in control. There are generally three
phases to a process ow diagram: as is, should be, and could be.
As Is
As is indicates the current state of process. To construct this phase, the fol-
lowing are required.
78 Quality Assurance
Select a Process for Investigation or Study
When a process is selected for improvement, effort is needed to map, evalu-
ate, and make changes to the process. It is important to select a process that,
if improved, will increase the performance of the service. To do this, brain-
storm a list of processes that you might like to work on. Then, select the rst
one to work on by asking the following questions:
• How much does the process affect the customer?
• Can the process be xed?
• How is the process performing?
• How important is the process to the company’s goals (critical success
factors)?
• What resources are currently available to work on the process?
To be a candidate for study, the process should display one of the following:
• Internal and external customer complaints
• Missed deadlines
• High costs
• Inconsistencies
• Long cycle times
• Information has shown that there is a better way
• New technologies are available
• High incidences of rework
• Low productivity
Select or Identify the Process Owner and Team Members
The process owner and team members are chosen to ensure that the process
will be effective, efcient, under control, and exible. In essence, both the
owner and members must be empowered to take action. It is imperative here
to emphasize that especially the process owner must see the cross-functional
perspective and realize that limited resources do exist in the organization.
Having said this, the process owner must
• Dene the scope of the process
• Select members for the process improvement team
• Ensure members of the team are trained
• Provide feedback to the team about any business changes
• Keep management abreast of progress the improvement team is
making
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.