Chapter 6 Process Analysis

Process—part of an organization = that transforms inputs into outputs. Ex: Tufting, roofing, registration.

Process Analysis usually undertaken to find way= s to improve a process—do it cheaper, faster, better, safer, etc.

Process Chart—flowcharting tool used to decompose and describe a process in a graphical format.

Key terms:

Buffering—storage area between stages/operations in a process. WIP is a good example, as is a waiting line in multi stage service operations.<= o:p>

Blocking—process can’t deli= ver to downstream process because there is nowhere for the output of upstream proc= ess to go.

Starving—Downstream process can&#= 8217;t operate because it has no inputs to work with—starved for something to work with!

Bottleneck—stage of a process, or operation that restricts output.

Parallel verses Sequential operations—parallel take place simultaneously, but a sequence (requires one action, then the ne= xt, then the next, etc. )

Operations can be characterized= as:

Make to stock        =                 Assem= ble to Order (hybrid)        =             &nb= sp;        Make to Order

ß---McDonalds-----------------------Wataburger-------------------------------------TGI Fridays-----à

Stan= dard                    =             &nb= sp;            =             &nb= sp;            =                    =             &nb= sp;            =   Custom

Proc= ess can be Paced or non-paced (paced by humans, or paced by machines).

Paced-- the timing of things is determ= ined (fixed, or reasonably so) by some aspect of the system, like conveyor belt speed, or machine speed, or worker speed.

Steady State—work is entering and exi= ting system at a steady rate (no build up or drawing down of inventory). Example: 100 units in system each day and 1= 00 units out each day.

Measuring Process Performance

We m= easure the process performance to know how it is performing relative to something = (a standard, a goal, a competitor, etc.).&nbs= p; We can do so to see if it needs improvement, or if proposed changes do/will improve the process. = The quality of the output of a proces= s is also a measure of process performance.

Benchmarks—internal or external, often aga= inst best practice. Goal of benchm= arking is to bring about improvement!

Utilization =3D time worked / time availab= le to work

Productivity =3D Output/Input

Efficiency =3D Input / Output   OR output for som= e time period / standard for that time period

Run Time =3D time to produce a batch (a= batch is what we often call a production run)

Setup Time =3D time required to ready equ= ipment , etc. for a batch to be run. (change tooling, settings, materials, etc. to g= et ready to make a batch)

Operation Time =3D Run Time + Setup Time (sometimes setup time is not consi= dered in computing utilization--considered same as maintenance and not added into time worked).

Cycle Time—Elapsed time between sta= rt and completion of a job (a unit produced every 45 seconds, for example).

Throughput time—time unit spends being w= orked on and idle as it passes through the system (sum of individual process component/activity times and all the waiting (idle) time).

        &= nbsp; Throughput time reduction—generally you can reduce throughput time by:

a.     Performing activities in parall= el

b.    Changing the sequence of activi= ties to save time, movement, steps, etc.

c.     Reduce interruptions=

d.    Change Equipment

e.     Change work methods<= /span>

f.      = Eliminate unnecessary activities/steps

Throughput rate – rate at which the syst= em produces output over some time period (so many units per hour, per day, per week, etc.) Mathematical inve= rse of cycle time. (if cycle time is 45 seconds, or .75 minutes, then the throughp= ut per hour would be (60 minutes / .75) or 80 units per hour.

Process Velocity (throughput ratio) =3D total throughput time / value added time &n= bsp; (Note: value added time is t= ime actually spent adding value to the product—idle time would not add va= lue)

Little’s Law—mathematical relationship betwe= en throughput rate, throughput time, and amount of WIP.

Throughput Time =3D WIP / Throu= ghput Rate (if you have any two, you can b= ack into the other)