Quick Changeover(QCO)

 

Quick-Changeover

Changeover Time:

 Elapsed time between the last good previous product and the first good next product at the right speed.

Changeover

M/C Changeover time = Setup time + Startup time

Setup time

The time to adjust or replace machine parts to accommodate the new product.

Startup time

The time to bring the process up to right speed and quality.

Two key element of Changeover time

1. internal Activities
2. External Activities

Internal Activities

Must be performed while the machine/process is stopped i.e.not making parts.

Example

• Removing work from the machine.
• Removing tools.
• Cleaning down the work surfaces.
• Fixing new tools in place.
• Trial run and adjustment the machine.

External Activities

Can be performed whilst the machine / process is running i.e.
making parts.

Example

•    Getting instructions for the next job
•    Operation chart
•    Layout or Line balance sheet
•    Measurement chart
•    Getting material for the next job from stores
•    Getting tools for the next job from tool stores.
•    Returning tools for the last job to tool stores.

The reason behind excess changeover time (lnternal)

•    Guide adjustment
•    Lopper adjustment
•    Trim adjustment
•    Tension adjustment
•    Knotting or breaking thread
•    Skipped stitches
•    Feed dog height and timing Needle position
•    Presser bar height and pressure

The reason behind excess changeover time (External)

•    Startup time is more because of unavailability of various
•    accessories at that time'
•    Sometimes operator makes delay without any reason'
•    Only the machine operator does the setup operation (if no
•    Problem in setup), no extra man is available to help
•    operator.
•    More time is spent for trial operation and for adjustment till
•    the machines are good enough for production'
•    Amateur mechanics are assigning to solve the problem.

What is SMED (Single Minute Exchange of Dies)

A system designed to radically reduce the amount of
time to perform a changeover or setup

•    SMED should be inexpensive
•    Well planned
•    Well practiced
•    Well executed
•    Without Standard Work, there is no continuous
•    Improvement

Six steps of SMED Methodology

1.    Observed the current changeover process (By video or
2.    time study)
3.    Identify internal and External Activities
4.    Convert activities from internal to External setup
5.    increase efficiency of the remaining internal activities
6.    Optimize the startup time
7.    increase efficiency of external activities

Guideline’s for changeover time reduction (lnternal)

•    Start the setup operation before the day of new style
•    operation.
•    Assign the expert mechanics at the right time to solve the
•    adjustment problem or any machine problem.
•    lmplement parallel operation for quicker setup.
•    Optimi2e the start-up time by eliminating trials and adjustment.
•    Eliminating trials and adjustments is done by making good
settings before the operator startup the machine for new operation.

Guidelines for changeover time reduction(External)

•    Make sure that all accessories are available when it is needed.
•    Make sure that all accessories and equipment's- are arranged
properly in store & maintenance department so all these things
can bring at a right speed without much time spends

Why Quick Changeover

•    Quick changeovers reduce lead time
•    Increase overall velocity
•    Machines only create value when they are
and not sitting idle

Advantage of Quick Changeover

•    Reduction of change-over costs.
•    Trial-runs are minimized
•    Reduction of inventory costs.
•    Reduced work in process(WlP).