methods (since test 2)


Terms in this set (...)

time standard tells us:
how long it should take to do a particular operation
measure observed time (OT) is
observed on a stop watch
normal time
OT*rating (workers rating)
the number of workers required cannot accurately be determined unless the time required to process the existing work is known
line balancing
the correct number of workstations for optimal work flow depends on the processing time, or standard, at each work station
materials requirement planning (MRP):
a production planning, scheduling and inventory control system used to manage manufacturing processes
Work measurement feeds into:
time and motion studies, predetermined time studies, and work sampling
Three types of time studies are:
1. stopwatch + performance rating
2. work sampling
3. predetermined time study
What is the platinum standard?
what is the gold standard?
stopwatch and performance rating
Who contributed to the development of time studies?
the Gilbreths (micro motion study - filming an activity to replay and study it)
recall therbligs:
18 types of elementary motions used in the study of motion economy in the workplace
Advantages of PDTS
no stop watches on the floor, no timing is required, eliminates inaccuracies, eliminates need for performance rating, useful in methods design and planning, and calculations are relatively accurate and consistent
disadvantages of PDTS
need trained personnel, judgement is required at various stages still (even though no need for performance rating), can be variability between practitioners
advantages of therbligs:
good way to describe motion details, improves skill of observation in most people, identifies wasted motion, predicts standard times for new or modified jobs
Methods-time measurement:
developed by westinghouse, times are at 100% which eliminates performance rating, specialized training is required
MOST (maynard operation sequence technique)
work measurement technique that concentrates on the movement of objects
measurements for MOST are measured in
standard TMU
1 TMU = 0.036 sec
work definition
displacement of a mass or object
3 types of sequence models
general move, controlled move, tool use
what are the phases of MOST
get, put, return
how to do MOST?
choose the sequence, go through the phases and assign a subscript to each value, add up values, multiply by 10 and multiply by TMU conversion factor
parameters for General move:
action distance (A) - horizontal distance
body motion (B) - vertical distance
Gain control (G)
placement (P)
General move accounts for __% of industrial work
general rules
each activity sequence is fixed, no letter may be added or omitted and index values are fixed, no interpolation, round UP if necessary
controlled move parameters
same as general except:
Move control (M)
process time (X) - machine time
alignment (I)
tool use accounts for __% of manual work
controlled move accounts for __% of manual work
sequence models:
general: ABG ABP A
controlled: ABG MXI A
tool use: ABG ABP * ABP A
conditions for controlled move
1. object is restrained by its attachment to another object (push button, lever, door, crank)
2. object is controlled during the move by the contact with surface of another object (pushing a box across a table)
if you use a tool, use:
tool use equation
if the object doesnt move freely use:
controlled move equation
if the object does move freely use:
general move equation
key words for controlled move:
slide, push, pull, rolls on a conveyer, crank
bend and arise
any type of vertical motion that allows the hands to reach below the knees
bend and arise 50%
vertical motion where your hands never drop below your knees
G3 - heavy or bulky explanation
- high muscle force or hesitation/pause required for muscles to tense
- non simo, blind or obstructed, free interlock/disengage
placement explanations
loose fit: washer on bolt, modest control
place with adjustment: some fumbling, key in a lock
place with care/precision: thread a needle
fingers can count as a:
lean manufacturing
a systematic method for waste minimization (muda) within a manufacturing system without sacrificing productivity
Toyota production system (TPS)
includes a strong focus on eliminating the seven types of muda (waste)
principle 1:
base your management decisions on a long term philosophy, even at the expense of short term financial goals
principle 2:
create a continuous process flow to bring problems to the surface
principle 3:
level out the workload (work like a tortoise not like a hare)
principle 4:
build a culture of stopping to fix problems, to get quality right the first time
futility, uselessness, wastefulness
9 approaches to operational analysis:
1. operational purpose
2. part design
3. tolerances and specifications
4. material
5. operation sequence
6. setup and tools
7. material handling
8. operational layout
9. work design
what question must you always ask?
why are we doing this?
the greatest driver of the cost of making a product is:
the design of the product
before you develop a method ask:
make or buy? (the most efficient process is one we are not doing)
design engineers are not ____ _____
manufacturing engineers
examples of design for manufacture and assembly (DFMA)
minimize part count by incorporating multiple functions into single parts, modularize multiple parts into single subassemblies, assemble in open space not confined space, make parts to identify how to orient them, standardize to reduce part variety
designers tend to incorporate tolerances that are:
more rigid than necessary, to be sure the product will function in all situations (bc they are unaware of cost and unconcerned with cost)
tight tolerance
high production cost and not needed by user
improving tolerances and specifications can
reduce cost due to inspections, scrap, and rework
system functional decomposition -
breaking down a system into its component parts
three D's (in regards to robots)
three H's (in regards to robots)
typical uses for robots:
die casting, forging, painting, welding, material handling
co bots
collaborative work space with robots and people
problems with co bots
run slowly to help safety
cycle time problems
low desire for these
needs a lot of methods engineering applied (in general)
humans excel in _____ over machines
perceiving patterns and making generalization about them, ability to exercise judgement when events cant be completely defined, ability to profit from experience and alter course of action, ability to perform manipulations especially where misalignments appears unexpected
machines excel in ____ over humans
performing routine operations, doing many things at one time, ability to repeat operations rapidly continuously and precisely the same way over a long period
SMED (single minute exchange of dies)
move setup tasks from internal setup to external setup, then reduce the time needed to complete the internal tasks
internal setup -
can only be performed when the machine is down
external setup -
can be performed when the machine is running
poka yoke
a quality management concept developed to prevent human errors from occurring in the production line
the best way to handle material is to:
not handle material
transportation is:
NOT value added
how does production move?
production flows like a river
two types of layout for plants
product layout: machines placed in order used in the manufacturing process
process layout: machines grouped by type (all drill presses together, lathes together, etc)
there is an inverse relationship between:
production variety and product quantity (relationship is also valid for size and complexity)
cellular manufacturing
cellular hybrid system that combines job shop with a continuous flow line
single model production line
little or no specialization
mixed model production line
customization by module change, batching/campaigning
5S system
sort; remove unnecessary items from workplace
set in order: arrange needed items so they are easy to find and use
shine: ensure cleanliness and tidiness
standardize: consistent housekeeping and methods
sustain: maintain
the causes of defects lie in:
worker errors (mistakes will not turn into defects if worker errors are discovered and eliminated beforehand (equipment must be designed to prevent the errors operators may make)
human factor perspective on mistakes
- reduce the work load on working memory
- brings information into the real world
direct labor
"touch" labor
expense labor
office, clerical, accounting, sales, management, engineering
indirect cost
shipping and receiving, trucking, stores, inspection, material handling, tool room, janitorial, maintenance
all indirect and expense work is a combination of four divisions:
direct work, transportation, indirect work, unnecessary work and delays
direct work:
segment of the operation that discernibly advances the progress of the work
work performed in movement during the course of the job from job to job (walk up and down stairs, ride elevators, walk, carry load, push truck, refueling forklift)
what should we look for in an admin flow chart?
waste and inefficiency
clerical/accounting/management processes
direct measurements/improvement: (work sampling etc)
tracking: (clicks per hour, PO/day computer tracking, etc)
morale: big brother is watching you
work standards can be applied to these processes;
equipment service
types of maintenance work
break down
planned work
maintenance work typical problems
inadequate communication
unavailability of parts
improper planning
not unusual to find workforce is productive 30-50% of the time
key performance indicators
hands on wrench time, reliability, planned vs unplanned work, equipment mean time btw failures, etc
direct measurement
work sampling, travel chart/layout
standard data
elemental times obtained from time studies that have been stored for later use (allows development of a job without the use of a stopwatch or PDTS)
advantages of Standard data
cost and time
available ahead of production
disadvantages of standard data
database $
diagram representing relations between 3 or more variable quantities by means of a number of scales. arranged where the value of 1 variable can be found by a simple geometric construction by drawing a straight line intersecting the other scales at the appropriate values
the process of joining two pieces of metal together whether perpendicular or at an angle
butt welding
welding technique used to connect parts which are nearly parallel and dont overlap
how long does it take?
the time it takes to weld depends on the size you need it to be/size you need to weld